title: The anatomy of a 'suture zone' in Amazonian butterflies: a coalescent-based test for vicariant geographic divergence and speciation.
abstract: Attempts by biogeographers to understand biotic diversification in the Amazon have often employed contemporary species distribution patterns to support particular theories, such as Pleistocene rainforest refugia, rather than to test among alternative hypotheses. Suture zones, narrow regions where multiple contact zones and hybrid zones between taxa cluster, have been seen as evidence for past expansion of whole biotas that have undergone allopatric divergence in vicariant refuges. We used coalescent analysis of mutilocus sequence data to examine population split times in 22 pairs of geminate taxa in ithomiine and heliconiine butterflies. We test a hypothesis of simultaneous divergence across a suture zone in NE Peru. Our results reveal a scattered time course of diversification in this suture zone, rather than a tight cluster of split times. Additionally, we find rapid diversification within some lineages such as Melinaea contrasting with older divergence within lineages such as the Oleriina (Hyposcada and Oleria). These results strongly reject simple vicariance as a cause of the suture zone. At the same time, observed lineage effects are incompatible with a series of geographically coincident vicariant events which should affect all lineages similarly. Our results suggest that Pleistocene climatic forcing cannot readily explain this Peruvian suture zone. Lineage-specific biological traits, such as characteristic distances of gene flow or varying rates of parapatric divergence, may be of greater importance.
authors.affiliation: Department of Genetics, Evolution and Environment, University College London, 4 Stephenson Way, London NW1 2HE, UKMuseo de Historia Natural, Universidad Nacional Mayor de San Marcos, Av. Arenales 1256, Apartado 14-0434, Lima-14, PeruRadcliffe Institute for Advanced Study, Byerly Hall, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Kanchon K
authors.initials: KK
authors.lastname: Dasmahapatra
authors.forename: Gerardo
authors.initials: G
authors.lastname: Lamas
authors.forename: Fraser
authors.initials: F
authors.lastname: Simpson
authors.forename: James
authors.initials: J
authors.lastname: Mallet
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D002080:Butterflies / Q000235:genetics*; D002467:Cell Nucleus / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics; D049810:Genetic Speciation; D005828:Genetics, Population; D005843:Geography; D016013:Likelihood Functions; D008957:Models, Genetic; D008969:Molecular Sequence Data; D058885:Multilocus Sequence Typing; D010568:Peru; D058974:Phylogeography; D011156:Population Density; D017422:Sequence Analysis, DNA
chemical_list: D004272:DNA, Mitochondrial