Data from: Divergence of ovipositor length and egg shape in a brood parasitic bitterling fish through the use of different mussel hosts

Bitterling fishes deposit their eggs on the gills of living mussels using
a long ovipositor. We examined whether ovipositor length and egg shape
correlated with differences in host mussel species in the family Unionidae
among populations of the tabira bitterling (Acheilognathus tabira) in
Japan. Bitterling populations that use mussels in the sub-family
Anodontinae possessed longer ovipositors and more elongated eggs than
those using mussels of Unioninae, as expected from the difference in host
size between the sub-families (anodontine mussels are larger than unionine
mussels). Based on a robust phylogeny of A. tabira populations, we
demonstrated that the evolution of both ovipositor length and egg shape
were correlated with host differences, but not with each other, suggesting
that these traits have been selected for independently. Our study
demonstrates how adaptive traits for brood parasitism may diverge with
host shift due to different host availability and/or interspecific
competition for hosts.

鳑鲏鱼类借助细长的产卵管将卵产在活贻贝的鳃上。本研究探讨了日本tabira鳑鲏（Acheilognathus tabira）不同种群中，产卵管长度与卵形态是否与蚌科（Unionidae）宿主贻贝种类的差异存在关联。结果显示，相较于利用珠蚌亚科（Unioninae）贻贝的种群，依赖无齿蚌亚科（Anodontinae）贻贝的鳑鲏种群具有更长的产卵管和更细长的卵——这与两亚科宿主体型差异（无齿蚌亚科贻贝大于珠蚌亚科）的预期一致。基于tabira鳑鲏种群稳健的系统发育关系，我们证实：产卵管长度与卵形态的进化均与宿主差异相关，但二者彼此独立，提示这两种性状是独立选择的结果。本研究揭示了育幼寄生的适应性性状如何因宿主可用性差异或种间宿主竞争，随宿主转移而发生分化。