Testing hypotheses for the function of the carnivoran baculum using finite-element analysis.
Testing hypotheses for the function of the carnivoran baculum using finite-element analysis.
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DOI：
10.1098/rspb.2018.1473
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发表时间：
2018-09-19
期刊：
影响因子：
--
通讯作者：
Kitchener AC
中科院分区：
文献类型：
--
作者：
Brassey CA;Gardiner JD;Kitchener AC
阴茎骨（阴茎骨）是哺乳动物阴茎龟头内的矿化骨，是哺乳动物骨骼中形态最多样化的结构之一。最近的实验工作为性选择塑造阴茎骨提供了令人信服的证据，但其发生的功能机制仍然未知。先前的研究已经基于长度和直径等简单指标测试了关于阴茎骨作用的生物力学假设，忽略了存在的大量额外形状复杂性。据我们所知，我们首次应用计算模拟方法（有限元分析；FEA）根据高分辨率微型计算机断层扫描来量化食肉动物杆状体（n = 74）的三维生物力学性能。我们发现性大小二态性和压缩载荷下的阴茎骨应力之间存在轻微显着的正相关性，这与“阴道摩擦”假说相反，即阴茎骨在最初的插入过程中变得更加强大以克服阻力。然而，插入持续时间和背腹弯曲下的阴茎骨应力之间存在高度显着的负相关关系。此外，额外的有限元分析证实腹侧沟的存在会减少尿道的变形。我们将此作为支持“长时间插入”假说的证据，表明食肉动物阴茎骨的进化是为了应对交配持续时间和保护尿道的压力。
The baculum (os penis) is a mineralized bone within the glans of the mammalian penis and is one of the most morphologically diverse structures in the mammal skeleton. Recent experimental work provides compelling evidence for sexual selection shaping the baculum, yet the functional mechanism by which this occurs remains unknown. Previous studies have tested biomechanical hypotheses for the role of the baculum based on simple metrics such as length and diameter, ignoring the wealth of additional shape complexity present. For the first time, to our knowledge, we apply a computational simulation approach (finite-element analysis; FEA) to quantify the three-dimensional biomechanical performance of carnivoran bacula (n = 74) based upon high-resolution micro-computed tomography scans. We find a marginally significant positive correlation between sexual size dimorphism and baculum stress under compressive loading, counter to the ‘vaginal friction’ hypothesis of bacula becoming more robust to overcome resistance during initial intromission. However, a highly significant negative relationship exists between intromission duration and baculum stress under dorsoventral bending. Furthermore, additional FEA simulations confirm that the presence of a ventral groove would reduce deformation of the urethra. We take this as evidence in support of the ‘prolonged intromission’ hypothesis, suggesting the carnivoran baculum has evolved in response to pressures on the duration of copulation and protection of the urethra.
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