Recknagel Hans, Elmer Kathryn R, Meyer Axel
Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, 78457 Konstanz, Germany; Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
Evolution. 2014 Jul;68(7):2145-55. doi: 10.1111/evo.12412. Epub 2014 May 5.
Adaptive radiations provide an excellent opportunity for studying the correlates and causes for the origin of biodiversity. In these radiations, species diversity may be influenced by either the ecological and physical environment, intrinsic lineage effects, or both. Disentangling the relative contributions of these factors in generating biodiversity remains a major challenge in understanding why a lineage does or does not radiate. Here, we examined morphological variation in body shape for replicate flocks of Nicaraguan Midas cichlid fishes and tested its association with biological and physical characteristics of their crater lakes. We found that variability of body elongation, an adaptive trait in freshwater fishes, is mainly predicted by average lake depth (N = 6, P < 0.001, R(2) = 0.96). Other factors considered, including lake age, surface area, littoral zone area, number of co-occurring fish species, and genetic diversity of the Midas flock, did not significantly predict morphological variability. We also showed that lakes with a larger littoral zone have on average higher bodied Midas cichlids, indicating that Midas cichlid flocks are locally adapted to their crater lake habitats. In conclusion, we found that a lake's habitat predicts the magnitude and the diversity of body elongation in repeated cichlid adaptive radiations.
适应性辐射为研究生物多样性起源的相关因素和成因提供了绝佳机会。在这些辐射过程中，物种多样性可能受到生态与物理环境、内在谱系效应或两者共同影响。厘清这些因素在生物多样性形成过程中的相对贡献，仍然是理解一个谱系为何发生或未发生辐射的主要挑战。在此，我们研究了尼加拉瓜米达斯丽鱼科鱼类多个种群的体型形态变异，并测试了其与所在火山口湖的生物和物理特征之间的关联。我们发现，作为淡水鱼类的一个适应性特征，身体伸长的变异性主要由湖泊平均深度预测（N = 6，P < 0.001，R² = 0.96）。其他考虑因素，包括湖泊年龄、表面积、沿岸带面积、共生鱼类物种数量以及米达斯种群的遗传多样性，均未显著预测形态变异性。我们还表明，沿岸带面积较大的湖泊中，米达斯丽鱼的体型平均更大，这表明米达斯丽鱼种群在当地适应了其所在的火山口湖栖息地。总之，我们发现，在重复发生的丽鱼科适应性辐射中，湖泊栖息地能够预测身体伸长的幅度和多样性。
