Changes in selection pressure can facilitate hybridization during biological invasion in a Cuban lizard
Changes in selection pressure can facilitate hybridization during biological invasion in a Cuban lizard
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DOI：
10.1073/pnas.2108638118
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发表时间：
2021-10-19
影响因子：
11.1
通讯作者：
Kolbe, Jason J.
中科院分区：
文献类型：
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作者：
Bock, Dan G.;Baeckens, Simon;Kolbe, Jason J.
杂交是最常被假设为推动入侵物种成功的进化机制之一，部分原因是杂交在入侵种群中很常见。对这种模式的一种解释是，生物入侵与限制原生范围内杂交的选择压力的变化相一致。为了调查这种可能性，我们研究了在美国东南部的棕色变色龙（Anolis sagrei）的引进。我们发现，土著人口的基因结构是高度复杂的。与此相反，所有的入侵种群显示出原生范围血统之间的杂交的证据。在入侵范围跨越15年的时间取样表明，入侵的遗传结构已经稳定，表明大规模的当代基因流是有限的入侵种群和杂交祖先保持。此外，我们的研究结果是一致的混合持久性在入侵种群的自然选择的变化，发生在入侵过程中。具体来说，我们确定了一个大的影响X染色体位点与肢体长度的变化，一个众所周知的适应性特征在anoles，并表明，这个位点往往是在本地范围内的选择，但很少这样的入侵范围。此外，我们发现，在这个位点上的等位基因对肢体长度的影响大小大大减少在不同的血统之间的杂交，符合上位性的相互作用。因此，在本地范围内，上位性表现在杂种可以加强外部交配后隔离。总之，我们的研究结果表明，自然选择的变化如何有助于增加入侵种群的杂交。
Hybridization is among the evolutionary mechanisms most frequently hypothesized to drive the success of invasive species, in part because hybrids are common in invasive populations. One explanation for this pattern is that biological invasions coincide with a change in selection pressures that limit hybridization in the native range. To investigate this possibility, we studied the introduction of the brown anole (Anolis sagrei) in the southeastern United States. We find that native populations are highly genetically structured. In contrast, all invasive populations show evidence of hybridization among native-range lineages. Temporal sampling in the invasive range spanning 15 y showed that invasive genetic structure has stabilized, indicating that large-scale contemporary gene flow is limited among invasive populations and that hybrid ancestry is maintained. Additionally, our results are consistent with hybrid persistence in invasive populations resulting from changes in natural selection that occurred during invasion. Specifically, we identify a large-effect X chromosome locus associated with variation in limb length, a well-known adaptive trait in anoles, and show that this locus is often under selection in the native range, but rarely so in the invasive range. Moreover, we find that the effect size of alleles at this locus on limb length is much reduced in hybrids among divergent lineages, consistent with epistatic interactions. Thus, in the native range, epistasis manifested in hybrids can strengthen extrinsic postmating isolation. Together, our findings show how a change in natural selection can contribute to an increase in hybridization in invasive populations.