AI Insight
This study examined how environmental factors affect evolutionary selection pressure on mitochondrial DNA in 176 species of Piciformes birds (woodpeckers, toucans, and honeyguides). Researchers found that birds living in areas with greater annual temperature variation experience stronger purifying selection on their mitochondrial genes, meaning harmful mutations are more efficiently removed. This suggests that maintaining optimal metabolism across broader climate ranges imposes stronger evolutionary constraints on mitochondrial function.
Why it matters
The findings indicate that molecular clocks used to estimate evolutionary divergence times may be inaccurate if they don't account for the different climatic conditions where species live. This has practical implications for reconstructing evolutionary histories and understanding how climate shapes genetic evolution in birds and potentially other animals.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Mitochondrial loci were for long considered as markers of choice to reconstruct phylogenies. The development of high-throughput sequencing over the past two decades fostered the sequencing of mitogenomes, allowing further macroevolutionary questions to be tested. Several biological traits of birds (e.g. body mass, migration distances) have been related to mitochondrial substitution rates. Environmental parameters in ectothermics vertebrates, and potentially in endotherms, have been further suggested to impact substitution rates for specific taxa or loci. Yet, the relative importance of biological traits versus bioclimatic variables is unknown because the former were not systematically controlled for in studies that underlined the effect of the bioclimatic variables. To assess the importance of bioclimatic variables on selection regimes, we analysed the thirteen mitochondrial protein-coding genes for 176 Piciformes (toucans, honeyguides, woodpeckers), a clade with homogeneous life-history traits that can be found in diverse bioclimatic environments. Our analyses highlighted a negative relationship between temperature annual range and the non synonymous to synonymous substitutions ratio. The higher purifying selection in temperate environments may be a result of the strong constraints on maintaining an optimal metabolism in broader climatic variations. Our results further highlight that care should be taken when applying general mitochondrial clocks to estimate divergence times among avian lineages distributed in different climatic conditions.