Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA.
J Evol Biol. 2011 Nov;24(11):2445-55. doi: 10.1111/j.1420-9101.2011.02370.x. Epub 2011 Aug 23.
Organisms vary their rates of growth and development in response to environmental inputs. Such developmental plasticity may be adaptive and positively correlate with environmental heterogeneity. However, the evolution of developmental plasticity among closely related taxa is not well understood. To determine the evolutionary pattern of plasticity, we compared plasticity in time to and size at metamorphosis in response to water desiccation in tadpoles among spadefoot species that differ in breeding pond and larval period durations. Like most tadpoles, spadefoot tadpoles possess the remarkable ability to accelerate development in response to pond drying to avoid desiccation. Here, we hypothesize that desert spadefoot tadpoles have evolved reduced plasticity to avoid desiccation in ephemeral desert pools compared to their nondesert relatives that breed in long-duration ponds. We recorded time to and size at metamorphosis following experimental manipulation of water levels and found that desert-adapted species had much less plasticity in larval period and size at metamorphosis than nondesert species, which retain the hypothetical ancestral state of plasticity. Furthermore, we observed a correlation between degree of plasticity and fat body content that may provide mechanistic insights into the evolution of developmental plasticity in amphibians.
生物会根据环境输入来调整其生长和发育速度。这种发育可塑性可能具有适应性，并与环境异质性呈正相关。然而，亲缘关系密切的分类群之间发育可塑性的进化情况还不太清楚。为了确定可塑性的进化模式，我们比较了不同繁殖池塘和幼虫期持续时间的铲足蟾蜍物种在对水干旱的反应中，变态时的时间和大小的可塑性。与大多数蝌蚪一样，铲足蟾蜍蝌蚪具有显著的能力，可以通过加速发育来应对池塘干涸，从而避免干旱。在这里，我们假设与在长时间池塘中繁殖的非沙漠亲缘物种相比，沙漠铲足蟾蜍蝌蚪已经进化出减少的可塑性，以避免在短暂的沙漠池塘中干旱。我们记录了在水位实验处理后变态的时间和大小，并发现适应沙漠的物种在幼虫期和变态时的大小方面的可塑性比非沙漠物种小得多，而非沙漠物种保留了假设的可塑性祖先状态。此外，我们观察到可塑性程度与脂肪体含量之间存在相关性，这可能为理解两栖动物发育可塑性的进化提供机制上的见解。
