Endemic mountain-gem hummingbirds Lampornis (Aves: Trochilidae) highlight the biogeographical complexity of Nuclear Central America

The present work reveals that biogeographical and evolutionary processes have fuelled in situ diversification within Nuclear Central America. We studied two hummingbird species, Lampornis viridipallens and L. sybillae, by integrating phylogeography, ecological niche modelling, and morphological measurements to understand variation and diversification in Central America. Mitochondrial and microsatellite data indicated that L. viridipallens and L. sybillae diverged in allopatry during the early Pleistocene on either side of the Honduras Depression. Ecological niche divergence followed or accompanied this allopatric divergence. Dry valleys that separate mountain ranges, mainly the Motagua–Polochic–Jocotán Fault System and the valley between Quaternary and Tertiary volcanoes in southern Guatemala, are the primary geographical barriers promoting isolation within L. viridipallens, a species restricted to montane forests. Genetic groups within L. viridipallens do not match currently recognized subspecies, and morphological measurements are similar across subspecific or genetic groups. Our extensive geographical sampling revealed that population differentiation is enhanced on the eastern side of the Motagua–Polochic–Jocotán Fault System, but not on the western side, which suggests that the isolating effect of this fault system is heterogeneous along its extent.