The question of how individual age influences demographic transition rates, such as survival probabilities and reproduction rates, has long been a main question for demographers and evolutionary ecologists. This has resulted in the accumulation of studies estimating the age-specific demographic transition rates across the tree of life over the last few decades. Although this accumulation of studies has enabled comparative demographic analyses to be developed, such analyses remain difficult to perform because age-specific data are scattered across literature. Here, we present a new open-access database, malddaba, which compiles age-specific demographic rates for mammals in the wild from published information. Currently, the database encompasses 174 species from 255 publications, representing 437 age- and sex-specific survival series and 201 age- and sex-specific reproduction series. Each series is reported using a standardized approach aimed at facilitating the extraction and use of that dataset by anyone interested in comparative evolutionary biology and demography. We show how malddaba can be used to address a variety of questions, ranging from comparative ageing with the assessment of actuarial and reproductive senescence patterns in a wide diversity of mammals to comparative population dynamics. For this purpose, in addition to the raw demographic rate records, we were able to build 45 population-specific life tables using malddaba records, which allow demographic outputs to be estimated accurately, such as population growth rate and generation time for those species. The malddaba database will be regularly updated to keep adding new demographic estimates and bring a comprehensive and dynamic view of the diversity of demographic trajectories across mammals.

Population Projection Matrices (PPM) are discrete mathematical formulations of population growth that are key tools in demographic population studies, enabling the prediction of growth for populations structured with age, size, or other life stages. However, several studies have identified errors stemming from misconceptions related to survival and reproduction parameters, as well as confusion between post-breeding and pre-breeding in the case of Leslie matrices. The present work aims to propose a simple and robust method called Matrices Alternated Products (MAP) for reliably constructing PPM directly from life tables and empirical data. The MAP approach provides a systematic framework for defining both survival and reproductive parameters and producing pre-breeding and post-breeding matrices. The method we propose allows reducing errors and improving the accuracy of demographic population models, and the code we provide will allow population ecologists and wildlife managers to apply this method to any case study in practice.

Advance in the phenology of plants and animals is a widely observed response to climate change. The magnitude of the changes is, however, very variable across species. Several biological factors could influence the strength of the phenological advances, including lifestyle. Hibernation has evolved in response to harsh environmental conditions and could, hence, potentially buffer organisms against changing climatic conditions. In the Alps, the Alpine marmot hibernates for almost 6 months. Owing to its slow pace-of-life, we expected Alpine marmots to be more responsive to earlier springs than non-hibernating species. Here we investigate temporal variation in the date at which pups emerge from their natal burrow for the first time. Using quantile regressions, we provide clear evidence of an earlier pup emergence between 1990 and 2023. Over the study period, the predicted change is 4.7 days. In particular, late emergence dates are becoming especially rare over time. Our findings are in line with previous works on other Alpine species, which suggest a general advance in reproductive phenology. The rate of change of pup emergence dates over years is, however, weaker in the Alpine marmot than in most other mammalian species studied so far.

Natal dispersal is a widespread inbreeding avoidance mechanism that serves to spatially segregate opposite-sex relatives. However, little is known about the alternative behavioural tactics that philopatric individuals employ to avoid inbreeding. When natal dispersal is partial and not sex biased, females may perform reproductive excursions outside of their usual range. As a form of breeding dispersal, this could represent an alternative tactic to reduce the likelihood of mating with close relatives. To investigate this at the individual level, we analysed the spatial behaviour of 90 first-time breeder roe deer, Capreolus capreolus, females. Using data from intensive GPS monitoring, we classified individuals as either philopatric or disperser, and then identified excursions during their subsequent first mating season. While philopatric primiparous females were, on average, somewhat more likely to perform an excursion during the rut than dispersers, this difference was not significant. However, philopatric females on average moved farther from the boundaries of their home ranges than disperser females. Because philopatric females are likely to live in close proximity to related males, their fathers in particular, our results indicate that reproductive excursions could mitigate the risk of incestuous matings. This is the first demonstration of an interaction between natal dispersal and a specific form of breeding dispersal in a mammal. (c) 2026 The Authors. Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour. This is an open access article under the CC BY license (http://creativecommons.org/licenses/ by/4.0/).

Eukaryotes show extraordinary diversity in form, function, and behavior, underpinned by a vast range of life history strategies shaped by selection, ancestry, and ecological constraints. Life history theory explains how organisms allocate limited energy and time to survival, growth, and reproduction. Finite resources impose unavoidable trade-offs, preventing the evolution of any single universally optimal life history strategy. Instead, eukaryotes have evolved manifold approaches to solve the problem of persistence. This review explores life history variation across eukaryotes, tracing key developments in life history theory. We synthesize core concepts including trade-offs, environmental variability, and major evolutionary innovations, including multicellularity, sexual reproduction, and life-cycle compartmentalization. To conclude, we highlight critical knowledge gaps and propose future research directions, emphasizing the value of comparative and experimental approaches that more fully span eukaryotic diversity. Integrating micro- and macroevolutionary perspectives, our review provides a concise synthesis of the principles governing life history variation in eukaryotes.

The ability to evaluate fatigability during locomotion is crucial in various fields, from wildlife biology to clinical medicine. In wildlife, resistance to fatigue, or endurance, can determine the success of certain predator-prey encounters and underpins the ability of animals to migrate or disperse over long distances. In clinical contexts, endurance provides a reliable marker of physiological function, which could help guide exercise prescriptions and aid clinical decision making. However, current methods do not allow for accurate, non-invasive assessment of physical capacities over extended periods in natural and clinical settings. We propose a method for modelling the intensity-duration relationship based on dynamic body acceleration (DBA) records, from which we derived critical intensity, a key metabolic threshold in exercise physiology that delimits heavy from severe intensity domains. We recorded accelerometer data from 19 free-ranging species (n=272) across a wide interspecific and intraspecific range: from rats (10-2 kg) to elephants (103 kg), including oncology patients to regular runners. The three-parameter hyperbolic DBA-duration model revealed an excellent fit on experimental DBA records (median r2=0.995). By retrieving laboratory estimates of metabolic threshold for 15 species (n=688) from the literature, we demonstrated that critical DBA is a reliable proxy of metabolic threshold assessed in the laboratory both at the interspecific (r2=0.88, P<0.001) and intraspecific (Homo sapiens) levels (r2=0.90, P=0.051). The proposed method opens up new avenues for deciphering interactions among animals and between animals and their environment, through the lens of movement and physiology, but also for individualising the assessment of physical capacity in a clinical context.

Natal dispersal is a key process in ecology and evolution. Similarities of dispersal patterns between relatives can lead to small-scale kin structure within populations with consequences for population dynamics and genetics. Most studies have focused on birds, lizards, and small mammals. How family effects may shape sex-specific natal dispersal patterns in a large-sized social mammal remains unexplored. We fill this gap thanks to a 30-year-long monitoring of a wild boar population. This polytocous, polygynous, and size dimorphic species displays a matrilineal social organization. From the monitoring of individuals from early life to adulthood, we characterized natal dispersal patterns by investigating the propensity to disperse and the dispersal distance. As expected for a species subjected to strong sexual selection, offspring males dispersed more often and farther than females. Looking specifically at similarities of dispersal patterns among relatives within a group, we found that offspring females from the same family displayed more similar dispersal propensity and distance than females from different groups, highlighting family effects. However, this dispersal pattern did not hold for males. Family effects can thus shape natal dispersal patterns in a sex-specific way in social mammals and are key to understanding individual variation in dispersal patterns.

Although the widespread effects of climate change impact almost all ecosystems, we lack a detailed understanding of how wildlife that thrive in human‐dominated environments are able to adjust their life history to modifications in land use of their natural habitat. In particular, spatial variation in environmental conditions is predicted to influence body development during the crucial early life phase, with marked impacts on individual performance and population dynamics for long‐lived species. Large herbivores have increased substantially in number and distribution over the last half century across Europe. The synanthropic roe deer ( Capreolus capreolus ) has been particularly successful, gradually colonizing agricultural landscapes. However, little is known about how habitat heterogeneity in this heavily human‐impacted environment impacts demographic performance. Specifically, we predicted that fawns born in predominantly cultivated local habitats would achieve faster early development due to the food subsidies obtained from agricultural crops by their mothers. Contrary to our expectations, fawns in semi‐natural forest were around 10% heavier at birth than those born in more mixed (by 0.163 ± 0.058 kg) and open (by 0.169 ± 0.006 kg) agricultural habitats. However, the body mass of all fawns subsequently increased at a similar average rate (0.148 ± 0.058 kg/day) over the first 20 days of life, irrespective of their habitat. This habitat‐dependent variation in early life mass appeared to be driven by reproductive phenology, as (1) early‐born fawns were heavier than late‐born fawns, and (2) mothers living in forest gave birth around 10 days earlier than those living in the mixed and open sectors. Semi‐natural habitats might thus be the more suitable for fawn early development, despite the availability and abundance of energetically rich food resources for lactating mothers in open and mixed habitats.

Reproductive senescence, the decline in any component of offspring recruitment with increasing age, has been well documented in mammalian females. Male reproductive senescence, however, is much less understood, partly due to the past complexities of getting reliable paternity assignment in the wild. Through a standardised literature search, we compiled age-specific reproductive data on both mating and reproductive success on 57 species encompassing 73 populations. We then explored the occurrence of male reproductive senescence and sought to identify key ecological and evolutionary drivers modulating its intensity. We found evidence of reproductive senescence in 59.6% of the studied species, with a detection probability increasing with larger sample sizes and longer age ranges relative to lifespan (i.e., relative maximum age measured as the ratio between the oldest age sampled and the species maximum longevity). As expected, both the onset and the rate of male reproductive senescence were aligned with the species position along the slow-fast continuum, with fast-living species exhibiting earlier and stronger reproductive senescence than slow-living species. Moreover, the rate of reproductive senescence also increased with the level of sexual size dimorphism, highlighting that males from species displaying a high level of sexual selection suffer from a steeper rate of reproductive senescence.

Although global change and landscape modifications have degraded natural habitats, some species are able to thrive in anthropized landscapes by exploiting agricultural subsidies. In heterogeneous agroecosystems, spatial variation in landscape composition is predicted to impact demographic performance of wildlife depending on predominant agricultural practices and the distribution of remnant fragments of semi-natural habitat. Body mass is a key driver of among-individual variation in performance which varies at a fine scale, depending on landscape structure. We tested the hypothesis that the availability of rich crops (i.e. sorghum, corn and sunflower) in heterogeneous agricultural landscapes promotes rapid first-year growth of roe deer fawns, potentially driving spatial variation in demographic performance. We used GPS data of 166 juveniles (8–10 months old) inhabiting a heterogeneous agricultural landscape to predict their home range and evaluate its composition in terms of crops that may provide complementary resources. We hypothesized that juveniles with a post-weaning home range that included these crop types would be the heaviest at the onset of winter. Winter body mass of juveniles decreased by 35 ± 5 g per percentage point increase of woodland in their home range, so that juveniles with almost no woodland in their home range were about 3.5 kg heavier than those living in pure forest. Further, individuals with at least some corn in their home range were, on average, 773 ± 237 g heavier than those with none. Agricultural food subsidies reshape the habitat-dependent body mass trajectory of large herbivores, likely driving improved reproductive performance in agricultural landscapes.

In Drosophila, like in many other animal species, females tend to live longer than males, a phenomenon known as sex gap in longevity (SGL). One of the possible causes underlying this phenomenon could be related to the high content of transposable elements (TE) in the Y chromosome (toxic Y hypothesis). TE activity is normally repressed by epigenetic mechanisms, but this regulation weakens with age. Since the Y chromosome is rich in TEs, age-related TE activity should be more pronounced in old males than in old females, likely affecting longevity patterns. In this work, we studied the natural variation in SGL in wild-type populations of three different Drosophila species that vary in their TE content: Drosophila melanogaster , Drosophila simulans , and Drosophila suzukii . Transcriptomic data revealed increased copy-specific TE expression in D. melanogaster and D. suzukii older flies. Moreover, we observed a higher number of upregulated TEs in old males compared to old females across all the three species tested. Additionally, we detected an increase in TE-chimeric transcript generation in some aged samples, particularly in D. suzukii males. Finally, the replacement of the Y chromosome between strains with different SGL led to a progressive reduction in male lifespan and increased TE transcriptional release over generations, suggesting a Y chromosome important role in male longevity. Our work contributes to a better understanding of the genomic differences that lead to variation in longevity patterns between sexes in several species, and emphasizes the importance of studying the role of TEs in male longevity. ### Competing Interest Statement The authors have declared no competing interest.

Across human cultures and historical periods, women, on average, live longer than men, a pattern best understood from a comparative evolutionary perspective. Here, we analyzed adult life expectancy in 528 mammal and 648 bird species in zoos. Like humans, 72% of mammals exhibited a female life expectancy advantage, while 68% of birds showed a male advantage, as expected from the harmful effects of sex chromosomes described by the heterogametic sex hypothesis. Yet, sex differences varied widely. In zoos, we found strong evidence that this variation generally correlated with both the mating system and sexual size dimorphism. Although with weaker evidence, the patterns remained consistent in populations from the wild, with an even larger effect of the mating system. Thus, even in zoos, where environmental pressures are largely reduced, precopulatory sexual selection seems to play a fundamental role in shaping sex differences in life expectancy in mammals and birds.

Reproductive senescence, the decline in reproductive performance with increasing age, is extensively documented in females but much less investigated in males. However, senescence of secondary sexual traits in males, such as horns or antlers, has been reported across various vertebrate species. Our study investigates reproductive senescence in antler size, a conspicuous precopulatory trait in male deer, by taking advantage of detailed monitoring of a free-ranging population of Fallow Deer (Dama dama) living in a peri-urban area. We focused on 2 metrics utilizing noninvasive photogrammetry to measure antler length and palm width in 127 free-living males. Our results demonstrate clear evidence of reproductive senescence, with both antler length and palm width declining synchronously from approximately 7 years of age onwards. This decline matches previously reported decreases in male mating success from ages 6 to 7, suggesting that antler size may impact sexual competition and mating success. Males older than 7 years of age may experience reduced competitive abilities and diminished attractiveness to females. This study provides new evidence of senescence of antler size in cervids, enhancing our understanding of the eco-evolutionary factors driving male senescence and emphasizing the importance that antler size may have in the reproductive success of Fallow Deer. This study provides evidence of antler size senescence in Fallow Deer (Dama dama), starting from approximately 7 years of age, with a simultaneous decline in antler length and palm width. These results align with the senescence previously observed in male mating success, suggesting that antler size may impact mating success and sexual competition in Fallow Deer.

Sex chromosomes can determine male and female phenotypes, and the resulting sex differences may have significant impacts on ecology and life history. One manifestation of this link is that ZW/ZZ sex-determination systems are associated with more male-skewed adult sex ratio (ASR, proportion of males in the adult population) than XX/XY systems across tetrapods (amphibians, reptiles, birds, and mammals). Here, we investigate four demographic processes: male and female offspring production, sex differences in juvenile and adult mortalities and in timing of maturation that can contribute to ASR variation between XX/XY and ZW/ZZ systems, using phylogenetic analyses of a large dataset collected from tetrapod species in the wild. We show that sex differences in adult mortality reliably predict ASR that is also more male-biased in XX/XY species than in ZW/ZZ species. Sex differences in juvenile mortality and in maturation time also contribute to ASR skews, but do not differ consistently between XX/XY and ZW/ZZ systems. Phylogenetic path analyses confirm an influence of sex-determination system on ASR through sex-biased adult mortalities. Together these results infer that sex chromosomes can impact, via demographic pathways, frequency-dependent selection emerging from the relative number of males and females. We call for follow-up studies to uncover the potentially complex web of associations between sex determination, population dynamics, and social behavior.

The European Union's Birds and Habitats Directives are intended to guarantee the persistence of species and natural habitats across member states. To achieve this laudable aim, the Natura 2000 network of protected areas was established in 1992. Since then, member states are required to regularly monitor species and habitats and report findings to the European Commission, which requires substantial investment from all countries. The Natura 2000 network is an invaluable example of a large-scale coordinated network developed to address major conservation issues. Based on our analysis of the 2020 Species Natura 2000 database and on expert opinions by Natura 2000 executives, we found that the network is failing to adequately show biodiversity status and guide conservation because it does not allow cross-border comparisons of species' and populations' conservation status. The main contributing factor to this failure is that member states frequently fail to follow reporting EU guidelines, resulting in heterogeneity in criteria for monitoring and registering species among Natura 2000 areas. We advocate developing new unified and realistic criteria for monitoring and reporting species data that correctly allow cross-border comparisons and conservation diagnosis. We propose that monitoring protocols and current criteria be modified slightly by considering species' life-history strategies, distribution, and conservation status. We do not suggest a major overhaul of the directives; rather, we propose debate on how relatively small changes in guidelines could improve the utility of the huge amount of data collected from the Natura 2000 network.

Latitude and elevation are the most commonly studied drivers of large-scale variation in the phenology of life-history events. However, these coarse gradients cannot reliably predict observed spatial variation in phenology. Although it is less often investigated, environmental predictability is also a selective force that constrains spatial variation in life-history events. Here, we explore how environmental predictability contributes to shaping spatial variation in the parturition phenology of roe deer across its distributional range in Europe. We compiled data on roe deer parturition dates across Europe within the research collaboration EURODEER, and from citizen scientists and related birth dates to elevation and environmental predictability, measured by Colwell's metrics of contingency and constancy, based on high-resolution climate and NDVI values. We predicted parturition timing and synchrony simultaneously within a single modelling framework using a distributional regression model (i.e. GAMLSS). Our approach provided more robust predictions of variation in birth phenology than commonly used approaches based on the combination of latitude and elevation. We found that roe deer align their parturition dates with both elevation and seasonality in environmental conditions. We also identified an apparent shift towards later parturition from west to east across the distributional range in Europe, putatively linked to relatively milder and more constant climates in the west. Contrary to our expectations, we did not find any consistent link between parturition synchrony and environmental predictability, suggesting that other factors, such as small-scale heterogeneities in landscape composition, play a key role. Our work emphasizes the importance of understanding macrophenological processes in the variation of life-history event timing across space. It also highlights the need to account for this spatial variation when investigating region-specific adaptations, particularly in light of climate change.

Why and how we age are 2 intertwined questions that have fascinated scientists for many decades. However, attempts to answer these questions remain compartmentalized, preventing a comprehensive understanding of the aging process. We argue that the current lack of knowledge about the evolution of aging mechanisms is due to a lack of clarity regarding evolutionary theories of aging that explicitly involve physiological processes: the disposable soma theory (DST) and the developmental theory of aging (DTA). In this Essay, we propose a new hierarchical model linking genes to vital rates, enabling us to critically reevaluate the DST and DTA in terms of their relationship to evolutionary genetic theories of aging (mutation accumulation (MA) and antagonistic pleiotropy (AP)). We also demonstrate how these 2 theories can be incorporated in a unified hierarchical framework. The new framework will help to generate testable hypotheses of how the hallmarks of aging are shaped by natural selection.

Commonly used two-sex discrete-time population projection models rely on mating functions developed for continuous-time frameworks that overestimate the number of unions between reproductive individuals. This has important consequences for our understanding of the evolution and demography of two-sex populations and consequently for management and conservation. Here, we propose a novel mating function that is robust by obeying all properties necessary to be ecologically valid and flexible by accommodating all mating systems and efficiency in mating encounters. We illustrate the usefulness of this novel function with an application to the sexually size-dimorphic and polygynous wild boar (Sus scrofa). We show that the population growth rate depends on the harem size, the operational sex ratio, and the mating efficiency. This novel function can be applied to all mating systems and tactics and is highly relevant in the context of global changes under which mating systems and mating efficiency are expected to change.