PDF(Pubmed)
Abstract：
Islands have played a key role in our understanding of rapid evolution. A large body of literature has examined morphological changes in response to insularity and isolation, which has yielded useful generalizations about how animals can adapt to live in very small geographic areas. However, understanding the evolution of morphological variation in insular populations often requires detailed data sets on longitudinal patterns of growth and development, and such studies typically necessitate long-term mark-recapture on a large sample of individuals. Rattlesnakes provide a unique opportunity to address some of these difficulties because the addition of rattle segments to the rattle string occurs with regular periodicity and their size directly correlates with the body size of the snake at the time of the ecdysis cycle generating the segment. Here, we used a large database of rattle segment sizes recorded from island (Isla Coronado Sur, Baja California, Mexico) and mainland (Camp Pendleton, California, United States) populations of Western Rattlesnakes (Crotalus oreganus and C. o. caliginis) that separated approximately 10,000 years ago to compare body sizes at different ecdysis cycles, which allowed us to assess differences in growth rates and patterns of sexual size dimorphism. Our results show that rattlesnakes on Isla Coronado Sur appear to be born smaller and grow more slowly than their mainland counterparts, resulting in a \"dwarfed\" island population. However, despite significant differences in body size, both populations exhibited the same degree of sexual dimorphism. Our study demonstrates the potential to use rattle characteristics to recover detailed estimates of fundamental demographic parameters.
摘要：
岛屿在我们对快速演变的理解中发挥了关键作用。大量文献研究了由于孤立和孤立而引起的形态变化，这对动物如何适应生活在非常小的地理区域产生了有用的概括。然而,了解岛礁种群形态变异的演变通常需要有关生长和发育纵向模式的详细数据集，这样的研究通常需要对大量个体进行长期的标记再捕获。响尾蛇提供了解决这些困难中的一些困难的独特机会,因为向响尾蛇串添加响尾蛇段以规则的周期性发生,并且它们的尺寸与在产生所述段的蜕皮周期时的蛇的身体尺寸直接相关。这里,我们使用了一个大型数据库，其中包含从岛上记录的拨浪鼓段大小(CoronadoSur岛，下加利福尼亚州,墨西哥)和大陆(彭德尔顿营地，加州,美国）西部响尾蛇（Crotalusorganus和C.o。caliginis）大约在10,000年前分离，以比较不同蜕皮周期下的体型，这使我们能够评估性别大小二态性的生长速度和模式的差异。我们的研究结果表明，与它们的大陆同行相比，CoronadoSur岛上的响尾蛇似乎出生得更小，生长得更慢，导致“矮化”的岛屿人口。然而,尽管体型有很大差异，这两个人群表现出相同程度的性二态性。我们的研究表明，有可能使用拨浪鼓特征来恢复基本人口参数的详细估计。
