不同生境间龟鳖类体型的差异

体型是动物重要的形态特征,影响动物的生境利用。为揭示龟鳖类体型与生境之间的关系,通过文献收集331种龟鳖(龟鳖目Tesudines总物种数的98.8%)的最大背甲长及其生境信息,将生境分为海洋、淡水、岛屿性陆地和大陆性陆地4种类型,再将淡水生境分为大静水、大流水、小静水、小流水和所有水域5种亚类型,大陆性陆地生境分为高地、平地和荒漠3种亚类型,从而比较不同生境类型或亚类型之间龟鳖类体型的差异。广义线性混合模型分析结果显示:1)海龟体型最大,岛屿性陆龟次之,淡水龟鳖和大陆性陆龟体型最小,且后两者差异无统计学意义。2)淡水龟鳖类的体型在5种亚类型生境间存在差异,大静水和大流水水域的体型均显著大于小静水和小流水水域,而体型在大静水与大流水水域、小静水与小流水水域之间的差异均无统计学意义,表明淡水龟鳖类体型与水域面积有关,而与水域是静水或流水无关。广布所有水域的淡水龟鳖类体型趋于中间型,且与其他4种亚类型生境中的体型之间的差异均无统计学意义。3)大陆性陆龟的体型从高地到平地再到荒漠有逐渐变大的趋势,但差异无统计学意义。本研究揭示龟鳖类的保护对策需要考虑其体型和生境面积的相关性。

Comparison of Body Size of Turtles in Different Habitats

Body size is important to animals because it can affect the habitat use of animals. We collected body size (maximum carapace length) data of 331 turtle species from published literatures which accounted for 98.8% of all 335 turtle species. To understand the evolution of body size, the collected turtle species were divided into 4 habitat types (marine, freshwater, island and mainland), and the freshwater species were further divided into 5 subtypes (large lentic, large lotic, small lentic, small lotic, and all water bodies), and the mainland species were divided into 3 subtypes (highland, lowland and wilderness). The results of generalized linear mixed model showed that sea turtles had the largest body size on average (134.86 cm±70.14 cm), while freshwater turtles (32.60 cm±20.57 cm) and mainland tortoises (27.08 cm±15.77 cm) had the smallest. Island tortoises were intermediate in body size (80.05 cm±37.11 cm). There were no significant differences of body size between the freshwater turtles and mainland tortoises. Moreover, body size was positively correlated with the total area of water bodies in habitat subtypes for freshwater turtles, because the body size of turtles from large lentic (50.30 cm±27.03 cm) and large lotic water bodies (39.86 cm±20.34 cm) were larger than those from small lentic (23.78 cm±7.47 cm) and small lotic water bodies (23.79 cm±10.57 cm), whereas there were no significant differences in turtle body sizes between the large lotic and lentic water bodies as well as between the small lotic and lentic water bodies. However, the freshwater turtles inhabited in all water bodies were intermediate in body size (41.50 cm±32.65 cm) compared to the 4 habitat subtypes as described above. Although there was a trend towards larger body size from highland (24.86 cm±10.09 cm) to lowland (26.15 cm±20.12 cm), and from lowland to wilderness (39.11 cm±19.43 cm) in mainland tortoises, there were also no significant differences among these habitat subtypes. This study indicated that conservation strategies for turtles should be considered in relation to their body size and habitat area.