Sexual selection and senescence:: Male size-dimorphic ungulates evolved relatively smaller molars than females
Sexual selection and senescence:: Male size-dimorphic ungulates evolved relatively smaller molars than females
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DOI：
10.1086/519852
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发表时间：
2007-09-01
影响因子：
2.9
通讯作者：
Perez-Barberia, F. Javier
中科院分区：
文献类型：
--
作者：
Carranza, Juan;Perez-Barberia, F. Javier
一般来说，两性有蹄类物种的雄性进化出比雌性更大的体型，但生殖寿命更短，这是它们为获得交配机会而进行性内竞争的策略的组成部分。衰老的进化理论预测，体细胞结构的耐久性应该与生殖寿命的长短有关。这一预测最近在马鹿(Cervus Elaffus)身上得到了验证：雄性的臼齿比雌性的更小，更不耐用，这与生殖寿命的性别差异相对应。然而，普遍证据表明，由于男性体重增加，性别选择导致男性牙齿比异速生长规则预期的要小，这需要对二型和非二型有蹄类进行种间比较。在这里，我们调查了123种现存的有蹄类的面颊牙齿大小(咬合表面积)和体重之间的关系。我们发现，与非二态物种相比，二态物种的斜率更低，并且与二态物种的雌性相比，二态物种的雄性的OSA相对于体质量更小。OSA相对于体质量进化的速率在雌性中大于雄性，在非二形性物种中也大于二形性物种。我们的结果与一夫多妻的雄性有蹄类动物的性别选择更有利于身体大小而不是牙齿大小的假设是一致的，与雌性相比，雄性可能会通过过早地耗尽牙齿而导致雄性衰老。
As a general rule, males of sexually dimorphic ungulate species have evolved larger body size than females but shorter reproductive life spans as elements of their strategy for intrasexual competition for mating opportunities. Evolutionary theories of senescence predict that the durability of somatic structures should relate to the length of reproductive life span. This prediction has recently been tested for red deer (Cervus elaphus): molariform teeth of males are smaller and less durable than those of females, which corresponds with sex differences in reproductive life span. However, general evidence that male teeth are smaller than expected by allometric rules as a consequence of sexual selection for increasing male body mass requires an interspecific comparison between dimorphic and nondimorphic ungulates. Here we investigate the relationship between cheek-teeth size ( occlusal surface area; OSA) and body mass in 123 species of extant ungulates. We found lower slopes for dimorphic species compared with nondimorphic ones and smaller OSA, relative to body mass, in males of dimorphic species compared with females of dimorphic species. Rates of evolution of OSA relative to rates of evolution of body mass were greater in females than in males and also greater in nondimorphic than in dimorphic species. Our results are consistent with the hypothesis that sexual selection in polygynous male ungulates favors body size more than tooth size, with possible consequences in male senescence via early depletion of male teeth compared to females.