Facultative traits can provide phenotypic lability in dynamic environments, but it is unclear how weaving between disparate habitats impacts non-facultative traits that are carried along the way. The life cycles of salamanders are associated with distinct ontogenies, aquatic-to-terrestrial (biphasic), completely-terrestrial (direct development), and completely-aquatic (larval form paedomorphic). Salamanders have some of the largest genomes among vertebrates, and the most extreme expansions have been attributed to paedomorphosis and life cycle simplification. Recent analyses of genome size evolution across amphibians have rejected this hypothesis for salamanders. Our analyses show that treatment of facultatively paedomorphic salamanders, which are alternatively biphasic, in part explains this discrepancy. Nearly all of the facultatively paedomorphic species analyzed have genome sizes that overlap with the optimum of biphasic species. We found that obligate paedomorphs, alone and when combined with direct developers, have significantly larger genome sizes than biphasics plus facultative paedomorphs. In general, salamander genome size variation fits life cycle models better than those for larval ecology, adult ecology, or aquatic habitat stability. Obligate transitions to a simple life cycle appear to have been an important route for lineages to evolve significant divergence in genome size from biphasic ancestors. Our analyses support the classic association between genome size variation and life cycle complexity in salamanders, which may ultimately reflect patterns of time limited development.

中文翻译：

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过渡性的转变很麻烦，但是稳定的生命周期可以预测Sal基因组的大小演变

兼性可以在动态环境中提供表型不稳定性，但是不清楚不同生境之间的编织如何影响沿途携带的非兼性。sal的生命周期与不同的个体发育，水生陆生（双相），完全陆生（直接发育）和完全水生（幼虫成虫状）有关）。am在脊椎动物中具有一些最大的基因组，而最极端的扩展归因于古怪形态和生命周期的简化。两栖动物的基因组大小进化的最新分析已经拒绝了sal的这一假设。我们的分析表明，对兼性的morph形treatment的处理是两相的，部分解释了这种差异。分析的几乎所有兼性古同种具有的基因组大小与最佳双相种重叠。我们发现，单独和与直接发育者结合时，专性古迹比双相加兼性古迹具有更大的基因组大小。一般而言，sal的基因组大小变异比幼虫生态学，成年生态学，或水生栖息地的稳定性。专心地过渡到简单的生命周期似乎已经成为谱系​​从双相祖先进化出明显的基因组大小差异的重要途径。我们的分析支持genome的基因组大小变化与生命周期复杂性之间的经典关联，这可能最终反映出时间有限的发展模式。