Complete mitochondrial genomes do not distinguish phenotypically distinct lineages of AndeanCoeligenahummingbirds

Abstract

AbstractLack of divergence in mitochondrial DNA between species with clear phenotypic differences may be the result of low resolution of markers, incomplete lineage sorting, introgression, or the interplay of various evolutionary mechanisms acting on different traits and genomic regions through time. Previous work revealed that the Andean hummingbirdsCoeligena bonaparteiandC. helianthealack genetic divergence in the mitochondrialND2gene, which shows variation discordant with coloration phenotype but consistent with geography. We sequenced and analyzed complete mitochondrial genomes forC. b. bonapartei, C. b. consita, C. h. heliantheaandC. h. tamaito assess whether patterns revealed byND2analyses hold when considering the entire mitogenome, and to shed light into the evolutionary history of these hummingbirds. We found very low genetic differentiation in mitogenomes among the four lineages ofCoeligena, confirming patterns based onND2data. Estimates of genetic differentiation, phylogenies and haplotype network analyses of complete mitogenomes did not separate phenotypically distinct taxa, but were consistent with a previously described pattern of northern vs. southern divergence along the Cordillera Oriental of Colombia. Mitogenomes ofC. b. bonaparteiandC. h. heliantheaare indistinguishable, suggesting incomplete lineage sorting or strong introgression. Mitogenomes ofC. b. consitaandC. h. tamaiare slightly differentiated, but they are more similar to each other than either is to that of its respective nominate subspecies, a result also suggestive of mtDNA introgression despite distinct phenotypic differences. Our results indicate that various evolutionary mechanisms playing out over a complex biogeographic scenario in the Colombian Andes drove divergence in phenotypes and mitochondrial genomes ofCoeligenahummingbirds, and lead to alternative hypotheses to be tested with whole-genome analyses.