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Abstract Background Conditions experienced by a female during early life may affect her reproductive strategies and maternal investment later in life. This effect of early environmental conditions is a potentially important mechanism by which animals can compensate for the negative impacts of climate change. In this study, we experimentally tested whether three-spined sticklebacks (Gasterosteus aculeatus) change their maternal strategy according to environmental temperatures experienced earlier in life. We studied maternal investment from a life-history perspective because females are expected to adjust their reproductive strategy in relation to their current and future reproductive returns as well as offspring fitness. Results F1 families were reared in control and elevated winter temperatures and their reproductive trajectories were studied when returned to common conditions. Females that had experienced the warm winter treatment (n = 141) had a lower fecundity and reduced breeding and total lifespan compared to the control individuals (n = 159). Whereas the control females tended to produce their heaviest and largest clutches in their first reproductive attempt, the warm-acclimated females invested less in their first clutch, but then produced increasingly heavy clutches over the course of the breeding season. Egg mass increased with clutch number at a similar rate in the two groups. The warm-acclimated females increased the investment of carotenoids in the first and last clutches of the season. Thus, any transgenerational effects of the maternal thermal environment on offspring phenotype may be mediated by the allocation of antioxidants into eggs but not by egg size. Conclusions Our results indicate that conditions experienced by females during juvenile life have a profound effect on life-time maternal reproductive strategies. The temperature-induced changes in maternal strategy may be due to constraints imposed by the higher energetic costs of a warm environment, but it is possible that they allow the offspring to compensate for higher energetic costs and damage when they face the same thermal stress as did their mothers.

Abstract One of the current challenges of evolutionary ecology is to understand the effects of phylogenetic history (PH) and/or ecological factors (EF) on the life‐history traits of the species. Here, the effects of environment and phylogeny are tested for the first time on the reproductive biology of South American xenodontine snakes. We studied 60% of the tribes of this endemic and most representative clade in a temperate region of South America. A comparative method (canonical phylogenetic ordination—CPO) was used to find the relative contributions of EF and PH upon life‐history aspects of snakes, comparing the reproductive mode, mean fecundity, reproductive potential, and frequency of nearly 1,000 specimens. CPO analysis showed that PH or ancestry explained most of the variation in reproduction, whereas EF explained little of this variation. The reproductive traits under study are suggested to have a strong phylogenetic signal in this clade, the ancestry playing a big role in reproduction. The EF also influenced the reproduction of South American xenodontines, although to a lesser extent. Our finding provides new evidence of how the evolutionary history is embodied in the traits of living species.

The evolution of resistance to herbicides is a classic example of rapid contemporary adaptation in the face of a novel environmental stress. Evolutionary theory predicts that selection for resistance will be accompanied by fitness trade-offs in environments where the stress is absent. Alopecurus myosuroides, an autumn-germinating grass weed of cereal crops in North-West Europe, has evolved resistance to seven herbicide modes-of-action, making this an ideal species to examine the presence and magnitudes of such fitness costs. Here, we use two contrasting A. myosuroides phenotypes derived from a common genetic background, one with enhanced metabolism resistance to a commercial formulation of the sulfonylurea (ALS) actives mesosulfuron and iodosulfuron, and the other with susceptibility to these actives (S). Comparisons of plant establishment, growth, and reproductive potential were made under conditions of intraspecific competition, interspecific competition with wheat, and over a gradient of nitrogen deprivation. Herbicide dose response assays confirmed that the two lines had contrasting resistance phenotypes, with a 20-fold difference in resistance between them. Pleiotropic effects of resistance were observed during plant development, with R plants having a greater intraspecific competitive effect and longer tiller lengths than S plants during vegetative growth, but with S plants allocating proportionally more biomass to reproductive tissues during flowering. Direct evidence of a reproductive cost of resistance was evident in the nitrogen deprivation experiment with R plants producing 27% fewer seed heads per plant, and a corresponding 23% reduction in total seed head length. However, these direct effects of resistance on fecundity were not consistent across experiments. Our results demonstrate that a resistance phenotype based on enhanced herbicide metabolism has pleiotropic impacts on plant growth, development and resource partitioning but does not support the hypothesis that resistance is associated with a consistent reproductive fitness cost in this species. Given the continued difficulties associated with unequivocally detecting costs of herbicide resistance, we advocate future studies that adopt classical evolutionary quantitative genetics approaches to determine genetic correlations between resistance and fitness-related plant life history traits.

An animal's behaviour can influence many variables, such as its energy reserves, its risk of injury or mortality, and its rate of reproduction. To identify the optimal action in a given situation, these various effects can be compared in the common currency of reproductive value. While this idea has been widely used to study trade-offs between pairs of variables, e.g. between energy gain versus survival, here we present a unified framework that makes explicit how these various trade-offs fit together. This unification covers a wide range of biological phenomena, highlighting similarities in their logical structure and helping to identify knowledge gaps. To fill one such gap, we present a new model of foraging under the risk of predation and damage accumulation. We conclude by discussing the use and limitations of state-dependent optimisation theory in predicting biological observations., (© 2023 The Authors. Biological Reviews published by John Wiley & Sons Ltd on behalf of Cambridge Philosophical Society.)

Temperature is an important environmental factor influencing the life-history traits of ectotherms. This study investigated the effects of larval-rearing temperature (21, 23, 25, and 27 °C) on the life-history traits and adult fitness of the fall webworm, Hyphantria cunea , an economically important invasive pest of China. With the increase in temperature during the larval stage, the larval developmental duration was significantly shortened, and the body mass was significantly increased, as was that of the body mass and size of pupae. The carbohydrate and lipid content of pupae significantly decreased with increasing larval-rearing temperature, whereas the protein content significantly increased. Adult body size and egg production increased significantly with increasing larval-rearing temperature, whereas there was no significant difference in egg diameter. These results indicate that H. cunea demonstrates life-history traits plasticity. In addition, the increase in fecundity would maintain a stable population size of H. cunea under higher temperatures. Such characteristics could enable H. cunea to spread to the more southern, warmer areas of China, posing an increased risk to the forestry industry in these regions.

Species traits are a new data currency to enhance our understanding of ecological patterns and processes. Trait‐based studies of fishes are numerous in comparison with other animal groups, reflecting the diversity of fish forms and functions they provide to aquatic ecosystems. We conduct a retrospective examination of literature to identify knowledge gaps and provide guidance for future research in trait‐based fish ecology. We apply an automated text mining and topic modelling to track the evolution of research topics within peer‐reviewed articles of functional traits in marine and freshwater fishes published over the past half century, explore the inter‐connections among those topics and identify emerging avenues for investigation. By mapping the topic landscape of the literature, 16 latent topics emerged that vary in their prevalence. Our results show a decline in the frequency of studies using reproductive traits to model and explore the way fish allocate energy for reproduction, and increase in studies reporting functional diversity metrics and utilizing the concept of multivariate functional space. Research focused on contributions of fish traits to ecosystem functioning also has increased in frequency. We revealed large gaps in information between growing and decreasing topics and that these gaps were derived from different types of traits being considered. We suggest that scientists break‐free from the traditions of their research field by targeting investigations that: (a) apply functional diversity metrics to a broader assortment of traits, (b) focus on traits influencing energy allocation to growth/reproduction and (c) integrate trophic‐web and behavioural studies with other topics. [ABSTRACT FROM AUTHOR]

Environmental change can have drastic effects on natural populations. To successfully predict such effects, we need to understand how species that follow different life-history strategies respond to stressful conditions. Here I focus on two stressors, increased flight and dietary restriction, and their effects on bioenergetics and life-history. Using the Glanville fritillary butterfly (Melitaea cinxia), I subjected mated females to three treatments: (1) control conditions, (2) repeated forced flight with unlimited food, and (3) repeated forced flight coupled with food restriction. Interestingly, flight increased fecundity: females in both flight treatments initiated oviposition earlier, laid more egg clutches, and had higher total fecundity than control females. However, food-restriction by 50% reduced clutch size and resulted in an approximately 25% decrease in total fecundity compared to flown females with unlimited food. There were no differences in egg wet mass, water content or hatching success. Flown females with unlimited food appeared to exhibit a trade-off between reproduction and lifespan: they had higher mass-independent resting metabolic rate and shorter lifespan than females in the other treatments. Mass-independent flight metabolic rate, reflecting flight capacity, did not differ among the treatments. There were no differences in the rate of metabolic senescence across the treatments. The current findings suggest a mechanistic link between flight and reproduction, potentially mediated by juvenile hormone signalling. It appears that this wing-monomorphic butterfly does not show an oogenesis-flight trade-off often found in wing-dimorphic insects. Nevertheless, nectar-feeding is needed for achieving maximum reproductive output, suggesting that diminishing nectar resources may negatively impact natural populations. [ABSTRACT FROM AUTHOR]

Many aquatic organisms detect and avoid damage-released cues from conspecifics, but the chemical basis of such responses, and the effects of prolonged exposure to such cues, remain poorly understood. Injured tadpoles of the cane toad (Rhinella marina) produce chemical cues that induce avoidance by conspecific tadpoles; and chronic exposure to those cues decreases rates of tadpole survival and growth, and reduces body size at metamorphosis. Such effects suggest that we might be able to use the cane toads' alarm cue for biocontrol of invasive populations in Australia. In the present study, we examined behavioral and ecological effects of compounds that are present in cane toad tadpoles and thus, might trigger avoidance of crushed conspecifics. Four chemicals (L-Arg, L-Leu-L-Leu-OH, L-Leu-L-Ile-OH and suberic acid) induced behavioral avoidance in toad tadpoles at some (but not all) dosage levels, so we then exposed toad larvae to these chemicals over the entire period of larval development. Larval survival and size at metamorphosis were decreased by chronic exposure to crushed conspecifics (consistent with earlier studies), but not by exposure to any of the four chemicals. Indeed, L-Arg increased body size at metamorphosis. We conclude that the behavioral response to crushed conspecifics by cane toad tadpoles can be elicited by a variety of chemical cues, but that consistent exposure to these individual chemical cues does not affect tadpole viability or developmental trajectory. The optimal behavioral tactic of a tadpole may be to flee if it encounters even a single chemical cue likely to have come from an injured conspecific (indicative of predation risk), whereas the continuing presence of that single chemical (but no others) provides a less reliable signal of predation risk. Our data are consistent with results from studies on fish, that suggest a role for multiple chemicals in initiating alarm responses to damage-released cues. [ABSTRACT FROM AUTHOR]

While many species suffer from human activities, some like geese benefit and may show range expansions. In some cases geese (partially) gave up migration and started breeding at wintering and stopover grounds. Range expansion may be facilitated and accompanied by physiological changes, especially when associated with changes in migratory behaviour. Interspecific comparisons found that migratory tendency is associated with a higher basal or resting metabolic rate (RMR). We compared RMR of individuals belonging to a migratory and a sedentary colony of barnacle geese Branta leucopsis. The migratory colony is situated in the traditional arctic breeding grounds (Russia), whereas the sedentary colony has recently been established in the now shared wintering area (the Netherlands). We measured RMR by oxygen consumption () during two ontogenetic phases (juvenile growth and adult wing moult). We also investigated juvenile growth rates and adult body mass dynamics. Mass‐independent was 13.6% lower in goslings from the sedentary colony than in goslings from the migratory colony. Similarly, in adult geese, mass‐independent was 15.5% lower in sedentary than in migratory conspecifics. Goslings in the Netherlands grew 36.2% slower than goslings in Russia, while we found no differences in body dimensions in adults. Adult geese from both colonies commenced wing moult with similar body stores, but whereas Russian barnacle geese maintained this level throughout moult, body stores in geese from the Netherlands fell, being 8.5% lower half‐way through the moult. We propose that the colony differences in resting metabolic rate, growth rate and body mass dynamics during moult can be explained by environmental and behavioural differences. The less stringent time constraints combined with poorer foraging opportunities allow for a smaller 'metabolic machinery' in non‐migratory geese. Our analysis suggests that range expansion may be associated with changes in physiology, especially when paired with changes in migratory tendency. [ABSTRACT FROM AUTHOR]

Although widespread, the large Hydrophiinae sea snake Hydrophis major is poorly known ecologically. We dissected 119 preserved specimens in museum collections to quantify body sizes and proportions, sexual dimorphism, reproductive biology and diet. The sexes mature at similar snout–vent lengths (SVLs, about 75 cm) and attain similar maximum sizes (females 123 cm vs. males 122 cm SVL), but females in our sample exhibited larger mean sizes than did males (means 98.8 vs. 93.1 cm SVL). The adult sex ratio in museum specimens was highly female-biased (64:30), and the high proportion of reproductive females during the austral summer suggests annual reproduction. At the same SVL, females had shorter tails and wider bodies than did males, but sex differences in other body proportions (e.g. tail shape, head dimensions, eye diameter) were minimal. Skin rugosity increased with SVL, was greater in males than females and was greater on the dorsal than the ventral surface of the body. Litter size averaged 4.9 offspring (range 2–10) and increased with maternal body size. Neonates were approximately 33 cm SVL. The only prey items found inside dissected snakes (and also, recorded as prey in free-ranging snakes in our New Caledonia field studies) were catfish (Plotosus lineatus), whereas previous studies have suggested a more diverse diet. Although H. major resembles its terrestrial relatives in some respects, other characteristics (such as scale rugosity, low proportion of juveniles in collections, frequent production of small litters of large offspring) may reflect adaptation to marine habitats. [ABSTRACT FROM AUTHOR]

Trinidadian guppies (Poecilia reticulata) are able to adapt to various environmental conditions and are even among the few species that can tolerate extensive pollution. In the Pitch Lake of Trinidad they live in highly toxic waters due to natural seepage of oil and bitumen. In this paper, we describe phenotypic divergence in several life-history traits between guppies from the Pitch Lake and from a nearby reference site with waters not polluted by bitumen/oil. We show that guppies from the Pitch Lake were (i) smaller and (ii) had a higher reproductive investment than those from the reference site. Furthermore, they (iii) produced more and smaller offspring. These results are congruent with a scenario of high mortality caused probably by a combination of water toxicity and higher predation than at the reference site. We therefore propose the Pitch Lake as an ideal system to study the effects of long-term (natural) water pollution on fishes, which might provide interesting insights into adaptation to extreme environments, and might further help to predict fish responses to anthropogenic pollution. [ABSTRACT FROM AUTHOR]

Plant species, populations and communities are under threat from climate change, invasive pathogens, weeds and habitat fragmentation. Despite considerable research effort invested in genome engineering for crop improvement, the development of genetic tools for the management of wild plant populations has rarely been given detailed consideration. Gene drive systems that allow direct genetic management of plant populations via the spread of fitness-altering genetic modifications could be of great utility. However, despite the rapid development of synthetic tools and their enormous promise, little explicit consideration has been given to their application in plants and, to date, they remain untested. This article considers the potential utility of gene drives for the management of wild plant populations, and examines the factors that might influence the design, spread and efficacy of synthetic drives. To gain insight into optimal ways to design and deploy synthetic drive systems, we investigate the diversity of mechanisms underlying natural gene drives and their dynamics within plant populations and species. We also review potential approaches for engineering gene drives and discuss their potential application to plant genomes. We highlight the importance of considering the impact of plant life-history and genetic architecture on the dynamics of drive, investigate the potential for different types of resistance evolution, and touch on the ethical, regulatory and social challenges ahead. [ABSTRACT FROM AUTHOR]

Larvae of the endemic dynastine scarabs Pericoptus truncatus and P. punctatus (Coleoptera: Scarabaeidae) occur in coastal sand dunes. Life cycles from egg to egg-laying adults were determined by rearing for the first time. They were 3–5 years (mean ± SD = 3.41 ± 0.53 years, n = 172) and 2–4 years (2.90 ± 0.45 years, n = 53) for P. truncatus and P. punctatus, respectively. The modal life cycle length was three years for both species. In the first year of development, survival of P. truncatus and P. punctatus was superior when larvae were provided with driftwood than with grass (Spinifex sericeus or Stenotaphrum secundatum). Head-capsule width could be used to reliably differentiate between instars of P. punctatus and P. truncatus except for second instar P. truncatus and third instar P. punctatus. These data may inform planning to protect sand scarabs and associated fauna of coastal sand dunes. [ABSTRACT FROM AUTHOR]

Complex environments, characterized by co-varying factors (e.g. temperature and food availability) may cause animals to invest resources differentially into fitness-related traits. Thus, experiments manipulating multiple environmental factors concurrently provide valuable insight into the role of the environment in shaping not only important traits (e.g. dispersal capacity or reproduction), but also trait–trait interactions (e.g. trade-offs between traits). We used a multi-factorial design to manipulate variation in temperature (constant 28 °C vs. 28 ± 5 °C daily cycle) and food availability (unlimited vs. intermittent access) throughout development in the sand field cricket (Gryllus firmus). Using a univariate approach, we found that temperature variability and unlimited food availability promoted survival, development, growth, body size and/or reproductive investment. Using principal components as indices of resource allocation strategy, we found that temperature variability and unlimited food reduced investment into flight capacity in females. Thus, we detected a sex-specific trade-off between flight and other life-history traits that was developmentally plastic in response to variation in temperature and food availability. We develop an experimental and statistical framework to reveal shifts in correlative patterns of investment into different life-history traits. This approach can be applied to a range of biological systems to investigate how environmental complexity influences traits and trait trade-offs. [ABSTRACT FROM AUTHOR]

Insights from long-term subsistence fisheries data can improve our understanding of the population-specific responses of Arctic charr, Salvelinus alpinus, to environmental conditions. In this study, associations were found between temporal environmental variation and Arctic charr length- and weight-based growth using data from fish captured in the Hornaday River fishery. Overall, spring precipitation and summer air temperature appear to be the most important environmental influences on Arctic charr probably because of their respective impacts on the opportunities for acquiring surplus energy for growth. A pattern of decreasing age-related importance of temperature and increasing age-related importance of precipitation suggested that the coupling between growth and environmental effects varied by life-period. The changing prominence of each variable seems to result from the shift in apportioning energy for increases in length to increases in weight, likely as a result of the onset of maturation. The linkage of population characteristics to environmental conditions provides a baseline reference against which future data may be compared to determine the significance of any observed changes in population characteristics as a result of continuing ecological change in the north. [ABSTRACT FROM AUTHOR]

The thermal biology of ectotherms is often used to infer species' responses to changes in temperature. It is often proposed that temperate species are more cold-tolerant, less heat-tolerant, more plastic, have broader thermal performance curves (TPCs) and lower optimal temperatures when compared to tropical species. However, relatively little empirical work has provided support for this using large interspecific studies. In the present study, we measure thermal tolerance limits and thermal performance in 22 species of Drosophila that developed under common conditions. Specifically, we measure thermal tolerance (CTmin and CTmax) as well as the fitness components viability, developmental speed and fecundity at seven temperatures to construct TPCs for each of these species. For 10 of the species, we also measure thermal tolerance and thermal performance following developmental acclimation to three additional temperatures. Using these data, we test several fundamental hypotheses about the evolution and plasticity of heat and cold resistance and thermal performance. We find that cold tolerance (CTmin) varied between the species according to the environmental temperature in the habitat from which they originated. These data support the idea that the evolution of cold tolerance has allowed species to persist in colder environments. However, contrary to expectation, we find that optimal temperature (Topt) and the breadth of thermal performance (Tbreadth) are similar in temperate, widespread and tropical species and we also find that the plasticity of TPCs was constrained. We suggest that the temperature range for optimal thermal performance is either fixed or under selection by the more similar temperatures that prevail during growing seasons. As a consequence, we find that Topt and Tbreadth are of limited value for predicting past, present and future distributions of species. This article is part of the theme issue 'Physiological diversity, biodiversity patterns and global climate change: testing key hypotheses involving temperature and oxygen'. [ABSTRACT FROM AUTHOR]

A trade‐off between reproduction and immune function has been suggested to potentially underpin between‐individual and genetic variation in reproductive strategy, immunity and life span, with potential consequences for host and parasite dynamics.Previous studies in wild animal populations have shown that experimentally induced or natural variation in reproductive effort is negatively associated with general immune markers. Few studies, however, have tackled this question by measuring specific immune responses against prevalent pathogens, and only rarely has variation in immune measures been linked to parasite burden, making it impossible to draw conclusions about the functional relevance of covariation between reproductive effort and immune markers.We collected faecal samples in a longitudinal manner from wild female Soay sheep across late pregnancy and early lactation and measured gastrointestinal nematode faecal egg count (FEC) and worm‐specific antibody responses.Faecal egg count was highly repeatable, with c. 80% of variation due to between‐individual differences, while three isotypes of worm‐specific and total antibodies had moderate repeatability (range: 11%–43%). Females making a greater reproductive effort (those that reproduced, and especially those with heavier litters) showed a more rapid increase in FEC across the season, while non‐reproducing females and those producing lighter litters experienced lower FEC and had higher antibody levels.Associations between antibodies and FEC were complex: worm‐specific immunoglobulin (Ig) G was negatively associated with FEC, while total IgM was positively associated, emphasizing the importance of measuring both immune markers and parasite burden in ecological studies.Our results support the predicted trade‐off between reproductive effort and parasite‐specific immunity: high reproductive effort can limit the ability of individuals to defend themselves against prevalent parasites, with potential downstream consequences for fitness and parasite transmission. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

The evolution of resistance to herbicides is a classic example of rapid contemporary adaptation in the face of a novel environmental stress. Evolutionary theory predicts that selection for resistance will be accompanied by fitness trade-offs in environments where the stress is absent. Alopecurus myosuroides , an autumn-germinating grass weed of cereal crops in North-West Europe, has evolved resistance to seven herbicide modes-of-action, making this an ideal species to examine the presence and magnitudes of such fitness costs. Here, we use two contrasting A. myosuroides phenotypes derived from a common genetic background, one with enhanced metabolism resistance to a commercial formulation of the sulfonylurea (ALS) actives mesosulfuron and iodosulfuron, and the other with susceptibility to these actives (S). Comparisons of plant establishment, growth, and reproductive potential were made under conditions of intraspecific competition, interspecific competition with wheat, and over a gradient of nitrogen deprivation. Herbicide dose response assays confirmed that the two lines had contrasting resistance phenotypes, with a 20-fold difference in resistance between them. Pleiotropic effects of resistance were observed during plant development, with R plants having a greater intraspecific competitive effect and longer tiller lengths than S plants during vegetative growth, but with S plants allocating proportionally more biomass to reproductive tissues during flowering. Direct evidence of a reproductive cost of resistance was evident in the nitrogen deprivation experiment with R plants producing 27% fewer seed heads per plant, and a corresponding 23% reduction in total seed head length. However, these direct effects of resistance on fecundity were not consistent across experiments. Our results demonstrate that a resistance phenotype based on enhanced herbicide metabolism has pleiotropic impacts on plant growth, development and resource partitioning but does not support the hypothesis that resistance is associated with a consistent reproductive fitness cost in this species. Given the continued difficulties associated with unequivocally detecting costs of herbicide resistance, we advocate future studies that adopt classical evolutionary quantitative genetics approaches to determine genetic correlations between resistance and fitness-related plant life history traits. [ABSTRACT FROM AUTHOR]

Organisms are faced with variable environments and one of the most common solutions to cope with such variability is phenotypic plasticity, a modification of the phenotype to the environment. These modifications are commonly modelled in evolutionary theories as adaptive, influencing ecological and evolutionary processes. If plasticity is adaptive, we would predict that the closer to fitness a trait is, the less plastic it would be. To test this hypothesis, we conducted a meta-analysis of 213 studies and measured the plasticity of each reported trait as a coefficient of variation. Traits were categorized as closer to fitness—life-history traits including reproduction and survival related traits, and farther from fitness—non-life-history traits including traits related to development, metabolism and physiology, morphology and behaviour. Our results showed, unexpectedly, that although traits differed in their amounts of plasticity, trait plasticity was not related to its proximity to fitness. These findings were independent of taxonomic groups or environmental types assessed. We caution against general expectations that plasticity is adaptive, as assumed by many models of its evolution. More studies are needed that test the adaptive nature of plasticity, and additional theoretical explorations on adaptive and non-adaptive plasticity are encouraged. [ABSTRACT FROM AUTHOR]

Identification of the most relevant habitat features necessary for the success of potential invaders, such as the bleak Alburnus alburnus with its high ecological risk, is fundamental for understanding the invasive process and, thus, for designing effective control programs. This study provides new insights into the residence time and variation of population traits of this species along a longitudinal gradient in one of the most regulated river basin in the Iberian Peninsula. Occurrence data collected from 25 sampling sites (three times in five years) along the Segura River Basin (SE Spain) showed that this species has spread rapidly and now inhabits more than 168 km of fluvial stretches (84.4% of the studied area). The captured individuals were four years old, although greater longevity and larger mature cohorts were more common in sites with longer residence times. Higher values in population abundance in the upstream part of the river basin were accompanied by increased growth rates and higher maximum sizes. The obtained results support the hypothesis that the wide plasticity of the population traits of A. alburnus plays an important role in its success in a highly regulated Mediterranean river basin, where this mechanism allows it to survive flow regulation events at various scales, as well as to resist the long-term environmental stress typical of Mediterranean-type rivers. [ABSTRACT FROM AUTHOR]

Populations at risk of extinction due to climate change may be rescued by adaptive evolution or plasticity. Selective agents, such as introduced predators, may enhance or constrain plastic or adaptive responses to temperature. We tested responses of Daphnia to temperature by collecting populations from lakes across an elevational gradient in the presence and absence of fish predators (long‐term selection). We subsequently grew these populations at two elevations in field mesocosms over two years (short‐term selection), followed by a common‐garden experiment at two temperatures in the lab to measure life‐history traits. Both long‐term and short‐term selection affected traits, suggesting that genetic variation of plasticity within populations enabled individuals to rapidly evolve plasticity in response to high temperature. We found that short‐term selection by high temperature increased plasticity for growth rate in all populations. Fecundity was higher in populations from fishless lakes and body size showed greater plasticity in populations from warm lakes (long‐term selection). Neither body size nor fecundity were affected by short‐term thermal selection. These results demonstrate that plasticity is an important component of the life‐history response of Daphnia, and that genetic variation within populations enabled rapid evolution of plasticity in response to selection by temperature. [ABSTRACT FROM AUTHOR]

Poor conditions during early development can initiate trade‐offs that favour current survival at the expense of somatic maintenance and subsequently, future reproduction. However, the mechanisms that link early and late life‐history are largely unknown. Recently it has been suggested that telomeres, the nucleoprotein structures at the terminal end of chromosomes, could link early‐life conditions to lifespan and fitness. In wild purple‐crowned fairy‐wrens, we combined measurements of nestling telomere length (TL) with detailed life‐history data to investigate whether early‐life TL predicts fitness prospects. Our study differs from previous studies in the completeness of our fitness estimates in a highly philopatric population. The association between TL and survival was age‐dependent with early‐life TL having a positive effect on lifespan only among individuals that survived their first year. Early‐life TL was not associated with the probability or age of gaining a breeding position. Interestingly, early‐life TL was positively related to breeding duration, contribution to population growth and lifetime reproductive success because of their association with lifespan. Thus, early‐life TL, which reflects growth, accumulated early‐life stress and inherited TL, predicted fitness in birds that reached adulthood but not noticeably among fledglings. These findings suggest that a lack of investment in somatic maintenance during development particularly affects late life performance. This study demonstrates that factors in early‐life are related to fitness prospects through lifespan, and suggests that the study of telomeres may provide insight into the underlying physiological mechanisms linking early‐ and late‐life performance and trade‐offs across a lifetime. [ABSTRACT FROM AUTHOR]

Adaptation of life-history traits is an important factor for the success of insects. Voltinism is a feature that descends from several life-history traits and, given that the latter depend on the specific environment of growth, voltinism can vary between populations across latitudes or habitats. In addition, some insects, like many odonates, have developed different patterns of voltinism within the same population, due to mechanisms of cohort splitting. Calopteryx splendens (Odonata: Calopterygidae) is a widespread damselfly in Europe that has been extensively studied regarding its evolutionary ecology, but detailed studies about its voltinism are relatively scarce and confined to the central and northern areas of Europe. So we investigated the voltinism and larval development of a population of C. splendens both by captive rearing and in the field in Northern Italy, the southernmost area in which its voltinism has been studied so far. We found an earlier start of larval growth, with respect to previous studies. Additionally, the head-width of larvae of the same instar decreased with the cohort ageing. Finally, the results are consistent with a two-groups emerging pattern that may support partial semivoltinism or partial bivoltinism of C. splendens in Northern Italy. [ABSTRACT FROM AUTHOR]

Being the spouse of a patient in a nursing home may be a conflicting experience. This article uses life-history interviews and the understanding of Bourdieu to understand and explain the phenomena. The data consist of five life-story interviews with two women and two men. The article looks at love and marriage structures during the lifetime of the agents. We also look at the development of the nursing home from a historical perspective. The research is based on Bourdieu's theory with the purpose of understanding and explaining the experiences of the spouse: 'Why is the experience of having a spouse in a nursing home often conflicting?' The ambition of praxeological optics is to objectify subjectivist and objectivist factors. The understanding is constructed as a habitus based on the trilogy of Bourdieu. In order to endure and cope with the challenges, spouses need to be strong. According to our analysis lived life expressed in attitudes and actions in marriage and at the nursing home are closely linked. 'For better or worse, in sickness and health', is a key element in these relations. Staff need to focus more on spouses in order to avoid conflicts both between staff and spouse and between the spouses themselves. [ABSTRACT FROM AUTHOR]

The aim of this multiple case study was to uncover a series of critical events and experiences related to the formation of the science identities of four beginning elementary female teachers, through a life-history approach and a conceptualization of teacher identity as lived experience. Grounded within the theoretical framework of Figured Worlds, the study used qualitative, interpretive methods for data collection (interviews, biographies, teaching philosophies) and analysis. The analysis shed light on the ways in which various experiences situated within different Figured Worlds (science, family and childhood, schooling, out-of-school, university, professional) impacted the participants' identity trajectories. The findings provided three main insights that contribute to science identity research and have implications for elementary teacher preparation: (a) science teacher identity is multidimensional and extends beyond cognitive domains of becoming to include affective dimensions; (b) science teacher identity is relational, linked and shaped by various other constructs or sub-identities; (c) place and time, defined as a space with meaning created by experiences, and science teacher identity are inextricably bound to one another. [ABSTRACT FROM AUTHOR]

1. Burying beetles (Nicrophorus spp.) provide an excellent model system to test predictions about the relationships between environment, life‐history and behaviour. All species in the genus display similar natural histories, breeding on vertebrate carcasses and providing parental care to developing offspring. However, variations in other aspects of species' ecologies provide a rich framework to examine the evolution of parental behaviours and other traits. 2. One little‐studied species, N. sayi, breeds in substantially colder temperatures than its congeners, creating a potentially harsh environment for offspring. Here, we examined the timing of reproductive and developmental events in this species, and also investigated the effects of removing parents on offspring performance. 3. We find that development is not only extremely slow in this species, but it is also delayed even in comparison to other burying beetles reared at similar temperatures. However, the presence of parents reduces the time that offspring take to leave the carcass. This decrease in development time does not appear to result in a trade‐off with mortality or body size. 4. From these results, we suggest that very slow development may be advantageous when living in a particularly cold environment. Additionally, one role of extended parental care may be to assist offspring in dealing with these harsh conditions, and to mitigate the potentially negative consequences of adopting such a slow life‐history strategy. Like all burying beetles, Nicrophorus sayi provides advanced parental care to its offspring, but is active in much colder temperatures than its congeners, due to its early breeding season.Offspring of this species develop extremely slowly, although the presence of extended parental care speeds up development without incurring other costs to the offspring.These results suggest that parental care may play a role in mitigating the consequences of living in harsh environmental conditions. [ABSTRACT FROM AUTHOR]

Background: A proposed mediator of trade-offs between survival and reproduction is oxidative stress resistance. Investments in reproduction are associated with increased oxidative stress that reduces lifespan. We used the bdelloid rotifer Adineta vaga to examine baseline patterns of survival, reproduction, and measures of oxidative stress, as well as how these patterns change in the face of treatments known to induce oxidative stress. Results: We discovered that under standard laboratory conditions late-life mortality may be explained by increased levels of oxidative stress induced by reproduction. However, following exposure to the oxidizing agent ionizing radiation, survival was unaffected while reproduction was reduced. Conclusions: We suggest that under normal environmental conditions, reduced survival is mediated by endogenously generated oxidative stress induced by reproduction, and thus represents a cost of reproduction. Alternatively, the reduced reproduction evident under exogenously applied oxidative stress represents a cost of somatic maintenance. Biochemical analyses designed to assess levels of oxidative stress, oxidative stress resistance, and oxidative damage under normal and oxidizing conditions suggest that varying investments in enzymatic and non-enzymatic based oxidative stress resistance determine whether a cost of reproduction or a cost of somatic maintenance is observed. [ABSTRACT FROM AUTHOR]

Aposematism is the combination of a primary signal with a secondary defence that predators must learn to associate with one another. However, variation in the level of defence, both within and between species, is very common. As secondary defences influence individual fitness, this variation in quality and quantity requires an evolutionary explanation, particularly as it may or may not correlate with variation in primary signals. The costs of defence production are expected to play a considerable role in generating this variation, yet studies of the cost of chemical defence have focused on species that sequester their defences, while studies in species that produce them de novo are scarce. Here we examine effects of resource availability on the production of chemical defences in female wood tiger moths Arctia plantaginis. This species produces defensive fluids when attacked, and advertises this protection with bright colours on its hindwings. Furthermore, the chemicals in these fluids are produced de novo. In order to establish if the production of this chemical protection is costly, and thus resource‐limited, we manipulated resource availability (i.e. food) during larval development and measured its subsequent effects on adult chemical defence. We presented defensive fluids from female moths to wild blue tits, in the absence of any visual cues, to determine their effectiveness against avian predators. Our results demonstrate that the defensive fluids produced by female moths repel birds, and that these defences require resource investment to produce. We found that moths that were resource‐limited during development had less effective chemical defences, despite producing the same volume of defensive fluids as the control moths. As a reduction in available resources negatively influences the effectiveness of the chemical defence, resource availability may explain the variation seen among individuals. [ABSTRACT FROM AUTHOR]

Summary: What causes individual tree death in tropical forests remains a major gap in our understanding of the biology of tropical trees and leads to significant uncertainty in predicting global carbon cycle dynamics.We measured individual characteristics (diameter at breast height, wood density, growth rate, crown illumination and crown form) and environmental conditions (soil fertility and habitat suitability) for 26 425 trees ≥ 10 cm diameter at breast height belonging to 416 species in a 52‐ha plot in Lambir Hills National Park, Malaysia. We used structural equation models to investigate the relationships among the different factors and tree mortality.Crown form (a proxy for mechanical damage and other stresses) and prior growth were the two most important factors related to mortality. The effect of all variables on mortality (except habitat suitability) was substantially greater than expected by chance.Tree death is the result of interactions between factors, including direct and indirect effects. Crown form/damage and prior growth mediated most of the effect of tree size, wood density, fertility and habitat suitability on mortality. Large‐scale assessment of crown form or status may result in improved prediction of individual tree death at the landscape scale. [ABSTRACT FROM AUTHOR]

In at least some unicellular organisms, mutation rates are temporarily raised upon exposure to environmental stress, potentially contributing to the evolutionary response to stress. Whether this is true for multicellular organisms, however, has received little attention. This study investigated the effects of chronic mild stress, in the form of low-level copper and nickel exposure, on mutational processes in Daphnia pulex using a combination of mutation accumulation, whole genome sequencing and life-history assays. After over 100 generations of mutation accumulation, we found no effects of metal exposure on the rates of single nucleotide mutations and of loss of heterozygosity events, the two mutation classes that occurred in sufficient numbers to allow statistical analysis. Similarly, rates of decline in fitness, as measured by intrinsic rate of population increase and of body size at first reproduction, were negligibly affected by metal exposure. We can reject the possibility that Daphnia were insufficiently stressed to invoke genetic responses as we have previously shown rates of large-scale deletions and duplications are elevated under metal exposure in this experiment. Overall, the mutation accumulation lines did not significantly depart from initial values for phenotypic traits measured, indicating the lineage used was broadly mutationally robust. Taken together, these results indicate that the mutagenic effects of chronic low-level exposure to these metals are restricted to certain mutation classes and that fitness consequences are likely minor and therefore unlikely to be relevant in determining the evolutionary responses of populations exposed to these stressors. [ABSTRACT FROM AUTHOR]

Copyright of Clio. Femmes, Genre, Histoire is the property of Belin Editeur and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Pupa‐eating cannibalism occurs naturally in several insect species. Byasa alcinous is a multivoltine species of Red‐bodied Swallowtail butterfly found in East Asia, which diapauses as pupa over the winter and whose larvae cannibalize eggs and pupae. We investigate the effects on population dynamics of increasing the asymmetric cannibalistic attack rate of a general insect species in different environmental conditions. We do this by theoretically formulating a generalized system of univoltine and bivoltine larvae over two generations in the spring and summer months. We predict that a lack of resources over the summer can force the population to become entirely univoltine, unless the second‐generation bivoltine larvae increase their cannibalistic attack rate, and consume the diapausing pupae from the first generation. The model shows that under extreme environmental conditions, the persistence of univoltine larvae is favoured when faced with the threat of extinction. The model also predicts the conditions for the coexistence of both univoltine and bivoltine larvae, and the degree to which they can both coexist, which decreases as the resource in the second generation increases. This work provides the grounding for future theoretical and experimental consideration of the role of cannibalism in determining insect voltinism. [ABSTRACT FROM AUTHOR]

Conspicuous warning colors that signal chemical or other defenses are common in the natural world. For instance, such aposematic warning patterns of red‐and‐black or yellow‐and‐black are common among insect taxa, particularly in the order Hemiptera, often forming the basis of Batesian and/or Müllerian mimicry rings. In addition, it has been repeatedly noted that color polymorphisms or mutants that influence pigmentation can show pleiotropy with other behavioral, physiological, or life‐history traits. Here, we describe a pale mutant of the seed bug Lygaeus simulans that appeared in our laboratory population in 2012, which differs in color to the wild‐type bugs. Through multigenerational experimental crosses between wild‐type and pale mutant L. simulans, we first show that the pale phenotype segregates as a single Mendelian locus, with the pale allele being recessive to the wild type. Next, we show (a) that there is a large heterozygous advantage in terms of fecundity, (b) that pale females suffer reduced longevity, and (c) that pale males have increased body length compared to wild‐type homozygotes. Our data therefore suggest that the color locus is pleiotropic with a number of life‐history traits, opening the door for a more complete genetic analysis of aposematic coloration in this species. In addition, this phenotype will be useful as a visible genetic marker, providing a tool for investigating sperm competition and other post‐copulatory drivers of sexual selection in this species. Our manuscript describes the discovery and analysis of a pale phenotype in the aposematic Lygaeus simulans. Through a series of experiments, we show that the pale phenotype inherits as a single Mendelian locus, recessive to the wild type. We then show that the pale phenotype is associated with variation in life‐history traits, including fecundity and body size. Moreover, we see heterozygous advantage for fecundity. As such, our data are consistent with an underlying "supergene" linking color with life‐history traits, as seen in other aposematic species, and the data represent the starting point for further analysis of the genetics of this system. [ABSTRACT FROM AUTHOR]

In animals, sex differences in immunity are proposed to shape variation in infection prevalence and intensity among individuals in a population, with females typically expected to exhibit superior immunity due to life‐history trade‐offs. We performed a systematic meta‐analysis to investigate the magnitude and direction of sex differences in immunity and to identify factors that shape sex‐biased immunocompetence. In addition to considering taxonomic and methodological effects as moderators, we assessed age‐related effects, which are predicted to occur if sex differences in immunity are due to sex‐specific resource allocation trade‐offs with reproduction. In a meta‐analysis of 584 effects from 124 studies, we found that females exhibit a significantly stronger immune response than do males, but the effect size is relatively small, and became non‐significant after controlling for phylogeny. Female‐biased immunity was more pronounced in adult than immature animals. More recently published studies did not report significantly smaller effect sizes. Among taxonomic and methodological subsets of the data, some of the largest effect sizes were in insects, further supporting previous suggestions that testosterone is not the only potential driver of sex differences in immunity. Our findings challenge the notion of pervasive biases towards female‐biased immunity and the role of testosterone in driving these differences. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Elasmobranch reproductive behaviour remains understudied, particularly for batoids (rays). Most of the information available originates from opportunistic observations of mating scars in the wild and/or from individuals held in captivity. Here we describe the first complete mating sequence of the marbled ray (Taeniurops meyeni) in the wild. The event was filmed at Isla del Coco National Park in Costa Rica, in the Tropical Eastern Pacific. The complete sequence lasted approximately 3 hrs and is defined by the following behaviours: (1) close following or chasing: a group of males swim in a close formation chasing an individual female; (2) pre-copulatory biting: oral grasping of the female’s posterior pectoral fin by the males, with anterior bending of one clasper and rotation of the pelvic region towards the female’s cloaca; (3) copulation/ insertion of the male’s clasper followed by ‘ventral to ventral’ position and energetic thrusting of the male’s pelvic region; (4) post-copulatory behaviour: the male removes its clasper from the female’s cloaca while releasing her posterior pectoral fin and (5) separation: the male sets the female free and separates himself from the group. The mating behaviour described here shares some similarities with the few other studies of batoids in the wild and highlights the need to further understand their mating system to guide conservation plans for this vulnerable species. [ABSTRACT FROM AUTHOR]

The effects of adult crowding on two components of fitness were studied in three sets of Drosophila melanogaster populations, subjected to life-stage-specific, density-dependent natural selection in the laboratory for over 50 generations. Three days of crowding, early in adult life, were observed to increase mortality significantly during the episode of crowding, as well as decrease subsequent fecundity. Populations selected for adaptation to high adult densities suffered significantly lower mortality during episodes of adult crowding, as compared to populations selected specifically for adaptation to larval crowding, as well as control populations typically maintained at low larval and adult densities. Moreover, populations adapted to larval crowding seemed to be adversely affected by adult crowding to a greater extent than the controls, raising the possibility of trade-offs between adaptations to larval and adult crowding, respectively. Preliminary evidence suggests that the populations adapted to adult crowding may have evolved a propensity to stay away from the food medium, which is where most deaths occur when adults are crowded in culture vials.

[Display omitted] • In response to infection, Mormon crickets elevated phenoloxidase activity. • Contrary to expectation, infected Mormon crickets decreased protein consumption. • Survivorship to infection was proportional to protein consumption. • Abrupt changes in allocation can lead to changes in acquisition that drives migration. Immune responses to infection result in behavioral changes that affect resource acquisition, such as general starvation and compensatory feeding to offset changes in resource allocation. Mormon crickets aggregate and march in bands containing millions of insects. Some bands are comprised of insects seeking proteins. They are also low in circulating phenoloxidase (PO) and more susceptible to fungal attack, as we have demonstrated in the lab. Here, we ask: Do Mormon crickets elevate PO and consume protein in response to infection by the pathogenic fungus Beauveria bassiana ? B. bassiana was applied topically (day 0), and mortality began on day 5. Total protein, PO, and prophenoloxidase (proPO) were assayed in hemolymph on day 1 and 4. On day 1, PO titers were not different between inoculated and control insects, whereas by day 4, PO was greater in the inoculated group. proPO activity was unchanged. Circulating protein declined in inoculated insects relative to controls. As predicted, PO titers were elevated as a result of fungal infection, and hemolymph protein was reduced, but the insects did not compensate behaviorally. Indeed, during the first three days post-infection, infected insects reduced protein consumption while maintaining carbohydrate consumption similar to the controls. Following day 3, a more general reduction in protein and carbohydrate intake was evident in infected insects. Survivorship to infection was associated with the amount of protein consumed and unrelated to carbohydrate consumption. Selective protein deprivation by the host seems counterintuitive, but it might limit growth and toxin production by the invading fungus. Alternatively, the fungus might control the host diet to compromise host immunity to infection. Abrupt changes in allocation resulting from an infection can lead to changes in acquisition that are not always intuitive. Because protein acquisition drives aggression between members of the migratory band, B. bassiana application may reduce cannibalism and slow band movement. [ABSTRACT FROM AUTHOR]

The article explores educational paths of disabled young people in Finland. Our approach is life-historical: we are interested in how individual paths are formed by historically and culturally specific discourses and practices, and in the cultural understandings concerning disability and educability these carry. We also focus on questions of subjectivity and agency by asking how individuals positioned in these practices build an understanding of themselves, and of the possibilities and obstacles in their educational path. Two life-history interviews are analysed in detail. Our analysis highlights the persistence of stereotypical cultural narratives of disability in the life stories. In addition, it suggests that disability rights discourse has provided an important counter discourse for disabled young adults – a new way of conceptualizing self and one's educational path.