Grant Peter R, Grant B Rosemary
Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, 08544-1003.
Evolution. 1995 Apr;49(2):229-240. doi: 10.1111/j.1558-5646.1995.tb02235.x.
We report the natural colonization of the small Galápagos island Daphne Major by the large ground finch (Geospiza magnirostris). Immigrants of this species were present in every year of a 22-yr study, 1973-1994. Typically they arrived after a breeding season and left at the beginning of the next one. Geospiza magnirostris bred on the island for the first time in the exceptionally wet El Niño year of 1982-1983, and bred in all subsequent years except drought years. In agreement with theoretical expectations the frequency of inbreeding was unusually high. Pronounced fluctuating asymmetry in tarsus length, together with slightly reduced breeding success of inbreeding pairs, suggests a low level of inbreeding depression. Despite this, the population increased from 5 breeding individuals in 1983 to 20 breeding individuals in 1992, and probably more than twice that number in 1993, largely through recruitment of locally born birds.
我们报告了大型地雀（大嘴地雀，Geospiza magnirostris）对加拉帕戈斯群岛小岛屿达芙妮主岛的自然殖民情况。在1973年至1994年长达22年的研究中，每年都有该物种的移民出现。通常情况下，它们在繁殖季节之后抵达，在下一个繁殖季节开始时离开。大嘴地雀于1982 - 1983年异常湿润的厄尔尼诺年份首次在该岛繁殖，除干旱年份外，在随后的所有年份都有繁殖。与理论预期一致，近亲繁殖的频率异常高。跗骨长度明显的波动不对称，以及近亲繁殖配对的繁殖成功率略有降低，表明近亲繁殖衰退程度较低。尽管如此，种群数量从1983年的5个繁殖个体增加到1992年的20个繁殖个体，1993年可能超过这个数字的两倍，这主要是通过本地出生鸟类的补充实现的。
