Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.
Mol Ecol. 2010 Dec;19(24):5511-20. doi: 10.1111/j.1365-294X.2010.04887.x. Epub 2010 Nov 4.
Conspecific aggregations in terrestrial and aquatic organisms can have a significant effect on an individual's survival, growth and reproductive fitness, particularly if these aggregations are composed of closely related individuals. Such aggregations can form passively, as a consequence of dispersal, or actively, as a consequence of kin recognition. In this study, we investigated the genetic composition of individuals in conspecific aggregations in the simultaneous hermaphroditic marine bryozoan Bugula stolonifera. Conspecific larvae routinely metamorphose on adult colonies; the possibility that larvae select or avoid their maternal colony was investigated utilizing 10 newly developed polymorphic microsatellite loci. Adult colonies were collected from Eel Pond, Woods Hole, Massachusetts and inspected for the presence of attached individuals. Adult colonies and their attached individuals were genotyped and compared to assess genetic relatedness within and among these groups relative to the overall genetic variability of the sampling site. Overall, the population of B. stolonifera at this site was found to be outside Hardy-Weinberg equilibrium because of significant levels of inbreeding. No significant genetic differentiation, however, was found between any groups, documenting that a group containing an adult colony and its attached individuals had as much genetic variability as was found for the entire sampling site. Parentage-exclusion analyses showed that the vast majority of attached individuals (>93%) could not have derived from the colony on which they were attached. Kinship analyses showed that the majority of attached individuals (≈63%) shared less than a half-sibling relationship. These results suggest that a colony's nearest neighbours are not composed of siblings, and thus, larval settlement preference can maximize outcrossing in this inbreeding population.
同种生物在陆地和水生生物中的聚集对个体的生存、生长和繁殖适应性有重大影响，特别是如果这些聚集是由密切相关的个体组成的。这种聚集可以是被动形成的，是扩散的结果，也可以是主动形成的，是亲缘识别的结果。在这项研究中，我们调查了同时性雌雄同体的海洋苔藓虫 Bugula stolonifera 同种聚集个体的遗传组成。同种幼虫通常在成年群体上变态；利用 10 个新开发的多态微卫星基因座，研究了幼虫选择或回避其母代群体的可能性。从马萨诸塞州伍兹霍尔的鳗鱼池塘收集成年群体，并检查是否有附着的个体。对成年群体及其附着的个体进行基因分型，并进行比较，以评估这些群体内和群体间相对于采样点整体遗传变异性的遗传相关性。总体而言，由于近亲繁殖水平较高，该地点的 B. stolonifera 种群处于哈迪-温伯格平衡之外。然而，任何群体之间都没有发现显著的遗传分化，这证明一个包含成年群体及其附着个体的群体具有与整个采样点相同的遗传变异性。亲子排除分析表明，绝大多数附着个体（>93%）不可能来自它们附着的群体。亲缘关系分析表明，大多数附着个体（≈63%）的亲缘关系不到半同胞。这些结果表明，一个群体的最近邻居不是由兄弟姐妹组成的，因此，在这个近亲繁殖的群体中，幼虫的定居偏好可以最大限度地增加异交。
