Coeligena (1 Viewer)

[Jacana]

Catalina Palacios, Silvana García, Juan Luis Parra, Andrés M. Cuervo, F. Gary Stiles, John E. McCormack, Carlos Daniel Cadena (2018) Shallow evolutionary divergence between two Andean hummingbirds: Speciation with gene flow? BioRxiv

https://www.biorxiv.org/content/biorxiv/early/2018/01/18/249755.full.pdf

Abstract
Ecological speciation can proceed despite genetic interchange when selection counteracts homogeneizing effects of migration. We tested predictions of this divergence-with-gene-flow model in Coeligena helianthea and C. bonapartei, two parapatric Andean hummigbirds with marked plumage divergence. We sequenced neutral markers (mtDNA and nuclear ultra conserved elements) to examine genetic structure and gene flow, and a candidate gene (MC1R) to assess its role underlying divergence in coloration. We also tested the prediction of Glogers’ rule that darker forms occur in more humid environments, and compared ecomorphological variables to assess adaptive mechanisms potentially promoting divergence. Genetic differentiation between species was very low and coalescent estimates of migration were consistent with divergence with gene flow. MC1R variation was unrelated to phenotypic differences. Species did not differ in macroclimatic niches but were distinct in ecomorphology. Although we reject adaptation to variation in humidity as the cause of divergence, we hypothesize that speciation likely occurred in the face of gene flow, driven by other ecological pressures or by sexual selection. Marked phenotypic divergence with no neutral genetic differentiation is remarkable for Neotropical birds, and makes C. helianthea and C. bonapartei an appropriate system in which to search for the genetic basis of species differences employing genomics.

 

[Peter Kovalik]

Catalina Palacios, Silvana García-R, Juan Luis Parra, Andrés M Cuervo, F Gary Stiles, John E McCormack, Carlos Daniel Cadena, Shallow genetic divergence and distinct phenotypic differences between two Andean hummingbirds: Speciation with gene flow?, The Auk, , ukz046, https://doi.org/10.1093/auk/ukz046

 

[Peter Kovalik]

Catalina Palacios, Leonardo Campagna, Juan Luis Parra, Carlos Daniel Cadena. Complete mitochondrial genomes do not distinguish phenotypically distinct lineages of Andean Coeligena hummingbirds. BioRxiv
doi: https://doi.org/10.1101/2020.04.14.041723

Abstract:

Lack 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 hummingbirds Coeligena bonapartei and C. helianthea lack genetic divergence in the mitochondrial ND2 gene, which shows variation discordant with coloration phenotype but consistent with geography. We sequenced and analyzed complete mitochondrial genomes for C. b. bonapartei, C. b. consita, C. h. helianthea and C. h. tamai to assess whether patterns revealed by ND2 analyses 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 of Coeligena, confirming patterns based on ND2 data. 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 of C. b. bonapartei and C. h. helianthea are indistinguishable, suggesting incomplete lineage sorting or strong introgression. Mitogenomes of C. b. consita and C. h. tamai are 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 of Coeligena hummingbirds, and lead to alternative hypotheses to be tested with whole-genome analyses.

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