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Sexual selection is an evolutionary process that favours the traits of individuals who compete more successfully for mating opportunities. These traits are not necessarily those favoured by natural selection on survival and can include exaggerated indicators of sexual fitness and increased ability for conflict within or between sexes.
Males and females often live different lengths of time, but why remains unclear. Here, the authors present a theoretical model showing that trade-offs between survival and reproduction, together with population dynamics, can bias lifespan evolution between the sexes.
An experiment with male-dimorphic mites shows long-lasting benefits of genetic rescue, regardless of type of male rescuer and despite introducing genetic load, in populations subjected to a thermal stress.
Adult sex ratio is important in breeding systems and sexual selection. Here, the authors show that sex-biased demographic processes, including differences in mortality and maturation between males and females, shape adult sex ratio variation in 261 bird species.
Comparative phylogenetic analysis of song features and social behaviours across songbirds shows a coevolutionary relationship between cooperative breeding and presence of female song that is more pronounced in species with weak territoriality.
Why do males typically compete more intensely for mating opportunities than do females and how does this relate to sex differences in gamete size? A new study provides a formal evolutionary link between gamete size dimorphism and ‘Bateman gradients’, which describe how much individuals of each sex benefit from additional matings.
Behavioural experiments and genetic manipulations reveal the mechanisms by which Drosophila females plastically alter their choosiness in response to mating, resolving trade-offs of mate choice.
Sperm length unexpectedly varies more than 3,000-fold across species, posing new questions for anisogamy theory and understanding the different forces shaping evolution of the male gamete.
The Y chromosome of the freshwater fish Poecilia parae may have successively evolved five haplotypes that are maintained in the population for alternative male reproductive strategies.
