Understanding Of Evolutionary Ecology Research Articles

A sex skew in life-history research: the problem of missing males.

Life-history strategies are diverse. While understanding this diversity is a fundamental aim of evolutionary biology and biodemography, life-history data for some traits—in particular, age-dependent reproductive investment—are biased towards females. While other authors have highlighted this sex skew, the general scale of this bias has not been quantified and its impact on our understanding of evolutionary ecology has not been discussed. This review summarizes why the sexes can evolve different life-history strategies. The scale of the sex skew is then discussed and its magnitude compared between taxonomic groups, laboratory and field studies, and through time. We discuss the consequences of this sex skew for evolutionary and ecological research. In particular, this sex bias means that we cannot test some core evolutionary theory. Additionally, this skew could obscure or drive trends in data and hinder our ability to develop effective conservation strategies. We finally highlight some ways through which this skew could be addressed to help us better understand broad patterns in life-history strategies.

Camera‐trapping provides insights into adult sex ratio variability in felids

Abstract Adult sex ratio (ASR) plays a pivotal role in many ecological processes, such as population dynamics in time and space, extinction risk and reproductive success, but few patterns in the variability in ASR have been found across species. Due to the socio‐spatial structure and polygynous mating system found in felids, ASR is expected to be female‐biased in felids in a finite area; however, ASR is also commonly found to be either balanced or male‐biased in this taxonomic group. Therefore, investigating ecological correlates of the pattern of ASR variability in felids is of prime importance both for a better understanding of evolutionary ecology and for a more evidence‐based conservation of these threatened taxa. The aim of this review was to investigate whether the expected female‐biased ASR occurs in felids, and whether ASR is influenced by the size of the study area, the species’ body mass and the population density, taking into account the species‐specific home‐range requirements. We reviewed the camera‐trapping literature on felids to build a large global multi‐species data set on ASR variation. We used general linear mixed models to investigate ecological correlates of ASR. In small study areas, the ASR was balanced for all species, but in large areas the ASR was female‐biased for large and medium cats and male‐biased for small cats; sampling designs that are unsuitable for small cats (due to ‘gaps’ within the trapping grid) might explain this latter finding. Moreover, in large study areas, an increase in cat density was associated with more females, whereas in small areas the reverse was true. Our study provides a scientifically sound background for management and conservation actions of these flagship‐threatened taxa of carnivores, by indicating the importance of the study area on ASR in felids. Large areas can promote the recovery of large and medium cats, as more females can be hosted.

Landscape-scale variation in an anthropogenic factor shapes immune gene variation within a wild population.

Understanding the spatial scale at which selection acts upon adaptive genetic variation in natural populations is fundamental to our understanding of evolutionary ecology, and has important ramifications for conservation. The environmental factors to which individuals of a population are exposed can vary at fine spatial scales, potentially generating localized patterns of adaptation. Here, we compared patterns of neutral and major histocompatibility complex (MHC) variation within an island population of Berthelot's pipit (Anthus berthelotii) to assess whether landscape-level differences in pathogen-mediated selection generate fine-scale spatial structuring in these immune genes. Specifically, we tested for spatial associations between the distribution of avian malaria, and the factors previously shown to influence that distribution, and MHC variation within resident individuals. Although we found no overall genetic structure across the population for either neutral or MHC loci, we did find localized associations between environmental factors and MHC variation. One MHC class I allele (ANBE48) was directly associated with malaria infection risk, while the presence of the ANBE48 and ANBE38 alleles within individuals correlated (positively and negatively, respectively) with distance to the nearest poultry farm, an anthropogenic factor previously shown to be an important determinant of disease distribution in the study population. Our findings highlight the importance of considering small spatial scales when studying the patterns and processes involved in evolution at adaptive loci.