Genomic vulnerability assessment reveals the potential benefits of adaptive introgression by mitigating the maladaptive risk of admixed populations

TL;DR

This study explores how genetic mixing in dove tree populations may help reduce their risk of maladaptation due to climate change.

Contribution

The study demonstrates that introgression can partially mitigate genomic vulnerability in admixed populations of a relict tree species.

Findings

Eastern admixed populations showed reduced genomic vulnerability due to introgression from the southern lineage.

Introgressive loci had moderate importance along environmental gradients but provided only partial counterbalance to maladaptation.

Genomic vulnerability analysis identified 747 climate-associated loci, with 138 found in admixed populations.

Abstract

As climate change accelerates, plant species largely rely on genetic variation to adapt and survive when they fail to track their ecological niches through range shifts. Predicted genomic vulnerability is able to identify populations lacking the necessary genetic variation for climate change adaptation. However, the role of introgression in genomic vulnerability remains poorly explored. Here, we used the dove tree (Davidia involucrata), a relict species native to southwestern China, to test whether introgression may reduce genomic vulnerability. By integrating population genomics and environmental data collected from 196 individuals of 18 populations, we identified 747 strictly climate-associated loci across the distribution range of D. involucrata, 138 of which were recovered from the genetically admixed populations. We estimated the genomic vulnerability for three genetic lineages and two admixed groups using the gradient forest approach, and found that eastern populations are likely to be at higher risk. The eastern admixed populations exhibited a significant reduction, with introgression from the southern lineage. Cumulative importance analysis showed moderate importance for introgressive loci along environmental gradients. This indicates that the introduction of novel alleles through introgression provides only a partial and insufficient counterbalance to the maladaptation observed in D. involucrata under climate change. Our study highlights the role of intraspecific introgression in response to climate change and emphasizes the importance of genomic vulnerability studies in informing conservation practices for relict and endangered species.

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