Multiple mating and its relationship to brood size in pregnant fishes versus pregnant mammals and other viviparous vertebrates

Abstract

We summarize the literature on rates of multiple paternity and sire numbers per clutch in viviparous fishes vs. mammals, two vertebrate groups in which pregnancy is common but entails very different numbers of embryos (for species surveyed, piscine broods averaged >10-fold larger than mammalian litters). As deduced from genetic parentage analyses, multiple mating by the pregnant sex proved to be common in assayed species but averaged significantly higher in fish than mammals. However, within either of these groups we found no significant correlations between brood size and genetically deduced incidence of multiple mating by females. Overall, these findings offer little support for the hypothesis that clutch size in pregnant species predicts the outcome of selection for multiple mating by brooders. Instead, whatever factors promote multiple mating by members of the gestating sex seem to do so in surprisingly similar ways in livebearing vertebrates otherwise as different as fish and mammals. Similar conclusions emerged when we extended the survey to viviparous amphibians and reptiles. One notion consistent with these empirical observations is that although several fitness benefits probably accrue from multiple mating, logistical constraints on mate-encounter rates routinely truncate multiple mating far below levels that otherwise could be accommodated, especially in species with larger broods. We develop this concept into a "logistical constraint hypothesis" that may help to explain these mating outcomes in viviparous vertebrates. Under the logistical constraint hypothesis, propensities for multiple mating in each species register a balance between near-universal fitness benefits from multiple mating and species-idiosyncratic logistical limits on polygamy.mating systems | fecundity | genetic parentage analysis | sexual selection P regnancy is a reproductive burden normally borne by females, ultimately because of anisogamy [the difference in size and mobility between male and female gametes (1, 2)]. In other words, because females in sexual species produce the costlier and less mobile class of gametes, the female sex is evolutionarily predisposed to be the sex that gestates its progeny internally. Indeed, pregnancy or embryonic brooding by females has evolved independently on numerous occasions, such that many taxonomic families of fishes, reptiles, and amphibians (as well as most mammals and many invertebrate taxa) include viviparous (livebearing) representatives. In contrast, male-pregnancy is exceedingly rare in the biological world, being displayed by only a few organisms (notably pipefishes and seahorses, Syngnathidae) that thus offer model systems for counterpoint evolutionary studies of reproductive modes, sexual selection, sex roles, and sexual dimorphism (3-12). All forms of pregnancy offer extreme examples of sex-biased parental investment (13), which ever since Bateman (14) has shared center stage with sex-biased sexual selection in research on animal mating systems (15)(16)(17)(18)(19).In effect, female...

Variation in parent-offspring kinship in socially monogamous systems with extra-pair reproduction and inbreeding

“…The four influential variables are unlikely to be entirely under male control or readily predictable across consecutive broods. Although brood size can be influenced by males, it might commonly be primarily a female trait (Avise and Liu 2011;Kokko and Jennions 2012). Although the degree of extra-pair paternity occurring in a brood can be influenced by both the socially-paired female and male, female effects are larger in song sparrows (Reid et al 2014a).…”

Extra-Pair Mating and Evolution of Cooperative Neighbourhoods

“…Extra-pair mating is also common among fish [49], [66], [67], also live-bearing ones [68]. The literature on mammals more often refers to multi-male mating, which occurs widely for example in rodents [69], [70] and group-living primates [56], [71].…”

In the surf zone: Reproductive strategy of the calico surfperch (Amphistichus koelzi) in a comparative context

“…Another species with variation in the pattern of multiple paternity is the tule perch ( Hysterocarpus traski ), which is the only freshwater species. In the tule perch, 92% of broods were sired by multiple fathers, which is similar to the occurrence of multiple paternity of other embiotocid species (Liu et al ., ), but the average number of fathers per brood is lower than other embiotocids examined, which may be associated with reduced mate encounter rates (Avise & Liu, ; Liu et al ., ). The variation in patterns of multiple paternity in the Embiotocinae may be associated with the increased species diversity compared to the Amphistichinae and variation in mating habitats and strategies.…”