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Life table response experiments (LTREs) decompose differences in population growth rate between environments into separate contributions from each underlying demographic rate. However, most LTRE analyses make the unrealistic assumption that the relationships between demographic rates and environmental drivers are linear and independent, which may result in diminished accuracy when these assumptions are violated. We extend regression LTREs to incorporate nonlinear (second‐order) terms and compare the accuracy of both approaches for three previously published demographic datasets. We show that the second‐order approach equals or outperforms the linear approach for all three case studies, even when all of the underlying vital rate functions are linear. Nonlinear vital rate responses to driver changes contributed most to population growth rate responses, but life history changes also made substantial contributions. Our results suggest that moving from linear to second‐order LTRE analyses could improve our understanding of population responses to changing environments. [ABSTRACT FROM AUTHOR]

Large‐scale commercial harvesting and climate‐induced fluctuations in ocean properties shape the dynamics of marine populations as interdependent drivers at varied timescales. Persistent selective removals of larger, older members of a population can distort its demographic structure, eroding resilience to fluctuations in habitat conditions and thus amplifying volatility in transient dynamics. Many historically depleted marine fish stocks have begun showing signs of recovery in recent decades following the implementation of stricter management measures. But these interventions coincide with accelerated changes in the oceans triggered by increasingly warmer, more variable climates. Applying multilevel models to annual estimates of demographic metrics of 38 stocks comprising 11 species across seven northeast Atlantic ecoregions, this study explores how time‐varying local and regional climates contributed to the transient dynamics of recovering populations exposed to variable fishing pressures moderated by management actions. Analyses reveal that progressive reductions in fishing pressure and shifting climate conditions discontinuously shaped rebuilding patterns of the stocks through restorations of maternal demographic structure (reversing age truncation) and reproductive capacity. As the survival rate and demographic structure of reproductive fish improved, transient growth became less sensitive to variability in recruitment and juvenile survival and more to that in adult survival. As the biomass of reproductive fish rose, recruitment success also became increasingly regulated by density‐dependent processes involving higher numbers of older fish. When reductions in fishing pressure were insufficient or delayed, however, stocks became further depleted, with more eroded demographic structures. Although warmer local climates in spawning seasons promoted recruitment success in some ecoregions, changing climates in recent decades began adversely affecting reproductive performances overall, amplifying sensitivities to recruitment variability. These shared patterns underscore the value of demographic transients in developing robust strategies for managing marine resources. Such strategies could form the foundation for effective applications of adaptive measures resilient to future environmental change. [ABSTRACT FROM AUTHOR]

How demographic factors lead to variation or change in growth rates can be investigated using life table response experiments (LTRE) based on structured population models. Traditionally, LTREs focused on decomposing the asymptotic growth rate, but more recently decompositions of annual 'realized' growth rates using 'transient' LTREs have gained in popularity.Transient LTREs have been used particularly to understand how variation in vital rates translate into variation in growth for populations under long‐term study. For these, complete population models may be constructed to investigate how temporal variation in environmental drivers affect vital rates. Such investigations have usually come down to estimating covariate coefficients for the effects of environmental variables on vital rates, but formal ways of assessing how they lead to variation in growth rates have been lacking.We extend transient LTREs to further partition the contributions from vital rates into contributions from temporally varying factors that affect them. The decomposition allows one to compare the resultant effect on the growth rate of different environmental factors, as well as density dependence, which may each act via multiple vital rates. We also show how realized growth rates can be decomposed into separate components from environmental and demographic stochasticity. The latter is typically omitted in LTRE analyses.We illustrate these extensions with an integrated population model (IPM) for data from a 26 years study on northern wheatears (Oenanthe oenanthe), a migratory passerine bird breeding in an agricultural landscape. For this population, consisting of around 50–120 breeding pairs per year, we partition variation in realized growth rates into environmental contributions from temperature, rainfall, population density and unexplained random variation via multiple vital rates, and from demographic stochasticity.The case study suggests that variation in first year survival via the unexplained random component, and adult survival via temperature are two main factors behind environmental variation in growth rates. More than half of the variation in growth rates is suggested to come from demographic stochasticity, demonstrating the importance of this factor for populations of moderate size. [ABSTRACT FROM AUTHOR]

Abstract Matrix population models are frequently built and used by ecologists to analyse demography and elucidate the processes driving population growth or decline. Life Table Response Experiments (LTREs) are comparative analyses that decompose the realized difference or variance in population growth rate (λ) into contributions from the differences or variances in the vital rates (i.e. the matrix elements). Since their introduction, LTREs have been based on approximations and have not included biologically relevant interaction terms. We used the functional analysis of variance framework to derive an exact LTRE method, which calculates the exact response of λ to the difference or variance in a given vital rate, for all interactions among vital rates—including higher‐order interactions neglected by the classical methods. We used the publicly available COMADRE and COMPADRE databases to perform a meta‐analysis comparing the results of exact and classical LTRE methods. We analysed 186 and 1487 LTREs for animal and plant matrix population models, respectively. We found that the classical methods often had small errors, but that very high errors were possible. Overall error was related to the difference or variance in the matrices being analysed, consistent with the Taylor series basis of the classical method. Neglected interaction terms accounted for most of the errors in fixed design LTRE, highlighting the importance of two‐way interaction terms. For random design LTRE, errors in the contribution terms present in both classical and exact methods were comparable to errors due to neglected interaction terms. In most examples we analysed, evaluating exact contributions up to three‐way interaction terms was sufficient for interpreting 90% or more of the difference or variance in λ. Relative error, previously used to evaluate the accuracy of classical LTREs, is not a reliable metric of how closely the classical and exact methods agree. Error compensation between estimated contribution terms and neglected contribution terms can lead to low relative error despite faulty biological interpretation. Trade‐offs or negative covariances among matrix elements can lead to high relative error despite accurate biological interpretation. Exact LTRE provides reliable and accurate biological interpretation, and the R package exactLTRE makes the exact method accessible to ecologists.

Matrix population models are frequently built and used by ecologists to analyse demography and elucidate the processes driving population growth or decline. Life Table Response Experiments (LTREs) are comparative analyses that decompose the realized difference or variance in population growth rate (λ) into contributions from the differences or variances in the vital rates (i.e. the matrix elements). Since their introduction, LTREs have been based on approximations and have not included biologically relevant interaction terms.We used the functional analysis of variance framework to derive an exact LTRE method, which calculates the exact response of λ to the difference or variance in a given vital rate, for all interactions among vital rates—including higher‐order interactions neglected by the classical methods. We used the publicly available COMADRE and COMPADRE databases to perform a meta‐analysis comparing the results of exact and classical LTRE methods. We analysed 186 and 1487 LTREs for animal and plant matrix population models, respectively.We found that the classical methods often had small errors, but that very high errors were possible. Overall error was related to the difference or variance in the matrices being analysed, consistent with the Taylor series basis of the classical method. Neglected interaction terms accounted for most of the errors in fixed design LTRE, highlighting the importance of two‐way interaction terms. For random design LTRE, errors in the contribution terms present in both classical and exact methods were comparable to errors due to neglected interaction terms. In most examples we analysed, evaluating exact contributions up to three‐way interaction terms was sufficient for interpreting 90% or more of the difference or variance in λ.Relative error, previously used to evaluate the accuracy of classical LTREs, is not a reliable metric of how closely the classical and exact methods agree. Error compensation between estimated contribution terms and neglected contribution terms can lead to low relative error despite faulty biological interpretation. Trade‐offs or negative covariances among matrix elements can lead to high relative error despite accurate biological interpretation. Exact LTRE provides reliable and accurate biological interpretation, and the R package exactLTRE makes the exact method accessible to ecologists. [ABSTRACT FROM AUTHOR]

Identifying successful management strategies for long‐lived species is challenging, especially in fluctuating environments, because the response of individual vital rates and overall growth rates to management action can vary over time. A demographic approach that isolates the impact of management and environment on individual vital rates, and assesses their importance for growth rate over time, can indicate whether and why a management strategy is successful.Here we take a demographic approach to assess the success of grazing management for the perennial grass Stipa pulchra, California's state grass and a focus on conservation efforts. We tracked S. pulchra populations in paired grazed and ungrazed plots over 6 years, which included a historic drought and an El Niño rain year, and calculated summary transition matrices for the main effects of year, grazing and year × grazing interaction for each site. We averaged these summary transition matrices to calculate population growth rates, λ, for the main effects of year, grazing and year × grazing and used life table response experiment (LTRE) analysis to compare how individual vital rates contributed to differences in λ between grazed and ungrazed plots over time.Overall we found that grazing was a successful management strategy; grazed populations maintained a positive average population growth rate whereas ungrazed populations declined. We found that grazing had a larger positive effect on growth rates in wet years than drought years. This was because grazed populations benefited from a greater contribution of adult growth immediately following the end of the drought compared with ungrazed populations and from adult survival thereafter.Synthesis and applications. Although Stipa pulchra is the focus of many management efforts, the use of grazing for management is contentious, and there have been few studies that take a demographic approach to understanding S. pulchra responses over time. Our results indicate that conservation and restoration efforts should move beyond recruitment to focus on adult growth and survival for overall population success. To this end, moderate grazing can be a successful strategy to maintain S. pulchra populations and is particularly important in wet years to promote plant growth. [ABSTRACT FROM AUTHOR]

The destinies of epiphytic orchids (about 70% of all orchids) are linked to their host trees. However, there is little information on if differences in host trees characteristics can affect the long-term persistence of orchid populations, and how this might vary under different climatic conditions. We compared the population dynamics of two epiphytic orchid species, Alamania punicea and Oncidium brachyandrum growing on two host trees with contrasting leaf phenologies: the deciduous Quercus martinezii and the semideciduous Q. rugosa, over 3 years with varying levels of rainfall, in a montane tropical oak forest in Oaxaca, Mexico. Using data from > 500 individuals growing on 63 host trees, we applied linear mixed effects models, Integral Projection Models, and Life Table Response Experiments to identify the effects of host tree on orchid vital rates and population growth rates. For both orchid species, survival and growth did not differ between host species during wettest year. However, during the driest year both vital rates were higher on the semi-deciduous host Q. rugosa than on the deciduous Q. martinezii. Host species did not affect fecundity for A. punicea, but for O. brachyandrum fecundity was higher on the deciduous host. For A. punicea, λ values were similar between hosts during the wettest and intermediate years, but significantly lower (Δ λ = 0.28) on the deciduous than on the semi-deciduous host during the driest year. This was due primarily to lower survival on the deciduous host. For O. brachyandrum, λ was slightly higher (Δ λ = 0.03) on the deciduous than the semideciduous host during the wettest year, due to higher growth and reproduction. However, during the intermediate and driest years, λ values were significantly higher on the semi-deciduous than on the deciduous host (Δ λ = 0.13 and 0.15, respectively). This was due to higher survival and growth. A. punicea populations appear more vulnerable to dry conditions than O. brachyandrum, likely due to its smaller pseudobulbs, and hence lower water-storing capacity. Our results show that host tree species can both influence the vital rates and the long-term dynamics of orchid populations, and these effects vary across orchids species and over time. Our results highlight the importance of maintaining a diversity of host trees to ensure long-term population persistence.

Spatially divergent natural selection can drive adaptation to contrasting environments and thus the evolution of ecotypes. In perennial plants, selection shapes life history traits by acting on subsequent life stages, each contributing to fitness. While evidence of adaptation in perennial plants is common, the expression of life history traits is rarely characterized, limiting our understanding of their role in adaptive evolution. We conducted a multi-year reciprocal transplant experiment with seedlings from low and high elevation populations of the alpine carnation Dianthus carthusianorum to test for adaptation linked to contrasting climates and inferred specific contributions of early life stages to fitness. We assessed genotype by environment interactions in single fitness components, applied matrix population models to achieve an integrated estimate of fitness through population growth rates, and performed trade-off analyses to investigate the advantage of alternate life history traits across environments. We found evidence of genotype by environment interactions consistent with elevational adaptation at multiple stages of the early life cycle. Estimates of population growth rates corroborated a strong advantage of the local genotype. Early reproduction and survival are alternate major contributors to adaptation at low and high elevation, respectively, and are linked by trade-offs that underlie the evolution of divergent life history traits across environments. While these traits have a strong genetic basis, foreign populations express co-gradient plasticity, reflecting the adaptive strategy of the local populations. Our study reveals that selection associated to climate has driven the evolution of divergent life histories and the formation of elevational ecotypes. While the high energy environment and strong competition favor investment in early reproduction at low elevation, limiting resources favor a more conservative strategy relying on self-maintenance at high elevation. The co-gradient plasticity expressed by high-elevation populations may facilitate their persistence under warming climatic conditions., Competing Interests: The authors declare no conflicts of interest., (© 2024 The Author(s). Ecology and Evolution published by John Wiley & Sons Ltd.)

European Turtle Doves Streptopelia turtur have experienced a sharp decline in population numbers over past decades. Much uncertainty exists about the main cause or causes. Several pressures have been suggested, but because they affect different stages of the life cycle of the Turtle Dove, it is difficult to compare their contributions to the population decline. Here we applied a full life cycle approach to study how different pressures may have resulted in the decline. This was achieved by combining a review of existing literature on possible threats, pressures and the vital rates they concerned, with the analysis of an age‐structured matrix model. The population model was parameterized using estimates from a mark–recapture analysis and supplemented with vital rate estimates from the literature. Comparison with a Life Table Response Experiment (LTRE) was used to determine whether the Turtle Dove literature focuses on those vital rates in which the most important changes have taken place over time. The population model projected a similar decline to that observed in population counts. The LTRE analysis showed that declines in the number of clutches (halved since the 1960s) and in juvenile survival (relative annual rate of change of –1.33% since the 1950s) contributed most to the decline in the projected population growth rate. Although these vital rates are often reported as possible causes of population decline, the reviewed studies often focused on specific reproductive stages, such as egg survival or nestling survival, which did not show a large temporal change. Thus, there is a partial mismatch between our modelling results and the focus in the literature. Juvenile survival is thought to be affected by hunting, degradation of wintering habitat and infection with Trichomonas gallinae, and loss of foraging habitat seems to affect the number of clutches. The focus of conservation measures should therefore be on these threats and pressures. The first steps have already been taken with the completion of the international single species action plan for the conservation of the Turtle Dove and the implementation of the first conservation measures on the breeding grounds. [ABSTRACT FROM AUTHOR]

Climate and land management are important environmental drivers that affect the structure of terrestrial plant communities worldwide. Demographic studies allow a mechanistic understanding of the pathways in which environmental factors change population size. Climate and land management might interactively influence vital rates and growth rates of populations, however, demographic studies have not heretofore considered both factors in combination. We used the Global Change Experimental Facility as a platform to study the effect of climate (ambient climate conditions vs. future climate conditions) and land management (sheep grazing vs. mowing) on the demography of the common grass, Bromus erectus growing in semi-natural grassland communities. Using an integral projection model, we found positive population growth rates for B. erectus under all treatment combinations, and an interactive effect of climate and land management. Under ambient climate conditions, population growth of B. erectus was higher in mowed than grazed grassland plots, while population growth rates were similar across both management types under future climatic conditions. This interaction was primarily due to between-treatment changes in seedling recruitment, a vital rate to which the population growth rate is particularly sensitive. The interaction found in this study highlights the importance of considering multiple environmental drivers in demographic studies, to better predict future plant population dynamics and ultimately changes in community structure. [ABSTRACT FROM AUTHOR]

Orchids (Orchidaceae) are a family of flowering plants with a high proportion of threatened taxa making them an important focus of plant conservation. Orchid conservation efforts are most effective when informed by reliable demographic research. We utilized transition matrix models to examine the population dynamics and demography within sympatric populations of a species pair of terrestrial round‐leaved orchids, Platanthera macrophylla and P. orbiculata. The models were parameterized from a large data set spanning 9 years from field observations of over 1,000 orchids. Life table response experiments (LTRE) were used to identify which life history transitions, and which vital rates within those transitions, most contributed to observed differences between the two species and most contributed to interannual variation within each species. Results from mean transition matrices projected finite rates of population growth that were not significantly different between the two species, with P. macrophylla near the replacement rate and P. orbiculata below it. LTRE revealed that the difference in population growth rates between the two species was mostly due to differences in fecundity (flowering adult to protocorm transition) driven by differences in fruit set and seed germination into protocorm, which were much greater for P. macrophylla. The two primary contributors to interannual variation in population growth rates for both orchids were adult survival and fruit set, respectively. These findings indicate that any environmental disturbances harming adult survival or fecundity will have a disproportionately negative effect on the orchid populations. [ABSTRACT FROM AUTHOR]

Abstract Climate change has the potential to reduce the abundance and distribution of species and threaten global biodiversity, but it is typically not listed as a threat in classifying species conservation status. This likely occurs because demonstrating climate change as a threat requires data‐intensive demographic information. Moreover, the threat from climate change is often studied in specific biomes, such as polar or arid ones. Other biomes, such as coastal ones, have received little attention, despite being currently exposed to substantial climate change effects. We forecast the effect of climate change on the demography and population size of a federally endangered coastal dune plant (Lupinus tidestromii). We use data from a 14‐yr demographic study across seven extant populations of this endangered plant. Using model selection, we found that survival and fertility measures responded negatively to temperature anomalies. We then produced forecasts based on stochastic individual‐based population models that account for uncertainty in demographic outcomes. Despite large uncertainties, we predict that all populations will decline if temperatures increase by 1°C. Considering the total number of individuals across all seven populations, the most likely outcome is a population decline of 90%. Moreover, we predict extinction is certain for one of our seven populations. These results demonstrate that climate change will profoundly decrease the current and future population growth rates of this plant, and its chance of persistence. Thus, our study provides the first evidence that climate change is an extinction threat for a plant species classified as endangered under the USA Endangered Species Act.

Climate change has the potential to reduce the abundance and distribution of species and threaten global biodiversity, but it is typically not listed as a threat in classifying species conservation status. This likely occurs because demonstrating climate change as a threat requires data‐intensive demographic information. Moreover, the threat from climate change is often studied in specific biomes, such as polar or arid ones. Other biomes, such as coastal ones, have received little attention, despite being currently exposed to substantial climate change effects. We forecast the effect of climate change on the demography and population size of a federally endangered coastal dune plant (Lupinus tidestromii). We use data from a 14‐yr demographic study across seven extant populations of this endangered plant. Using model selection, we found that survival and fertility measures responded negatively to temperature anomalies. We then produced forecasts based on stochastic individual‐based population models that account for uncertainty in demographic outcomes. Despite large uncertainties, we predict that all populations will decline if temperatures increase by 1°C. Considering the total number of individuals across all seven populations, the most likely outcome is a population decline of 90%. Moreover, we predict extinction is certain for one of our seven populations. These results demonstrate that climate change will profoundly decrease the current and future population growth rates of this plant, and its chance of persistence. Thus, our study provides the first evidence that climate change is an extinction threat for a plant species classified as endangered under the USA Endangered Species Act. [ABSTRACT FROM AUTHOR]

Subtropical coral assemblages are threatened by similar extreme thermal stress events to their tropical counterparts. Yet, the mid‐ and long‐term thermal stress responses of corals in subtropical environments remain largely unquantified, limiting our capacity to predict their future viability.The annual survival, growth and recruitment of 311 individual corals within the Solitary Islands Marine Park (Australia) was recorded over a 3‐year period (2016–2018), including the 2015/2016 thermal stress event. These data were used to parameterise integral projection models quantifying the effect of thermal stress within a subtropical coral assemblage. Stochastic simulations were also applied to evaluate the implications of recurrent thermal stress scenarios predicted by four different Representative Concentration Pathways.We report differential shifts in population growth rates (λ) among coral populations during both stress and non‐stress periods, confirming contrasting bleaching responses among taxa. However, even during non‐stress periods, the observed dynamics for all taxa were unable to maintain current community composition, highlighting the need for external recruitment sources to support the community structure.Across all coral taxa, projected stochastic growth rates (λs) were found to be lowest under higher emissions scenarios. Correspondingly, predicted increases in recurrent thermal stress regimes may accelerate the loss of coral coverage, species diversity and structural complexity within subtropical regions.We suggest that these trends are primarily due to the susceptibility of subtropical specialists and endemic species, such as Pocillopora aliciae, to thermal stress. Similarly, the viability of many tropical coral populations at higher latitudes is highly dependent on the persistence of up‐current tropical systems. As such, the inherent dynamics of subtropical coral populations appear unable to support their future persistence under unprecedented thermal disturbance scenarios. [ABSTRACT FROM AUTHOR]

The adult sex ratio (ASR) is important within ecology due to its predicted effects on behaviour, demography and evolution, but research examining the causes and consequences of ASR bias have lagged behind the studies of sex ratios at earlier life stages. Although ungulate ASR is relatively well‐studied, exceptions to the usual female‐biased ASR challenge our understanding of the underlying drivers of biased ASR and provide an opportunity to better understand its consequences.Some feral ungulate populations, including multiple horse populations, exhibit unusually male‐biased ASR. For example, research suggests that the feral horse Equus ferus caballus population on Sable Island, Nova Scotia, Canada may exhibit a male‐biased ASR. Such exceptions to the rule provide a valuable opportunity to reveal the contributions of environmental context and trait differences to ASR bias.We aimed to test for bias in Sable Island horse ASR, identify the demographic drivers of bias, and explore its demographic and social consequences. To do this, we used life history, movement and group membership information for hundreds of horses followed through a long‐term individual‐based study between 2007 and 2018.Sable Island horse ASR is male biased and this skew has increased over time, reaching 62% male in 2018. Our life table response experiment suggested that ASR skew was driven predominantly by male‐biased adult survival. Further analyses pointed to sex‐biased survival being driven by reduced female survival post‐reproduction. Male‐biased ASR was associated with reduced harem sizes, an increase in the number of social groups on the island, and reduced reproduction in young females.Our results support the idea that male‐biased ASR in feral ungulate populations may be caused by a combination of high population density and high reproductive output. We suggest that female‐biased mortality may be caused by females continuing to reproduce at high density, and thus being more susceptible to resource shortages. Thus, our results highlight the strong context dependence of ASR. Furthermore, our work indicates the potential for ASR to substantially alter a population's social organisation. Such changes in social structure could have knock‐on consequences for demography by altering the formation/stability of social relationships, or competition for matings. [ABSTRACT FROM AUTHOR]

Major disturbance events can have large impacts on the demography and dynamics of animal populations. Hurricanes are one example of an extreme climatic event, predicted to increase in frequency due to climate change, and thus expected to be a considerable threat to population viability. However, little is understood about the underlying demographic mechanisms shaping population response following these extreme disturbances. Here, we analyse 45 years of the most comprehensive free-ranging non-human primate demographic dataset to determine the effects of major hurricanes on the variability and maintenance of long-term population fitness. For this, we use individual-level data to build matrix population models and perform perturbation analyses. Despite reductions in population growth rate mediated through reduced fertility, our study reveals a demographic buffering during hurricane years. As long as survival does not decrease, our study shows that hurricanes do not result in detrimental effects at the population level, demonstrating the unbalanced contribution of survival and fertility to population fitness in long-lived animal populations.

Abstract Climate projections forecast more extreme interannual climate variability over time, with an increase in the severity and duration of extreme drought and rainfall events. Based on bioclimatic envelope models, it is projected that changing precipitation patterns will drastically alter the spatial distributions and density of plants and be a primary driver of biodiversity loss. However, many other underlying mechanisms can impact plant vital rates (i.e., survival, growth, and reproduction) and population dynamics. In this study, we developed a size‐dependent integral projection model (IPM) to evaluate how interannual precipitation and mollusk herbivory influence the dynamics of a Hawaii endemic short‐lived shrub, Schiedea obovata (Caryophyllaceae). Assessing how wet season precipitation effects population dynamics it critical, as it is the timeframe when most of the foliar growth occurs, plants flower and fruit, and seedlings establish. Temporal variation in wet season precipitation had a greater effect than mollusk herbivory on S. obovata population growth rate λ, and the impact of interannual precipitation on vital rates shifted across plant ontogeny. Furthermore, wet season precipitation influenced multiple vital rates in contrasting ways and the effect of precipitation on the survival of larger vegetative and reproductively mature individuals contributed the most to variation in the population growth rate. Among all combination of wet season precipitation and herbivory intensities, the only scenario that led to a growing population was when high wet precipitation was associated with low herbivory. Our study highlights the importance of evaluating how abiotic factors and plant–consumer interactions influence an organism across its life cycle to fully understand the underpinning mechanisms that structure its spatial and temporal distribution and abundance. Our results also illustrate that for short‐lived species, like S. obovata, seedling herbivory can have less of an effect on the dynamics of plant populations than decreased interannual precipitation.

Multiple introductions are hypothesized to facilitate the success of invasive plant species, because they can result in novel genotypes through intraspecific hybridization potentially increasing the ability to adapt to the novel environment. In this study, we address the question of how the demography of an invader with multiple introductions and intraspecific hybridization varies across sites. This was done by modeling the population dynamics of Brazilian pepper, Schinus terebinthifolia Raddi (Anacardiaceae), a shrub native to Brazil, Paraguay and Argentina that has invaded the global subtropics and was introduced to Florida on two separate occasions. This species exhibits variability in growth form such that vertical and lateral growth are not strongly associated. Our demographic field work took place at six sites spanning the introduced range in Florida and differing in introduction history. For each site we constructed integral projection models where the probabilities of survival, growth and reproduction were modeled as functions of two different metrics of size, the continuous variables diameter and height, metrics of vertical and lateral growth, respectively. We performed a Life Table Response Experiment analysis to decompose the effects of variation among sites in vital rates on the population dynamics of S. terebinthifolia. We found that spatial variation in population dynamics was driven primarily by site-level differences in the maturation of seedlings into reproductive adults. The survival and growth of the largest individuals had the highest elasticity, suggesting that management actions capable of decreasing these vital rates would have the greatest effect on reducing the population growth rate. [ABSTRACT FROM AUTHOR]

The direct role of non‐native plant invaders in driving negative population‐ and community‐level processes of native species has been recently questioned. Addressing this controversy requires determining quantitatively if invaders negatively affect native population fitness. Because the invasion of non‐natives often coincides with other anthropogenic stressors, experiments that partition the putative impact of non‐natives from other known stressors and assess their potential synergies are required. While many studies have examined the effects of non‐natives on components of native plant performance, studies that decompose the net fitness effects of non‐natives from other anthropogenic stressors on population growth rate are lacking.We used 6 years of detailed demographic data to parameterize a size‐dependent integral projection model to examine the individual and combined effects of an allelochemical‐producing invader (Alliaria petiolata) and an overabundant ungulate herbivore (Odocoileus virginianus) on the population dynamics of an understory perennial (Trillium erectum).We show that Alliaria consistently and negatively affects the population dynamics of Trillium. Specifically, this invader reduces native population growth rate and alters the size distribution of the population at equilibrium. Alliaria also works in concert with the known negative impacts of overabundant white‐tailed deer, illustrating the additive effects of anthropogenic stressors on native plant dynamics.Synthesis. Alliaria's effects on vital rates differed in magnitude and sign across the native's life cycle, highlighting the importance of detailed demographic analyses. Our study provides novel empirical support for the claim that non‐native invasive species can significantly and directly reduce the fitness of native plants. [ABSTRACT FROM AUTHOR]

Plant population dynamics is fundamental to identify which parts of the life cycle are important when designing management actions. In this study, the short-term population dynamics of Helianthemum caput-felis (Cistaceae), a perennial plant distributed throughout the western Mediterranean Basin, was investigated by monitoring 98 permanent plots randomly placed along the overall distribution range for three years (2013-2015). Demographic surveys were analysed by Integral Projection Models (IPMs), and the analysis of population growth rates, elasticities, and life table response experiment (LTRE) analyses were performed. Under deterministic conditions, the H. caput-felis population showed a slight increase in the first censuses, but a general population decline followed. This trend was probably due to the shrinkage of plants in the last year, which correlated negatively with reproductive traits. Despite this decline, the population was at equilibrium under the simulated environmental stochasticity. The population dynamics of H. caput-felis followed the general pattern typical for long-lived Mediterranean plants: populations with growth rates closer to the equilibrium in the long term, determinant role of the survival-growth transitions for the population growth rate, slow growth and stasis, longevity of established individuals, shrinkage of medium-large plants, low recruitment rate, high generation times and mean long lifespans. The results of this study, which highlight how conservation measures can be focused on protecting and increasing the number of plants of medium-large size, provide important information for the planning management conservation actions for H. caput-felis and for several Mediterranean plants that show a similar life-history strategy. [ABSTRACT FROM AUTHOR]

Population dynamics are the result of an interplay between extrinsic and intrinsic environmental drivers. Predicting the effects of environmental change on wildlife populations therefore requires a thorough understanding of the mechanisms through which different environmental drivers interact to generate changes in population size and structure.In this study, we disentangled the roles of temperature, food availability and population density in shaping short‐ and long‐term population dynamics of the African striped mouse, a small rodent inhabiting a semidesert with high intra‐ and interannual variation in environmental conditions.We parameterized a female‐only stage‐structured matrix population model with vital rates depending on temperature, food availability and population density, using monthly mark–recapture data from 1609 mice trapped over 9 years (2005–2014). We then applied perturbation analyses to determine relative strengths and demographic pathways of these drivers in affecting population dynamics. Furthermore, we used stochastic population projections to gain insights into how three different climate change scenarios might affect size, structure and persistence of this population.We identified food availability, acting through reproduction, as the main driver of changes in both short‐ and long‐term population dynamics. This mechanism was mediated by strong density feedbacks, which stabilized the population after high peaks and allowed it to recover from detrimental crashes. Density dependence thus buffered the population against environmental change, and even adverse climate change scenarios were predicted to have little effect on population persistence (extinction risk over 100 years <5%) despite leading to overall lower abundances.Explicitly linking environment–demography relationships to population dynamics allowed us to accurately capture past population dynamics. It further enabled establishing the roles and relative importances of extrinsic and intrinsic environmental drivers, and we conclude that doing this is essential when investigating impacts of climate change on wildlife populations. Small mammal populations are sensitive to their environment and strongly regulated by density. Using state‐of‐the‐art demographic models, the authors show not only that population dynamics of a semidesert rodent are buffered against environmental change by strong density feedbacks, but quantify through which demographic pathways this regulation works. [ABSTRACT FROM AUTHOR]

Abstract: Classical biological control has been a key technology in the management of invasive arthropod pests globally for over 120 years, yet rigorous quantitative evaluations of programme success or failure are rare. Here, I used life table and matrix model analyses, and life table response experiments to quantitatively assess a classical biological control programme for an invasive insect pest in the western United States. Life tables and matrix models were developed for populations of Bemisia tabaci (sweetpotato whitefly) on cotton in Arizona before (1997–1999) and after (2001–2010) the permanent establishment of two exotic aphelinid parasitoids. Analyses tested multiple hypotheses relative to the expected outcome of a successful programme. Marginal rates of parasitism, rates of irreplaceable mortality from parasitism, total generational mortality and finite population growth (λ) were unchanged for B. tabaci populations before and after exotic parasitoid establishment. Prospective analyses showed that predation during the final nymphal stadium had the greatest influence on population growth rates regardless of parasitoid establishment. Retrospective LTREs showed that predation and unknown mortality contributed most to changes in λ after parasitoid establishment. Marginal parasitism acted weakly in a direct density dependence fashion after parasitoid establishment, and for all 14 years combined. However, this did not translate into an association between pest population density and marginal rates of parasitism for the 10‐year period following establishment. Synthesis and applications. Rarely are classical biological control programme outcomes assessed rigorously. Life tables, matrix models, and life table response experiments showed that the decline in the pest status of Bemisia tabaci (sweetpotato whitefly) was not associated with the establishment of two exotic parasitoid species in the cotton system. Instead, native arthropod predators play a major role in pest dynamics. Further efforts to enhance conservation of the extant natural enemy community, with focus on increasing mortality in final stage nymphs and adults, may be the most efficient means of increasing biological control services. Analyses deployed here should be more widely applied to assessing and improving biological control generally. [ABSTRACT FROM AUTHOR]

Species' geographic ranges and climatic niches are likely to be increasingly mismatched due to rapid climate change. If a species' range and niche are out of equilibrium, then population performance should decrease from high-latitude "leading" range edges, where populations are expanding into recently ameliorated habitats, to low-latitude "trailing" range edges, where populations are contracting from newly unsuitable areas. Demographic compensation is a phenomenon whereby declines in some vital rates are offset by increases in others across time or space. In theory, demographic compensation could increase the range of environments over which populations can succeed and forestall range contraction at trailing edges. An outstanding question is whether range limits and range contractions reflect inadequate demographic compensation across environmental gradients, causing population declines at range edges. We collected demographic data from 32 populations of the scarlet monkeyflower (Erythranthe cardinalis) spanning 11° of latitude in western North America and used integral projection models to evaluate population dynamics and assess demographic compensation across the species' range. During the 5-y study period, which includedmultiple years of severe drought and warming, population growth rates decreased from north to south, consistent with leading-trailing dynamics. Southern populations at the trailing range edge declined due to reduced survival, growth, and recruitment, despite compensatory increases in reproduction and faster life-history characteristics. These results suggest that demographic compensation may only delay population collapse without the return of more favorable conditions or the contribution of other buffering mechanisms such as evolutionary rescue. [ABSTRACT FROM AUTHOR]

Abstract: Effective reintroduction strategies require accurate estimates of vital rates and the factors that influence them. The hirola (Beatragus hunteri) is the rarest antelope on Earth, with a global population size of <500 individuals restricted to the Kenya–Somali border. We estimated vital rates of hirola populations exposed to varying levels of predation and rangeland quality from 2012 to 2015, and then built population matrices to estimate the finite rate of population change (λ) and demographic sensitivities. Mean survival for all age classes and population growth was highest in the low‐predation–high‐rangeland‐quality setting (λ = 1.08 ± 0.03 [mean ± SE]), and lowest in the high‐predation–low‐rangeland‐quality setting (λ = 0.70 ± 0.22). Retrospective demographic analyses revealed that increased fecundity (the number of female calves born to adult females annually) and female calf survival were responsible for higher population growth where large carnivores were absent. In contrast, variation in adult female survival was the primary contributor to differences in population growth attributable to rangeland quality. Our analyses suggest that hirola demography is driven by a combination of top‐down (predation) and bottom‐up (rangeland quality) forces, with populations in the contemporary geographic range impacted both by declining rangeland quality and predation. To enhance the chances of successful reintroductions, conservationists can consider rangeland restoration to boost both the survival and fecundity of adult females within the hirola's historical range. [ABSTRACT FROM AUTHOR]

Climate projections forecast more extreme interannual climate variability over time, with an increase in the severity and duration of extreme drought and rainfall events. Based on bioclimatic envelope models, it is projected that changing precipitation patterns will drastically alter the spatial distributions and density of plants and be a primary driver of biodiversity loss. However, many other underlying mechanisms can impact plant vital rates (i.e., survival, growth, and reproduction) and population dynamics. In this study, we developed a size-dependent integral projection model ( IPM) to evaluate how interannual precipitation and mollusk herbivory influence the dynamics of a Hawaii endemic short-lived shrub, Schiedea obovata (Caryophyllaceae). Assessing how wet season precipitation effects population dynamics it critical, as it is the timeframe when most of the foliar growth occurs, plants flower and fruit, and seedlings establish. Temporal variation in wet season precipitation had a greater effect than mollusk herbivory on S. obovata population growth rate [ABSTRACT FROM AUTHOR]

Lychnophora ericoides Mart. (Asteraceae), popularly known as arnica, is a plant species subjected to non-timber forest products extraction. Evidence is mounting that some local populations are on the brink of extinction. However, demographic studies of Lychnophora ericoides are rare. Therefore, as a step towards conservation, a remnant population of Lychnophora ericoides located in an area of the Cerrado (Brazilian Savanna) in Central Brazil was evaluated from 2010 through 2014. Disturbances such as wildfires and harvesting of Lychnophora ericoides were randomly distributed throughout the study period in this area. Four annual transition matrices (A1, A2, A3 and A4) were constructed, based on life stages. The main results of studies of population dynamics for this species are as follows: 1) population growth rates (λ) with 95% confidence intervals indicated a declining population in all periods from 2010 to 2014; 2) stochastic population growth rate considering the four matrices was < 1 with value λ = 0.358 and CI95% = (0.354–0.362); 3) survival with permanence at the same stage of reproductive adult individuals (46–80%) contributed most to population growth rate, based on elasticity analysis; 4) the population is much less likely to have increases in density, compared with reduction, for all intervals from 2010 to 2014, based on transient indices; 5) the low value of λ in the high-mortality year was caused by lower stasis of individuals in the seedling or sapling and juvenile life stages, as well as fecundity in the 2011–2012 and 2012–2013 intervals, as shown by a life table response experiment; and 6) 100% of the population will probably be extinct within 15 years. There is evidence that the main cause for local extinction of Lychnophora ericoides could be the effects of frequent wildfires. Based on these results, it is suggested that the time has come for significant conservation efforts to rescue this population, including monitoring, protection and education as the first steps towards protection of this vulnerable plant species. [ABSTRACT FROM AUTHOR]

Background: As global climate change transforms average temperature and rainfall, species distributions may meet, increasing the potential for hybridization and altering individual fitness and population growth. Altered rainfall specifically may shift the strength and direction of selection, also manipulating population trajectories. Here, we investigated the role of interspecific hybridization and selection imposed by rainfall on the evolution of weedy life-history in non-hybrid (Raphanus raphanistrum) and hybrid (R. raphanistrum x R. sativus) populations using a life table response experiment. Results: In documenting long-term population dynamics, we determined intrinsic (r) and asymptotic (λ) population growth rates and sensitivities, a measure of selection imposed on demographic rates. Hybrid populations experienced 8.7-10.3 times stronger selection than wild populations for increased seedling survival. Whereas crop populations generally exhibit little dormancy and wild populations often exhibit dormancy, non-hybrid populations experienced 10% stronger selection than hybrid populations for exhibiting seed dormancy. Selection on survival-to-flowering in wild, not hybrid, populations declined marginally with increasing soil moisture. Hybrid populations exhibited greater r, but not λ, than wild populations regardless of moisture environment. In general, fecundity contributed most to differences in λ but fecundity only contributed positively to hybrid λ relative to wild λ when precipitation was altered (either higher or lower than control) and not under control watering conditions. Conclusions: Selection on key demographic traits may not change dramatically in response to rainfall, and hybridization may more strongly influence the demography of these weedy species than rainfall. If hybrid populations can respond to selection for increased dormancy, this may make it more difficult to deplete weed seed banks and increase the persistence of crop genes in weed populations. [ABSTRACT FROM AUTHOR]

Vascular epiphytes constitute up to 25% of tropical plant diversity and play an important role in providing food, water, and shelter to many organisms. However, the factors that drive their population dynamics, including the influence of their host plants (phorophytes) and of climatic factors, are still poorly understood. We provide the first test of whether host tree genus can affect population dynamics of an epiphytic species, and assess the interactive effects of host tree and rainfall. We carried out a five-year study of the demography of >1000 plants of the endemic bromeliad, Tillandsia macdougallii L. B. Sm, growing on pine and oak trees in a Mexican montane forest. We tested for differences in vital rates and used integral projection models to test whether these scaled up to differences in long-term population growth rates between the two host genera and as a function of rainfall. T. macdougallii survival and growth were higher on pines than on oaks for larger plants but not for seedlings. The probability of producing capsules was higher for T. macdougallii on oaks than on pines. Increasing dry season rainfall was significantly correlated with increased survival of individuals, but not of ramets, growing on both oaks and pines. The probability of clonal reproduction increased significantly with increasing dry season rainfall for T. macdougallii growing on oaks, but not on pines. Projected long-term population growth rates, λ, for T. macdougallii on pines were higher than on oaks. Lambda increased steeply as a function of dry season rainfall for T. macdougallii populations on both host tree genera, but the increase was steeper for populations on oaks, likely because the former are deciduous. Our results show that host tree genus can affect the long-term dynamics of epiphyte populations and suggest that these effects may depend on rainfall. The high sensitivity of this species to changes in dry season rainfall suggests that a better understanding of how rainfall may drive vascular epiphyte populations will be critical for understanding the effects of climate change on species persistence. [ABSTRACT FROM AUTHOR]

Abstract Understanding the impact of herbivory on plant populations is a fundamental goal of ecology. Damage to individual plants can be visually striking and affect the fates of individuals, but these impacts do not necessarily translate into population‐level differences in vital rates (survival, growth, or fecundity) or population growth rates. In biological control of weeds, quantitative assessments of population‐level impacts of released agents on both target invasive plants and native, nontarget plants are needed to inform evaluations of the benefits and risks of releasing agents into new regions. Here we present a 3‐yr experimental demographic field study using the European root‐feeding biocontrol weevil, Mogulones crucifer, first released in Canada in 1997 to control the invasive weed Cynoglossum officinale (Boraginaceae). Mogulones crucifer is an effective “search and destroy” agent in Canada, but sporadically feeds, oviposits, and develops on native nontarget Boraginaceae. We investigated the population‐level impacts of this biocontrol insect on its target weed and a native nontarget plant, Hackelia micrantha (Boraginaceae), by releasing large numbers of weevils into naturally occurring patches of H. micrantha growing isolated from or interspersed with C. officinale. We followed the fates of individual plants on release and nonrelease (control) sites for two transition years, developed matrix models to project population growth rates (λ) for each plant species, and examined the contributions from differences in vital rates to changes in λ using life table response experiments (LTRE). In contrast to studies of the insect–plant interaction in its native range, as a biocontrol agent, M. crucifer increased mortality of C. officinale rosettes in the year immediately following release, depressing the weed's λ to below the population replacement level. However, λ for H. micrantha was never depressed below the replacement level, and any differences between release and nonrelease sites in the nontarget could not be explained by significant contributions from vital rates in the LTRE. This study is the first to simultaneously and experimentally examine target and nontarget population‐level impacts of a weed biocontrol insect in the field, and supports the theoretical prediction that plant life history characteristics and uneven herbivore host preferences can interact to produce differences in population‐level impacts between target and nontarget plant species.

Abstract Species conservation efforts often use short‐term studies that fail to identify the vital rates that contribute most to population growth. Although the greater sage‐grouse (Centrocercus urophasianus; sage‐grouse) is a candidate for protection under the U.S. Endangered Species Act, and is sometimes referred to as an umbrella species in the sagebrush (Artemisia spp.) biome of western North America, the failure of proposed management strategies to focus on key vital rates that may contribute most to achieving population stability remains problematic for sustainable conservation. To address this dilemma, we performed both prospective and retrospective perturbation analyses of a life cycle model based on a 12‐yr study that encompassed nearly all sage‐grouse vital rates. To validate our population models, we compared estimates of annual finite population growth rates (λ) from our female‐based life cycle models to those attained from male‐based lek counts. Post‐fledging (i.e., after second year, second year, and juvenile) female survival parameters contributed most to past variation in λ during our study and had the greatest potential to change λ in the future, indicating these vital rates as important determinants of sage‐grouse population dynamics. In addition, annual estimates of λ from female‐based life cycle models and male‐based lek data were similar, providing the most rigorous evidence to date that lek counts of males can serve as a valid index of sage‐grouse population change. Our comparison of fixed and mixed statistical models for evaluating temporal variation in nest survival and initiation suggest that conservation planners use caution when evaluating short‐term nesting studies and using associated fixed‐effect results to develop conservation objectives. In addition, our findings indicated that greater attention should be paid to those factors affecting sage‐grouse post‐fledging females. Our approach demonstrates the need for more long‐term studies of species vital rates across the life cycle. Such studies should address the decoupling of sampling variation from underlying process (co)variation in vital rates, identification of how such variation drives population dynamics, and how decision makers can use this information to re‐direct conservation efforts to address the most limiting points in the life cycle for a given population.

Background: Selective logging alters tree growth, mortality and recruitment, and the subsequent population dynamics of trees. However, little information is available on how tree populations reduce local extinction in logged forests. Aims: We evaluated the effects of selective logging on tree performance and population dynamics of five dominant dipterocarp species in the Pasoh Forest Reserve, Malaysia. Methods: We used demographic data derived from a forest that was selectively logged in 1958 as well as those from an unlogged primary forest and constructed population transition matrix models to project the population dynamics. Results: The dipterocarp species studied showed minor differences in mortality and diameter growth, but there was a large difference in recruitment between logged and unlogged forest; populations in the logged forest had 10 times slower recruitment rates into the smallest size class than those in the primary forest. Population size structures differed between the two forest types but, despite a large difference in the recruitment rates, there were only minor differences in both asymptotic- and matrix-projected population growth rates. Conclusions: A single selective logging event had only minor impacts on the growth rates of dipterocarp trees in the Pasoh forest. But at the same time it had a large impact on the size structure of the dipterocarp populations through a reduction in recruitment showing that the impacts of selective logging are still seen on dipterocarp population after 50 years. [ABSTRACT FROM PUBLISHER]

Fitness trade-offs between environments are central to the evolution of biodiversity. Although transplant studies often document fitness trade-offs consistent with local adaptation (LA), many have also found an advantage of foreign genotypes (foreign advantage (FA)). Understanding the mechanisms driving the magnitude and distribution of fitness variation requires comparative approaches that test the ecological scales at which these different patterns emerge., We used a common garden transplant experiment to compare the relative fitnesses of native vs foreign genotypes at three nested ecological scales within Mimulus guttatus: annual vs perennial life history races, perennial ecotypes across an elevational range, and populations within perennial elevational ecotypes. We integrated fitness across the life-cycle and decomposed LA vs FA into contributions from different fitness components., We found LA, measured as home-site advantage, between annual and perennial races and a trend towards LA among populations within montane habitats. Conversely, we found strong FA of low-elevation perennials in a montane environment., LA between life history races reflects the fitness advantages of adult survival and vegetative growth in a mesic environment. Within the perennial race, recent climate conditions or nonselective processes, such as dispersal limitation or mutational load, could explain FA of low-elevation perennials in a montane environment. [ABSTRACT FROM AUTHOR]

Gene flow in crop-wild complexes between phenotypically differentiated ancestors may transfer adaptive genetic variation that alters the fecundity and, potentially, the population growth ( λ) of weeds. We created biotypes with potentially invasive traits, early flowering or long leaves, in wild radish ( Raphanus raphanistrum) and F5 crop-wild hybrid ( R. sativus × R. raphanistrum) backgrounds and compared them to randomly mated populations, to provide the first experimental estimate of long-term fitness consequences of weedy life-history variation. Using a life table response experiment design, we modeled λ of experimental, field populations in Pellston, MI, and assessed the relative success of alternative weed strategies and the contributions of individual vital rates (germination, survival, seed production) to differences in λ among experimental populations. Growth rates ( λ) were most influenced by seed production, a trait altered by hybridization and selection, compared to other vital rates. More seeds were produced by wild than hybrid populations and by long-leafed than early-flowering lineages. Although we did not detect a biotype by selection treatment effect on lambda, lineages also exhibited contrasting germination and survival strategies. Identifying life-history traits affecting population growth contributes to our understanding of which portions of the crop genome are most likely to introgress into weed populations. [ABSTRACT FROM AUTHOR]

One of the most important current challenges for ecologists is to evaluate how human-induced changes in ecosystems would impact viability of populations. Demographic response to anthropogenic impact could help us to understand how to manage those impacts. Using demographic techniques and population projection models, here we assess if demography and population dynamics of the tree Prosopis flexuosa change in cattle grazed areas compared to ungrazed areas in the Central Monte desert, Mendoza, Argentina. To this end, we quantified vital rates and constructed a population projection matrix model to compare the deterministic population growth rate ( λ ) between grazed and ungrazed areas. We also estimated elasticities of vital rates to evaluate their potential importance for future changes in λ and performed a life table response experiment (LTRE) to identify the life cycle transitions that contribute the most to the observed differences in λ between the two treatments. Although we found differences in demographic processes, such as lower seed production and higher probability of reversion to smaller size classes in young individuals when cattle were present, our results indicate that cattle grazing had no significant effect on λ for this species. According to the elasticity analysis, survival of large trees is the main driver of the population growth rate ( λ ) of P. flexuosa , and the vital rates related to tree reproduction, such as seed production and germination, have a poor contribution to λ . Therefore, limitations of activities that can affect survival of large trees should be considered as part of the conservation strategy for this species. Our study provides a compilation of demographic information that can be useful to set policies connecting the conservation objectives for this woodlands with that of ranch managers of the area. [ABSTRACT FROM AUTHOR]

Understanding the impact of herbivory on plant populations is a fundamental goal of ecology. Damage to individual plants can be visually striking and affect the fates of individuals, but these impacts do not necessarily translate into population-level differences in vital rates (survival, growth, or fecundity) or population growth rates. In biological control of weeds, quantitative assessments of population-level impacts of released agents on both target invasive plants and native, nontarget plants are needed to inform evaluations of the benefits and risks of releasing agents into new regions. Here we present a 3-yr experimental demographic field study using the European root-feeding biocontrol weevil, Mogulones crucifer, first released in Canada in 1997 to control the invasive weed Cynoglossum officinale (Boraginaceae). Mogulones crucifer is an effective 'search and destroy' agent in Canada, but sporadically feeds, oviposits, and develops on native nontarget Boraginaceae. We investigated the population-level impacts of this biocontrol insect on its target weed and a native nontarget plant, Hackelia micrantha (Boraginaceae), by releasing large numbers of weevils into naturally occurring patches of H. micrantha growing isolated from or interspersed with C. officinale. We followed the fates of individual plants on release and nonrelease (control) sites for two transition years, developed matrix models to project population growth rates (λ) for each plant species, and examined the contributions from differences in vital rates to changes in λ using life table response experiments ( LTRE). In contrast to studies of the insect-plant interaction in its native range, as a biocontrol agent, M. crucifer increased mortality of C. officinale rosettes in the year immediately following release, depressing the weed's λ to below the population replacement level. However, λ for H. micrantha was never depressed below the replacement level, and any differences between release and nonrelease sites in the nontarget could not be explained by significant contributions from vital rates in the LTRE. This study is the first to simultaneously and experimentally examine target and nontarget population-level impacts of a weed biocontrol insect in the field, and supports the theoretical prediction that plant life history characteristics and uneven herbivore host preferences can interact to produce differences in population-level impacts between target and nontarget plant species. [ABSTRACT FROM AUTHOR]

Species conservation efforts often use short‐term studies that fail to identify the vital rates that contribute most to population growth. Although the greater sage‐grouse (Centrocercus urophasianus; sage‐grouse) is a candidate for protection under the U.S. Endangered Species Act, and is sometimes referred to as an umbrella species in the sagebrush (Artemisia spp.) biome of western North America, the failure of proposed management strategies to focus on key vital rates that may contribute most to achieving population stability remains problematic for sustainable conservation. To address this dilemma, we performed both prospective and retrospective perturbation analyses of a life cycle model based on a 12‐yr study that encompassed nearly all sage‐grouse vital rates. To validate our population models, we compared estimates of annual finite population growth rates (λ) from our female‐based life cycle models to those attained from male‐based lek counts. Post‐fledging (i.e., after second year, second year, and juvenile) female survival parameters contributed most to past variation in λ during our study and had the greatest potential to change λ in the future, indicating these vital rates as important determinants of sage‐grouse population dynamics. In addition, annual estimates of λ from female‐based life cycle models and male‐based lek data were similar, providing the most rigorous evidence to date that lek counts of males can serve as a valid index of sage‐grouse population change. Our comparison of fixed and mixed statistical models for evaluating temporal variation in nest survival and initiation suggest that conservation planners use caution when evaluating short‐term nesting studies and using associated fixed‐effect results to develop conservation objectives. In addition, our findings indicated that greater attention should be paid to those factors affecting sage‐grouse post‐fledging females. Our approach demonstrates the need for more long‐term studies of species vital rates across the life cycle. Such studies should address the decoupling of sampling variation from underlying process (co)variation in vital rates, identification of how such variation drives population dynamics, and how decision makers can use this information to re‐direct conservation efforts to address the most limiting points in the life cycle for a given population. [ABSTRACT FROM AUTHOR]

Key message: Sprouting is a key component of the population dynamics of woody species. Regeneration via sprouting contributes substantially to population growth when resource availability varies. Abstract: Basal sprouting is an important trait that facilitates the persistence of woody species under different environmental conditions. Environmental heterogeneity can have variable effects on allocation to sexual reproduction and vegetative growth over an individual's ontogeny; consequently, environmental heterogeneity can influence the dynamics of woody plant populations. However, the effects of environmental factors on the ramet and genet dynamics of woody species have yet to be fully explored. This study investigated the population dynamics of Curatella americana L. (Dilleniaceae), an abundant tree species with a wide geographic distribution. The following hypotheses were tested: (1) density, vital rates and population growth rate are constrained by low rainfall and low soil fertility and (2) ramet production contributes more than seedling production to population growth at low rainfall levels and low soil fertility. Population dynamics were evaluated at two soil types (low and high fertility) over 3 years (2010, 2011 and 2012) with varying rainfall levels (average, average and low rainfall levels, respectively). Both hypotheses were supported. Vegetative growth and the population growth rate were limited by low rainfall and low soil fertility. The survival rates of adults and immature ramets had the largest effect on population growth. Although sprouting was limited by resource availability, this regeneration mode contributed more than seedlings to population growth. Basal sprouting not only ensures species persistence but also, as indicated by these results, permits a species to tolerate a lack of seedling recruitment. Basal sprouting was, therefore, determined to play an important role in the population growth of woody species in heterogeneous environments. [ABSTRACT FROM AUTHOR]

Tetanus was a major cause of mortality in the free-ranging population of rhesus monkeys on Cayo Santiago prior to 1985 when the entire colony was given its first dose of tetanus toxoid. The immediate reduction in mortality that followed tetanus toxoid inoculation (TTI) has been documented, but the long-term demographic effects of eliminating tetanus infections have not. This study uses the Cayo Santiago demographic database to construct comparative life tables 12 years before, and 12 years after, TTI. Life tables and matrix projection models are used to test for differences in: (i) survival among all individuals as well as among social groups, (ii) long-term fitness of the population, (iii) age distribution, (iv) reproductive value, and (v) life expectancy. A retrospective life table response experiment (LTRE) was performed to determine which life cycle transition contributed most to observed changes in long-term fitness of the population post-TTI. Elimination of clinical tetanus infections through mass inoculation improved the health and well-being of the monkeys. It also profoundly affected the population by increasing survivorship and long-term fitness, decreasing the differences in survival rates among social groups, shifting the population's age distribution towards older individuals, and increasing reproductive value and life expectancy. These findings are significant because they demonstrate the long-term effects of eradicating a major cause of mortality at a single point in time on survival, reproduction, and overall demography of a naturalistic population of primates. Am. J. Primatol. 77:211-221, 2015. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Dynamics of populations may be synchronized at large spatial scales, indicating driving forces acting beyond local scales, but may also vary locally as a result of site-specific conditions. Conservation measures for fragmented and declining populations may need to address such local effects to avoid local extinction before measures at large spatial scales become effective. To assess differences in local population dynamics, we aimed to determine the demographic drivers controlling population trends in three remaining populations of the Northern Wheatear Oenanthe oenanthe in the Netherlands, as a basis for conservation actions. An integrated population model ( IPM) was fitted to field data collected in each site in 2007-2011 to estimate fecundity, survival and immigration. Sites were 40-120 km apart, yet first-year recruits were observed to move between some of the sites, albeit rarely. All three populations were equally sensitive to changes in fecundity and first-year survival. One population was less sensitive to adult survival but more sensitive to immigration. A life table response experiment suggested that differences in immigration were important determinants of differences in population growth between sites. Given the importance of immigration for local dynamics along with high philopatry, resulting in low exchange between sites, creating a metapopulation structure by improving connectivity and the protection of local populations are important for the conservation of these populations. Site-specific conservation actions will therefore be efficient and, for the short term, we propose different site-specific conservation actions. [ABSTRACT FROM AUTHOR]

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A major goal in ecology is to understand mechanisms that increase invasion success of exotic species. A recent hypothesis implicates altered species interactions resulting from ungulate herbivore overabundance as a key cause of exotic plant domination. To test this hypothesis, we maintained an experimental demography deer exclusion study for 6 y in a forest where the native ungulate Odocoileus virginianus (white-tailed deer) is overabundant and Alliaria petiolata (garlic mustard) is aggressively invading. Because population growth is multiplicative across time, we introduce metrics that correctly integrate experimental effects across treatment years, the cumulative population growth rate, λc, and its geometric mean, λper-year, the time-averaged annual population growth rate. We determined λc and λper-year of the invader and of a common native, Trillium erectum. Our results conclusively demonstrate that deer are required for the success of Alliaria; its projected population trajectory shifted from explosive growth in the presence of deer (λper-year = 1.33) to decline toward extinction where deer are excluded (λper-year = 0.88). In contrast, Trillium's λper-year was suppressed in the presence of deer relative to deer exclusion (λper-year = 1.04 vs. 1.20, respectively). Retrospective sensitivity analyses revealed that the largest negative effect of deer exclusion on Alliaria came from rosette transitions, whereas the largest positive effect on Trillium came from reproductive transitions. Deer exclusion lowered Alliaria density while increasing Trillium density. Our results provide definitive experimental support that interactions with overabundant ungulates enhance demographic success of invaders and depress natives' success, with broad implications for biodiversity and ecosystem function worldwide. [ABSTRACT FROM AUTHOR]

Population growth rates ( λ) of the riparian tree Aesculus turbinata varied from 0.9988 to 1.0524 spatiotemporally. We conducted a series of pair-wise demographic and matrix analyses, including randomization tests, three types of life table response experiments (LTREs), analysis of variance and χ tests, to test which life stages had the greatest effect on this variation in λ. Randomization tests detected significant variations in λ between plots affected or not by typhoons in three habitats and between periods with high and low recruitment in one habitat. Mixed-level LTREs identified that the demographic processes and life stages that had the strongest effect on the actual variation in λ were: (1) progressions of small and intermediate juveniles and (2) founding process from seeds to 1-year-old seedlings. These juvenile stages had medium sensitivities and variances that explained high upper-level LTRE contributions. Lower-level LTREs showed that the vital rates contributing the most were the growth rates of these juvenile stages. These findings demonstrate that progression from one stage to the next, growth rates of 1-year-old seedlings, and stunted aging juveniles are the most important stages in the population dynamics of this long-lived primary tree species. Transition matrix elements with high elasticities had little effect on the variation in λ, indicating that high-elasticity vital rates do not necessarily drive variation in population growth. As compared with the results of randomization tests, significant differences in vital rates examined using ANOVA or χ tests showed that typhoon disturbance had the greatest effect on the demographic parameters of individual trees. [ABSTRACT FROM AUTHOR]

Pharmaceutical and personal care products (PPCPs), some of which have endocrine-disrupting effects at environmentally relevant concentrations, have been detected in many surface waters. The authors evaluated the effects of 2 common endocrine disrupting PPCPs on the life history traits of the snail, Physa pomilia, using a life table response experiment with snails raised in environmentally relevant concentrations of 17α-ethynylestradiol (EE2), fluoxetine, or their mixture. Exposure to fluoxetine or the mixture reduced snail reproduction, but EE2 did not. Generally, individual life history traits were affected minimally by the PPCPs, but when integrated using a demographic model, all 3 chemical exposure scenarios decreased population growth rates, with the EE2 and fluoxetine mixture causing the most adverse effects. Overall, the results provide additional insight into the effects of PPCPs on freshwater invertebrates and point to the importance of testing simultaneous exposures to multiple PPCPs. In addition, using a demographic model to integrate individual endpoints provided insights into effects that were not apparent from individual life history traits alone and suggest at least a potential for adverse ecological effects under realistic environmental exposures concentrations. Environ Toxicol Chem 2013;32:2771-2778. © 2013 SETAC [ABSTRACT FROM AUTHOR]

Density-dependence is hypothesized as the major mechanism of population regulation. However, the lack of long-term demographic data has hampered the use of density-dependent models in nonhuman primates. In this study, we make use of the long-term demographic data from Cayo Santiago's rhesus macaques to parameterize and analyze both a density-independent and a density-dependent population matrix model, and compare their projections with the observed population changes. We also employ a retrospective analysis to determine how variance in vital rates, and covariance among them, contributed to the observed variation in long-term fitness across different levels of population density. The population exhibited negative density-dependence in fertility and the model incorporating this relationship accounted for 98% of the observed population dynamics. Variation in survival and fertility of sexually active individuals contributed the most to the variation in long-term fitness, while vital rates displaying high temporal variability exhibited lower sensitivities. Our findings are novel in describing density-dependent dynamics in a provisioned primate population, and in suggesting that selection is acting to lower the variance in the population growth rate by minimizing the variation in adult survival at high density. Because density-dependent mechanisms may become stronger in wild primate populations due to increasing habitat loss and food scarcity, our study demonstrates that it is important to incorporate variation in population size, as well as demographic variability into population viability analyses for a better understanding of the mechanisms regulating the growth of primate populations. Am. J. Primatol. 75:1152-1164, 2013. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]