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In social mammals, social integration is generally assumed to improve females' reproductive success. Most species demonstrating this relationship exhibit complex forms of social bonds and interactions. However, female eastern grey kangaroos ( Macropus giganteus ) exhibit differentiated social relationships, yet do not appear to cooperate directly. It is unclear what the fitness consequences of such sociability could be in species that do not exhibit obvious forms of cooperation. Using 4 years of life history, spatial and social data from a wild population of approximately 200 individually recognizable female eastern grey kangaroos, we tested whether higher levels of sociability are associated with greater reproductive success. Contrary to expectations, we found that the size of a female's social network, her numbers of preferential associations with other females and her group sizes all negatively influenced her reproductive success. These factors influenced the survival of dependent young that had left the pouch rather than those that were still in the pouch. We also show that primiparous females (first-time breeders) were less likely to have surviving young. Our findings suggest that social bonds are not always beneficial for reproductive success in group-living species, and that female kangaroos may experience trade-offs between successfully rearing young and maintaining affiliative relationships.

Taxonomic distinction of species forms the foundation of biodiversity assessments and conservation priorities. However, traditional morphological and/or genetics-based taxonomic assessments frequently miss the opportunity of elaborating on the ecological and functional context of species diversification. Here, we used 3D geometric morphometrics of the cranium to improve taxonomic differentiation and add ecomorphological characterization of a young cryptic divergence within the carnivorous marsupial genus Antechinus. Specifically, we used 168 museum specimens to characterize the recently proposed clades A. stuartii ‘south’, A. stuartii ‘north’ and A. subtropicus. Beyond slight differences attributable to overall size (and, therefore, not necessarily diagnostic), we also found clear allometry-independent shape variation. This allowed us to define new, easily measured diagnostic traits in the palate, which differentiate the three clades. Contrary to previous suggestions, we found no support for a latitudinal gradient as causing the differentiation between the clades. However, skull shape co-varied with temperature and precipitation seasonality, suggesting that the clades may be adapted to environmental variables that are likely to be impacted by climate change. Our study demonstrates the use of 3D geometric morphometrics to improve taxonomic diagnosis of cryptic mammalian species, while providing perspectives on the adaptive origins and potential future threats of mammalian diversity.

The biogeographic distribution of diversity among populations of threatened mammalian species is generally investigated using population genetics. However, intraspecific phenotypic diversity is rarely assessed beyond taxonomy‐focused linear measurements or qualitative descriptions. Here, we use a technique widely used in the evolutionary sciences—geometric morphometrics—to characterize shape diversity in the skull of an endangered marsupial, the northern quoll, across its 5,000 km distribution range along Northern Australia. Skull shape is a proxy for feeding, behavior, and phenotypic differentiation, allowing us to ask whether populations can be distinguished and whether patterns of variation indicate adaptability to changing environmental conditions. We analyzed skull shape in 101 individuals across four mainland populations and several islands. We assessed the contribution of population, size, sex, rainfall, temperature, and geography to skull shape variation using principal component analysis, Procrustes ANOVA, and variation partitioning analyses. The populations harbor similar amounts of broadly overlapping skull shape variation, with relatively low geographic effects. Size predicted skull shape best, coinciding with braincase size variation and differences in zygomatic arches. Size‐adjusted differences in populations explained less variation with far smaller effect sizes, relating to changes in the insertion areas of masticatory muscles, as well as the upper muzzle and incisor region. Climatic and geographic variables contributed little. Strikingly, the vast majority of shape variation—76%—remained unexplained. Our results suggest a uniform intraspecific scope for shape variation, possibly due to allometric constraints or phenotypic plasticity beyond the relatively strong allometric effect. The lack of local adaptation indicates that cross‐breeding between populations will not reduce local morphological skull (and probably general musculoskeletal) adaptation because none exists. However, the potential for heritable morphological variation (e.g., specialization to local diets) seems exceedingly limited. We conclude that 3D geometric morphometrics can provide a comprehensive, statistically rigorous phenomic contribution to genetic‐based conservation studies.

16Aims: Aquatic and terrestrial realms display stark differences in key 17 environmental factors and phylogenetic composition. Despite such differences, 18 their consequences for the evolution of species' life history strategies remain 19 poorly understood. Here, we examine whether and how life history strategies 20 vary between terrestrial and aquatic species. 21 Location: Global. 22 Time period: Variable, the earliest year being in 1906 and the most recent in 23 2015. 24 Major taxa studies: Macroscopic animals and plants species. 25Methods: We use demographic information for 638 terrestrial and 117 aquatic 26 animal and plant species, to derive key life history traits capturing their 27 population turnover, and investments in survival, development, and 28 reproduction. We use phylogenetically corrected least squares regression to 29 explore the differences in the trade-offs between life history traits in both 30 realms. We then quantify the life history strategies of aquatic and terrestrial 31 species using a phylogenetically corrected principal component analysis. 32Results: We find that the same trade-offs structure terrestrial and aquatic life 33 histories, resulting in two dominant axes of variation describing species' pace-34 of-life and reproductive spread through time. Life history strategies differ 35 between aquatic and terrestrial environments, with phylogenetic relationships 36 playing a minor role. We show that adaptations of plants and animals to 37 terrestrial environments have resulted in different life history strategies, 38 particularly with their reproductive mode and longevity. Terrestrial plants display 39 a great diversity of life history strategies, including the species with the longest 40 lifespans. Aquatic animals, on the contrary, exhibit higher reproductive 41 frequency than terrestrial animals, likely due to reproductive adaptations (i.e. 42 internal fecundation) of the later to land. 43 Main conclusions: Our findings show that aquatic and terrestrial species are 44 ruled by the same life history principles, but have evolved different strategies 45 due to distinct selection pressures. Such contrasting life history strategies have 46 important consequences for the conservation and management of aquatic and 47 terrestrial species. 48 Keywords: Aquatic-terrestrial comparisons, comparative demography, fast-slow 49 continuum, life history trait, matrix population model, phylogenetic inertia 50 51