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Finding interventions to break the trade-off between reproduction and lifespan can provide insight into physiological limitations of animals. Effects of dietary protein quality on the trade-off are currently unclear, but clarity could lead to better designed diets that match animal needs. Dietary amino acid blends matching yolk proteins support reproduction and extend lifespan in fruit flies. To test if this is conserved across species, we matched dietary amino acids to vitellogenin to test reproduction and lifespan in adult females of the lubber grasshopper. Specifically, we compared varying degrees of protein quality by manipulating dietary essential amino acids. We identified a high-quality protein diet (amino acids matched to vitellogenin, or reproductive needs) that increased reproduction and matched lifespan in comparison to diets that differed only in the ratios of essential amino acids (i.e., were isocaloric and isonitrogenous). All these diets had longer lifespan but lower reproductive output than fully fed controls. In a separate experiment, full reproduction was possible on the high-quality artificial diet when offered at a 78% higher protein quantity and with a larger lettuce supplement (~ 17% of ad libitum). Additionally, we observed that as dietary protein quality was decreased (i.e., diets were less matched to vitellogenin), reproduction was reduced, and lifespan was extended in the more extreme scenarios. Taken together, these results indicate that the balance of dietary essential amino acids plays an important role in the lifespan and reproduction trade-off, while more work needs to be conducted to find the optimal diet mix for this species. [ABSTRACT FROM AUTHOR]

Life history theory suggests that females should allocate greater resources to immune function than males to increase their lifetime fitness. Although higher immune responses in adult females compared to males have been reported across various insect species, sexual differences in immunity during juvenile stages have been less explored. We investigated sexual differences in haemocyte density and phenoloxidase (PO) activiy in two species of rhinoceros beetles, Trypoxylus dichotomus (Linnaeus) (Coleoptera: Scarabaeidae) and Oryctes rhinoceros (Linnaeus) (Coleoptera: Scarabaeidae), during their larval stages. We found that male T. dichotomus larvae consistently displayed lower haemocyte densities than females, and this sexual difference persisted until adulthood. The sexual difference in immunity across life stages may be associated with sex-specific resource allocation patterns throughout lifetime. However, the less sexually-dimorphic species, O. rhinoceros, did not exhibit sexual differences in haemocyte densities during immature stages. PO activities did not exhibit sexual differences in larvae of either species. Additionally, we observed an increase in haemocyte densities with larval developmental stages in both species. However, while T. dichotomus exhibited lower PO activities in later stages, PO activities in O. rhinoceros did not largely change throughout development. Path analysis revealed that the ontogenetic changes in constitutive immune parameters were primarily driven by direct effects of body size rather than age. The species- and parameter-specific ontogenetic trends in immunity could be associated with allocation to other life history traits or tradeoffs among immunity parameters. [ABSTRACT FROM AUTHOR]

While engagement in school learning is key to high attainment, very little research has explored what motivates engagement as seen from the child’s perspective. This paper addresses what motivates engagement – and alternatively what might promote aversion from engagement – among primary-school children designated by the current system in England as ‘lower-attaining’. We consider the relationship between their distress and educational policy that promotes grouping by attainment. We used Self Determination Theory (SDT) as our guiding theoretical framework to explore these children’s distress as related to lack of motivation to engage in school-work. We employed the life-history approach with a group of 23 ‘lower-attaining’ primary-school children. We report how two of these children, as case studies, described their engagement during schooling over five years from age 7 in primary-school to age 12 in secondary-school, during termly activity-interviews and classroom observations (for full details of the wider study, see https://profiles.ucl.ac.uk/48423-eleanore-hargreaves). We found that the children sometimes experienced distress, which took the form of anxiety, sorrow, anger and pain. These were triggered by, and in turn further promoted, a weak Sense of Competence, Autonomy and Relatedness. We consider in this article whether these negative experiences were related to policy emphasis on attainment in tests, because of how these defined competence narrowly in terms of test results in core subjects. The life-histories portray how distress may have hindered engagement, learning and wellbeing, ultimately infringing social justice. [ABSTRACT FROM AUTHOR]

Phenology is a major component of animals’ breeding, as they need to adjust their breeding timing to match optimal environmental conditions. While the effects of shifting phenology are well-studied on populations, few studies emphasise its ecological causes and consequences at the inter-individual level. Using a 20-year monitoring of more than 2500 breeding events from ~ 500 breeding little penguins (Eudyptula minor), a very asynchronously breeding seabird, we investigated the consequences of late breeding on present and next breeding events. We found that individuals breeding later had reduced breeding success, lighter chicks at fledging, lower probability of laying a second clutch, and decreased parents’ post-breeding body condition. Importantly, we found important cycling effects where delayed breeding during a given year led to significantly later laying date, lower breeding probability and lower breeding success when they breed during the next season, suggesting potential carry-over effects from one season to the next. To further understand the causes of such variability in phenology while earlier breeding is associated with better individual fitness, we aimed to assess intrinsic differences amongst individuals. We showed that the heterogeneity in breeding timing was partly fixed, the laying date being a significantly repeatable behaviour (17%), asking for more studies on heritability or early-development effects. This extensive study highlights the combined roles of carry-over effects and intrinsic differences on individual phenology, with important implications on breeding capacity through life. [ABSTRACT FROM AUTHOR]

Isolation and limited migration among populations and differences in the environments they inhabit set up conditions for population differentiation of life‐history traits, even across a regional spatial scale, such as a statewide landscape of lakes and reservoirs. Our objective was to understand how largemouth bass (Micropterus nigricans) life histories differ across a regional spatial scale (Ohio, USA) and whether environmental differences are influencing this variation. To address this, we (1) described spatial variation in largemouth bass life‐history traits, with a specific interest in potential correlations between early‐life growth and later‐life traits and (2) tested whether life‐history traits can be predicted by reservoir characteristics. We found two groups of correlated population traits: the inverse relationship of early‐life growth rate with population density and asymptotic length and the positive relationship between adult size and asymptotic length. Early‐life growth had a positive relationship (and population density and asymptotic length had a negative relationship) with littoral habitat availability and other environmental conditions expected to enhance early growth. Despite the strong influence of reservoir characteristics on life‐history traits in our analysis, the most plausible model could not give precise predictions of these life‐history traits, suggesting that the availability of data on other aspects of the populations and environments may improve our ability to understand life‐history differences. Overall, our results suggest that, even among recently separated populations, we should expect differences in growth patterns and that we cannot understand drivers of these differences without considering possible correlations in growth patterns across the lifespan. [ABSTRACT FROM AUTHOR]

Non-lethal injury in animals is both common and costly. The cost of regenerating autotomized limbs may leave less energy available for processes such as reproduction and growth, leading to trade-offs. Such trade-offs are context-dependent, and an individual's energy allocation strategies may vary widely based on its condition and the environment. However, many traditional bioenergetics models have relied on fixed energy allocation rules, such as the -rule of dynamic energy budget theory, which assumes a fixed proportion (κ) of assimilated energy is always allocated to growth and maintenance. To determine whether incorporating optimality approaches into bioenergetics models improves the ability to predict energy allocation, we developed a dynamic state variable model that identifies optimal limb regeneration strategies in a model system, the Asian shore crab Hemigrapsus sanguineus. Our model predictions align with known patterns for this species, including increased regeneration effort with injury severity, a shift from reproduction to growth as consumption amount increases, and an increase in regeneration effort as regeneration progresses. Lastly, Monte Carlo simulations of individuals from a previous experiment demonstrate that flexible energy allocation successfully predicts reproductive effort, suggesting that this approach may improve the accuracy of bioenergetics modeling. [ABSTRACT FROM AUTHOR]

Abstract Maximizing the life-long reproductive output would lead to the prediction that short-lived and fast aging species would undergo no – if any – reproductive senescence. Turquoise killifish (Nothobranchius furzeri) are naturally short-lived teleosts, and undergo extensive somatic aging, characterized by molecular, cellular, and organ dysfunction following the onset of sexual maturation. Here, we tested whether naturally short-lived and fast aging male turquoise killifish maximize reproduction and display minimal – if any, reproductive senescence. We analysed age-related changes in sperm traits, the proportion of fertilized eggs, as well as embryo survival. Contrary to the expectation of no reproductive aging, we found that turquoise killifish males undergo extensive reproductive aging, consisting in the age-dependent decline in sperm quality, decreased proportion of fertilized eggs and lower embryo survival. Our results indicate that male turquoise killifish do not trade-off age-dependent soma decline with life-long sustained reproductive fitness. Instead, somatic and reproductive aging appear to occur simultaneously. Our findings question generalized soma vs. reproductive senescence trade-off models and highlight the importance of integrating species-specific ecological and demographic constraints to explain observed life history traits.

Although still prevalent in many human societies, the practice of cousin marriage has precipitously declined in populations undergoing rapid demographic and socioeconomic change. However, it is still unclear whether changes in the structure of the marriage pool or changes in the fitness-relevant consequences of cousin marriage more strongly influence the frequency of cousin marriage. Here, we use genealogical data collected by the Tsimane Health and Life History Project to show that there is a small but measurable decline in the frequency of first cross-cousin marriage since the mid-twentieth century. Such changes are linked to concomitant changes in the pool of potential spouses in recent decades. We find only very modest differences in fitness-relevant demographic measures between first cousin and non-cousin marriages. These differences have been diminishing as the Tsimane have become more market integrated. The factors that influence preferences for cousin marriage appear to be less prevalent now than in the past, but cultural inertia might slow the pace of change in marriage norms. Overall, our findings suggest that cultural changes in marriage practices reflect underlying societal changes that shape the pool of potential spouses.

Abstract Hox genes are transcriptional regulators that elicit cell positional identity along the anterior–posterior region of the body plan across different lineages of Metazoan. Comparison of Hox gene expression across distinct species reveals their evolutionary conservation; however, their gains and losses in different lineages can correlate with body plan modifications and morphological novelty. We compare the expression of 11 Hox genes found within Streblospio benedicti, a marine annelid that produces two types of offspring with distinct developmental and morphological features. For these two distinct larval types, we compare Hox gene expression through ontogeny using hybridization chain reaction (HCR) probes for in situ hybridization and RNA-seq data. We find that Hox gene expression patterning for both types is typically similar at equivalent developmental stages. However, some Hox genes have spatial or temporal differences between the larval types that are associated with morphological and life-history differences. This is the first comparison of developmental divergence in Hox gene expression within a single species and these changes reveal how body plan differences may arise in larval evolution.

In North America, most ungulate species exhibit life‐history traits typical of long‐lived, iteroparous species wherein young males tend to prioritize essential life functions including body growth and maintenance that constrains allocation of resources to horn, antler, and pronghorn growth. As a result, males of most ungulate species require several years of growth before reaching asymptotic body size and thereafter, peak weapon size is attained. Unique among ungulate species in North America, pronghorn possess a suite of life‐history traits resulting in a precocious (i.e., unusually early development) pace of life relative to other North American ungulates. We tested the hypothesis that the fast pace of life of pronghorn extends to precocious development of large horns, and evaluated how horn size was affected by environmental conditions during the year they were grown and the potential for cohort effects associated with environmental signatures during the year of birth. We evaluated the influence of age and the environment on horn size of pronghorn using data collected from 1,789 male pronghorn harvested from 2019 to 2022 in Wyoming, USA. Pronghorn attained 95% of their peak horn size by 3.5 years old. Climatic conditions influenced horn growth through cohort effects and year of growth pathways. Snow depth during the year of birth positively influenced horn size, whereas the effects of environmental conditions during the year of horn growth were dependent on age. For young animals, snow depth and moderate drought positively influenced horn size during the year of horn growth, but the effect was negligible for prime aged and old animals. The precocious nature of pronghorn extended to their horn growth characteristics, resulting in early attainment of a large proportion of their peak horn size. The unique ecology of pronghorn and rapid attainment of size early in life can allow for greater flexibility to balance hunter opportunity and production of large‐horned males for pronghorn as compared with other ungulates. [ABSTRACT FROM AUTHOR]

The association between migratory strategies and life-history traits helps explain how migratory organisms balance the energetic costs and survival risks with the benefits of migration. However, there is no consensus on how life-history traits associate with migration, and on migrant's position at the slow–fast continuum of life history. Birds subject to different selective pressures are likely to show distinct patterns from each other. We used data from egg collections to investigate the relationship between reproduction and migration by assessing clutch size and egg size of 58 migratory and non-migratory tyrant flycatchers breeding in South America. We first compared clutch size and egg size of migrants and non-migrants, and then we assessed how migrants balance these reproductive traits with migration distance. Despite energy expenditure faced by migrants during their journey, migratory behavior was not a factor influencing clutch size and egg size of migrants and non-migrants. On the other hand, migration distance positively correlated with clutch size in migrants. Our study provides evidence that migration distance may constrain migrants in terms of costs and pressure reproduction in the direction of a faster life-history strategy, while migratory behavior per se may not be a determinant to place migrants in the slow–fast continuum of life history. Thus, among tyrant flycatchers breeding in South America variation in migratory strategies might be more important than migratory behavior in interacting with life-history traits. This study also demonstrates the potential of museum egg collections to test ecological hypotheses that investigate large-scale variation in breeding parameters of birds. [ABSTRACT FROM AUTHOR]

Annuality and perenniality represent two different life‐history strategies in plants, and an analysis of genomic differentiation between closely related species of different life histories bears the potential to identify the underlying targets of selection. Additionally, understanding the interactions between patterns of recombination and signatures of natural selection is a central aim in evolutionary biology, because patterns of recombination shape the evolution of genomes by affecting the efficacy of selection. Here, our aim was to characterise the landscape of genomic differentiation between weedy annual rye (Secale cereale L.) and wild perennial rye (Secale strictum C. Presl), and explore the extent to which signatures of selection are influenced by recombination rate variation. We used population‐level sequence data of annual and perennial rye to analyse population structure and their demographic history. Based on our analyses, annual and perennial rye diverged approximately 26,500 years ago (ya) from an ancestral population size of ~85,000 individuals. We analysed patterns of genetic diversity and genetic differentiation, and found highly differentiated regions located in low‐recombination regions, indicative of linked selection. Although all highly differentiated regions, as revealed by FST‐outlier scans, were located in low‐recombining regions, not all chromosomes showed this tendency. We therefore performed a gene ontology enrichment analysis, which showed that highly differentiated regions comprise genes involved in photosynthesis. This enrichment was confirmed when FST outlier scans were performed separately in low‐ and intermediate‐recombining regions, but not in high‐recombining regions, suggesting that local recombination rate variation in rye affects outlier scans. Cultivated rye is an annual crop, but the introduction of perenniality may be advantageous in regions with poor soil quality or under low‐input farming. Although the resolution of our analysis is limited to a broad‐scale, knowledge about the evolutionary divergence between annual and perennial rye might support breeding efforts towards perennial rye cultivation. [ABSTRACT FROM AUTHOR]

Hox genes are transcriptional regulators that elicit cell positional identity along the anterior–posterior region of the body plan across different lineages of Metazoan. Comparison of Hox gene expression across distinct species reveals their evolutionary conservation; however, their gains and losses in different lineages can correlate with body plan modifications and morphological novelty. We compare the expression of 11 Hox genes found within Streblospio benedicti, a marine annelid that produces two types of offspring with distinct developmental and morphological features. For these two distinct larval types, we compare Hox gene expression through ontogeny using hybridization chain reaction (HCR) probes for in situ hybridization and RNA-seq data. We find that Hox gene expression patterning for both types is typically similar at equivalent developmental stages. However, some Hox genes have spatial or temporal differences between the larval types that are associated with morphological and life-history differences. This is the first comparison of developmental divergence in Hox gene expression within a single species and these changes reveal how body plan differences may arise in larval evolution. [ABSTRACT FROM AUTHOR]

The costs of reproductive conflict can shape the evolution of life-histories in animal societies. These costs may change as individuals age and grow, and with within-group competition. Social costs of reproductive conflict have been invoked to explain why females might gain from delaying maturity or ceasing reproduction midway through life, but not in males. Here, we analyse more than 20 years of data to understand how individual male banded mongooses adjust their reproductive activity in response to the costs of reproductive conflict. In banded mongoose groups, multiple female breeders enter oestrus synchronously that are each guarded by a single male that aggressively wards-off rivals. The heaviest males in the group gained the greatest share of paternity. Those lighter males that are reproductively active paid disproportionate survival costs, and by engaging in reproductive activity early had lower lifetime reproductive success. Our results suggest that reproductive inactivity early in life is adaptive, as males recoup any lost fitness by first growing before engaging in less costly and more profitable reproductive activity later in life. These results suggest that resource holding potential of males and the intensity of reproductive conflict interact to shape lifetime schedules of reproductive behaviour. [ABSTRACT FROM AUTHOR]

Life history trade‐offs are one of the central tenets of evolutionary demography. Trade‐offs, depicting negative covariances between individuals' life history traits, can arise from genetic constraints, or from a finite amount of resources that each individual has to allocate in a zero‐sum game between somatic and reproductive functions. While theory predicts that trade‐offs are ubiquitous, empirical studies have often failed to detect such negative covariances in wild populations. One way to improve the detection of trade‐offs is by accounting for the environmental context, as trade‐off expression may depend on environmental conditions. However, current methodologies usually search for fixed covariances between traits, thereby ignoring their context dependence. Here, we present a hierarchical multivariate ‘covariance reaction norm’ model, adapted from Martin (2023), to help detect context dependence in the expression of life‐history trade‐offs using demographic data. The method allows continuous variation in the phenotypic correlation between traits. We validate the model on simulated data for both intraindividual and intergenerational trade‐offs. We then apply it to empirical datasets of yellow‐bellied marmots (Marmota flaviventer) and Soay sheep (Ovis aries) as a proof‐of‐concept showing that new insights can be gained by applying our methodology, such as detecting trade‐offs only in specific environments. We discuss its potential for application to many of the existing long‐term demographic datasets and how it could improve our understanding of trade‐off expression in particular, and life history theory in general. [ABSTRACT FROM AUTHOR]

Climate change is altering temperature means and variation, and both need to be considered in predictions underpinning conservation. However, there is no consensus in the literature regarding the effects of temperature fluctuations on biological functions. Fluctuations may affect biological responses because of inequalities from non‐linear responses, endocrine regulation or exposure to damaging temperatures. Here we establish the current state of knowledge of how temperature fluctuations impact biological responses within individuals and populations compared to constant temperatures with the same mean. We conducted a meta‐analysis of 143 studies on ectothermic animals (1492 effect sizes, 118 species). In this study, 89% of effect sizes were derived from diel cycles, but there were no significant differences between diel cycles and shorter (<8 h) or longer (>48 h) cycles in their effect on biological responses. We show that temperature fluctuations have little effect overall on trait mean and variance. Nonetheless, temperature fluctuations can be stressful: fluctuations increased 'gene expression' in aquatic animals, which was driven mainly by increased hsp70. Fluctuating temperatures also decreased longevity, and increased amplitudes had negative effects on population responses in aquatic organisms. We conclude that mean temperatures and extreme events such as heat waves are important to consider, but regular (particularly diel) temperature fluctuations are less so. [ABSTRACT FROM AUTHOR]

Reproductive activity is costly in terms of future reproduction and survival. Oxidative stress has been identified as a likely mechanism underlying this cost of reproduction. However, empirical studies have yielded the paradoxical observation that breeders often sustain lower levels of oxidative damage than non-breeders. The oxidative shielding hypothesis attempts to explain such data, and posits that breeders pre-emptively reduce levels of oxidative damage in order to protect their germ cells, and any resultant offspring, from harm caused by exposure to oxidative damage. While there is some empirical evidence of oxidative shielding in females, there have been no explicit tests of this hypothesis in males, despite evidence of the oxidative costs to the male reproductive effort and the vulnerability of sperm cells to oxidative damage. In this study, we assess lipid oxidative damage (malondialdehyde, MDA) in the ejaculates of reproducing and non-reproducing wild banded mongooses. We found that, among breeding males, ejaculate MDA levels were lower during mate competition compared to 2 months later, when individuals were not mating, which is consistent with the oxidative shielding hypothesis, and similar to findings in females. However, ejaculate MDA levels did not differ significantly between breeding and non-breeding individuals at the time of mating, contrary to expectation. The finding that ejaculate MDA was not higher in non-breeders may reflect individual differences in quality and hence oxidative stress. In particular, breeders were significantly older than non-breeders, which may obscure differences in oxidative damage due to reproductive investment. Further research is needed to establish the causal relationship between reproductive investment and oxidative damage in ejaculates, and the consequences for offspring development in banded mongooses and other species. [ABSTRACT FROM AUTHOR]

ABSTRACT Over lifetime, organisms can be repeatedly exposed to stress, shaping their phenotype. At certain, so‐called sensitive phases, individuals might be more receptive to such stress, for example, nutritional stress. However, little is known about how plastic responses differ between individuals experiencing nutritional stress early versus later in life or repeatedly, particularly in species with distinct ontogenetic niches. Moreover, there may be sex‐specific differences due to distinct physiology. Larvae of the holometabolous turnip sawfly, Athalia rosae, consume leaves and flowers, while the adults take up nectar. We examined the effects of starvation experienced at different life stages on life‐history, adult behavioural and metabolic traits to determine which stage may be more sensitive and how specific these traits respond. We exposed individuals to four nutritional regimes, either no, larval, adult starvation or starvation periods as larvae and adults. Larvae exposed to starvation had a prolonged development, and starved females reached a lower initial adult body mass than non‐starved individuals. Males did not differ in initial adult body mass regardless of larval starvation, suggesting the ability to conform well to poor nutritional conditions. Adult behavioural activity was not significantly impacted by larval or adult starvation. Individuals starved as larvae had similar carbohydrate and lipid (i.e., fatty acid) contents as non‐starved individuals, potentially due to building up energy reserves during development, while starvation during adulthood or at both stages led to reduced energy reserves in males. This study indicates that the sensitivity of a life stage to stress depends on the specific trait under consideration. Life‐history traits were mainly affected by larval stress, while activity appeared to be more robust and metabolism mostly impacted by the adult conditions. Individuals differed in their ability to conform to the given environment, with the responses being life stage‐ and sex‐specific.

Males and females often differ in ecology, behaviour and lifestyle, and these differences are expected to lead to sex differences in parasite susceptibility. However, neither the sex differences in parasite prevalence, nor their ecological and evolutionary drivers have been investigated across a broad range of taxa using phylogenetically corrected analyses. Using the most extensive dataset yet that includes 755 prevalence estimates from 151 wild bird species in a meta-analytic framework, here we compare sex differences in blood and gastrointestinal parasites. We show that despite sex differences in parasite infection being frequently reported in the literature, only Haemoproteus infections were more prevalent in females than in males. Notably, only seasonality was strongly associated with the sex-specific parasite prevalence of both Leucocytozoon and Haemoproteus, where birds showed greater female bias in prevalence during breeding periods compared to the non-breeding period. No other ecological or sexual selection variables were associated with sex-specific prevalence of parasite prevalence. We suggest that much of the variation in sex-biased prevalence could be idiosyncratic, and driven by local ecology and behavioural differences of the parasite and the host. Therefore, breeding ecology and sexual selection may only have a modest influence on sex-different parasite prevalence across wild birds. [ABSTRACT FROM AUTHOR]

We made separate experiments to examine life‐history traits and activities of protective enzymes as affected by carbon dioxide (CO2) elevation to 780 μL/L as compared to 390 μL/L in imidacloprid‐ or buprofezin‐resistant strains of the brown planthopper (BPH) Nilaparvata lugens. We found an interaction effect between resistance and the CO2 level on the nymphal survival and duration in both resistant strains. Nymphal durations in both resistant strains were much shorter in the resistant than susceptible BPH at 780 μL/L but similar between them or slightly shorter in the resistant than susceptible BPH at 390 μL/L. Nymphal survival was lower for imidacloprid‐resistant than its susceptible BPH at 390 μL/L but higher at 780 μL/L; it stayed unaffected by the CO2 elevation in buprofezin‐resistant BPH. We did not observe an interaction effect between resistance and the CO2 level on major reproductive parameters in both resistant strains. But the 2 strains were not consistent across CO2 levels in all parameters. Our measurements of protective enzyme activities of superoxide dismutase, catalase, and peroxidase showed an interaction between resistance and the CO2 level. Overall, these enzymes became similar in activity between resistant and susceptible BPH at 780 μL/L compared to 390 μL/L and the change was more distinct in the imidacloprid‐ than buprofezin‐resistant BPH strains. Our findings suggest that CO2 elevation can affect life‐history traits of insecticide‐resistant BPH, while the effect may vary depending on the kind of insecticides it is resistant to. [ABSTRACT FROM AUTHOR]

Linking reproductive fitness with adaptive traits at the genomic level can shed light on the mechanisms that produce and maintain sex‐specific selection. Here, we construct a multigenerational pedigree to investigate sex‐specific selection on a maturation gene, vgll3, in a wild Atlantic salmon population. The vgll3 locus is responsible for ~40% of the variation in maturation (sea age at first reproduction). Genetic parentage analysis was conducted on 18,265 juveniles (parr) and 685 adults collected at the same spawning ground over eight consecutive years. A high proportion of females (26%) were iteroparous and reproduced two to four times in their lifetime. A smaller proportion of males (9%) spawned at least twice in their lifetime. Sex‐specific patterns of reproductive fitness were related to vgll3 genotype. Females showed a pattern of overdominance where vgll3*EL genotypes had three‐fold more total offspring than homozygous females. In contrast, males demonstrated that late‐maturing vgll3*LL individuals had two‐fold more offspring than either vgll3*EE or vgll3*EL males. Taken together, these data suggest that balancing selection in females contributes to the maintenance of variation at this locus via increased fitness of iteroparous vgll3*EL females. This study demonstrates the utility of multigenerational pedigrees for uncovering complex patterns of reproduction, sex‐specific selection and the maintenance of genetic variation. [ABSTRACT FROM AUTHOR]

Species exploiting seasonal environments must alter timings of key life‐history events in response to large‐scale climatic changes in order to maintain trophic synchrony with required resources. Yet, substantial among‐species variation in long‐term phenological changes has been observed. Advancing from simply describing such variation towards predicting future phenological responses requires studies that rigorously quantify and explain variation in the direction and magnitude of changing timings across diverse species in relation to key ecological and life‐history variables. Accordingly, we fitted multi‐quantile regressions to 59 years of multi‐species data on spring and autumn bird migration timings through northern Scotland. We demonstrate substantial variation in changes in timings among 72 species, and tested whether such variation can be explained by species ecology, life‐history and changes in local abundance. Consistent with predictions, species that advanced their migration timing in one or both seasons had more seasonally restricted diet types, fewer suitable breeding habitat types, shorter generation lengths and capability to produce multiple offspring broods per year. In contrast, species with less seasonally restricted diet types and that produce single annual offspring broods, showed no change. Meanwhile, contrary to prediction, long‐distance and short‐distance migrants advanced migration timings similarly. Changes in migration timing also varied with changes in local migratory abundance, such that species with increasing seasonal abundance apparently altered their migration timing, whilst species with decreasing abundance did not. Such patterns broadly concur with expectation given adaptive changes in migration timing. However, we demonstrate that similar patterns can be generated by numerical sampling given changing local abundances. Any apparent phenology‐abundance relationships should, therefore, be carefully validated and interpreted. Overall, our results show that migrant bird species with differing ecologies and life‐histories showed systematically differing phenological changes over six decades contextualised by large‐scale environmental changes, potentially facilitating future predictions and altering temporal dynamics of seasonal species co‐occurrences. [ABSTRACT FROM AUTHOR]

Individuals must reproduce to survive and thrive from generation to generation. In fish, the fecundity of individuals and estimates of total reproductive output are critical for evaluating reproductive success and understanding population dynamics. Estimating fecundity is an onerous task; therefore, many populations lack contemporary estimates of fecundity and size‐fecundity relationships. However, reproductive dynamics are not static in time; therefore, it is important to develop contemporary fecundity estimates to better inform conservation and management action. To highlight the importance of contemporary fecundity estimates, we examined the fecundity of southern Gulf of St. Lawrence (sGSL) spring and fall spawning Atlantic herring in 2022, developed size‐fecundity models, and compared these to historical fecundity estimates and models. Our results suggest that the average fecundity of sGSL spring and fall herring has undergone a substantial temporal decline of approximately 47% and 58%, respectively, since the 1970s and 1980s. The size‐fecundity relationships for fall spawning herring have shifted, with fish of a given size exhibiting lower fecundity in 2022 compared to the 1970s. Alternatively, the size‐fecundity relationships for spring spawning herring have remained relatively static. Furthermore, simulations highlighted a substantial reduction in potential reproductive output in 2022 compared to 1970 of approximately 32% and 68% for spring and fall spawners, respectively, based on a fixed number of mature females, which may have negative implications for stock rebuilding. Overall, our study provides support for periodic estimates of fecundity in fish populations to better understand temporal changes in reproductive and population dynamics. [ABSTRACT FROM AUTHOR]

Climate change has appeared as a major issue in recent years, and its impacts are seen multi-dimensionally. The local people are the key eyewitnesses of climate change, although the discourse is disciplinary, geographic, and gender biased. In this context, this paper documents the perceptions and narratives of the Tamang, an Indigenous people, who live on the outskirts of the Kathmandu Valley. This is an ethnographic study and applied quantitative and qualitative data. The data of the study were gathered using triangulation methods, i.e., household questionnaire survey (HQS), key informant interview (KII), and focus group discussion (FGD). A total of 94 HQS, nine KII, and three FGD were carried out in 2018 in three sample sites in the outskirts of the valley. The station-based observed climatic data from 1969 to 2022 were collected from the Department of Hydrology and Meteorology. The observed data shows increasing annual rainfall and temperature in Kathmandu; however, the rate of temperature increase is much larger. Seasonal precipitation shows decreasing rainfall in post-monsoon, which enhances the winter drought. The Tamang are the key eyewitness of the changes in climate and this knowledge is inbuilt with their memories which are closely bound to the place. Hence, the life history of elderly people can be an appropriate way of understanding the micro-climatic changes in the local context, which largely failed or ignored to document in scientific or macro-level assessments. [ABSTRACT FROM AUTHOR]

Black bullhead Ameiurus melas is a widespread invasive fish in Europe and is considered an ecological and economic threat. Yet, sporadic data are available on its life-history traits. This study assessed the fecundity, growth, and body condition of black bullhead in three oxbows in Hungary. Samples were collected in the resting (October) and pre-spawning (April) periods. Considerable negative allometric growth was observed (b slope ranged between 1.64 and 1.67). The Fulton's condition factor was lower than any previously reported data (mean = 1.01; SD = 0.09). The mean male : female ratio of the three populations was 1.18:1. Mean absolute fecundity was 3,319 eggs (SD = 1521; range = 1,111-12,727), and mean relative fecundity was 78.8 eggs g-1 (SD = 21.8; range = 34.8-146.0). The mean oocyte diameter was 0.39 mm in autumn and 0.41 mm in spring. Oocyte size positively correlated with body length. The mean standard length at age was 76.5-81.00 mm at 1+, 126.23-134.35 at 2+, 153-154.5 mm at 3+, and 180-181 mm at 4+. Our results confirmed the phenotypic plasticity of black bullhead out of its native range. [ABSTRACT FROM AUTHOR]

Non-lethal injury in animals is both common and costly. The cost of regenerating autotomized limbs may leave less energy available for processes such as reproduction and growth, leading to trade-offs. Such trade-offs are context-dependent, and an individual’s energy allocation strategies may vary widely based on its condition and the environment. However, many traditional bioenergetics models have relied on fixed energy allocation rules, such as the -rule of dynamic energy budget theory, which assumes a fixed proportion (κ) of assimilated energy is always allocated to growth and maintenance. To determine whether incorporating optimality approaches into bioenergetics models improves the ability to predict energy allocation, we developed a dynamic state variable model that identifies optimal limb regeneration strategies in a model system, the Asian shore crab Hemigrapsus sanguineus. Our model predictions align with known patterns for this species, including increased regeneration effort with injury severity, a shift from reproduction to growth as consumption amount increases, and an increase in regeneration effort as regeneration progresses. Lastly, Monte Carlo simulations of individuals from a previous experiment demonstrate that flexible energy allocation successfully predicts reproductive effort, suggesting that this approach may improve the accuracy of bioenergetics modeling.

Evolutionary medicine - i.e. the application of insights from evolution and ecology to biomedicine - has tremendous untapped potential to spark transformational innovation in biomedical research, clinical care and public health. Fundamentally, a systematic mapping across the full diversity of life is required to identify animal model systems for disease vulnerability, resistance, and counter-resistance that could lead to novel clinical treatments. Evolutionary dynamics should guide novel therapeutic approaches that target the development of treatment resistance in cancers (e.g., via adaptive or extinction therapy) and antimicrobial resistance (e.g., via innovations in chemistry, antimicrobial usage, and phage therapy). With respect to public health, the insight that many modern human pathologies (e.g., obesity) result from mismatches between the ecologies in which we evolved and our modern environments has important implications for disease prevention. Life-history evolution can also shed important light on patterns of disease burden, for example in reproductive health. Experience during the COVID-19 (SARS-CoV-2) pandemic has underlined the critical role of evolutionary dynamics (e.g., with respect to virulence and transmissibility) in predicting and managing this and future pandemics, and in using evolutionary principles to understand and address aspects of human behavior that impede biomedical innovation and public health (e.g., unhealthy behaviors and vaccine hesitancy). In conclusion, greater interdisciplinary collaboration is vital to systematically leverage the insight-generating power of evolutionary medicine to better understand, prevent, and treat existing and emerging threats to human, animal, and planetary health.

Exposure to persistent organic pollutants (POPs) can significantly impact marine mammal health, reproduction, and fitness. This study addresses a significant 20-year gap in gray whale contaminant monitoring through analysis of POPs in 120 blubber biopsies. The scope of this substantial sample set is noteworthy in its range and diversity with collection between 2003 and 2017 along North Americas west coast and across diverse sex, age, and reproductive parameters, including paired mothers and calves. Mean blubber concentrations of polychlorinated biphenyls (∑PCBs), dichlorodiphenyltrichloroethanes (∑DDTs), and chlordanes (∑CHLs) generally decreased since previous reports (1968-1999). This is the first report of polybrominated diphenyl ethers (PBDEs) and select hexachlorocyclohexanes (HCHs) in this species. Statistical modeling of the 19 most frequently detected compounds in this dataset revealed sex-, age-, and reproductive status-related patterns, predominantly attributed to maternal offloading. Mean POP concentrations differed significantly by sex in adults (17 compounds, up to 3-fold higher in males) but not in immatures (all 19 compounds). Mean POP concentrations were significantly greater in adults versus immatures in both males (17 compounds, up to 12-fold) and females (13 compounds, up to 3-fold). POP concentrations were detected with compound-specific patterns in nursing calves, confirming maternal offloading for the first time in this species.

Fish experiencing harvest mortality often evolve a fast life-history that prioritizes investment in current versus future reproduction, thereby potentially limiting energetic investment in the brain. Fisheries may also select for shy fish that are less willing to learn, or directly select fish with poor cognitive ability. The resulting evolutionary changes can alter the cognitive performance of individuals and affect fish populations and fisheries quality. [ABSTRACT FROM AUTHOR]

Improve the knowledge base on the ecomorphological adaptation of teleost species to different environments, trying to reconstruct how habitat can shape sagittae, is essential for conservational purposes, evolutionary evaluations, and population dynamics studies. Here is provided a comparative study between sagittae features, growth rates and age composition of two Scorpaena porcus populations inhabiting the Mediterranean waters, one from the Strait of Messina (Central Mediterranean Sea) and one from the Split area (Adriatic Sea). Additionally, the stomach contents of the Messina specimens have also been analysed to provide some preliminary information on the diet of S. porcus. A total of ninety individuals, half from each area, have been obtained from two extremely different environments. Results showed an overall different morphology, shape, and morphometry of sagittae among the size classes of the two investigated populations. Samples from Messina were characterized by a most elliptical and slender shape, with a more regular serration of margins than those from Split, which exhibited a wider sagitta, with a most enhanced anti-rostrum and longer rostrum. Concerning diet, specimens from Messina showed a preference for Crustacea (especially Brachyura and Amphipoda) and Teleost species, showing some differences with literature data from other geographical areas (Split one included). Results have confirmed the reliability of sagittae to detect the interpopulation variability of S. porcus from different geographical areas, an essential tool for stock assessment, population studies and investigation on ecomorphological adaptation of teleost species to different habitats. [ABSTRACT FROM AUTHOR]

Mammalian life history strategies can be characterised by a few axes of variation, conforming a space where species are positioned based on the life history strategies favoured in the environment they exploit. Yet, we still lack global descriptions of the diversity of realised mammalian life history and how this diversity is shaped by the environment. We used six life history traits to build a life history space covering worldwide mammalian adaptation, and we explored how environmental realms (land, air, water) influence mammalian life history strategies. We demonstrate that realms are tightly linked to distinct life history strategies. Aquatic and aerial species predominantly adhere to slower life history strategies, while terrestrial species exhibit faster life histories. Highly encephalised terrestrial species are a notable exception to these patterns. Furthermore, we show that different mode of life may play a significant role in expanding the set of strategies exploitable in the terrestrial realm. Additionally, species transitioning between terrestrial and aquatic realms, such as seals, exhibit intermediate life history strategies. Our results provide compelling evidence of the link between environmental realms and the life history diversity of mammals, highlighting the importance of differences in mode of life to expand life history diversity. [ABSTRACT FROM AUTHOR]

The amniote eggshell is a fundamental aspect of the embryo life‐support system, protecting it from UV light, microbes and mechanical damage, while regulating gas exchange and providing calcium for growth. The thickness of eggshells is highly diverse across modern birds and influences multiple eggshell functions, yet the selective pressures driving eggshell thickness have not been clearly identified. Here, we use a global dataset of avian eggshell thickness indices for 4260 (> 41%) avian species to assess trends in eggshell thickness across the phylogeny, as these indices are strongly correlated with direct measures of eggshell thickness and are non‐destructive to the sample. We analysed the dataset within a phylogenetic framework to assess the relative importance of climatic and ecological explanations for variation in eggshell thickness indices. The distribution of avian eggshell thickness indices across species was found to be primarily driven by phylogenetic relatedness, in addition to evolutionary processes that do not match a Brownian model of evolution. Across modern birds, thicker eggshells were more prevalent in species (1) with precocial young, (2) which exhibit a scavenger‐based diet, (3) which primarily feed on vertebrates or plants (excluding nectivores, seed and fruit specialists) and (4) which breed in open habitats. Thicker eggshells found in species with precocial young probably enable higher rates of calcium removal for the more advanced embryo development. Excessive light transmission through the shell damages developing embryos, while too little light transmission can impede development. Eggs in shaded habitats experience low light exposure, and thus thinner shells are more prevalent in these environments potentially to increase light transmission through the shell. Overall, variation in eggshell thickness indices appears to be driven largely by phylogeny, with certain life‐history traits linked to embryo growth rate, calcium content of their food, and the need to mitigate excessive light transmission through the shell. [ABSTRACT FROM AUTHOR]

Life‐history theory predicts that reproductive investments are traded‐off against self‐maintenance. Telomeres, the protective caps on the ends of chromosomes, offer a promising avenue for assessing life‐history trade‐offs, as they shorten in response to stressors and are predictive of the remaining lifespan. In males, testosterone frequently mediates life‐history trade‐offs, in part, through its effects on sexual ornamentation, which is an important aspect of reproductive investment. However, studies of within‐individual associations between telomere dynamics and sexual ornamentation are limited in number and have produced mixed results. Furthermore, most such studies have been observational, making it difficult to discern the nature of any causal relationship. To address this, we used short‐acting testosterone implants in free‐living male superb fairy‐wrens (Malurus cyaneus) to stimulate the production of a sexual ornament: early moult into a costly blue breeding plumage. We found no evidence that elevated testosterone, and the consequent earlier moult into breeding plumage, accelerated telomere shortening. We therefore followed up with a systematic review and two meta‐analyses (28 studies, 54 effect sizes) exploring the associations between telomeres and (1) testosterone and (2) sexual ornamentation. In line with our experimental findings, neither meta‐analysis showed an overall correlation of testosterone or sexual ornamentation with telomere length or telomere dynamics. However, meta‐regression showed that experimental, compared to observational, studies reported greater evidence of trade‐offs. Our meta‐analyses highlight the need for further experimental studies to better understand potential responses of telomere length or telomere dynamics to testosterone or sexual ornamentation. [ABSTRACT FROM AUTHOR]

How the origin of novel behaviors can shape the evolutionary trajectory of organisms in response to environmental change remains poorly understood. Birds, especially those with big brains like parrots, are benchmarks for their behavioral innovation capacity in novel environments. Here, we assess whether and how the emergence of open areas in the Neotropics that started in the middle Miocene influenced the evolution of nesting behavior in parrots and how they triggered changes in other life‐history traits. To address these questions, we use a phylogenetic‐based analyses of trait evolution in the subfamily Arinae (Neotropical parrots), focusing on habitat, nesting behavior, morphology, and life‐history traits (clutch size, incubation period and fledging period). Evolutionary reconstructions show that transitions to excavating behavior mostly happened when species colonized open areas, providing evidence that this behavior originated in open environments. Evolutionary models suggest that the new open areas and the excavator nesting behavior exerted new selective pressures on morphology and life‐history traits, leading to evolutionary changes towards larger clutch sizes and shorter fledging periods in excavator parrots. Our study indicates that excavator nesting behavior in Neotropical parrots has likely played a key role in allowing them to exploit the ecological opportunities available in newly formed open biomes. [ABSTRACT FROM AUTHOR]

Life-history traits have been identified as major indicators of mammals' susceptibility and exposure to viruses due to evolutionary constraints that link life-history speed with species’ ecology and immunity. Nonetheless, it is unclear where along the fast-slow continuum of mammalian life-history lies the greatest diversity of host species. Consequently, life-history patterns that govern host–virus associations remain largely unknown. Here we analyse the virome of 1350 wild mammals and detect the characteristics that drive species' compatibility with different groups of viruses. We highlight that mammals with larger body size and either very rapid or very slow life histories are more likely to carry different groups of viruses, particularly zoonotic ones. While some common life-history patterns emerge across carriers, eco-evolutionary characteristics of viral groups appear to determine association with certain carrier species. Our findings underline the importance of incorporating both mammals’ life-history information and viruses' ecological diversity into surveillance strategies to identify potential zoonotic carriers in wildlife.

Reproductive activity is costly in terms of future reproduction and survival. Oxidative stress has been identified as a likely mechanism underlying this cost of reproduction. However, empirical studies have yielded the paradoxical observation that breeders often sustain lower levels of oxidative damage than non-breeders. The oxidative shielding hypothesis attempts to explain such data, and posits that breeders pre-emptively reduce levels of oxidative damage in order to protect their germ cells, and any resultant offspring, from harm caused by exposure to oxidative damage. While there is some empirical evidence of oxidative shielding in females, there have been no explicit tests of this hypothesis in males, despite evidence of the oxidative costs to the male reproductive effort and the vulnerability of sperm cells to oxidative damage. In this study, we assess lipid oxidative damage (malondialdehyde, MDA) in the ejaculates of reproducing and non-reproducing wild banded mongooses. We found that, among breeding males, ejaculate MDA levels were lower during mate competition compared to 2 months later, when individuals were not mating, which is consistent with the oxidative shielding hypothesis, and similar to findings in females. However, ejaculate MDA levels did not differ significantly between breeding and non-breeding individuals at the time of mating, contrary to expectation. The finding that ejaculate MDA was not higher in non-breeders may reflect individual differences in quality and hence oxidative stress. In particular, breeders were significantly older than non-breeders, which may obscure differences in oxidative damage due to reproductive investment. Further research is needed to establish the causal relationship between reproductive investment and oxidative damage in ejaculates, and the consequences for offspring development in banded mongooses and other species.

Many organisms live in fragmented populations, which has profound consequences on the dynamics of associated parasites. Metapopulation theory offers a canonical framework for predicting the effects of fragmentation on spatiotemporal host–parasite dynamics. However, empirical studies of parasites in classical metapopulations remain rare, particularly for vector-borne parasites. Here, we quantify spatiotemporal patterns and possible drivers of infection probability for several ectoparasites (fleas, Ixodes trianguliceps and Ixodes ricinus) and vector-borne microparasites (Babesia microti, Bartonella spp., Hepatozoon spp.) in a classically functioning metapopulation of water vole hosts. Results suggest that the relative importance of vector or host dynamics on microparasite infection probabilities is related to parasite life-histories. Bartonella, a microparasite with a fast life-history, was positively associated with both host and vector abundances at several spatial and temporal scales. In contrast, B. microti, a tick-borne parasite with a slow life-history, was only associated with vector dynamics. Further, we provide evidence that life-history shaped parasite dynamics, including occupancy and colonization rates, in the metapopulation. Lastly, our findings were consistent with the hypothesis that landscape connectivity was determined by distance-based dispersal of the focal hosts. We provide essential empirical evidence that contributes to the development of a comprehensive theory of metapopulation processes of vector-borne parasites.

Improve the knowledge base on the ecomorphological adaptation of teleost species to different environments, trying to reconstruct how habitat can shape sagittae, is essential for conservational purposes, evolutionary evaluations, and population dynamics studies. Here is provided a comparative study between sagittae features, growth rates and age composition of two Scorpaena porcus populations inhabiting the Mediterranean waters, one from the Strait of Messina (Central Mediterranean Sea) and one from the Split area (Adriatic Sea). Additionally, the stomach contents of the Messina specimens have also been analysed to provide some preliminary information on the diet of S. porcus. A total of ninety individuals, half from each area, have been obtained from two extremely different environments. Results showed an overall different morphology, shape, and morphometry of sagittae among the size classes of the two investigated populations. Samples from Messina were characterized by a most elliptical and slender shape, with a more regular serration of margins than those from Split, which exhibited a wider sagitta, with a most enhanced anti-rostrum and longer rostrum. Concerning diet, specimens from Messina showed a preference for Crustacea (especially Brachyura and Amphipoda) and Teleost species, showing some differences with literature data from other geographical areas (Split one included). Results have confirmed the reliability of sagittae to detect the inter-population variability of S. porcus from different geographical areas, an essential tool for stock assessment, population studies and investigation on ecomorphological adaptation of teleost species to different habitats.

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. [ABSTRACT FROM AUTHOR]

Simple Summary: The fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Erebidae, Arctiidae), is a major invasive pest of China. Although it has spread from Dandong City (about 40° N) in Liaoning Province to Nanjing City (about 32° N) in Jiangsu Province and other areas, the effects of temperature changes associated with its geographical spread on its life-history traits and adult fecundity are still unknown. Thus, the current study investigated the effects of larval-rearing temperature on the developmental duration and body mass of larvae, body size, body mass, and energy reserves of pupae, as well as the body size and fecundity of adults. We found that higher larval-rearing temperatures shortened the larval developmental period and increased larval and pupal body mass as well as pupal and adult body size. Higher larval-rearing temperatures also decreased the lipid and carbohydrate content of the pupae but increased their soluble protein content and adult egg production. These results suggest that the life-history traits and fecundity of H. cunea are plastic. This information is crucial for better understanding the dispersal adaptation strategies of H. cunea and for improving the prediction of population dynamics of this species according to environmental temperatures in different years. 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. [ABSTRACT FROM AUTHOR]

The transition between lytic and lysogenic life cycles is the most important feature of the life-history of temperate viruses. To explain this transition, an optimal life-history model is offered based a discrete-time formulation of phage/bacteria population dynamics that features infection of bacteria by Poisson sampling of virions from the environment. The time step is the viral latency period. In this model, density-dependent viral absorption onto the bacterial surface produces virus/bacteria coexistence and density dependence in bacterial growth is not needed. The formula for the transition between lytic and lysogenic phases is termed the 'fitness switch'. According to the model, the virus switches from lytic to lysogenic when its population grows faster as prophage than as virions produced by lysis of the infected cells, and conversely for the switch from lysogenic to lytic. A prophage that benefits the bacterium it infects automatically incurs lower fitness upon exiting the bacterial genome, resulting in its becoming locked into the bacterial genome in what is termed here as a 'prophage lock'. The fitness switch qualitatively predicts the ecogeographic rule that environmental enrichment leads to microbialization with a concomitant increase in lysogeny, fluctuating environmental conditions promote virus-mediated horizontal gene transfer, and prophage-containing bacteria can integrate into the microbiome of a eukaryotic host forming a functionally integrated tripartite holobiont. These predictions accord more with the 'Piggyback-the-Winner' hypothesis than with the 'Kill-the-Winner' hypothesis in virus ecology. [ABSTRACT FROM AUTHOR]

The aim of our work was to experimentally test the hypothesis that changes in the thermal stratification in lakes of the temperate zone, expected as a result of progressive global warming, will cause an increase in fitness costs in a planktonic cladoceran Daphnia, associated with diel vertical migrations. In a programmable thermostatic chamber, Daphnia magna have been cultured from the first juvenile instar till the first reproduction, in thermal regimes corresponding to the conditions experienced by non-migratory (remaining in epilimnion day and night) and migrating (spending nights in epilimnion and days in hypolimnion) animals. We exposed Daphnia to thermal regimes: corresponding to the temperatures typically reigning stratified lakes nowadays (20 °C in epilimnion and 8 °C in hypolimnion), and expected at the end of this century (28 °C and 12 °C, respectively). The analysis of life-history parameters confirmed the assumption of an increase in metabolic costs resulting from vertical migration of Daphnia along with the expected increase in temperature differences between epilimnion and hypolimnion, which is a daily anti-predator refuge for migrating animals. This may consequently lead to significant changes in the composition of lake zooplankton communities, i.e., to an increase in the share of non-migrating species with small body sizes. [ABSTRACT FROM AUTHOR]

Ectothermic animals like amphibians have unique life histories that are impacted by a variety of eco-geographical variables. In this study, the impacts of altitude, which is one of the most frequently used parameters, were examined concerning the age structure, age upon attaining sexual maturity, sexual dimorphism, and growth of two populations of marsh frogs (Pelophylax ridibundus) living at different elevations. The maximum lifespan was 13 years, the highest lifespan ever recorded for P. ridibundus, in the high-altitude population (Sultansazlığı), while it was eight years in the low-altitude population (Ulubağ). In this study, we estimated that individuals living at low altitudes generally reach sexual maturity at the end of their 2nd or 3th year, while individuals living at high altitudes reach sexual maturity approximately one year later. Our results indicated that the population living in the high-altitude site has an average larger body size, higher age, and body weight compared to the population living in the low-altitude site. [ABSTRACT FROM AUTHOR]

All organisms face resource limitations that will ultimately restrict population growth, but the controlling mechanisms vary across ecosystems, taxa, and reproductive strategies. Using four decades of data, we examine how variation in the environment and population density affect reproductive outcomes in a capital-breeding carnivore, the northern elephant seal (Mirounga angustirostris). This species provides a unique opportunity to examine the relative importance of resource acquisition and density-dependence on breeding success. Capital breeders accrue resources over large temporal and spatial scales for use during an abbreviated reproductive period. This strategy may have evolved, in part, to confer resilience to short-term environmental variability. We observed density-dependent effects on weaning mass, and maternal age (experience) was more important than oceanographic conditions or maternal mass in determining offspring weaning mass. Together these findings show that the mechanisms controlling reproductive output are conserved across terrestrial and marine systems and vary with population dynamics, an important consideration when assessing the effect of extrinsic changes, such as climate change, on a population.

A collection of forty populations were used to study the phenotypic adaptation of Drosophila melanogaster larvae to urea-laced food. A long-term goal of this research is to map genes responsible for these phenotypes. This mapping requires large numbers of populations. Thus, we studied fifteen populations subjected to direct selection for urea tolerance and five controls. In addition, we studied another twenty populations which had not been exposed to urea but were subjected to stress or demographic selection. In this study, we describe the differentiation in these population for six phenotypes: (1) larval feeding rates, (2) larval viability in urea-laced food, (3) larval development time in urea-laced food, (4) adult starvation times, (5) adult desiccation times, and (6) larval growth rates. No significant differences were observed for desiccation resistance. The demographically/stress-selected populations had longer times to starvation than urea-selected populations. The urea-adapted populations showed elevated survival and reduced development time in urea-laced food relative to the control and nonadapted populations. The urea-adapted populations also showed reduced larval feeding rates relative to controls. We show that there is a strong linear relationship between feeding rates and growth rates at the same larval ages feeding rates were measured. This suggests that feeding rates are correlated with food intake and growth. This relationship between larval feeding rates, food consumption, and efficiency has been postulated to involve important trade-offs that govern larval evolution in stressful environments. Our results support the idea that energy allocation is a central organizing theme in adaptive evolution.

Although still prevalent in many human societies, the practice of cousin marriage has precipitously declined in populations undergoing rapid demographic and socioeconomic change. However, it is still unclear whether changes in the structure of the marriage pool or changes in the fitness-relevant consequences of cousin marriage more strongly influence the frequency of cousin marriage. Here, we use genealogical data collected by the Tsimane Health and Life History Project to show that there is a small but measurable decline in the frequency of first cross-cousin marriage since the mid-twentieth century. Such changes are linked to concomitant changes in the pool of potential spouses in recent decades. We find only very modest differences in fitness-relevant demographic measures between first cousin and non-cousin marriages. These differences have been diminishing as the Tsimane have become more market integrated. The factors that influence preferences for cousin marriage appear to be less prevalent now than in the past, but cultural inertia might slow the pace of change in marriage norms. Overall, our findings suggest that cultural changes in marriage practices reflect underlying societal changes that shape the pool of potential spouses.

Flowering phenology is important in the adaptation of many plants to their local environment, but its adaptive value has not been extensively studied in herbaceous perennials. We used Arabis alpina as a model system to determine the importance of flowering phenology to fitness of a herbaceous perennial with a wide geographical range. Individual plants representative of local genetic diversity (accessions) were collected across Europe, including in Spain, the Alps and Scandinavia. The flowering behaviour of these accessions was documented in controlled conditions, in common-garden experiments at native sites and in situ in natural populations. Accessions from the Alps and Scandinavia varied in whether they required exposure to cold (vernalization) to induce flowering, and in the timing and duration of flowering. By contrast, all Spanish accessions obligately required vernalization and had a short duration of flowering. Using experimental gardens at native sites, we show that an obligate requirement for vernalization increases survival in Spain. Based on our analyses of genetic diversity and flowering behaviour across Europe, we propose that in the model herbaceous perennial A. alpina, an obligate requirement for vernalization, which is correlated with short duration of flowering, is favoured by selection in Spain where the plants experience a long growing season. [ABSTRACT FROM AUTHOR]