Differences in habitat and diet between species are often associated with morphological differences. Habitat and trophic adaptation have therefore been proposed as important drivers of speciation and adaptive radiation. Importantly, habitat and diet shifts likely impose changes in exposure to different parasites and infection risk. As strong selective agents influencing survival and mate choice, parasites might play an important role in host diversification. We explore this possibility for the adaptive radiation of Lake Tanganyika (LT) cichlids. We first compare metazoan macroparasites infection levels between cichlid tribes. We then describe the cichlids’ genetic diversity at the major histocompatibility complex (MHC), which plays a key role in vertebrate immunity. Finally, we evaluate to what extent trophic ecology and morphology explain variation in infection levels and MHC, accounting for phylogenetic relationships. We show that different cichlid tribes in LT feature partially non-overlapping parasite communities and partially non-overlapping MHC diversity. While morphology explained 15% of the variation in mean parasite abundance, trophic ecology accounted for 16% and 22% of the MHC variation at the nucleotide and at the amino acid level, respectively. Parasitism and immunogenetic adaptation may thus add additional dimensions to the LT cichlid radiation.

中文翻译：

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坦噶尼喀湖慈鲷辐射中寄生虫、营养生态学、形态学和免疫遗传学之间联系的探索

物种之间栖息地和饮食的差异通常与形态差异有关。因此，栖息地和营养适应被认为是物种形成和适应性辐射的重要驱动因素。重要的是，栖息地和饮食的变化可能会导致接触不同寄生虫的风险和感染风险发生变化。作为影响生存和配偶选择的强选择剂，寄生虫可能在宿主多样化中发挥重要作用。我们探索了坦噶尼喀湖 (LT) 慈鲷适应性辐射的这种可能性。我们首先比较慈鲷部落之间的后生动物大寄生虫感染水平。然后，我们描述了慈鲷在主要组织相容性复合体 (MHC) 中的遗传多样性，该复合体在脊椎动物免疫中起关键作用。最后，我们评估营养生态学和形态学在多大程度上解释了感染水平和 MHC 的变化，说明了系统发育关系。我们表明 LT 中的不同慈鲷部落具有部分不重叠的寄生虫群落和部分不重叠的 MHC 多样性。虽然形态学解释了平均寄生虫丰度变化的 15%，但营养生态学分别解释了核苷酸和氨基酸水平的 MHC 变化的 16% 和 22%。因此，寄生和免疫遗传适应可能会为 LT 慈鲷辐射增加额外的维度。虽然形态学解释了平均寄生虫丰度变化的 15%，但营养生态学分别解释了核苷酸和氨基酸水平的 MHC 变化的 16% 和 22%。因此，寄生和免疫遗传适应可能会为 LT 慈鲷辐射增加额外的维度。虽然形态学解释了平均寄生虫丰度变化的 15%，但营养生态学分别解释了核苷酸和氨基酸水平的 MHC 变化的 16% 和 22%。因此，寄生和免疫遗传适应可能会为 LT 慈鲷辐射增加额外的维度。