An understanding of the drivers of individual fitness is a fundamental component of evolutionary ecology and life-history theory. Reproductive senescence, mate and mating tactic choice and latent heterogeneity in individual quality interact to affect individual fitness. We sought to disentangle the effects of these fitness drivers, where longitudinal data are required to understand their respective impacts. We used reproductive allocation and success data from a long-term (1989-2018) study of white-throated dippers Cinclus cinclus in Switzerland to simultaneously examine the effects of female and male age, mating tactic, nest initiation date and individual heterogeneity on reproductive performance. We modelled quadratic and categorical effects of age on reproductive parameters. The probability of polygyny increased with age in both sexes before declining in older age classes. Similarly, hatching probability in monogamous pairs and the number of nestlings hatched in both monogamous and polygynous pairs increased with female age before declining later in life. As predicted, offspring survival in monogamous pairs increased with male age before declining in older age classes, but male age had no effect on offspring survival in polygynous nesting attempts. Our results demonstrate that parental age, mating tactic and individual heterogeneity all affect reproductive success, and that the impacts of senescent decline are expressed across different demographic components as a function of sex-specific senescent decline and mating tactic.
Across diverse species with sexual reproduction, typically the more male-biased the adult sex ratio (ASR), the greater the investments by the more populous males in the rarer females who hold greater bargaining power in a mating context. Relatively few studies have examined this effect in humans however, and almost none involve observations of actual male investment in a potential mating context. Here, we present one of the first studies to observe investments of men in a potential mating context under differing ASRs.
The bewildering courtship phenotypes of male birds of paradise () represent a classic example of sexual selection through mate choice. While the majority of sexual selection studies have focused on either mate choice or intrasexual competition, males across a variety of taxa adopt alternative mating tactics as additional means of obtaining fertilization when they are otherwise unable to. For example, across various polygynous birds, subordinate males engage in sneak copulations, which may offset the fitness costs of prolonged subordinate periods.
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.
The dissolving of social bonds is disruptive and leads to increased stress responsivity and a strong desire for reunion. The oxytocin (OXT) system is critical for the formation of social attachments, such as pair bonds, and is also involved in social recognition, social memory, and social vigilance. Therefore, long-term changes in the OXT system resulting from cohabitation and pair bonding may contribute to reunion-seeking behavior.
Environmental conditions, like climate variability, impact the costs and benefits of reproductive traits, affecting sexual selection.
The study focused on nuptial gift-giving spiders, examining how different climatic conditions influence male sexual traits and female mate choice.
Results showed that in highly variable environments, female choice is limited, leading to a preference for deceptive worthless gifts, while more stable environments promote better mate selection.
