Unusual sexual dimorphism and small adult size for olive ridley sea turtles are linked to volumetric geometric constraints
Unusual sexual dimorphism and small adult size for olive ridley sea turtles are linked to volumetric geometric constraints
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DOI：
10.1007/s00227-020-03814-7
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发表时间：
2021-01-01
期刊：
影响因子：
2.4
通讯作者：
Girondot, Marc
中科院分区：
文献类型：
--
作者：
Girard, Alexandre;Breheret, Nathalie;Girondot, Marc
确定海龟的性别大小二态性（SSD）是具有挑战性的，因为雌性海龟在筑巢的海滩上被观察到，而雄性海龟则留在海上，很少遇到。在刚果共和国同一地区进行的海龟兼捕调查和筑巢监测计划获得的数据提供了雄性和雌性橄榄ridley（Lepidochelys olivacea）的体型。弯曲甲壳长度（CCL）在男性和女性的橄榄ridleys揭示SSD，男性大于女性。这个大的男性SSD与女性偏见或缺乏SSD通常在海龟中观察到形成鲜明对比。这里讨论了可能起作用的最终和近似机制，并在可能的情况下进行了测试。较小女性SSD的主要驱动因素之一可能是卵子生产。我们表明，产蛋橄榄ridleys在刚果是最佳的中间女性CCL时，纠正筑巢日期。当雌性更长时，产卵量减少，可能是因为三维体积受到限制。CCL和产卵之间的这种违反直觉的关系可能是橄榄里德利龟中较大雄性SSD的不寻常进化背后的驱动力，最终，与其他海龟相比，这个物种的体型较小。
Determination of sexual size dimorphism (SSD) in marine turtles is challenging because females are observed on nesting beaches, while males remain at sea and are rarely encountered. Data obtained from a sea turtle bycatch survey and a nesting monitoring program conducted in the same area in the Republic of the Congo give access to the body size of both male and female olive ridleys (Lepidochelys olivacea). Curved carapace length (CCL) in male and female olive ridleys reveals SSD, with males being larger than females. This large male SSD contrasts with the female-biased or absence of SSD commonly observed in sea turtles. The ultimate and proximate mechanisms potentially at play are discussed here and tested where possible. One of the main drivers of smaller female SSD could be egg production. We show that egg production in olive ridleys in the Congo is optimal for intermediate female CCL when corrected to nesting date. When females are longer, egg production decreases, probably because of the constrained three-dimensional volume. This counterintuitive relationship between CCL and egg production could be the driving force behind the unusual evolution of larger male SSD in olive ridley turtles, and ultimately, the small size of this species as compared to other marine turtles.