Life-history theory predicts that as males age they should increase investment in reproductive effort because their residual reproductive value (RRV) – the opportunity for future reproductive events – declines (Stearns 1992). Such investment is often manifested as age-related increases in the intensity, rate, or duration of a costly behaviour important for acquiring mates. Sexual traits showing...

Reproductive character displacement--the evolution of traits that minimize reproductive interactions between species--can promote striking divergence in male signals or female mate preferences between populations that do and do not occur with heterospecifics. However, reproductive character displacement can affect other aspects of mating behaviour. Indeed, avoidance of heterospecific interactio...

The following hypotheses were tested for groups of simultaneous hermaphrodites Biomphalaria tenagophila: (a) snails that have low reproductive success during the process of self-fertilization do not increase their reproductive success after the end of grouping; (b) the copulation behaviour and the presence of one snail whose eggs have a low viability rate influence the partner's reproductive su...

Reproductive behaviour of animals requires a well-adapted muscular system. This study examines the structural and functional development of ovipositor muscle properties in female locusts during reproductive development. A possible regulation by juvenile hormone (JH) was assessed by comparing muscle properties in immature and mature females and with those whose JH production was inhibited by all...

Fish exhibit an enormous variety of reproductive patterns. There is external and internal fertilization, simultaneous and sequential hermaphroditism as well as gonochorism, and an extremely widespread occurrence of parasitic reproductive behaviour among males. In most fish species there is a great size range of reproductive males, setting the stage for divergent, intraspecific reproductive patt...

Variance in reproductive success among individuals is a defining characteristic of many social vertebrates. Yet, our understanding of which male attributes contribute to reproductive success is still fragmentary in most cases. Male-male reproductive coalitions, where males jointly display to attract females, are of particular interest to evolutionary biologists because one male appears to foreg...

In this paper, we assess the relationship between behavioural (social) and genetic mating success in sockeye salmon (Oncorhynchus nerka) and the frequency of multiple genetic partnering in both sexes. We introduced groups of 13 ripe adults (7 males, 6 females) into four spawning arenas in the Weaver Creek spawning channel, British Columbia, and monitored their behaviour until spawning was compl...

Current international attention to reproductive health behaviour is inspired by a western celebration of individual rights, autonomous action and rational choice. A predominant idea is that individuals should be free to act in accordance with their reproductive intentions and that, in doing so, they will attain their desired (and quantifiable) fertility outcomes. Yet such a framework leads to a...

Floating males are usually thought of as nonbreeders. However, some floating individuals are able to reproduce through extra-pair copulations. Floater reproductive success can impact breeders' sex ratio, reproductive variance, multiple paternity and inbreeding, particularly in small populations. Changes in reproductive variance alter the rate of genetic drift and loss of genetic diversity. Ther...