Speciation History of Sunbeams (Aglaeactis)

Project authors: Jessica McLaughlin (PhD student, project lead),Matthew Miller, and Chris Witt (Museum of Southwest Biology)
Project github repository

Hummingbirds are one of the most species rich bird families on Earth. In particular, hummingbirds in the Andes have undergone and continue to demonstrate rapid cladogenesis. Although approximately 340 hummingbird species currently exist, McGuire et al (2014, Current Biology) demonstrate that the hummingbirds are diversifying at a rate that suggests that as manby as 720 species might co-occur in the future. Many hummingbird species are fairly young, and this makes hummingbirds, particularly in the Andes, a compelling group in which to study avian speciation dynamics, especially as a counterpoint to many other Neotropical systems where speciation dynamics might differ.

The Aglaeactis sunbeams are a lineage of common hummingbirds in the Andean highlands of Colombia, Ecuador, Peru, and Bolivia. Four species are currently recognized (Figure 1). The Shining Sunbeam (A. cupripennis) is the most widespread species , ranging from Colombia to Cuzco, Peru. It is polytypic, with the northern nominate subspecies generally more orange and the southern caumatanotus more brown.

Figure 1: Range of Sunbeam Hummingbirds

The White-tufted Sunbeam, A. castelnaudii, is also polytypic with a disjunct range: the nominate subspecies is found in Cuzco, Apurimac, and Urubamba in southern Peru. The regalis subspecies occurs to the north around Junin and Pasco. The Black-hooded Sunbeam, A. pamela, is the southernmost species, with no known range overlap with its congeners in its range in the Bolivian highlands (Schuchmann, 1985, 1999). Finally, The Purple-backed Sunbeam (A. aliciae) occurs only in the MaranĂ³n Valley of Peru (Lambert & Angulo-Pratolongo, 2007), and is classified as Endangered due to its restricted range.

Jess McLaughlin has sequenced low coverage whole genomes using a novel, high-multiplex, low cost WGS library prep method. She has generated ~4X coverage libraries for 46 sunbeams across all four species. Her results are forthcoming, but in general suggest a pattern of rapid speciation, low genomic divergence and on-going gene flow consistent with the hypothesis that a few genomic regions responsible for pre-zygotic reproductive isolation may drive speciation in the group.