Molecular evolution of phototransduction pathway genes in nocturnal and diurnal fireflies (Coleoptera: Lampyridae)

Most organisms are dependent on sensory cues from their environment for
survival and reproduction. Fireflies (Coleoptera: Lampyridae) represent an
ideal system for studying sensory niche adaptation due to many species
relying on bioluminescent communication, as well as a diversity of
ecology. Here we examine the phototransduction pathway in this non-model
organism, and provide some of the first evidence for positive selection in
the PT pathway in insects. Duplications are found in calmodulin,
inactivation no afterpotential C, inactivation no afterpotential D, and
transient receptor potential. We also find strong support for positive
selection in arrestin-2, inactivation no afterpotential D, and transient
receptor potential, with weak support for positive selection in guanine
nucleotide-binding protein G(q) subunit alpha and  neither
inactivation nor afterpotential C. This represents an exciting new avenue
of study as we seek to further understand these molecular players.

绝大多数生物依赖环境中的感官线索以完成生存与繁衍。萤火虫（鞘翅目Coleoptera：萤科Lampyridae）因诸多物种依赖生物发光通讯，且兼具丰富的生态多样性，成为研究感官生态位适应的理想模型体系。本研究针对该非模式生物的光转导通路（phototransduction pathway）展开分析，并首次为昆虫光转导通路存在正选择提供了部分实证依据。研究发现钙调蛋白（calmodulin）、无失活后电位C（inactivation no afterpotential C, INAC）、无失活后电位D（inactivation no afterpotential D, INAD）以及瞬时受体电位（transient receptor potential, TRP）均存在基因重复事件；同时在抑制蛋白2（arrestin-2）、无失活后电位D以及瞬时受体电位中检测到了正选择的强力支持证据，而在鸟苷酸结合蛋白G(q)亚基α（guanine nucleotide-binding protein G(q) subunit alpha, GNAQ）与无失活亦无后电位C（neither inactivation nor afterpotential C, NINAC）中仅获得较弱的正选择支持信号。这为我们深入解析这些分子调控元件开辟了极具前景的全新研究方向。