Filippov Alexander E, Matsumura Yoko, Kovalev Alexander E, Gorb Stanislav N
Department Functional Morphology and Biomechanics, Zoological Institute of the Kiel University, Am Botanischen Garten 9, D-24118 Kiel, Germany.
Donetsk Institute for Physics and Engineering, National Academy of Science, 340114, Donetsk, Ukraine.
Sci Rep. 2016 Jun 23;6:27608. doi: 10.1038/srep27608.
It is well known that sexual selection is the main driving force of substantial diversity of genitalia found in animals. However, how it facilitates the diversity is still largely unknown, because genital morpho/physical features and motions/functional morphology of the structures in sexual intercourse are not linked for the vast majority of organisms. Here we showed the presence of material gradient and numerically studied an effect of stiffness gradient of the beetle penis during its propulsion through the female duct. We found that stiffness gradient on the penis essentially affects its propulsion. Microscopic investigation suggests the possibility that the tip of the hyper-elongated penis is softer than the rest of it, and our numerical model confirms that this type of distribution of stiffness gradient aids in faster propulsion than other types. This result indicates that previously ignored physical properties of genital materials are of crucial importance in evolutionary studies of genitalia.
众所周知，性选择是动物生殖器存在大量多样性的主要驱动力。然而，性选择如何促进这种多样性在很大程度上仍然未知，因为对于绝大多数生物来说，生殖器的形态/物理特征与性交过程中这些结构的运动/功能形态并无关联。在此，我们展示了物质梯度的存在，并通过数值研究了甲虫阴茎在通过雌性交配管推进过程中刚度梯度的影响。我们发现阴茎上的刚度梯度本质上会影响其推进。微观研究表明，超细长阴茎的尖端可能比其他部分更柔软，并且我们的数值模型证实，这种刚度梯度分布类型比其他类型更有助于更快地推进。这一结果表明，此前被忽视的生殖器材料的物理特性在生殖器的进化研究中至关重要。
