八島 亮子

Understanding how genetic variation is maintained within a species is important in ecology, evolution, conservation and population genetics. Tremendous efforts have been made to evaluate the patterns of genetic variation in natural populations of various species. For this purpose, microsatellites have played a major role since the 1990s. Here we describe a comprehensive database, VARVER (Variation in Vertebrates) that provides complete information regarding microsatellite variation in natural populations of vertebrates. For each species, VARVER includes basic information of the species, a list of publications reporting the microsatellite variation, and tables of genetic variation within and between populations (heterozygosity and F-ST). The geographic location and rough sampling range are also shown for each sampled population. The database should be useful for researchers interested in not only specific species but also comparing multiple species. We discuss the utility of microsatellite data, particularly for meta-analyses that involve multiple microsatellite loci from various species. We show that in such analyses, it is extremely important to correct for biases caused by differences in mutation rate, mainly due to repeat unit and number.

Reproductive skew in multimale groups may be determined by the need for alpha males to offer reproductive opportunities as staying incentives to subordinate males (concessions), by the relative fighting ability of the alpha male (tug-of-war) or by how easily females can be monopolized (priority-of-access). These models have rarely been investigated in species with exceptionally long male tenures, such as white-faced capuchins, where female mate choice for novel unrelated males may be important in shaping reproductive skew. We investigated reproductive skew in white-faced capuchins at Sector Santa Rosa, Costa Rica, using 20years of demographic, behavioural and genetic data. Infant survival and alpha male reproductive success were highest in small multimale groups, which suggests that the presence of subordinate males can be beneficial to the alpha male, in line with the concession model's assumptions. None of the skew models predicted the observed degree of reproductive sharing, and the probability of an alpha male producing offspring was not affected by his relatedness to subordinate males, whether he resided with older subordinate males, whether he was prime aged, the number of males or females in the group or the number of infants conceived within the same month. Instead, the alpha male's probability of producing offspring decreased when he was the sire of the mother, was weak and lacked a well-established position and had a longer tenure. Because our data best supported the inbreeding avoidance hypothesis and female choice for strong novel mates, these hypotheses should be taken into account in future skew models.

Sex-biased dispersal can reduce kin cooperation and kin competition in the dispersed sex. However, this may not be the case when group-living animals engage in parallel dispersal, which occurs when an individual transfers between groups together with other animals or immigrates alone into a group that contains familiar animals. Despite this potential effect on kin cooperation and competition, few studies have thoroughly investigated how parallel dispersal affects the kin composition of groups. To further our understanding of this topic, we investigated the effect of parallel dispersal on access to coresident kin in male white-faced capuchins, Cebus capucinus. Between 2006 and 2013, we collected demographic and genetic data from two to five groups in Sector Santa Rosa, Costa Rica. We genotyped 41 females and 39 males at 14 short tandem repeat loci, and we calculated their estimated relatedness values. The majority of males dispersed in parallel, and parallel dispersing males were more closely related to one another than were other males. Parallel immigrant males and natal females resided with a similar number of same-sex kin. Single immigrant males in multimale groups rarely resided with male kin, and they resided with fewer same-sex kin than did parallel immigrant males and natal females. Because parallel dispersal offers an opportunity for males to form long-lasting cooperative relationships with familiar kin, this dispersal pattern should be taken into account in future models of the evolution of social structure. (C) 2014 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.