Exploring modes of Neotropical speciation

New species arise as geographic barriers divide and isolate populations, but sometimes speciation takes place within populations occupying the same geographic location.

Data resources used via GBIF : 4,229 species occurrences
Preserved specimen of Costus scaber

Preserved specimen of Costus scaber collected in Peru. Photo from the Field Museum of Natural History.

Speciation, the evolutionary process by which populations become distinct species, is often related to geographic alterations as uplifting mountain ranges and rising oceans create barriers and new climates to support increased diversity. More evident in the Neotropics than anywhere, the high levels of biological diversity draw attention from researchers looking to explain evolutionary patterns. In this study, researchers examine the diversification dynamics of the Neotropical region using a phylogenetic framework of the Spiral Gingers (Costaceae family). Through GenBank downloads and de novo DNA sequencing combined with GBIF-mediated occurrences, the researchers produce a dated phylogeny of Costaceae showing an Eocene origin of the family with the large Costus genus diverging about 30 million years ago. The most-recent common ancestor of the Neotropical Costus clade is estimated to have occurred only 10 million years ago, with speciation without geographic separation (sympatry) being high, as opposed to the older South American clade dominated by speciation as a result of separation (allopatry).

André T, Salzman S, Wendt T and Specht CD (2016) Speciation dynamics and biogeography of Neotropical spiral gingers (Costaceae). Molecular Phylogenetics and Evolution. Elsevier BV 103: 55–63. Available at doi:10.1016/j.ympev.2016.07.008.