Data from: 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 behavior 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 disk-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 neighborhood area based on father-offspring distances provided direct estimates of mean gamete dispersal distances (ˆr ) greater than 10 roosting home range equivalents. Indirect estimates based on genetic distance provided even larger estimates of ˆr , suggesting 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.

对于两性均具有恋巢性（philopatry）的物种而言，配偶选择是避免近交的关键行为，但该行为对基因流的影响却鲜有量化研究。本研究以斯皮氏盘翼蝠（Thyroptera tricolor）——一种所有后代均表现出恋巢性的物种——为研究对象，提供了其种群内群外交配引发雄性配子介导的基因流的相关证据。本研究借助微卫星标记（microsatellite）和捕获重捕数据，对哥斯达黎加西南部两个研究地点历经四个繁殖季的社会群体结构与配偶对的分布特征进行了解析。亲缘关系与遗传空间自相关分析结果显示，群体内部以及短距离（<50米）范围内存在紧密的亲缘关系，这源于母系群体结构以及狭小的栖息家域（约0.2 ha）。尽管群体成员间亲缘关系较高，但观测到的近交系数却较低（FIS = 0.010和0.037）。亲权分析表明，母本与后代均隶属于同一社会群体，而父本则来自不同群体，与栖息家域相比，其分布间距可达约500 m。模拟随机交配实验显示，配偶选择并非基于中等程度的亲缘关系，且平均而言，配偶对之间的亲缘关系低于社会群体内成年个体间的亲缘关系。基于父本-后代间距构建的遗传邻域面积距离隔离（Isolation-by-distance, IBD）模型，直接估算得到的平均配子扩散距离（ˆr）超过10倍栖息家域的等效值。基于遗传距离得到的间接估算结果则显示ˆr数值更大，这表明直接估算值存在偏低的偏差。本研究结果表明，群外交配可降低斯皮氏盘翼蝠（T. tricolor）的近交发生率，且雄性配子扩散可替代幼体出生扩散，进而促进基因流。