Facultative Transitions Have Trouble Committing, But Stable Life Cycles Predict Salamander Genome Size Evolution
Facultative Transitions Have Trouble Committing, But Stable Life Cycles Predict Salamander Genome Size Evolution
复制标题
DOI：
10.1007/s11692-020-09497-8
复制
发表时间：
2020-03-31
影响因子：
2.5
通讯作者：
Ledbetter, Nicholus M.
中科院分区：
文献类型：
--
作者：
Bonett, Ronald M.;Hess, Alexander J.;Ledbetter, Nicholus M.
兼性性状可以在动态环境中提供表型稳定性，但目前尚不清楚在不同栖息地之间的编织如何影响沿途携带的非兼性性状。蝾螈的生命周期与不同的个体发生有关，水生到陆地（双相），完全陆地（直接发育）和完全水生（幼虫形态）。蝾螈拥有脊椎动物中最大的基因组，最极端的扩张归因于幼体发育和生命周期简化。最近对两栖动物基因组大小进化的分析否定了蝾螈的这一假设。我们的分析表明，治疗兼性童形蝾螈，这是交替双相，部分解释了这种差异。几乎所有被分析的兼性童胚物种的基因组大小都与双相物种的最佳基因组大小重叠。我们发现，专性童胚，单独或与直接发育者结合时，其基因组大小明显大于双相和兼性童胚。一般来说，蝾螈基因组大小的变化比幼虫生态学、成虫生态学或水生栖息地稳定性更适合生命周期模型。专性过渡到一个简单的生命周期似乎是谱系在基因组大小上与双相祖先进化出显著差异的重要途径。我们的分析支持了蝾螈基因组大小变化与生命周期复杂性之间的经典关联，这可能最终反映了时间有限的发育模式。
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.