Paternity in wild ring-tailed lemurs (Lemur catta): Implications for male mating strategies.

In group-living species with male dominance hierarchies where receptive periods of females do not overlap, high male reproductive skew would be predicted. However, the existence of female multiple mating and alternative male mating strategies can call into question single-male monopolization of paternity in groups. Ring-tailed lemurs (Lemur catta) are seasonally breeding primates that live in multi-male, multi-female groups. Although established groups show male dominance hierarchies, male dominance relationships can break down during mating periods. In addition, females are the dominant sex and mate with multiple males during estrus, including group residents, and extra-group males-posing the question of whether there is high or low male paternity skew in groups. In this study, we analyzed paternity in a population of wild L. catta from the Bezà Mahafaly Special Reserve in southwestern Madagascar. Paternity was determined with 80-95% confidence for 39 offspring born to nine different groups. We calculated male reproductive skew indices for six groups, and our results showed a range of values corresponding to both high and low reproductive skew. Between 21% and 33% of offspring (3 of 14 or three of nine, counting paternity assignments at the 80% or 95% confidence levels, respectively) were sired by extra-troop males. Males siring offspring within the same group during the same year appear to be unrelated. Our study provides evidence of varying male reproductive skew in different L. catta groups. A single male may monopolize paternity across one or more years, while in other groups, >1 male can sire offspring within the same group, even within a single year. Extra-group mating is a viable strategy that can result in extra-group paternity for L. catta males.

When genes move farther than offspring: gene flow by male gamete dispersal in the highly philopatric bat species Thyroptera tricolor.

For species characterized by philopatry of both sexes, mate selection represents an important behaviour for inbreeding avoidance, yet the implications for gene flow are rarely quantified. Here, we present evidence of male gamete-mediated gene flow resulting from extra-group mating in Spix's disc-winged bat, Thyroptera tricolor, a species which demonstrates all-offspring philopatry. We used microsatellite and capture-recapture data to characterize social group structure and the distribution of mated pairs at two sites in southwestern Costa Rica over four breeding seasons. Relatedness and genetic spatial autocorrelation analyses indicated strong kinship within groups and over short distances (<50 m), resulting from matrilineal group structure and small roosting home ranges (~0.2 ha). Despite high relatedness among-group members, observed inbreeding coefficients were low (FIS  = 0.010 and 0.037). Parentage analysis indicated mothers and offspring belonged to the same social group, while fathers belonged to different groups, separated by large distances (~500 m) when compared to roosting home ranges. Simulated random mating indicated mate choice was not based on intermediate levels of relatedness, and mated pairs were less related than adults within social groups on average. Isolation-by-distance (IBD) models of genetic neighbourhood area based on father-offspring distances provided direct estimates of mean gamete dispersal distances (r^) > 10 roosting home range equivalents. Indirect estimates based on genetic distance provided even larger estimates of r^, indicating direct estimates were biased low. These results suggest extra-group mating reduces the incidence of inbreeding in T. tricolor, and male gamete dispersal facilitates gene flow in lieu of natal dispersal of young.