Postglacial northward expansion and genetic differentiation between migratory and sedentary populations of the broad‐tailed hummingbird (Selasphorus platycercus)

Abstract

Unlike other migratory hummingbirds in North America, the broad-tailed hummingbird (Selasphorus platycercus) exhibits both long-distance migratory behaviour in the USA and sedentary behaviour in Mexico and Guatemala. We examined the evolution of migration linked to its northward expansion using a multiperspective approach. We analysed variation in morphology, mitochondrial and nuclear DNA, estimated migration rates between migratory and sedentary populations, compared divergence times with the occurrence of Quaternary climate events and constructed species distribution models to predict where migratory and sedentary populations resided during the Last Glacial Maximum (LGM) and Last Interglacial (LIG) events. Our results are consistent with a recent northward population expansion driven by migration from southern sedentary populations. Phylogeographical analyses and population genetics methods revealed that migratory populations in the USA and sedentary populations in Mexico of the platycercus subspecies form one admixed population, and that sedentary populations from southern Mexico and Guatemala (guatemalae) undertook independent evolutionary trajectories. Species distribution modelling revealed that the species is a niche tracker and that the climate conditions associated with modern obligate migrants in the USA were not present during the LIG, which provides indirect evidence for recent migratory behaviour in broad-tailed hummingbirds on the temporal scale of glacial cycles. The finding that platycercus hummingbirds form one genetic population and that suitable habitat for migratory populations was observed in eastern Mexico during the LIG also suggests that the conservation of overwintering sites is crucial for obligate migratory populations currently facing climate change effects.

Historical and current introgression in a Mesoamerican hummingbird species complex: a biogeographic perspective

“…Increased genomic resources and behavioural data will likely confirm that they constitute separate taxonomic species. These findings are in line with several examples of recent speciation events reported in hummingbird species, some of which show congruent genetic and phenotypic divergence (González, Ornelas & Gutiérrez-Rodríguez, 2011;, while others show genetic divergence and no apparent plumage divergence (Rodríguez-Gó mez, Licona-Vera & Ornelas, 2014;Malpica & Ornelas, 2014). Additional genome-wide markers might help to elucidate the evolutionary history of this young system, in which detecting divergence in a few genes under selection may be critical for proper species delimitation.…”

“…This divergence time has been reported for species/subspecies mtDNA level splits in other Mesoamerican avian groups (e.g., Barrera-Guzmán et al, 2012;Ornelas et al, 2013;Malpica & Ornelas, 2014;Rodríguez-Gómez & Ornelas, 2014), suggesting an important role of Pleistocene glacial cycles in autochthonous diversification. Given that divergence time estimates were obtained with mtDNA only (not likely to resemble the species phylogeny), divergence times might differ substantially if estimated with both mtDNA and nuDNA sequence data (McCormack, Zellemer & Knowles, 2010).…”

“…The resulting distribution dynamics have been suggested as the primary cause of historical mtDNA introgression events (Mao et al, 2013;Rodríguez-Gómez & Ornelas, 2015), which might result in complex morphological and genetic scenarios (Rheindt & Edwards, 2011;Acevedo et al, 2015). Climatic fluctuations can increase or decrease the available habitat for a species, having important consequences on its population size (Malpica & Ornelas, 2014;Giarla & Jansa, 2015). An increase in population size and range expansion might promote secondary contact between two different populations leading to hybridization and genetic interchange (Zamudio & Savage, 2003;Campagna et al, 2014), whereas a decrease in population size and range contraction can isolate populations and promote allopatric speciation (Wiens, 2004;Wiens & Graham, 2005).…”

Serial founder effects and genetic differentiation during worldwide range expansion of monarch butterflies

“…Owing to the panmictic nature of the population in North America, our results provide a new outlook on monarch butterfly migration pathways. Results here also indicate that different migration strategies, such as the use of different overwintering sites or the presence of non-migratory behaviour, can be maintained between populations despite high levels of gene flow [38], as also seen in the admixed populations of migratory and sedentary groups of broad-tailed hummingbirds in North America [59]. A similar lack of neutral genetic differentiation has been observed in other highly mobile, migrating species, such as hoverflies with different overwintering strategies in France [60] and blackcaps with different migratory behaviours and destinations in Europe [61].…”

Genetic, Ecological and Morphological Divergence between Populations of the Endangered Mexican Sheartail Hummingbird (Doricha eliza)

“…We ran two individual analyses to estimate TMRCA, one with all the ND2 sequences of bee hummingbirds available from previous studies [6]–[7],[37]–[38] and retrieved from GenBank, and the second with the mtDNA sequences (ND2 and ATPase) generated in our study for D. eliza and the other hummingbird species listed above. All sequences used and those retrieved from GenBank are listed with their accession numbers in Table S2 .…”