Dwarf males in the epizoic barnacle Octolasmis unguisiformis and their implications for sexual system evolution

作者：Sawada Kota; Yoshida Ryuta; Yasuda Keiko; Yamaguchi Sachi; Yusa Yoichi

来源：Invertebrate Biology, 2015, 134(2): 162-167.

DOI：10.1111/ivb.12083

• androdioecy
• hermaphroditism
• Crustacea
• Cirripedia
• Thoracica

Descriptions of the diversity of sexual systems in animal taxa such as the thoracican barnacles are needed to study the evolution of sexual systems. Androdioecious systems (coexistence of hermaphrodites and males) are particularly important due to their possible role as evolutionary intermediates in transitions between hermaphroditism and dioecy. In this study, we used histology to examine the sexual system of the crab-epizoic barnacle Octolasmis unguisiformis to determine if dwarf males were present or not; a previous study reported the existence of conspecific-attached individuals, but did not investigate their sexuality. All conspecific-attached individuals were dwarf males, irrespective of their attachment site. However, crab-attached individuals never acted as dwarf males even if they were small and lived together with large individuals. The result emphasizes the importance of attachment to conspecifics, but not to specific sites on conspecifics, in the evolution of dwarf males. Other individuals were hermaphroditic, indicating androdioecy in this species. However, their functional sexuality (that is, whether they actually do act as males) requires further study. The presence of dwarf males in this species supports theoretical predictions that small group size, short-lived habitats, or spatial limitation favor the evolution of dwarf males.

• 出版日期2015-6