Stable Heliconius butterfly hybrid zones are correlated with a local rainfall peak at the edge of the Amazon basin
Stable Heliconius butterfly hybrid zones are correlated with a local rainfall peak at the edge of the Amazon basin
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稳定的 Heliconius 蝴蝶杂交区与亚马逊盆地边缘的局部降雨高峰相关
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发表时间：
2014
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影响因子：
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通讯作者：
J. Mallet
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作者：
N. Rosser;K. Dasmahapatra;J. Mallet
Heliconius 蝴蝶的缪勒拟态种族之间的多位点克隆提供了混合区维持及其在物种形成中的重要性的经典例子。秘鲁北部的拟态Heliconiuserato和H.melpomene的一致混合区在20世纪80年代被仔细记录，这项先前的工作现在允许对这些区域的运动或停滞进行历史分析。之前的研究预测，由于选择性不对称，这些区域可能会向安第斯山脉移动。大规模的森林砍伐和气候变化也可能会影响混合区的位置和宽度。我们发现，这些混合区域的位置和形状在 1985 年至 2012 年间一直保持非常稳定。这种相互作用的稳定性强烈暗示着持续的选择，而不是二次接触后的中性混合。 25 年来，系宽度和强连锁不平衡（未连锁位点配子相关系数 Rmax = 0.35-0.56）的稳定性表明，每个颜色模式位点的拟态选择压力保持大致恒定（两个物种中每个位点 s ≈ 0.13-0.40）。安第斯山脉最东部边缘的异常高水平的降水可能会成为蝴蝶的种群密度槽，将混合区困在山脚下，并阻止其移动。因此，我们的结果证伪了更新世避难所理论的一项预测：不同物种或亚种的范围应该集中在降雨量最大的地区，而混合区则落在它们之间更干旱的地区。
Multilocus clines between Müllerian mimetic races of Heliconius butterflies provide a classic example of the maintenance of hybrid zones and their importance in speciation. Concordant hybrid zones in the mimics Heliconius erato and H. melpomene in northern Peru were carefully documented in the 1980s, and this prior work now permits a historical analysis of the movement or stasis of the zones. Previous work predicted that these zones might be moving toward the Andes due to selective asymmetry. Extensive deforestation and climate change might also be expected to affect the positions and widths of the hybrid zones. We show that the positions and shapes of these hybrid zones have instead remained remarkably stable between 1985 and 2012. The stability of this interaction strongly implicates continued selection, rather than neutral mixing following secondary contact. The stability of cline widths and strong linkage disequilibria (gametic correlation coefficients Rmax = 0.35–0.56 among unlinked loci) over 25 years suggest that mimetic selection pressures on each color pattern locus have remained approximately constant (s ≈ 0.13–0.40 per locus in both species). Exceptionally high levels of precipitation at the edge of the easternmost Andes may act as a population density trough for butterflies, trapping the hybrid zones at the foot of the mountains, and preventing movement. As such, our results falsify one prediction of the Pleistocene Refugium theory: That the ranges of divergent species or subspecies should be centered on regions characterized by maxima of rainfall, with hybrid zones falling in more arid regions between them.