Peacock M M, Smith A T
Department of Zoology, Arizona State University, Tempe 85287-1501, USA.
Mol Ecol. 1997 Sep;6(9):801-11.
The extent and effect of inbreeding in natural populations remain largely undetermined. Pikas Ochotona princeps have been considered a likely candidate for close inbreeding in natural populations due to observations of frequent juvenile philopatry (colonization of natal home range or neighbouring home range) and high levels of spatial overlap and social tolerance between neighbouring individuals of the opposite sex. A 4-year investigation of inbreeding in pikas, however, has revealed that dispersal and mating patterns are uncoupled in this species, i.e. explained by different hypotheses. DNA fingerprinting analysis revealed that band-sharing scores between mated pairs, identified via parentage analysis, were not commensurate with band-sharing among known first-order relatives, but were similar to scores for a small sample of known second-order relatives (i.e. half-siblings grandparent-grandchild pairs). Band-sharing scores between mated pairs were then compared with those between potential mated pairs within the population to assess whether mating was random or nonrandom with respect to genetic similarity. The results of Monte Carlo randomization tests show that pikas mated with individuals with intermediate genetic similarity in greater proportion than would be expected by chance. These data suggest mate choice in pikas may be based upon intermediate levels of relatedness.
自然种群中近亲繁殖的程度和影响在很大程度上仍未确定。由于观察到幼年鼠兔频繁留居出生地（在出生地或相邻的家域内定居）以及异性相邻个体之间存在高度的空间重叠和社会容忍度，北美鼠兔被认为是自然种群中近亲繁殖的一个可能候选物种。然而，一项为期4年的北美鼠兔近亲繁殖调查显示，该物种的扩散和交配模式并不相关，即由不同的假设来解释。DNA指纹分析表明，通过亲权分析确定的配偶对之间的条带共享分数与已知一级亲属之间的条带共享情况不相称，但与一小部分已知二级亲属（即同父异母或同母异父的兄弟姐妹、祖孙对）的分数相似。然后将配偶对之间的条带共享分数与种群中潜在配偶对之间的分数进行比较，以评估交配在遗传相似性方面是随机的还是非随机的。蒙特卡洛随机化测试结果表明，北美鼠兔与具有中等遗传相似性的个体交配的比例高于偶然预期的比例。这些数据表明，北美鼠兔的配偶选择可能基于中等程度的亲缘关系。
