Abstract
The evolution of large vultures linked to mountainous habitats was accompanied by extreme physiological and behavioral specializations for energetically efficient flights. However, little is known on the genetic traits associated with the evolution of these obligate soaring scavengers. Mitochondrial DNA plays a vital role in regulating oxidative stress and energy production, and hence may be an important target of selection for flight performance. Herein, we characterized the first mitogenomes of the Andean and California condors, the world’s heaviest flying birds and the only living representatives of the Vultur and Gymnogyps genus. We reconstructed the phylogenetic relationships and evaluated possible footprints of convergent evolution associated to the life-history traits and distributional range of vultures. Our phylogenomic analyses supported the independent evolution of vultures, with the origin of Cathartidae in the early Paleogene (~ 61 Mya), and estimated the radiation of extant condors during the late Miocene (~ 11 Mya). Selection analyses indicated that vultures exhibit signals of relaxation of purifying selection relative to other accipitrimorph raptors, possibly indicating the degeneration of flapping flight ability. Overall, our results suggest that the extreme specialization of vultures for efficient soaring flight has compensated the evolution of large body sizes mitigating the selection pressure on mtDNA.
Highlights
The evolution of large vultures linked to mountainous habitats was accompanied by extreme physiological and behavioral specializations for energetically efficient flights
Selective analyses in Andean sparrows (Zonotrichia capensis) showed an elevational cline related to mt-haplotype frequency, but not with nuclear m arkers[5], while a single mtDNA mutation was found to contribute to the exceptional ability of the bar-headed geese (Anser indicus) to migrate over the H imalayas[4] and recent mitogenomic analysis revealed evidence of polygenic selection related to mitochondrial efficiency in high altitude Galliforms[6]
Recent nuclear genomic analyses showed that Falconiformes excluded the Turkey vulture (Cathartes aura), and suggested that Cathartidae split from a common ancestor of their sister group Accipitridae at some point between the late Cretaceous and early Paleogene or even later[10,11]
Summary
The evolution of large vultures linked to mountainous habitats was accompanied by extreme physiological and behavioral specializations for energetically efficient flights. The mitochondrial genome of the Andean and California condor was 16.808 and 16.870 bp in length, respectively, containing all 37 genes typical of vertebrates, including 22 tRNAs, 2 rRNAs, 13 PCGs, and a control region (Fig. 1).
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