鸟类羽色和鸣声演化速率的纬度变化

Latitudinal variations in rates of feather color and song evolution in birds

生物多样性随纬度而变化是自然界的重要现象,而生物的性状差异是生物多样性最直接的体现。鸟类的羽色和鸣声在保卫领域、吸引配偶时起着重要作用,与物种形成和性选择联系密切。本文综述了鸟类羽色和鸣声演化速率随纬度变化的规律,探讨了影响其演化速率的因素。影响鸟类性状演化速率的因素包括近缘姊妹种的竞争、有效种群大小、繁殖期、世代周期等。分布区重叠的姊妹近缘物种的种间竞争和避免杂交的压力大,可促进性状的快速分化;小种群遗传漂变速度快,加快性状的演化;高纬度地区鸟类繁殖期短,性选择压力强,加剧性选择性状的演化;世代时间对性状演化的积累有决定性影响。基于美洲鸟类的研究,高纬度地区近缘种羽色和鸣声的演化更快。本文提出,在性状演化的研究中,需要充分考虑亲缘谱系的影响和解释变量的选择,并建议尝试从鸟类可感知的角度衡量性状的演化,关注羽色和鸣声的相互影响及其对性状演化速率的作用,增加对亚洲地区鸟类的研究。

One explanation for the latitudinal gradient of biodiversity is that evolutionary rates of traits that are important to speciation （e.g. color pattern, song） vary across latitude. The reasons for this include sympatry of sister species, effective population size, breeding season length and generation time. Sister species in sympatry encounter intense interspecific competition and cost of hybridization, which may lead to faster evolutionary rates through displacement of traits. Genetic drift can accelerate evolutionary rates in populations with a small effective size. Traits of sexual selection may undergo faster evolutionary rates in birds at higher latitudes that have a shorter breeding season. There is more accumulated divergence in traits among species with shorter generation time, even though the evolutionary rates are unchanged. In birds, color patterns and song features are essential for territory defense and mate attraction, and these features evolve faster in birds at high latitudes based on the studies from New World bird taxa. We further discussed the phylogenetic approach and variable selection in studies of evolutionary rates of avian traits. Quantification of divergence in traits from the bird’s viewpoint, including evolutionary tradeoff between color patterns and song features, may need to be taken into account in future research. In addition, we argue that more attention should be paid to Asian birds.