Berven Keith A, Chadra Brian G
Department of Biological Sciences, Oakland University, 48063, Rochester, MI, USA.
Oecologia. 1988 Feb;75(1):67-72. doi: 10.1007/BF00378815.
Although inter- and intraspecific variation in egg size among amphibians has been well documented, the relationship between egg size and fitness remains unclear. Recent attempts to correlate egg size intraspecifically with larval developmental patterns have been equivocal. In this study the development of larvae derived from large eggs and small eggs, from a single population in Maryland were compared under a range of food levels and larval population densities. Both food level and density had significant effects on the length of the larval period and size at metamorphosis. However, the response among larvae derived from different egg sizes was not additive. At low densities and high food levels, larvae from small eggs had longer larval periods and a larger size at metamorphosis than larvae derived from large eggs. In contrast, at high densities larvae from small eggs had longer developmental periods but were smaller at metamorphosis than larvae from large eggs. In addition, larvae from small eggs were more sensitive to density irrespective of food level. These results suggest that optimal egg size is correlated with environmental factors, which may explain the maintenance of both geographic and within population variation in egg size commonly observed in amphibians.
尽管两栖动物卵大小的种间和种内变异已有充分记载，但卵大小与适合度之间的关系仍不明确。近期关于种内卵大小与幼体发育模式相关性的研究结果并不确定。在本研究中，比较了来自马里兰州单个种群的大卵和小卵所孵化幼体在一系列食物水平和幼体种群密度下的发育情况。食物水平和密度对幼体期长度和变态时的大小均有显著影响。然而，不同卵大小来源的幼体之间的反应并非相加性的。在低密度和高食物水平下，小卵孵化的幼体比大卵孵化的幼体有更长的幼体期和更大的变态时大小。相反，在高密度下，小卵孵化的幼体发育时间更长，但变态时比大卵孵化的幼体更小。此外，无论食物水平如何，小卵孵化的幼体对密度更为敏感。这些结果表明，最佳卵大小与环境因素相关，这可能解释了两栖动物中常见的卵大小地理变异和种群内变异为何得以维持。
