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Leaf traits reflect the ecological strategy in heterogeneous contexts and are widely used to explore the adaption of plant species to environmental change. However, the knowledge of short-term effect of canopy management on understorey plant leaf traits is still limited. Here, we studied the short-term effect of crown–thinning on the leaf morphological traits of bamboo (Chimonobambusa opienensis), an important understorey plant and staple food for the giant panda (Ailuropoda melanoleuca) of Niba Mountain. Our treatments were two crown–thinnings (spruce plantation, CS, and deciduous broad-leaved forest, CB) and two controls (broad-leaved forest canopy, FC, and the bamboo grove of clearcutting, BC). The results showed that: the CS enhanced the annual leaf length, width, area, and thickness, CB decreased almost all annual leaf traits, and perennial leaf traits in CS and CB were the opposite. The log-transformed allometric relationships of length vs. width, biomass vs. area were significantly positive while those of specific leaf area vs. thickness were significantly negative, which varied largely in treatments and age. The leaf traits and allometric relationships suggested that the CS created a more suitable habitat for bamboo growth. This study highlighted that the understorey bamboo leaf traits could adapt the improved light environment induced by crown–thinning rapidly.

Under controlled laboratory conditions, previous studies have shown that selection can produce repeatable evolutionary trajectories. Yet, the question remains for many of these studies if, given identical starting populations, evolution in the wild proceeds in a non-random direction. In the present study, we investigated the extent to which rapid evolution in the wild is parallel by monitoring the genetic composition of replicate populations of Daphnia in field mesocosms containing two clonal genotypes. We found parallel changes across all nine mesocosms, in which the same genotype increased in frequency. To probe whether genotype-specific response to resource abundance could have led to this frequency change, we conducted a life-history assay under high-resource abundance and low-resource abundance. We found that resource exploitation differed by genotype, in that, while one genotype (the winner in the field mesocosms) was more fit than the other genotype at high resources, the other genotype performed slightly better at low resources. We suspect that levels of resource abundance found in the summer field mesocosms had values in which the genotype better with abundant resources had the advantage. These findings suggest that variation in certain traits associated with resource acquisition can drive genotype frequency change.

Interacting abiotic stresses exert a fundamental selective pressure on the adaptive syndromes of long-living organisms such as woody plants. However, general patterns and mechanisms describing woody plant adaptations to tolerate multiple abiotic stressors are yet to emerge. This hampers our ability to build predictive frameworks foreseeing species responses to stochastic changes in abiotic stress regimes due to climate change. With this Virtual Special Issue (VSI), we aimed to summarize what we know, and what we do not know, about woody plant adaptations to achieve tolerance to multiple abiotic limitations. To this end, we brought together studies exploring ecological or ecophysiological perspectives on woody plant adaptations to tolerate multiple abiotic stresses. Ecological studies suggest patterns associating trait trade-offs, climate, and biotic interactions with woody plants’ multi-stress tolerance. Ecophysiological studies point to traits and conceptual frameworks that might explain some processes underpinning woody plant multi-stress tolerance. Here, we first revised the definitions of stress and stress tolerance used in ecological and ecophysiological research, providing a nomenclature of tolerance that could be used to unify definitions across research fields. Then, we summarized the main theories and evidence on woody plant adaptations to tolerate multiple abiotic stresses. Finally, we introduced the ecological and ecophysiological perspectives on this matter and placed the contributions to this VSI within the current state of the art. Altogether, this VSI allowed us to identify the lack of large-scale integration of patterns and processes describing woody plant adaptations to multiple abiotic stresses as a major gap in this field. Ministerio de Ciencia e Innovación IJC2020- 043331-I, MCIN/AEI /10.13039/501100011033, PID2021-122214NA-I00 National Institute of Food and Agriculture 7003279

Our understanding of how novel warning color traits evolve in natural populations is largely based on studies of reproductive stages and organisms with endogenously produced pigmentation. In these systems, genetic drift is often required for novel alleles to overcome strong purifying selection stemming from frequency-dependent predation and positive assortative mating. Here, we integrate data from field surveys, predation experiments, population genomics, and phenotypic correlations to explain the origin and maintenance of geographic variation in a diet-based larval pigmentation trait in the redheaded pine sawfly (Neodiprion lecontei), a pine-feeding hymenopteran. Although our experiments confirm that N. lecontei larvae are indeed aposematic-and therefore likely to experience frequency-dependent predation-our genomic data do not support a historical demographic scenario that would have facilitated the spread of an initially deleterious allele via drift. Additionally, significantly elevated differentiation at a known color locus suggests that geographic variation in larval color is currently maintained by selection. Together, these data suggest that the novel white morph likely spread via selection. However, white body color does not enhance aposematic displays, nor is it correlated with enhanced chemical defense or immune function. Instead, the derived white-bodied morph is disproportionately abundant on a pine species with a reduced carotenoid content relative to other pine hosts, suggesting that bottom-up selection via host plants may have driven divergence among populations. Overall, our results suggest that life stage and pigment source can have a substantial impact on the evolution of novel warning signals, highlighting the need to investigate diverse aposematic taxa to develop a comprehensive understanding of color variation in nature.

In many insect taxa, there is a well‐established trade‐off between flight capability and reproduction. The wing types of Acridoidea exhibit extremely variability from full length to complete loss in many groups, thus, provide a good model for studying the trade‐off between flight and reproduction. In this study, we completed the sampling of 63 Acridoidea species, measured the body length, wing length, body weight, flight muscle weight, testis and ovary weight, and the relative wing length (RWL), relative flight muscle weight (RFW), and gonadosomatic index (GSI) of different species were statistically analyzed. The results showed that there were significant differences in RWL, RFW, and GSI among Acridoidea species with different wing types. RFW of long‐winged species was significantly higher than that of short‐winged and wingless species (p, Flight‐capable individuals (long‐winged) of Acridoidea expend energy developing and maintaining the flight apparatus at the expense of reproduction. Flight‐incapable individuals (short‐winged or wingless) cannot fly, but has a greater reproductive output. The results provide evidence for the trade‐off between flight and reproduction in Acridoidea.

Life-history theory posits that investment into reproduction might occur at the expense of investment into somatic maintenance, including immune function. If so, reduced or curtailed reproductive effort might be expected to increase immunity. In support of this notion, work in Caenorhabditis elegans has shown that worms lacking a germline exhibit improved immunity, but whether the antagonistic relation between germline proliferation and immunity also holds for other organisms is less well understood. Here, we report that transgenic ablation of germ cells in late development or early adulthood in Drosophila melanogaster causes elevated baseline expression and increased induction of Toll and Imd immune genes upon bacterial infection, as compared to fertile flies with an intact germline. We also identify immune genes whose expression after infection differs between fertile and germline-less flies in a manner that is conditional on their mating status. We conclude that germline activity strongly impedes the expression and inducibility of immune genes and that this physiological trade-off might be evolutionarily conserved.

Although many empirical experiments have shown that increasing degradation results in lower aboveground biomass (AGB), our knowledge of the magnitude of belowground biomass (BGB) for individual plants is a prerequisite for accurately revealing the biomass trade‐off in degraded grasslands. Here, by linking the AGB and BGB of individual plants, species in the community, and soil properties, we explored the biomass partitioning patterns in different plant functional groups (grasses of Stipa capillacea and forbs of Anaphalis xylorhiza). Our results indicated that 81% and 60% of the biomass trade‐off variations could be explained by environmental factors affecting grasses and forbs, respectively. The change in community species diversity dominated the biomass trade‐off via either direct or indirect effects on soil properties and biomass. However, the community species diversity imparted divergent effects on the biomass trade‐off for grasses (scored at −0.72) and forbs (scored at 0.59). Our findings suggest that plant communities have evolved two contrasting strategies of biomass allocation patterns in degraded grasslands. These are the “conservative” strategy in grasses, in which plants with larger BGB trade‐off depends on gigantic roots for soil resources, and the “opportunistic” strategy in forbs, in which plants can adapt to degraded lands using high variation and optimal biomass allocation., Two contrasting strategies of biomass allocation patterns were detected in grasses and forbs. “Conservative” strategy in grasses, in which plants with belowground trade‐off depend on gigantic roots for soil resources. “Opportunistic” strategy in forbs, in which plants can adapt to degraded lands via high variation and optimal biomass allocation.

Plasmids are extrachromosomal segments of DNA that can transfer genes between bacterial cells. Many plasmid genes benefit bacteria but cause harm to human health by granting antibiotic resistance to pathogens. Transfer rate is a key parameter for predicting plasmid dynamics, but observed rates are highly variable, and the effects of selective forces on their evolution are unclear. We apply evolutionary analysis to plasmid conjugation models to investigate selective pressures affecting plasmid transfer rate, emphasizing host versus plasmid control, the costs of plasmid transfer, and the role of recipient cells. Our analyses show that plasmid-determined transfer rates can be predicted with three parameters (host growth rate, plasmid loss rate, and the cost of plasmid transfer on growth) under some conditions. We also show that low-frequency genetic variation in transfer rate can accumulate, facilitating rapid adaptation to changing conditions. Furthermore, reduced transfer rates due to host control have limited effects on plasmid prevalence until low enough to prevent plasmid persistence. These results provide a framework to predict plasmid transfer rate evolution in different environments and demonstrate the limited impact of host mechanisms to control the costs incurred when plasmids are present.

1. Repeatable individual variation in behaviour has been demonstrated in all taxa, though few studies have explored the broader ecological consequences of such consistent behaviour.2. We tagged and tracked 401 individual sea trout (Salmo trutta) with passive integrated transponder telemetry over two to four spawning seasons as they migrated between freshwater and marine environments to spawn and feed, respectively.3. We found the timing (time of river entry) and duration of migration (time spent in freshwater and time spent at sea) to be repeatable within individuals across years. In addition, we identified two peaks in return migration timing; a group of summer-migrating fish, and a group of fall-migrating fish. At the time of first spawning, sea trout differed in size depending on how long the first marine phase was, but summer-migrating fish were smaller in all subsequent spawnings. Furthermore, summer-migrating fish had significantly better marine survival than fall-migrating fish.4. Our study suggests that the timing of arrival in freshwater is an important fitness-relevant trait, such that summer-migrating fish have decreased fitness but remain in somewhat safer conditions, while fall-migrating fish have increased fitness but are exposed to more risky conditions. Taken together, our findings suggest that migration timing and duration is determined via a trade-off between size and survival, which resulted in two evolutionary stable strategies.

Eusocial insect societies possess complex multilevel disease defences, including individual level protection conferred by physical (e.g. cuticle) and immunological obstacles and colony level protection mediated by collective behaviours (social immunity). It remains unclear whether and how these two levels of disease protection are related to one another in jointly driving colonies’ susceptibility to disease. Here, we examine whether a relationship exists between individual worker survival after exposure to a fungal pathogen (a proxy for immunity) and corpse removal (a colony level social immunity metric) in the acorn ant Temnothorax curvispinosus. Since behavioural avoidance is the first line of defence against infection, we also tested whether individual ants exhibited parasite avoidance behaviour during exploration and whether colonies exhibit avoidance behaviour during foraging. We found that individual level and colony level immunity were negatively correlated: colonies that removed corpses more rapidly contained workers with weaker individual defences. We did not detect parasite avoidance behaviour by individual workers or whole colonies, nor were these two factors related. These data suggest that individual immunity and social immunity may trade off, regulating overall parasite protection. Alternatively, optimized social immunity at the colony level may compensate for disease vulnerability to infection at the individual level, and thus provide a protective benefit in overall colony defence in the absence of pathogen avoidance.

The use of translocations to recover populations requires a sufficiently large number of individuals from source populations, but removing too many individuals could lead to source population collapse. To understand the trade-off between the probabilities of source population extirpation and translocation success, matrix population models that incorporate Allee effects, density dependence, and demographic and environmental stochasticity were combined with a model that simulates removals from source populations. We apply these models to eastern sand darter (Ammocrypta pellucida; Species at Risk Act status: Threatened) translocation scenarios in Canada. The results suggest that translocations most often require source populations >20 000 individuals, as source population extirpation probability increased with the number and frequency of removals. Transport mortality or losses immediately following introduction further affected translocation success. Uncertainty around life-history parameters and the strength of Allee effects led to additional uncertainty about the required source population size. Although stochastic processes affected the probability of translocation success, factors such as stocking density and frequency can be controlled, and translocation may therefore be a viable strategy for eastern sand darter recovery, even when applying cautious thresholds to guard against uncertainty.

The proximate and ultimate mechanisms behind individual behavioural phenotypes are still only partially understood, with studies often focusing on a single or a few factor(s) that affect behaviour in a controlled environment. To understand the development and consequences of individual behavioural phenotypes in their complexity, a comprehensive approach is needed that analyses the effects of a broad spectrum of factors and their interactions on behaviour within the natural environment. We used focal observations to quantify four key behavioural components of Gala = pagos sea lion, Zalophus wollebaeki, pups under natural conditions: general social interactions, swimming, resting and social play behaviour. We then investigated the influence and interplay of age, sex, body condition, basal cortisol and testosterone levels, personality scores and the social environment on the observed behaviour. We identified significant correlations between all measured factors and behaviour. Complex interactions between testosterone, boldness and social play especially stand out, with the effect of boldness on social play being dependent on testosterone levels. We also demonstrate the importance of the early social environment, defined as local population density, for social play and, interestingly, time spent swimming. This could have consequences for the development of social and hunting skills, crucial for later stages of ontogeny. For this endangered pinniped, a decline in the diversity of social environments due to dwindling population numbers could lead to a decline in behavioural diversity and lower coping abilities towards future changes in their environment. Our study reveals important factors for the development of individual behavioural phenotypes of young Gala = pagos sea lions and elucidates some aspects of the architecture behind this individual variation in behaviour. (c) 2021 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

The use of lytic bacteriophages for treating harmful bacteria (phage therapy) is faced with the challenge of bacterial resistance evolution. Phage strains with certain traits, for example, rapid growth and relatively broad infectivity ranges, may enjoy an advantage in slowing bacterial resistance evolution. Here, we show the possibility for laboratory selection programs (“evolutionary training”) to yield phage genotypes with both high growth rate and broad infectivity, traits between which a trade‐off has been assumed. We worked with a lytic phage that infects the bacterium Pseudomonas fluorescens and adopted three types of training strategies: evolution on susceptible bacteria, coevolution with bacteria, and rotation between evolution and coevolution phases. Overall, there was a trade‐off between growth rate and infectivity range in the evolved phage isolates, including those from the rotation training programs. A small number of phages had both high growth rate and broad infectivity, and those trade‐off‐overcoming phages could slow or even completely prevent resistance evolution in initially susceptible bacterial populations. Our findings show the promise of well‐designed evolutionary training programs, in particular an evolution/coevolution rotation selection regime, for obtaining therapeutically useful phage materials.

Whether populations can adapt to predicted climate change conditions, and how rapidly, are critical questions for the management of natural systems. Experimental evolution has become an important tool to answer these questions. In order to provide useful, realistic insights into the adaptive response of populations to climate change, there needs to be careful consideration of how genetic differentiation and phenotypic plasticity interact to generate observed phenotypic changes. We exposed three populations of the widespread copepod Acartia tonsa (Crustacea) to chronic, sublethal temperature selection for 15 generations. We generated thermal survivorship curves at regular intervals both during and after this period of selection to track the evolution of thermal tolerance. Using reciprocal transplants between ambient and warming conditions, we also tracked changes in the strength of phenotypic plasticity in thermal tolerance. We observed significant increases in thermal tolerance in the Warming lineages, while plasticity in thermal tolerance was strongly reduced. We suggest these changes are driven by a negative relationship between thermal tolerance and plasticity in thermal tolerance. Our results indicate that adaptation to warming through an increase in thermal tolerance might not reduce vulnerability to climate change if the increase comes at the expense of tolerance plasticity. These results illustrate the importance of considering changes in both a trait of interest and the trait plasticity during experimental evolution.

How and if organisms can adapt to changing temperatures has drastic consequences for the natural world. Thermal adaptation involves finding a match between temperatures permitting growth and the expected temperature distribution of the environment. However, if and how this match is achieved, and how tightly linked species change together, is poorly understood. Paramecium bursaria is a ciliate that has a tight physiological interaction with endosymbiotic green algae (zoochlorellae). We subjected a wild population of P. bursaria to a cold and warm climate (20 and 32℃) for ∼300 generations. We then measured the thermal performance curve (TPC) for intrinsic rate of growth (rmax ) for these evolved lines across temperatures. We also evaluated number and size of the zoochlorellae populations within paramecia cells. TPCs for warm-adapted populations were shallower and broader than TPCs of cold-adapted populations, indicating that the warm populations adapted by moving along a thermal generalist/specialist trade off rather than right-shifting the TPC. Zoochlorellae populations within cold-adapted paramecia had fewer and larger zoochlorellae than hot-adapted paramecia, indicating phenotypic shifts in the endosymbiont accompany thermal adaptation in the host. Our results provide new and novel insight into how species involved in complex interactions will be affected by continuing increasing global temperatures.

Maternal effects are ubiquitous. Yet, the pathways through which maternal effects occur in wild mammals remain largely unknown. We hypothesise that maternal immune transfer is a key mechanism by which mothers can affect their offspring fitness, and that individual variation in maternally-derived antibodies mainly depends on a mother’s characteristics and the environmental conditions she experiences. To test this, we assayed six colostrum-derived anti bodies in the plasma of 1,447 neonates in a wild red deer population. Neonatal antibody levels were mainly affected by maternal genes, environmental variation, and costs of prior reproductive investment. We found consistent heterogeneity in maternal performance across traits, with mothers producing the heaviest calves also having calves with more antibodies. Unexpectedly, antibody levels were not associated with calf survival. We provide a unique example of how evolutionary theory on maternal effects can be used to gain insight into the causes of maternal effects in wild populations.

13 pages, 5 figures, 4 tables.-- This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license, Daily growth patterns and their relationship with reproduction was analyzed in the European hake from the Galician Shelf, where it shows a very protracted spawning with three spawning peaks. The daily growth analysis was performed in otoliths of adult females on the transversal section of the sagittae otolith. Daily increments were measured from the border to the nucleus in females until they were discernible. Results show that daily growth of females decreases during the spawning period because they allocate less energy to somatic growth in favor of the production of gametes, with an increase in growth in July. Lastly, daily growth individual trends showed a “spawning pattern” in 28% of medium and large females, suggesting an individual spawning period of one to two months, with 4–5 valleys of narrow daily increments, likely associated to batch release: individual spawning frequency would be 4–5 days. This is the first time that individual spawning frequency in hake is estimated based on individual data. Finally, the spawning pattern is detected only once per year, indicating that a single female participates only in one spawning peak per year, supporting the hypothesis of the existence of two or more spawning components in the stock, C.G.-F. was funded by Predoctoral Fellowship from the Fundación Tatiana Pérez de Guzmán el Bueno and the study was carried out with financial support from the DREAMER project (CTM2015-66676-C2-1-R) funded by the Spanish National Research Program

Current global challenges call for a rigorously predictive ecology. Our understanding of ecological strategies, imputed through suites of measurable functional traits, comes from decades of work that largely focussed on plants. However, a key question is whether plant ecological strategies resemble those of other organisms. Among animals, ants have long been recognised to possess similarities with plants: as (largely) central place foragers. For example, individual ant workers play similar foraging roles to plant leaves and roots and are similarly expendable. Frameworks that aim to understand plant ecological strategies through key functional traits, such as the ‘leaf economics spectrum’, offer the potential for significant parallels with ant ecological strategies. Here, we explore these parallels across several proposed ecological strategy dimensions, including an ‘economic spectrum’, propagule size-number trade-offs, apparency-defence trade-offs, resource acquisition trade-offs and stress-tolerance trade-offs. We also highlight where ecological strategies may differ between plants and ants. Furthermore, we consider how these strategies play out among the different modules of eusocial organisms, where selective forces act on the worker and reproductive castes, as well as the colony. Finally, we suggest future directions for ecological strategy research, including highlighting the availability of data and traits that may be more difficult to measure, but should receive more attention in future to better understand the ecological strategies of ants. The unique biology of eusocial organisms provides an unrivalled opportunity to bridge the gap in our understanding of ecological strategies in plants and animals and we hope that this perspective will ignite further interest. Read the free Plain Language Summary for this article on the Journal blog.

Growth and reproduction are two essential life‐history traits for fungi. Understanding life‐history strategies provides insight into the environmental adaption of species. Here, we investigated the colonial morphology, vegetative growth, and asexual reproduction of the ascomycete fungus Bionectria ochroleuca in response to a variety of environmental conditions. We demonstrated that the increased temperature from 15 to 25°C induced mycelial growth and conidiation in B. ochroleuca. We also found that the optimal temperatures for mycelial growth and conidial formation in this fungus species were 25 and 30°C, respectively. However, as the temperature increased from 25 to 30°C, mycelial growth was suppressed, but the total number of conidia was significantly increased. The shift in light–dark cycles dramatically changed the morphological features of the colonies and affected both vegetative growth and asexual reproduction. Under incubation environments of alternating light and dark (16:8 and 8:16 light:dark cycles), conidiophores and conidia in the colonies formed dense‐sparse rings and displayed synchronous wave structures. When the light duration was prolonged in the sequence of 0, 8, 16, and 24 hr per day, mycelial growth was suppressed, but conidiation was promoted. Together, our results indicate that temperature and light period may trigger a trade‐off between vegetative growth and asexual reproduction in B. ochroleuca.

Fil: Garibaldi, Lucas A. Universidad Nacional de Río Negro. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural. Río Negro, Argentina. Fil: Garibaldi, Lucas A. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural. Río Negro, Argentina. Fil: Aizen, Marcelo A. Universidad Nacional del Comahue. Instituto de Investigaciones en Biodiversidad y Medioambiente. Río Negro, Argentina. Fil: Sáez, Agustín. Universidad Nacional del Comahue. Instituto de Investigaciones en Biodiversidad y Medio Ambiente Argentina. Río Negro, Argentina. Fil: Gleiser, Gabriela. Universidad Nacional del Comahue. Instituto de Investigaciones en Biodiversidad y Medio Ambiente Argentina. Río Negro, Argentina. Fil: Strelin, Marina M. Universidad Nacional del Comahue. Instituto de Investigaciones en Biodiversidad y Medio Ambiente Argentina. Río Negro, Argentina. Domestication generally involves two sequential processes: initial identification of wild species with desirable characteristics (‘progenitor filtering’) and subsequent artificial and natural selection that, respectively, improve features preferred by humans and adapt species to cultivation/captivity (‘domestication selection’). Consequently, domesticated species can differ from wild species and may share characteristics owing to convergent evolution (‘domestication syndrome’). Baring evolutionary constraints, domestication selection may generate extreme phenotypes that transcend the ‘boundaries of nature’ evident for wild species. Despite evidence of domestication syndromes in some clades, broader contributions of progenitor filtering and domestication selection to characteristics of contemporary domesticated species have received limited attention. Using comparative analysis of 49 grain-crop and 87 wild annual plant species from 15 families, we (1) addressed whether plants of crop and wild species differ for mean seed number, per-seed mass and total seed-mass investment; (2) assessed contributions of (a) progenitor filtering and (b) domestication selection to these differences; (3) evaluated whether crop characteristics exceed the boundaries of nature and (4) assessed whether seed-production characteristics of grain crops constitute components of a generic domestication syndrome. On average, grain-crop plants produce heavier seeds and greater total seed mass than wild species, but seed number per plant does not differ. Comparison of wild species between genera with or without crop species found no evidence of progenitor filtering. In contrast, crop species differed from congeneric wild species for the mass traits, but not for seed number. Greater seed investment by crops is consistent with artificial selection for enhanced seed yield (mass per harvested area), whereas heavier individual seeds suggest selection for improved nutritional quality and (or) adaptation to cultivation environments. Seed number–size characteristics of grain-crop species lie within the bivariate variation among wild species and so do not exceed the boundaries of nature. Seed number and size varied similarly between species types and generally aligned with seed-investment isoclines, suggesting an upper investment limit. Despite greater average investment in seed production and individual seeds by grain-crop species, seed-production characteristics did not vary less among crop species than among wild species, which is inconsistent with a common domestication syndrome. Domestication generally involves two sequential processes: initial identification of wild species with desirable characteristics (‘progenitor filtering’) and subsequent artificial and natural selection that, respectively, improve features preferred by humans and adapt species to cultivation/captivity (‘domestication selection’). Consequently, domesticated species can differ from wild species and may share characteristics owing to convergent evolution (‘domestication syndrome’). Baring evolutionary constraints, domestication selection may generate extreme phenotypes that transcend the ‘boundaries of nature’ evident for wild species. Despite evidence of domestication syndromes in some clades, broader contributions of progenitor filtering and domestication selection to characteristics of contemporary domesticated species have received limited attention. Using comparative analysis of 49 grain-crop and 87 wild annual plant species from 15 families, we (1) addressed whether plants of crop and wild species differ for mean seed number, per-seed mass and total seed-mass investment; (2) assessed contributions of (a) progenitor filtering and (b) domestication selection to these differences; (3) evaluated whether crop characteristics exceed the boundaries of nature and (4) assessed whether seed-production characteristics of grain crops constitute components of a generic domestication syndrome. On average, grain-crop plants produce heavier seeds and greater total seed mass than wild species, but seed number per plant does not differ. Comparison of wild species between genera with or without crop species found no evidence of progenitor filtering. In contrast, crop species differed from congeneric wild species for the mass traits, but not for seed number. Greater seed investment by crops is consistent with artificial selection for enhanced seed yield (mass per harvested area), whereas heavier individual seeds suggest selection for improved nutritional quality and (or) adaptation to cultivation environments. Seed number–size characteristics of grain-crop species lie within the bivariate variation among wild species and so do not exceed the boundaries of nature. Seed number and size varied similarly between species types and generally aligned with seed-investment isoclines, suggesting an upper investment limit. Despite greater average investment in seed production and individual seeds by grain-crop species, seed-production characteristics did not vary less among crop species than among wild species, which is inconsistent with a common domestication syndrome.

Males have the ability to compete for fertilizations through both precopulatory and postcopulatory intrasexual competition. Precopulatory competition has selected for large weapons and other adaptations to maximize access to females and mating opportunities, while postcopulatory competition has resulted in ejaculate adaptations to maximize fertilization success. Negative associations between these strategies support the hypothesis that there is a trade‐off between success at pre‐ and postcopulatory mating success. Recently, this trade‐off has been demonstrated with experimental manipulation. Males of the leaf‐footed cactus bug Narnia femorata use hind limbs as the primary weapon in male–male competition. However, males can drop a hind limb to avoid entrapment. When this autotomy occurs during development, they invest instead in large testes. While evolutionary outcomes of the trade‐offs between pre‐ and postcopulatory strategies have been identified, less work has been done to identify proximate mechanisms by which the trade‐off might occur, perhaps because the systems in which the trade‐offs have been investigated are not ones that have the molecular tools required for exploring mechanism. Here, we applied knowledge from a related model species for which we have developmental knowledge and molecular tools, the milkweed bug Oncopeltus fasciatus, to investigate the proximate mechanism by which autotomized N. femorata males developed larger testes. Autotomized males had evidence of a higher rate of transit amplification divisions in the spermatogonia, which would result more spermatocytes and thus in greater sperm numbers. Identification of mechanisms underlying a trade‐off can help our understanding of the direction and constraints on evolutionary trajectories and thus the evolutionary potential under multiple forms of selection.

The role of natural enemies in promoting coexistence of competing species has generated substantial debate. Modern coexistence theory provides a detailed framework to investigate this topic, but there have been remarkably few empirical applications to the impact of natural enemies. We tested experimentally the capacity for a generalist enemy to promote coexistence of competing insect species, and the extent to which any impact can be predicted by trade-offs between reproductive rate and susceptibility to natural enemies. We used experimental mesocosms to conduct a fully factorial pairwise competition experiment for six rainforest Drosophila species, with and without a generalist pupal parasitoid. We then parameterised models of competition and examined the coexistence of each pair of Drosophila species within the framework of modern coexistence theory. We found idiosyncratic impacts of parasitism on pairwise coexistence, mediated through changes in fitness differences, not niche differences. There was no evidence of an overall reproductive rate-susceptibility trade-off. Pairwise reproductive rate-susceptibility relationships were not useful shortcuts for predicting the impact of parasitism on coexistence. Our results exemplify the value of modern coexistence theory in multi-trophic contexts and the importance of contextualising the impact of generalist natural enemies to determine their impact. In the set of species investigated, competition was affected by the higher trophic level, but the overall impact on coexistence cannot be easily predicted just from knowledge of relative susceptibility. Methodologically, our Bayesian approach highlights issues with the separability of model parameters within modern coexistence theory and shows how using the full posterior parameter distribution improves inferences. This method should be widely applicable for understanding species coexistence in a range of systems.同生态位物种间的共存受到它们共同天敌的调控。这一调控的影响仍备受争议。现代共存理论为这一问题提供了量化的研究框架, 但相关的实证研究还远远落后于理论进展。 我们通过实验探究了非特异性寄生蜂如何调控其宿主之间的竞争性共存, 并尝试用宿主的繁殖力与免疫力间的关系对共存结果加以解释。 在实验室的模拟实验中, 我们将六个热带雨林果蝇物种两两组合后放置于有或者没有寄生蜂的环境下, 记录子代果蝇的数量。我们用这些实验数据拟合出宿主间的物种竞争模型, 再通过现代共存理论推导宿主间的共存关系。 我们发现非特异性寄生蜂改变了不同宿主物种间的适合度差异, 但并没有改变它们的生态位差异。非特异性寄生蜂最终的调控效果依宿主组合的不同而不同, 并没有统一的规律。宿主的繁殖力和免疫力间并不普遍存在此消彼长的关系。即使在某几对宿主间存在负相关性, 寄生蜂的调控也并不总是促进共存。 我们的研究示范了如何将现代共存理论应用于多营养级生态网络,强调了寄生蜂对宿主间共存的影响依具体情况而定: 宿主物种间的竞争受到更高营养级的调控, 而此调控对宿主间共存的影响并不能简单地通过它们的对寄生蜂的免疫能力进行预测。另外, 我们的统计分析指出了在应用现代共存理论到实际系统时将面临的参数协变性问题, 并展示了如何利用贝叶斯统计方法完善对物种共存关系的推测。我们推荐这一方法被更广泛地应用于物种间共存的研究。.

Evidence for selective disadvantages of large body size remains scarce in general. Previous studies of the yellow dung fly Scathophaga stercoraria have demonstrated strong positive sexual and fecundity selection on male and female size. Nevertheless, the body size of flies from a Swiss study population has declined by ~10% 1993–2009. Given substantial heritability of body size, this negative evolutionary response of an evidently positively selected trait suggests important selective factors being missed. An episodic epidemic outbreak of the fungus Entomophthora scatophagae permitted assessment of natural selection exerted by this fatal parasite. Fungal infection varied over the season from ~50% in the cooler and more humid spring and autumn to almost 0% in summer. The probability of dying from fungal infection increased with adult fly body size. Females never laid any eggs after infection, so there was no fungus effect on female fecundity beyond its impact on mortality. Large males showed their typical mating advantage in the field, but this positive sexual selection was nullified by fungal infection. Mean fluctuating asymmetry of paired appendages (legs, wings) did not affect the viability, fecundity or mating success of yellow dung flies in the field. This study documents rare parasite-mediated disadvantages of large-sized flies in the field. Reduced ability to combat parasites such as Entomophthora may be an immunity cost of large body size in dung flies, although the hypothesized trade-off between fluctuating asymmetry, a presumed indicator of developmental instability and environmental stress, and immunocompetence was not found here.

Background Sexual dimorphism in immunity is believed to reflect sex differences in reproductive strategies and trade-offs between competing life history demands. Sexual selection can have major effects on mating rates and sex-specific costs of mating and may thereby influence sex differences in immunity as well as associated host–pathogen dynamics. Yet, experimental evidence linking the mating system to evolved sexual dimorphism in immunity are scarce and the direct effects of mating rate on immunity are not well established. Here, we use transcriptomic analyses, experimental evolution and phylogenetic comparative methods to study the association between the mating system and sexual dimorphism in immunity in seed beetles, where mating causes internal injuries in females. Results We demonstrate that female phenoloxidase (PO) activity, involved in wound healing and defence against parasitic infections, is elevated relative to males. This difference is accompanied by concomitant sex differences in the expression of genes in the prophenoloxidase activating cascade. We document substantial phenotypic plasticity in female PO activity in response to mating and show that experimental evolution under enforced monogamy (resulting in low remating rates and reduced sexual conflict relative to natural polygamy) rapidly decreases female (but not male) PO activity. Moreover, monogamous females had evolved increased tolerance to bacterial infection unrelated to mating, implying that female responses to costly mating may trade off with other aspects of immune defence, an hypothesis which broadly accords with the documented sex differences in gene expression. Finally, female (but not male) PO activity shows correlated evolution with the perceived harmfulness of male genitalia across 12 species of seed beetles, suggesting that sexual conflict has a significant influence on sexual dimorphisms in immunity in this group of insects. Conclusions Our study provides insights into the links between sexual conflict and sexual dimorphism in immunity and suggests that selection pressures moulded by mating interactions can lead to a sex-specific mosaic of immune responses with important implications for host–pathogen dynamics in sexually reproducing organisms.

To examine the habitat usage of adult Pacific bluefin tuna (PBF), electronic tagging was conducted in the Sea of Japan during May and June of 2012-2017. Archival tags were internally implanted and pop-up satellite archival transmitting tags were deployed; data on the horizontal movements and diving behaviours of 36 individual PBF were successfully retrieved. In the summer spawning season, the tagged PBF were concentrated near Sado Island and Oki Island in the Sea of Japan, and they were distributed widely to the southwest (near Tsushima Island) or northeast (near the Tsugaru Strait) in the autumn and winter. We obtained the first long-term tracking record (246 d) for adult PBF, and this individual exhibited residency in a known spawning region during the spawning season in the proximity of warm-core eddy features. This fish spent most of the daytime below the thermocline between 30 and 150 m depths where the surface ambient temperature was 26.0 ± 1.5°C, but at night it ventured into the warm surface layer. Its whole-body heat transfer coefficient increased when it experienced warm waters (≥24°C), which we suggest is a physiological response to avoid overheating. The mean peritoneal cavity temperature was only 1.8°C higher than the ambient temperature, compared with 6.9°C higher during the cooler autumn-winter period. Our hypothesis is that the warm surface temperatures found in the spawning grounds induce a physiology-reproduction trade-off in adult PBF, which must behaviourally and physiologically thermoregulate their body temperature to gain spatial and temporal access to oceanographic conditions that may promote larval survivorship and growth.

Adaptation to environmental temperature depends on both direct and correlated responses to selection for reproduction and survival at elevated temperature. Sexual selection is one of the most powerful of all evolutionary forces and we tested both fecundity and longevity for their correlated responses to sexual selection on the ability to mate (mating success) at high temperature. Replicated lines selected for 15 generations of mating at 33 °C (S lines) were compared to their respective controls (C lines) in D. buzzatii in three thermal regimes: 25 °C, 30 °C and a cyclic thermal regime for longevity from 17 to 32 °C. Previous work showed that S lines successfully responded for the trait selected and the present results show a trade-off in males between mating success at elevated temperature and longevity in all three thermal regimes tested. In addition, inter-sexual relationships of trade-offs were apparent between male longevity and female fecundity as correlated selection responses. In this sex-specific association of trade off, S females exhibited higher fecundity than C females at 30 °C only if females were exposed to a limited social environment of a single male. Overall, selection for mating at high temperature increases female fecundity at high temperature but decreases longevity in males. This sex-specific and negative impact on longevity in males could be the result of a genetic correlation between mating success at high temperature and reduced longevity in this sex.

We investigated the performance trade-offs of fleas (Siphonaptera) while adapting to a novel host using two host generalists (Xenopsylla conformis and Xenopsylla ramesis) and one host specialist (Parapulex chephrenis) maintained on their principal hosts (Meriones crassus for Xenopsylla and Acomys cahirinus for P. chephrenis). We asked whether, over generations, (i) a host generalist may become a specialist by evolving the ability to exploit a novel host and losing the ability to exploit an original host and (ii) a host specialist can become a generalist by evolving the ability to exploit a novel host without losing the ability to exploit an original host. We established an experimental line of each species on a novel host (Acomys russatus for Xenopsylla and M. crassus for P. chephrenis) and maintained this line on this host during 23 generations. We compared reproductive performance of progenitors of each line and their descendants when they exploited either original or novel host in terms of egg number and size, hatching success, offspring production, and offspring size. We found changes in performance over generations in female offspring size only. Xenopsylla conformis demonstrated a tendency to become a host specialist (increased performance on the novel host with a concomitant decreased performance on the original host), whereas P. chephrenis demonstrated a tendency to become a host generalist (increased performance on the novel host without a concomitant decreased performance on the original host). We conclude that the probability of generalist to specialist transition, and vice versa, is context-dependent and varies between species.

In many vertebrate societies dominant individuals breed at substantially higher rates than subordinates, but whether this hastens ageing remains poorly understood. While frequent reproduction may trade off against somatic maintenance, the extraordinary fecundity and longevity of some social insect queens highlight that breeders need not always suffer more rapid somatic deterioration than their nonbreeding subordinates. Here, we used extensive longitudinal assessments of telomere dynamics to investigate the impact of dominance status on within-individual age-related changes in somatic integrity in a wild social bird, the white-browed sparrow-weaver (Plocepasser mahali). Dominant birds, who monopolise reproduction, had neither shorter telomeres nor faster telomere attrition rates over the long-term (1-5 years) than their subordinates. However, over shorter (half-year) time intervals dominants with shorter telomeres showed lower rates of telomere attrition (and evidence suggestive of telomere lengthening), while the same was not true among subordinates. Dominants may therefore invest more heavily in telomere length regulation (and/or somatic maintenance more broadly); a strategy that could mitigate the long-term costs of reproductive effort, leaving their long-term telomere dynamics comparable to those of subordinates. Consistent with the expectation that reproduction entails short-term costs to somatic integrity, telomere attrition rates were most severe for all birds during the breeding seasons of wetter years (rainfall is the key driver of reproductive activity in this arid-zone species). Our findings suggest that, even in vertebrate societies in which dominants monopolise reproduction, dominants may experience long-term somatic integrity trajectories indistinguishable from those of their nonreproductive subordinates.

Immune responses are intuitively beneficial, but they can incur a variety of costs, many of which are poorly understood. The nature and extent of trade-offs between immune activity and other components of the integrated phenotype can vary, and depend on the type of immune challenge, as well as the energetic costs of simultaneously expressing other traits. There may also be sex differences in both immune activity and immunity-induced trade-offs, particularly in the case of trade-offs involving functional traits such as whole-organism performance capacities that might be of different fitness value to males and females. We tested the response of three performance traits (sprinting, endurance, and biting) to two different immune challenges (LPS injection and wound healing) in both male and female Anolis carolinensis lizards. We found clear differences in how male and female performance capacities were affected by immune activation. LPS injection and wound healing had interactive effects on all three performance traits in males, but immune activation did not affect female performance. We also found that the degree of wound healing exhibited complex interactive effects involving sex and type of immune activation that varied depending on the performance trait in question. These results demonstrate that male and female green anoles experience different consequences of immune responses, and also that the type and extent of that activation can drive trait-specific performance trade-offs.

Jumping spiders (Salticidae) are diurnal visual predators known for elaborate, vision-mediated behaviour achieved through the coordinated work of four pairs of camera-type eyes. One pair (‘principal’ eyes) is responsible for colour and high spatial acuity vision, while three pairs (‘secondary’ eyes) are mostly responsible for motion detection. Based on its unusual capacity to visually discriminate specific prey in very low, but also under bright light settings, we investigated the structure of the principal and one pair of secondary eyes (antero-lateral eyes) of Cyrba algerina to determine how these eyes achieve the sensitivity, while maintaining spatial acuity, needed to sustain behaviour in low light. Compared to salticids that live in bright light, the principal eyes of C. algerina have a short focal length, and wide contiguous twin rhabdomeres that support optical pooling, overall favouring sensitivity (0.39 μm2), but without fully compromising acuity (12.4 arc min). The antero-lateral eye retinae have large receptors surrounded by pigment granules, providing effective shielding from scattered light. These adaptations may be beneficial for a xeric salticid species with a ‘blended’ lifestyle: generally living and hunting under stones in the dark, but sometimes venturing above them, in dramatically different light conditions.

Invertebrate immune priming is defined as an enhanced protection against secondary pathogenic infections when individuals have been previously exposed to the same or a different pathogen. Immune priming can be energetically costly for individuals, thus impacting trade-offs between life-history traits, like reproduction, growth, and lifetime. Here, the reproductive cost(s) and senescence patterns of immune priming against S. enterica in the common woodlouse A. vulgare (Crustacea, Isopoda) were investigated. Four different groups of females were used that either (1) have never been injected (control), (2) were injected twice with S. enterica (7 days between infections), (3) were firstly injected with LB-broth, then with S. enterica, and (4) females injected only once with S. enterica. All females were allowed to breed with one non-infected male and were observed for eight months. Then, the number of clutches produced, the time taken to produce the clutch(es), the number of offspring in each clutch, the senescence biomarkers of females, and parameters of their haemocytes were compared. The result was that immune priming did not significantly impact reproductive abilities, senescence patterns, and haemocyte parameters of female A. vulgare, but had an indirect effect through body weight. The lighter immune primed females took less time to produce the first clutch, which contained less offspring, but they were more likely to produce a second clutch. The opposite effects were observed in the heavier immune primed females. By highlighting that immune priming was not as costly as expected in A. vulgare, these results provide new insights into the adaptive nature of this immune process.

Trivers and Willard proposed that female mammals should adjust their investment in male versus female offspring relative to their ability to produce high-quality offspring. We tested whether litter size-sex ratio trade-offs predicted by Adaptive Sex Allocation (ASA) theory occur among Richardson's ground squirrel (Urocitellus richardsonii) dams over 10 distinct breeding years in a population where individuals experienced variability in food availability and habitat disruption. Litters of primiparous dams became increasingly female-biased with increasing litter size, but that trend waned among second litters born to dams, and reversed among third litters, with larger litters becoming more male-biased, suggesting that ASA is a product of interacting selection pressures. Trade-offs were not associated with habitat disruption, the availability of supplementary food, or dam age. An association between habitat disruption and male-biased sex ratios, the prevalence of litter size-sex ratio trade-offs and placental scar counts exceeding the number of juveniles at weaning in our population, but not in a geographically distinct population of conspecifics exposed to different environmental conditions reveal that the expression of ASA varies among populations and among years within populations, illustrating the conditional nature of ASA.

Overwintering is a challenging period in the life of temperate insects. A limited energy budget characteristic of this period can result in reduced investment in immune system. Here, we investigated selected physiological and immunological parameters in laboratory‐reared and field‐collected harlequin ladybirds (Harmonia axyridis). For laboratory‐reared beetles, we focused on the effects of winter temperature regime (cold, average, or warm winter) on total haemocyte concentration aiming to investigate potential effects of ongoing climate change on immune system in overwintering insects. We recorded strong reduction in haemocyte concentration during winter; however, there were only limited effects of winter temperature regime on changes in haemocyte concentration in the course of overwintering. For field‐collected beetles, we measured additional parameters, specifically: total protein concentration, antimicrobial activity against Escherichia coli, and haemocyte concentration before and after overwintering. The field experiment did not investigate effects of winter temperature, but focused on changes in inducibility of insect immune system during overwintering, that is, measured parameters were compared between naïve beetles and those challenged by Escherichia coli. Haemocyte concentration decreased during overwintering, but only in individuals challenged by Escherichia coli. Prior to overwintering, the challenged beetles had a significantly higher haemocyte concentration compared to naïve beetles, whereas no difference was observed after overwintering. A similar pattern was observed also for antimicrobial activity against Escherichia coli as challenged beetles outperformed naïve beetles before overwintering, but not after winter. In both sexes, total protein concentration increased in the course of overwintering, but females had a significantly higher total protein concentration in their hemolymph compared to males. In general, our results revealed that insect’s ability to respond to an immune challenge is significantly reduced in the course of overwintering., Prior to overwintering, the challenged insects had a significantly higher haemocyte concentration compared to naïve insects, whereas no difference was observed after overwintering. A similar pattern was observed also for antimicrobial activity against Escherichia coli as challenged insects outperformed naïve insects before overwintering, but not after winter.

Offspring desertion is often a plastic behavioral strategy that requires precise timing as the termination of parental care may have profound consequences for the fitness of parents and offspring. However, the decision process involved with termination of care is still poorly understood. Snowy Plovers Charadrius nivosus show highly flexible brood care with some females deserting the brood early and re-mate, whereas others provide extended care until the young are independent. Using a dynamic modeling framework, we investigated the effect of multiple factors on the decision-making process of female brood care in Ceuta, Mexico over a 7-year period. Females were more likely to stay with larger broods, while their probability of care was lower at the beginning of the season, when re-mating opportunities are higher than later in the season. Offspring condition at hatching did not influence the length of female care. Chick death and offspring desertion frequently coincided, suggesting that deteriorating offspring condition may trigger female desertion. Females deserted broods with high survival prospects when their absence did not impact negatively chick survival. Conversely, females deserted broods with low survival prospects when chick mortality despite female care reduced the value of the brood and re-mating was still possible. This suggests that female Snowy Plovers are sensitive to the needs and the value of their broods and adjust their parental care strategy accordingly. Taken together, we conclude that offspring desertion is a highly plastic behavior that allows females to maximize their reproductive success in a stochastic environment.

Life‐history trade‐offs are important coexistence mechanisms in plant communities. In particular, a trade‐off between seed quality and seed output may explain coexistence among species with a wide variety of seed sizes in heterogeneous landscapes with varying degrees of local stresses such as shade, drought and browsing. Under spatially implicit formulations of the tolerance‐fecundity trade‐off, species diversity is only bounded by community size and environmental heterogeneity. However, these formulations leave unanswered the question of how dispersal limitation, an important aspect of real communities, impacts the ability of the tolerance‐fecundity trade‐off to support coexistence. Here we show using stochastic cellular automata that coexistence under the tolerance‐fecundity trade‐off in a spatially structured landscape is strongly modulated by the interactions between the spatial scales of species dispersal and environmental variability. Specifically, coexistence in a patchy landscape is higher under short dispersal scales relative to the scale of environmental variation. These conditions allow species to segregate spatially and thus avoid interspecific competition. In addition to dispersal limitation, coexistence under the tolerance‐fecundity trade‐off is promoted by a sharp drop in tolerance as local environmental stress increases, a high overall seed output across species, local homogeneity in environmental conditions and weak age structure in fertility. In particular, coexistence is much higher when species have full tolerance to stress levels below a threshold and zero tolerance above that threshold, with nothing in between. This steep gradient contributes to coexistence because it maximizes niche separation between similar species. Synthesis. When plants compete for space, dispersal limitation and landscape spatial structure can conspire to boost coexistence and diversity. Our results show that the tolerance‐fecundity trade‐off is a strong niche differentiation mechanism when species experience a well‐defined distinction between suitable and unsuitable environments, and supports higher diversity when dispersal scales are shorter than the scales of variation in the environment. We conclude that the trade‐off is more likely to be a relevant coexistence mechanism in the context of large‐scale environmental variation, such as topography, than small‐scale variation, such as in litter cover and canopy shading.

Exploitative parasites are predicted to evolve in highly connected populations or in expanding epidemics. However, many parasites rely on host dispersal to reach new populations, potentially causing conflict between local transmission and global spread. We performed experimental range expansions in interconnected microcosms of the protozoan Paramecium caudatum, allowing natural dispersal of hosts infected with the bacterial parasite Holospora undulata. Parasites from range front treatments facilitated host dispersal and were less virulent, but also invested less in horizontal transmission than parasites from range cores. These differences were consistent with parameter estimates derived from an epidemiological model fitted on population-level time-series data. Our results illustrate how dispersal selection can have profound consequences for the evolution of parasite life history and virulence. Decrypting the eco-evolutionary processes that shape parasite 'dispersal syndromes' may be important for the management of spreading epidemics in changing environments, biological invasions or in other spatial non-equilibrium settings.

Premise of research. A trade-off between seed mass and seed output defines a central axis of ecological variation among plant species. While an observed negative seed mass–seed output relationship ...

We investigate the evolution of a gene for paternal care, with pleiotropic effects on male mating fitness and offspring viability, with and without extrapair copulations (EPCs). We develop a population genetic model to examine how pleiotropic effects of a male mating advantage and paternal care are affected by “good genes” and EPCs. Using this approach, we show that the relative effects of each on fitness do not always predict the evolutionary change. We then find the line of combinations of mating success and paternal care that bisects the plane of possible values into regions of positive or negative gene frequency change. This line shifts when either good genes or EPCs are introduced, thereby expanding or contracting the region of positive gene frequency change and significantly affecting the evolution of paternal care. Predictably, a direct viability effect of “good genes” that enhances offspring viability constrains or expands the parameter space over which paternal care can evolve, depending on whether the viability effect is associated with the paternal care allele or not. In either case, the effect of a “good gene” that enhances offspring viability is substantial; when strong enough, it can even facilitate the evolution of poor paternal care, where males harm their young. When nonrandom mating is followed by random EPCs, the genetic regression between sire and offspring is reduced and, consequently, the relative strengths of selection are skewed away from paternal care and toward the male mating advantage. However, when random mating is followed by nonrandom EPCs, a situation called “trading up” by females, we show that selection is skewed in the opposite direction, away from male mating advantage and toward paternal care across the natural range of EPC frequencies., We present a population genetic model to investigate the evolution of a gene for paternal care, when it also has pleiotropic effects on male mating fitness and offspring viability, with and without extrapair copulations (EPCs). We illustrate the quantitative evolutionary relationship between the different direct and indirect fitness effects hypothesized to influence the evolution of male parental care. We model trade‐offs: (1) between a direct effect on male mating success and an indirect effect on paternal caregiving; (2) between male mating success and offspring viability; and, (3) between good genes and bad parenting or vice versa. We show that a male mating bias is an episode of selection occurring before reproduction and offspring viability selection. Moreover, it differentially affects the direct and indirect components of offspring viability selection as they affect mean fitness and gene frequency change.

Understanding the evolution of plant defenses against herbivores requires identifying the benefits and costs of defense. Here, we tested the hypothesis that the benefits and costs of hydrogen cyanide (HCN) defense against herbivory on white clover (Trifolium repens) are temperature dependent. We first tested how temperature affected HCN production in vitro, and then examined how temperature influenced the efficacy of HCN defense of T. repens against a generalist slug (Deroceras reticulatum) herbivore using no-choice and choice feeding trial assays. To understand how temperature affected the costs of defense, plants were exposed to freezing, and HCN production, photosynthetic activity, and ATP concentration were quantified. HCN production increased linearly from 5 °C to 50 °C, and cyanogenic plants experienced reduced herbivory compared to acyanogenic plants only at warmer temperatures when fed upon by young slugs. Freezing temperatures induced cyanogenesis in T. repens and decreased chlorophyll fluorescence. Cyanogenic plants experienced lower ATP levels than acyanogenic plants due to freezing. Our study provides evidence that the benefits of HCN defense against herbivores are temperature dependent, and freezing may inhibit ATP production in cyanogenic plants, but the physiological performance of all plants recovered quickly following short-term freezing. These results contribute to understanding how varying environments alter the benefits and costs of defense in a model system for the study of plant chemical defenses against herbivores.

Countergradient variation has been detected in diverse taxa. In a common manifestation, individuals from colder environments develop faster than conspecifics from warmer environments when placed in a common garden. Where such a pattern exists, it implies a trade-off: Individuals from warmer environments have intrinsic rates of development lower than those demonstrated by other individuals of the same species. We explored a trade-off between development rate and locomotor performance in the wood frog (Rana sylvatica), an amphibian for which countergradient variation has been well documented. We reared wood frogs from 10 populations under two temperature regimes, bracketing the temperatures observed in local natural ponds. Individuals reared under warmer conditions developed more rapidly but exhibited burst speeds 20% lower than individuals reared under colder conditions. The slope of the reaction norm was consistent across the 10 populations and thus, we found no evidence of countergradient variation in performance. Burst speed assays of wild-caught tadpoles from the same populations showed a similar but nonsignificant trend, with greater variability among ponds. Overall, our findings support the existence of a development-performance trade-off that may be of broad importance and which may help explain the widespread occurrence of countergradient variation.

We analyzed diel vertical migration (DVM) of overwintering Antarctic krill at South Georgia, a region that remains ice-free during the austral winter. We considered DVM in relation to krill body length, based on Japanese krill fishery data (1990-2012), and examined DVM in relation to food availability and predator (Antarctic fur seal) avoidance. We report that diel changes in median trawling depth (a proxy for krill vertical distribution) showed significant interannual variation; the overall trend was such that during both daytime and nighttime, the larger the average size of krill, the deeper their median depth. Consistent with the literature, this size-dependent DVM relates to food availability and size-dependent diet; that is, with increasing body length, krill tend to rely less on phytoplankton (which are available in surface layers) as a winter food source. Concerning predator avoidance, and based on analyses using an optimal foraging dive model for fur seals, DVM showed close agreement with size-dependent predation risk; that is, larger krill remained deeper, thereby reducing mortality from fur seals. Therefore, DVM of overwintering krill appears to reflect a compromise between adequate feeding conditions and minimizing predation risk. There was, however, an exception that krill occurred at a shallow depth in winter 2006 when phytoplankton abundance was particularly low and krill density was very high. This supports the hypothesis that physiological demands (i.e. hunger) may become a more important factor affecting DVM than predator avoidance under conditions of insufficient food availability.

The need for reliable prediction of species distributions dependent upon traits has been hindered by a lack of model transferability testing. We tested the predictive capacity of trait-SDMs by fitting hierarchical generalised linear models with three trait and four environmental predictors for 20 eucalypt taxa in a reference region. We used these models to predict occurrence for a much larger set of taxa and target areas (82 taxa across 18 target regions) in south-eastern Australia. Median predictive performance for new species in target regions was 0.65 (area under receiver operating curve) and 1.24 times random (area under precision recall curve). Prediction in target regions did not worsen with increasing geographic, environmental or community compositional distance from the reference region, and was improved with reliable trait–environment relationships. Transfer testing also identified trait–environment relationships that did not transfer. These results give confidence that traits and transfer testing can assist in the hard problem of predicting environmental responses for new species, environmental conditions and regions.

Adaptation to current and future climates can be constrained by trade‐offs between fitness‐related traits. Early seedling emergence often enhances plant fitness in seasonal environments, but if earlier emergence in response to seasonal cues is genetically correlated with lower potential to spread emergence among years (i.e., bet‐hedging), then this functional trade‐off could constrain adaptive evolution. Consequently, selection favoring both earlier within‐year emergence and greater spread of emergence among years—as is expected in more arid environments—may constrain adaptive responses to trait value combinations at which a performance gain in either function (i.e., evolving earlier within‐ or greater among‐year emergence) generates a performance loss in the other. All such trait value combinations that cannot be improved for both functions simultaneously are described as Pareto optimal and together constitute the Pareto front. To investigate how this potential emergence timing trade‐off might constrain adaptation to increasing aridity, we sourced seeds of two grasses, Stipa pulchra and Bromus diandrus, from multiple maternal lines within populations across an aridity gradient in California and examined their performance in a greenhouse experiment. We monitored emergence and assayed ungerminated seeds for viability to determine seed persistence, a metric of potential among‐year emergence spread. In both species, maternal lines with larger fractions of persistent seeds emerged later, indicating a trade‐off between within‐year emergence speed and potential among‐year emergence spread. In both species, populations on the Pareto front for both earlier emergence and larger seed persistence fraction occupied significantly more arid sites than populations off the Pareto front, consistent with the hypothesis that more arid sites impose the strongest selection for earlier within‐year emergence and greater among‐year emergence spread. Our results provide an example of how evaluating genetically based correlations within populations and applying Pareto optimality among populations can be used to detect evolutionary constraints and adaptation across environmental gradients.

Behavioural thermoregulation can ameliorate thermal stress but is costly. For species that court in a thermally stressful microhabitat, sexual selection via endurance rivalry favours individuals that are able and willing to endure harsh conditions in the courtship habitat, as retreats to a thermal refuge will reduce mating opportunities. The relative costs and benefits of refuge use versus continued courtship in the face of thermal risk, which vary across abiotic and biotic contexts, determine the optimal behavioural strategy. We examined the social and abiotic factors driving behavioural decisions related to thermoregulatory retreat in the fiddler crab Austruca mjoebergi. Male fiddler crabs perform a courtship display on the thermally stressful intertidal sediment surface. Time on the surface, and thus time available for display, was limited by high temperatures; as temperature increased, surface time decreased. Yet when presented with a stimulus female, males were more likely to perform the courtship display, displayed at a higher rate and increased time spent on the surface. These results demonstrate that behavioural decisions related to thermal retreat depend both on the abiotic conditions that influence the degree of thermal stress and on the social conditions that influence the reproductive prospects of the individual.