O lince-ibérico tem menos mutações altamente nocivas do que o seu irmão lince-euroasiático

Análises aos genomas do lince-ibérico e do lince-euroasiático mostram-nos as diferenças na carga de mutações genéticas nocivas nesses dois felinos. Todo o conhecimento é importante na conservação destas espécies tão carismáticas.

📸 © Antonio Rivas Salvador

Há cerca de 1100 linces-ibéricos a viver em liberdade

Não chegava ter um grande plano geral da informação genética do lince-ibérico – como já se tinha com a sequenciação do genoma deste felino. Agora, fez-se um plano mais aproximado desse material contido no seu ADN. Nessa análise, observou-se que as populações de linces-ibéricos têm uma carga menor de mutações altamente nocivas do que as populações de uma espécie irmã, o lince-euroasiático. Neste mesmo trabalho, publicado esta semana na revista científica Proceedings of the National Academy of Sciences ( PNAS ), também se elaborou um álbum com as revelações das mutações nocivas no lince-ibérico, o que pode ajudar na conservação deste animal.

O lince-ibérico tem menos mutações altamente nocivas do que o seu irmão lince-euroasiático

Purging of deleterious burden in the endangered Iberian lynx

Significance

The dynamics of deleterious variation under contrasting demographic scenarios remain poorly understood in spite of their relevance in evolutionary and conservation terms. Here we apply a genomic approach to study differences in the burden of deleterious alleles between the endangered Iberian lynx (Lynx pardinus) and the widespread Eurasian lynx (Lynx lynx). Our analysis unveils a significantly lower deleterious burden in the former species that should be ascribed to genetic purging, that is, to the increased opportunities of selection against recessive homozygotes due to the inbreeding caused by its smaller population size, as illustrated by our analytical predictions. This research provides theoretical and empirical evidence on the evolutionary relevance of genetic purging under certain demographic conditions.

Abstract

Deleterious mutations continuously accumulate in populations, building up a burden that can threaten their survival, particularly in small populations when inbreeding exposes recessive deleterious effects. Notwithstanding, this process also triggers genetic purging, which can reduce the deleterious burden and mitigate fitness inbreeding depression. Here, we analyzed 20 whole genomes from the endangered Iberian lynx and 28 from the widespread Eurasian lynx, sister species which constitute a good model to study the dynamics of deleterious mutation burden under contrasting demographies, manifested in the consistently smaller population size and distribution area of the Iberian lynx. We also derived analytical predictions for the evolution of the deleterious burden following a bottleneck. We found 11% fewer derived alleles for the more putatively deleterious missense category in the Iberian lynx than in the Eurasian lynx, which, in light of our theoretical predictions, should be ascribed to historical purging. No signs of purging were found in centromeres nor in the X chromosome, where selection against recessive deleterious alleles is less affected by demography. The similar deleterious burden levels for conspecific populations despite their contrasting recent demographies also point to sustained differences in historical population sizes since species divergence as the main driver of the augmented purging in the Iberian lynx. Beyond adding to the ongoing debate on the relationship between deleterious burden and population size, and on the impact of genetic factors in endangered species viability, this work contributes a whole-genome catalog of deleterious variants, which may become a valuable resource for future conservation efforts.

Purging of deleterious burden in the endangered Iberian lynx

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