Evolution of horn length and lifting strength in the Japanese rhinoceros beetle Trypoxylus dichotomus

Jesse N. Weber*, Wataru Kojima, Romain P. Boisseau, Teruyuki Niimi, Shinichi Morita, Shuji Shigenobu, Hiroki Gotoh, Kunio Araya, Chung Ping Lin, Camille Thomas-Bulle, Cerisse E. Allen, Wenfei Tong, Laura Corley Lavine, Brook O. Swanson, Douglas J. Emlen*


研究成果: 雜誌貢獻期刊論文同行評審

3 引文 斯高帕斯(Scopus)


What limits the size of nature's most extreme structures? For weapons like beetle horns, one possibility is a tradeoff associated with mechanical levers: as the output arm of the lever system—the beetle horn—gets longer, it also gets weaker. This “paradox of the weakening combatant” could offset reproductive advantages of additional increases in weapon size. However, in contemporary populations of most heavily weaponed species, males with the longest weapons also tend to be the strongest, presumably because selection drove the evolution of compensatory changes to these lever systems that ameliorated the force reductions of increased weapon size. Therefore, we test for biomechanical limits by reconstructing the stages of weapon evolution, exploring whether initial increases in weapon length first led to reductions in weapon force generation that were later ameliorated through the evolution of mechanisms of mechanical compensation. We describe phylogeographic relationships among populations of a rhinoceros beetle and show that the “pitchfork” shaped head horn likely increased in length independently in the northern and southern radiations of beetles. Both increases in horn length were associated with dramatic reductions to horn lifting strength—compelling evidence for the paradox of the weakening combatant—and these initial reductions to horn strength were later ameliorated in some populations through reductions to horn length or through increases in head height (the input arm for the horn lever system). Our results reveal an exciting geographic mosaic of weapon size, weapon force, and mechanical compensation, shedding light on larger questions pertaining to the evolution of extreme structures.

頁(從 - 到)4285-4297.e5
期刊Current Biology
出版狀態已發佈 - 2023 10月 23

ASJC Scopus subject areas

  • 一般生物化學,遺傳學和分子生物學
  • 一般農業與生物科學


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