Convergent changes in the trophic ecology of extremophile fish along replicated environmental gradients
Convergent changes in the trophic ecology of extremophile fish along replicated environmental gradients
复制标题
极端微生物的营养生态学沿着复制的环境梯度的趋同变化
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
F. J. García‐de‐León
中科院分区：
文献类型：
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作者：
M. Tobler;K. Scharnweber;Ryan Greenway;C. Passow;Lenin Arias;F. J. García‐de‐León
摘要
沿着环境梯度的不同选择，连接当地受限的极端生境和邻近的良性生境，可以形成与应对理化应激源有关的特征的趋同进化，并可以推动物种形成。与此同时，这种应激源的存在改变了生物环境的各个方面，包括资源的可获得性和竞争机制。然而，目前尚不清楚极端和良性环境中的种群生态是否以及如何以可预测的方式发生变化。
我们调查了Poecilia属活鱼的营养生态，这些鱼独立地在墨西哥南部含有有毒硫化氢的多个泉水中定居。硫化物泉鱼适应独特的环境条件，并与邻近非硫化物生境的祖先种群进行繁殖隔离。我们使用肠道内容物分析来测试极端栖息地的定居是否伴随着营养资源使用的变化和营养生态位宽度的扩大。此外，我们通过比较野生捕获和普通园养个体的肠道长度来测试饮食变化是否反映在营养形态上。
肠道内容物分析显示，生活在有毒泉水中的鱼类扩大了它们的营养生态位宽度，并改变了它们对食物资源的利用，从碎屑和藻类转向硫化物细菌和无脊椎动物。这种饮食转变与肠道形态的变化是平行的，即硫化物春鱼的肠道比邻近非硫化物栖息地的鱼的肠道更短。对常见园养鱼类的分析表明，硫化物种群和非硫化物种群之间的形态差异至少部分是由于遗传分化。在硫酸盐和非硫化物种群的复制对中，营养资源利用和营养形态分化的模式都是一致的，尽管不同的河流流域的分化程度不同。
我们的结果表明，墨西哥南部硫化物泉水的定居和适应与营养生态的趋同变化是平行的。这突出了环境梯度的复杂性，以及在研究复杂表型的进化时考虑多个选择来源的必要性。
Summary
Divergent selection along environmental gradients connecting locally restricted extreme habitats and adjacent benign habitats can shape convergent evolution of traits involved in coping with physiochemical stressors and can drive speciation. At the same time, the presence of such stressors alters aspects of the biotic environment, including resource availability and competitive regimes. However, it remains unclear whether and how the ecology of populations occurring in both extreme and benign environments varies in a predictable fashion.
We investigated the trophic ecology of live-bearing fishes of the genus Poecilia that have independently colonised multiple springs containing toxic hydrogen sulphide in southern Mexico. Sulphide spring fish are adapted to the unique environmental conditions and are reproductively isolated from ancestral populations in adjacent non-sulphidic habitats. We used gut content analyses to test whether colonisation of extreme habitats was accompanied by shifts of trophic resource use and expansions of trophic niche width. Furthermore, we tested whether dietary shifts were reflected in trophic morphology by comparing intestinal tract lengths among populations using both wild-caught and common garden-raised individuals.
Gut content analyses revealed that fish inhabiting toxic springs expanded their trophic niche width and changed their dietary resource use from detritus and algae to sulphide bacteria and invertebrates. This dietary shift was paralleled by changes in intestinal tract morphology, whereby sulphide spring fish had shorter intestines than fish from adjacent non-sulphidic habitats. Analysis of common garden-raised fish indicated that morphological differences between sulphidic and non-sulphidic populations are at least in part due to genetic differentiation. Both patterns of trophic resource use and differentiation in trophic morphology were consistent across replicated pairs of sulphidic and non-sulphidic populations, although the magnitude of differentiation varied among river drainages.
Our results suggest that colonisation of and adaptation to sulphide springs in southern Mexico was paralleled by convergent changes in trophic ecology. This highlights the complexity of environmental gradients and the necessity of considering multiple sources of selection when studying the evolution of complex phenotypes.