Environmental conditions affect the magnitude of inbreeding depression in survival of Darwin's finches
Environmental conditions affect the magnitude of inbreeding depression in survival of Darwin's finches
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DOI：
10.1111/j.0014-3820.2002.tb01434.x
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发表时间：
2002-06-01
期刊：
影响因子：
3.3
通讯作者：
Petren, K
中科院分区：
文献类型：
--
作者：
Keller, LF;Grant, PR;Petren, K
了解近亲交配(近亲交配衰退)的适合性后果对进化和保护生物学很重要。有充分的证据表明圈养动物近亲繁殖减少，而且来自野生种群的数据正在积累。然而，我们仍然缺乏对近亲繁殖衰退的很好的量化理解，以及是什么影响了自然种群中近亲繁殖衰退的程度。具体地说，近亲繁殖衰退的程度和环境严重程度之间的关系尚不清楚。我们量化了生活在加拉帕戈斯群岛大岛上的仙人掌雀和中型地雀(Geospiza Fortis)种群在生存和繁殖方面的近亲繁殖抑制。我们的分析表明，近亲繁殖大大降低了这两个物种的招募概率(考虑到一只成虫还活着的情况下进行繁殖的可能性)。此外，在烟粉虱中，f=0.25的后代的第一年存活率降低了21%，而f=0.25的成虫的年存活概率降低了45%。该物种成虫和幼虫存活的近亲繁殖抑制程度受到两个环境条件的强烈影响，即食物的可获得性和竞争对手的数量。在青少年中，近亲繁殖抑制只出现在食物可获得性较低的年份，而在成年人中，近亲繁殖抑制在食物可获得性较低和种群规模较大的年份严重五倍。近亲繁殖的生存衰退相对严重，再加上招募概率的降低，导致近交系繁殖成功的人寥寥无几。除了招募概率外，没有其他性状显示出近亲繁殖抑制的证据，这可能是由于两个原因：相对较高的异对父亲率(20%)，这可能导致对明显的近亲繁殖抑制的低估；以及高度近亲繁殖的东方刺参样本量较低，导致统计能力较低。利用幼虫存活数据，我们估计了丑闻革兰氏菌、富蒂斯革兰氏菌和另一种同类巨嘴龙携带的致死当量的数量。这些结果表明，在岛上的鸟类种群中可能存在大量的近亲繁殖抑制，近亲繁殖抑制的程度是环境条件的函数。
Understanding the fitness consequences of inbreeding (inbreeding depression) is of importance to evolutionary and conservation biology. There is ample evidence for inbreeding depression in captivity, and data from wild populations are accumulating. However, we still lack a good quantitative understanding of inbreeding depression and what influences its magnitude in natural populations. Specifically, the relationship between the magnitude of inbreeding depression and environmental severity is unclear. We quantified inbreeding depression in survival and reproduction in populations of cactus finches (Geospiza scandens) and medium ground finches (Geospiza fortis) living on Isla Daphne Major in the Galapagos Archipelago. Our analyses showed that inbreeding strongly reduced the recruitment probability (probability of breeding given that an adult is alive) in both species. Additionally, in G. scandens, first-year Survival of an offspring with f = 0.25 was reduced by 21% and adults with,f = 0.25 experienced a 45% reduction in their annual probability of survival. The magnitude of inbreeding depression in both adult and juvenile survival of this species was strongly modified by two environmental conditions, food availability and number of competitors. In juveniles, inbreeding depression was only present in years with low food availability, and in adults inbreeding depression was five times more severe in years with low food availability and large population sizes. The combination of relatively severe inbreeding depression in survival and the reduced recruitment probability led to the fact that very few inbred G. scandens ever succeeded in breeding. Other than recruitment probability, no other trait showed evidence of inbreeding depression in G. fortis, probably for two reasons: a relatively high rate of extrapair paternity (20%), which may lead to an underestimate of the apparent inbreeding depression, and low sample sizes of highly inbred G. fortis, which leads to low statistical power. Using data from juvenile survival, we estimated the number of lethal equivalents carried by G. scandens, G. fortis, and another congener, G. magnirostris. These results suggest that substantial inbreeding depression can exist in insular populations of birds, and that the magnitude of the inbreeding depression is a function of environmental conditions.