1 Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara , Santa Barbara, CA 93106-9620 , USA.
2 Department of Biology, University of Wisconsin , La Crosse, WI 54601 , USA.
Proc Biol Sci. 2019 Jan 16;286(1894):20182621. doi: 10.1098/rspb.2018.2621.
Mating behaviours are diverse and noteworthy, especially within species radiations where they may contribute to speciation. Studying how differences in mating behaviours arise between species can help us understand how diversity is generated at multiple biological levels. The bioluminescent courtship displays of cypridinid ostracods (or sea fireflies) are an excellent system for this because amazing variety evolves while using a conserved biochemical mechanism. We find that the evolution of one aspect in this behavioural phenotype-the duration of bioluminescent courtship pulses-is shaped by biochemical function. First, by measuring light production from induced bioluminescence in 38 species, we discovered differences between species in their biochemical reactions. Then, for 16 species for which biochemical, phylogenetic and behavioural data are all available, we used phylogenetic comparative models to show that differences in biochemical reaction are nonlinearly correlated with the duration of courtship pulses. This relationship indicates that changes to both enzyme (c-luciferase) function and usage have shaped the evolution of courtship displays, but that they differentially contribute to these phenotypic changes. This nonlinear dynamic may have consequences for the disparity of signalling phenotypes observed across species, and demonstrates how unappreciated diversity at the biochemical level can lead to inferences about behavioural evolution.
交配行为多种多样，值得关注，尤其是在物种辐射中，它们可能有助于物种形成。研究交配行为在物种之间的差异如何产生，可以帮助我们了解多样性是如何在多个生物学层次上产生的。发光求偶展示的介形纲甲壳动物（或海萤火虫）就是一个很好的系统，因为在使用保守的生化机制的同时，惊人的多样性在进化。我们发现，这种行为表型的一个方面——发光求偶脉冲的持续时间——的进化受到生化功能的影响。首先，通过测量 38 个物种诱导发光产生的光产量，我们发现物种之间的生化反应存在差异。然后，对于 16 个具有生化、系统发育和行为数据的物种，我们使用系统发育比较模型表明，生化反应的差异与求偶脉冲的持续时间呈非线性相关。这种关系表明，酶（c-荧光素酶）功能和用途的变化塑造了求偶展示的进化，但它们对这些表型变化的贡献不同。这种非线性动态可能对观察到的物种间信号表型的差异有影响，并表明生化水平上未被重视的多样性如何导致对行为进化的推断。
