Jones Steven M, Ballinger Royce E
Ecology. 1987 Dec;68(6):1828-1838. doi: 10.2307/1939874.
The life histories of the iguanid lizards Holbrookia maculata and Sceloporus undulatus were studied in western Nebraska during 1978-1984. The two species differ in their reproductive strategies and age-specific survival. The reproductive strategy of H. maculata is invariant from year to year. Yearlings consistently produced a single clutch and older females (≥2 yr) consistently produced two clutches. The reproductive strategy of S. undulatus is opportunistic. Clutch frequency of S. undulatus varied among years, ranging from 1-3 for yearlings and 2-3 for older females. This variation in clutch frequency was a function of the length of the breeding season. Significant differences in the age-specific survivals of H. maculata and S. undulatus were found for juveniles and yearling females. In both cases, survival of H. maculata was greater. Despite differences in their life histories, H. maculata and S. undulatus are exposed to similar selective pressures in western Nebraska. Food does not appear to be limiting and mortality due to predation is low. Mortality is density-independent and is highest during the overwintering period. Differences in the reproductive strategies of H. maculata and S. undalatus are most likely due to their phylogenetic histories rather than to adaptation to different environments. The different reproductive strategies of the two species may account for differences in their age-specific survival. The high fecundity of yearling S. undulatus may explain its lower survival relative to H. maculata. Evidence for a cost of reproduction is provided by a negative relationship between clutch frequency of yearling S. undulatus and postreproductive survival. Because the response of lizards to specific environments may be constrained by their phylogenetic histories, comparison of life history strategies among syntopic species may not provide adequate tests of life history models. We conclude that identification of the mechanisms underlying variation in life history traits will most likely come from intraspecific comparisons.
1978年至1984年期间，在内布拉斯加州西部对鬣鳞蜥科蜥蜴黄斑霍氏蜥和波形健肢蜥的生活史进行了研究。这两个物种在繁殖策略和特定年龄的存活率方面存在差异。黄斑霍氏蜥的繁殖策略每年不变。一岁的蜥蜴始终只产一窝卵，而年龄较大的雌性蜥蜴（≥2岁）始终产两窝卵。波形健肢蜥的繁殖策略具有机会主义性。波形健肢蜥的产卵频率随年份而变化，一岁蜥蜴的产卵频率为1至3窝，年龄较大的雌性蜥蜴为2至3窝。这种产卵频率的变化是繁殖季节长度的函数。在幼年蜥蜴和一岁雌性蜥蜴中，黄斑霍氏蜥和波形健肢蜥在特定年龄的存活率存在显著差异。在这两种情况下，黄斑霍氏蜥的存活率都更高。尽管它们的生活史存在差异，但黄斑霍氏蜥和波形健肢蜥在内布拉斯加州西部面临着相似的选择压力。食物似乎不是限制因素，因捕食导致的死亡率较低。死亡率与种群密度无关，在越冬期间最高。黄斑霍氏蜥和波形健肢蜥繁殖策略的差异很可能是由于它们的系统发育历史，而不是对不同环境的适应。这两个物种不同的繁殖策略可能解释了它们在特定年龄存活率上的差异。一岁波形健肢蜥的高繁殖力可能解释了其相对于黄斑霍氏蜥较低的存活率。一岁波形健肢蜥的产卵频率与繁殖后存活率之间的负相关关系提供了繁殖成本的证据。由于蜥蜴对特定环境的反应可能受到其系统发育历史的限制，对同域物种生活史策略的比较可能无法充分检验生活史模型。我们得出结论，确定生活史特征变异背后的机制很可能来自种内比较。
