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You are here: Home / Research Teams / M. AVEROF - Comparative developmental biology and regeneration / Publications / Publications IGFL / Repeated co-option of a conserved gene regulatory module underpins the evolution of the crustacean carapace, insect wings and other flat outgrowths

Repeated co-option of a conserved gene regulatory module underpins the evolution of the crustacean carapace, insect wings and other flat outgrowths

Yasuhiro Shiga, Yasuhiko Kato, Yuko Aragane-Nomura, Takayuki Haraguchi, Theodora Saridaki, Hajime Watanabe, Taisen Iguchi, Hideo Yamagata, and Michalis Averof (2017)

bioRxiv.

How novelties arise is a key question in evolutionary developmental biology. The crustacean carapace is a novelty that evolved in the early Cambrian. In an extant crustacean, Daphnia magna, the carapace grows from the body wall as a double-layered sheet with a specialized margin. We show that the growing margin of this carapace expresses vestigial, scalloped and wingless, genes that are known to play key roles in regulating growth at the insect wing margin. RNAi-mediated knockdown of scalloped and wingless impair carapace development, indicating that carapace and wing might share a common mechanism for margin outgrowth. However, carapace and wings arise in different parts of the body and their margins have different orientations, arguing that these structures have independent evolutionary origins. We show that scalloped is also expressed at the margin of unrelated flat outgrowths (tergites and coxal plates) in the distantly related crustacean Parhyale hawaiensis. Based on these observations, we propose that the vestigial-scalloped-wingless gene module has a common role in the margin of diverse flat structures, originating before the divergence of major crustacean lineages and the emergence of insects. Repeated co-option of this module occurred independently in the carapace, wing and other flat outgrowths, underpinning the evolution of distinct novelties in different arthropod lineages.

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