Data from: Does habitat specialization shape the evolutionary potential of wild bird populations?

Because specialist species evolved in more temporally and spatially homogeneous environments than generalist species, they are supposed to experience less fluctuating selection. For this reason, we expect specialists to show lower overall genetic variation as compared to generalists. We also expect populations from specialist species to be smaller and more fragmented, with lower neutral genetic diversity. We tested these hypotheses by investigating patterns of genetic diversity along a habitat specialization gradient in wild birds, based on estimates of heritability, coefficients of variation of additive genetic variance, and heterozygosity available in the literature. We found no significant effect of habitat specialization on any of the quantitative genetic estimators but generalists had higher heterozygosity. This effect was mainly a consequence of the larger population size of generalists. Our results suggest that evolutionary potential does not differ at the population level between generalist and specialist species, but the trend observed in heterozygosity levels and population sizes may explain their difference in susceptibility to extinction.由于特化物种（specialist species）相较于广适物种（generalist species）演化于时间与空间均质性更高的环境中，其经历的波动选择理应更弱。基于此，我们推测特化物种的整体遗传变异水平要低于广适物种。此外，我们还预期特化物种的种群规模更小、种群结构更破碎，且中性遗传多样性更低。我们基于文献中已有的遗传力（heritability）、加性遗传方差（additive genetic variance）变异系数以及杂合度（heterozygosity）估算结果，通过探究野生鸟类沿生境特化梯度的遗传多样性模式，对上述假说进行了验证。研究结果显示，生境特化程度对所有数量遗传估计量均无显著影响，但广适物种的杂合度更高。这一现象主要源于广适物种拥有更大的种群规模。我们的研究结果表明，广适物种与特化物种在种群水平上的进化潜力并无差异，但二者在杂合度水平与种群规模上的差异趋势，或可解释它们在灭绝易感性方面的不同。