Garland Theodore
Department of Zoology, NJ-15, University of Washington, Seattle, WA, 98195.
Evolution. 1988 Mar;42(2):335-350. doi: 10.1111/j.1558-5646.1988.tb04137.x.
Recent conceptual advances in physiological ecology emphasize the potential selective importance of whole-animal performance. Empirical studies of locomotor performance in reptiles have revealed surprising amounts of individual variation in speed and stamina. The present study is the first in a series examining the genetic basis of variation in locomotor performance, activity metabolism, and associated behaviors in garter snakes. Maximal sprint crawling speed, treadmill endurance, and antipredator displays (Arnold and Bennett, 1984; exhibited as snakes reached exhaustion on the treadmill) were measured for approximately six offspring (presumed to be full siblings) from each of 46 wild-caught gravid garter snakes (Thamnophis sirtalis). Each character was measured on two days; all were individually repeatable. Correlations of these characters with body mass, snout-vent length, age at testing, litter size, dam mass, and dam snout-vent length were removed by computing residuals from multiple-regression equations. These residuals were used in subsequent genetic analyses. Approximate coefficients of variation of residuals were 17% for speed, 48% for endurance, and 31% for antipredator displays. Broad-sense heritabilities were significant for all characters: speed h = 0.58; stamina h = 0.70; antipredator display h = 0.42. All three residual characters showed positive and statistically significant phenotypic correlations (r = 0.19-0.36). Genetic correlations (estimated and tested by restricted maximum likelihood) among residuals were positive and highly significant between speed and endurance (0.58), but nonsignificant between speed and antipredator display (0.43), and between endurance and antipredator display (0.26). All environmental correlations were nonsignificant. These data suggest that, contrary to expectations based on previous physiological studies, there may be no necessary evolutionary trade-off between speed and stamina in these animals. This tentative conclusion will have important implications for future theoretical studies of the evolution of locomotor performance and associated antipredator behaviors.
生理生态学领域最近的概念进展强调了动物整体表现潜在的选择重要性。对爬行动物运动表现的实证研究揭示了速度和耐力方面惊人的个体差异。本研究是一系列研究中的首个，旨在探究束带蛇运动表现、活动代谢及相关行为变异的遗传基础。对46条野生捕获的怀孕束带蛇（美洲束带蛇）中的每一条所产的约6只后代（假定为全同胞）测量了最大冲刺爬行速度、跑步机耐力和反捕食展示行为（Arnold和Bennett，1984；表现为蛇在跑步机上筋疲力尽时的行为）。每个特征在两天内进行测量；所有测量结果均具有个体可重复性。通过从多元回归方程计算残差，消除了这些特征与体重、吻肛长度、测试时的年龄、窝卵数、母蛇体重和母蛇吻肛长度之间的相关性。这些残差用于后续的遗传分析。残差的近似变异系数分别为：速度17%、耐力48%、反捕食展示行为31%。所有特征的广义遗传力均显著：速度h = 0.58；耐力h = 0.70；反捕食展示行为h = 0.42。所有三个残差特征均呈现出正的且具有统计学显著性的表型相关性（r = 0.19 - 0.36）。残差之间的遗传相关性（通过限制最大似然估计和检验）为正，速度与耐力之间高度显著（0.58），但速度与反捕食展示行为之间不显著（0.43），耐力与反捕食展示行为之间也不显著（0.26）。所有环境相关性均不显著。这些数据表明，与基于先前生理学研究的预期相反，这些动物的速度和耐力之间可能不存在必然的进化权衡。这一初步结论将对未来运动表现进化及相关反捕食行为的理论研究产生重要影响。
