Weak geographical structure in sperm morphology across the range of two willow warbler Phylloscopus trochilus subspecies in Scandinavia

Sperm morphology is highly diversified among species and at higher taxonomic levels. In birds, there is also increasing evidence of geographical differentiation in sperm traits within species, especially in those with strong sperm competition. Geographical divergences in sperm traits might imply the formation of a reproductive barrier in a speciation process. Here we study sperm morphology variation of willow warblers Phylloscopus trochilus in a geographical context in Scandinavia, across the range of two subspecies that are differentiated in certain genetic markers, morphology and migratory routes. We describe geographical patterns in genotypes (two previously described single-nucleotide polymorphism (SNP) markers and four polymorphic microsatellites); in wing length, tarsus length and body mass; and in sperm traits of 330 male willow warblers sampled at 33 localities across Norway (58°N–69°N). Birds were on average larger and longer-winged in the north (spp. acredula) than in the sout...精子形态在物种间及更高分类阶元中具有高度多样性。鸟类类群中亦有日益增多的证据表明，同一物种内的精子性状存在地理分化，尤其在精子竞争强烈的类群中。精子性状的地理分化或暗示物种形成过程中生殖隔离的形成。本研究以斯堪的纳维亚半岛的柳莺（Phylloscopus trochilus）为研究对象，在地理背景下探讨其精子形态变异，涵盖了两个在部分遗传标记、形态特征及迁徙路线上存在分化的亚种的分布范围。我们对挪威33个采样点（北纬58°–69°）的330只雄性柳莺进行采样，分析其基因型（包含2个已报道的单核苷酸多态性（single-nucleotide polymorphism, SNP）标记与4个多态性微卫星标记）、翅长、跗跖长及体质量，同时检测其精子性状。北部的acredula亚种个体平均体型更大、翅长更长，而东南部...