No inbreeding avoidance in an isolated population of bighorn sheep
No inbreeding avoidance in an isolated population of bighorn sheep
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DOI：
10.1016/j.anbehav.2010.08.006
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发表时间：
2010-11
期刊：
影响因子：
2.5
通讯作者：
Elise Rioux-Paquette;M. Festa‐Bianchet;D. Coltman
中科院分区：
文献类型：
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作者：
Elise Rioux-Paquette;M. Festa‐Bianchet;D. Coltman
当近亲交配产生健康成本时，应选择近亲交配避免机制，如配偶选择。然而，几项研究表明，尽管近亲交配的成本很高，但动物仍能容忍近亲交配。我们研究了加拿大阿尔伯塔省拉姆山的加拿大大角羊的近亲繁殖避免，这是一个扩散有限的种群。我们使用随机化程序来模拟如果每年的交配是随机的，那么羔羊的平均近亲繁殖系数，并将这些随机交配场景与1996年至2007年的已知配对进行比较。我们考虑了三组候选雄性：所有2岁或2岁以上的雄性，只有已知能繁殖的雄性，以及所有雄性，但在生殖成功方面考虑了年龄差异。在所有情况下，平均队列近亲繁殖系数与随机交配下的预期系数没有差异。我们没有发现在近亲之间避免交配的证据(同父异母的表亲和较高的亲属关系)。配偶选择可能受到种群中个体之间普遍较高水平的亲缘关系的限制。然而，对于该物种来说，避免近亲繁殖的选择压力可能也很小，因为近亲繁殖的性别差异成本、与近亲见面的机会有限以及雄性的繁殖迁徙。明显缺乏近亲繁殖避免对保护小而孤立的大角羊种群具有重要影响，在这些种群中，近亲交配水平应该很高。
Inbreeding avoidance mechanisms such as mate choice should be selected for when inbreeding produces fitness costs. Several studies, however, suggest that animals tolerate inbreeding despite its costs. We studied inbreeding avoidance in bighorn sheep, Ovis canadensis, on Ram Mountain, Alberta, Canada, a population with limited dispersal. We used a randomization procedure to simulate a mean inbreeding coefficient of lambs if mating was random every year, and compared these random mating scenarios with known pairings from 1996 to 2007. We considered three sets of candidate males: all males aged 2 years or more, only males known to reproduce, and all males but accounting for age differences in reproductive success. In all cases, mean cohort inbreeding coefficients did not differ from those expected under random mating. We found no evidence of avoidance of mating between close relatives (half-cousins and higher degrees of relatedness). Mate choice was possibly constrained by the generally high level of relatedness among individuals in the population. Selective pressures for inbreeding avoidance, however, may also be weak for this species because of sex-differential costs of inbreeding, limited opportunities of meeting close relatives and breeding migrations of males. The apparent lack of inbreeding avoidance has important implications for the conservation of small and isolated populations of bighorn sheep, where high levels of inbreeding should be expected.