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| Coeligena helianthea |
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| Coeligena bonapartei |
A preprint of study of two Andean neotropical hummingbirds, Coeligena helianthea (blue-throated starfrontlet) and the Coeligena bonapartei (Golden-bellied starfrontlet), with different plumage became separate species in spite of gene flow. Palacios and colleagues, the authors of this study, tried to identify the cause of the different plumage and speciation by testing the neutral markers of mtDNA and ultraconserved elements of nuclear DNA. They also examined the candidate gene MC1R which in previous studies of vertebrates has been associated with changes in the darkness and lightness of pigmentation and tested Glogers’ rule which predicts darker coloration will occur more often in humid environments as well as compared ecomorphological variables, such as physical adaptations of bills and wings to microhabitats and food resources.
Palacios and colleagues found very low genetic differences between the two species of hummingbirds which was expected due to the estimates of gene flow occurring. What was not expected was the phenotype differences is plumage color not caused by MC1R or Glogers’ rule. No difference was found the two species in their macroclimatic niches, but distinct differences in their ecomorphology, particularly in their wings.
The authors conclude the cause of speciation and plumage differences are due to other ecological pressures not examined in their study or sexual selection.
Link to the preprint can be found here.
-Kristen Tuosto
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