Hybridization of Darwin's Finches on the Galapagos Islands

杂交的研究在进化生物学中是重要的，因为它揭示了在物种形成的最后阶段起作用的力量。有些动物种群通常会杂交，但要确定自然界中杂交的原因和结果通常是困难的，如果不是不可能的话。本研究利用了一个非常有利的条件来研究杂交的原因和杂种相对高适合度的原因。在加拉帕戈斯群岛的达芙妮梅杰小岛上，中型地雀（Geospiza fortis）偶尔会与另外两种地雀杂交；常住种scandens，外来种G. fuliginosa。系谱分析表明，杂交后代在若干年的时间里，可以和亲本物种一样存活和繁殖，甚至比亲本物种更好。它们高适应性的生态原因将通过对饲养效率和饲料的深入研究来调查。通过分析G.fortis和G.scandens群体的近交效应来评估杂合性增强可能带来的优势。杂交的原因将通过对交配模式的统计分析来确定。本研究分为基础研究和应用研究两个方面。结果将对我们理解物种形成具有理论意义。证明杂交在维持小种群和潜在濒危种群的遗传变异方面的作用将对保护生物学的应用领域具有重要价值。

9306753 Grant The study of hybridization is important in evolutionary biology because it reveals the forces at work in the final stages of speciation. Some populations of animal species commonly hybridize, but it is usually difficult if not impossible tho determine the causes and consequences of hybridization in nature. The proposed research takes advantage of an exceptionally favorable situation for investigating the causes of hybridization and the reasons for relatively high fitness of the hybrids. On the small island of Daphne Major in the Galapagos archipelago the medium ground finch, Geospiza fortis, occasionally interbreeds with the two others; G.scandens, a resident species, G. fuliginosa, an immigrant. Pedigree analysis has shown that hybrids may survive and breed as well or better than the parental species, over several years. Ecological reasons for their high fitness will be investigated by intensive study of feeding efficiencies and diets. Possible advantages arising from enhanced heterozygosity will be assessed by an analysis of inbreeding effects in the G.fortis and G.scandens populations. Causes of interbreeding will be identified by statistical analysis of mating patterns. %%% There are basic and applied aspects of the proposed research. Results will be of theoretical importance to our understanding of speciation. A demonstration of the role of hybridization in maintaining genetic variation in small and potentially endangered populations will be the value to the applied field of conservation biology.