Population genetics of the Sao Tome caecilian (gymnophiona: dermophiidae: schistometopum thomense) reveals strong geographic structuring

Stoelting, Ricka E.; Measey, G. John; Drewe, Robert C.

Population genetics of the Sao Tome caecilian (gymnophiona: dermophiidae: schistometopum thomense) reveals strong geographic structuring

dc.contributor.author	Stoelting, Ricka E.	en_ZA
dc.contributor.author	Measey, G. John	en_ZA
dc.contributor.author	Drewe, Robert C.	en_ZA
dc.date.accessioned	2016-08-30T08:47:33Z
dc.date.available	2016-08-30T08:47:33Z
dc.date.issued	2014
dc.description	CITATION: Stoelting, R. E, Measey, G. J. & Drewe, R. C. 2014. Population genetics of the Sao Tome caecilian (gymnophiona: dermophiidae: schistometopum thomense) reveals strong geographic structuring. PLoS ONE, 9(8):1-13, doi:10.1371/journal.pone.010462.
dc.description	The original publication is available at http://journals.plos.org/plosone
dc.description.abstract	Islands provide exciting opportunities for exploring ecological and evolutionary mechanisms. The oceanic island of São Tomé in the Gulf of Guinea exhibits high diversity of fauna including the endemic caecilian amphibian, Schistometopum thomense. Variation in pigmentation, morphology and size of this taxon over its c. 45 km island range is extreme, motivating a number of taxonomic, ecological, and evolutionary hypotheses to explain the observed diversity. We conducted a population genetic study of S. thomense using partial sequences of two mitochondrial DNA genes (ND4 and 16S), together with morphological examination, to address competing hypotheses of taxonomic or clinal variation. Using Bayesian phylogenetic analysis and Spatial Analysis of Molecular Variance, we found evidence of four geographic clades, whose range and approximated age (c. 253 Kya – 27 Kya) are consistent with the spread and age of recent volcanic flows. These clades explained 90% of variation in ND4 (φCT = 0.892), and diverged by 4.3% minimum pairwise distance at the deepest node. Most notably, using Mismatch Distributions and Mantel Tests, we identified a zone of population admixture that dissected the island. In the northern clade, we found evidence of recent population expansion (Fu's Fs = −13.08 and Tajima's D = −1.80) and limited dispersal (Mantel correlation coefficient = 0.36, p = 0.01). Color assignment to clades was not absolute. Paired with multinomial regression of chromatic data, our analyses suggested that the genetic groups and a latitudinal gradient together describe variation in color of S. thomense. We propose that volcanism and limited dispersal ability are the likely proximal causes of the observed genetic structure. This is the first population genetic study of any caecilian and demonstrates that these animals have deep genetic divisions over very small areas in accordance with previous speculations of low dispersal abilities.	en_ZA
dc.description.sponsorship	European Commission Marie Curie Fellowship (HPMF-CT-2001-01407, field work support for GJM),	en_ZA
dc.description.sponsorship	G. Lindsay Field Research Fund of the California Academy of Sciences (field work support for RES and RCD in 2001)	en_ZA
dc.description.sponsorship	Hagey Research Investment Fund of the California Academy of Sciences (field work support for RCD in 2006)	en_ZA
dc.description.uri	http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0104628
dc.description.version	Publisher's version
dc.format.extent	13 pages
dc.identifier.citation	Stoelting, R. E, Measey, G. J. & Drewe, R. C. 2014. Population genetics of the Sao Tome caecilian (gymnophiona: dermophiidae: schistometopum thomense) reveals strong geographic structuring. PLoS ONE, 9(8):1-13, doi:10.1371/journal.pone.010462
dc.identifier.issn	1932-6203 (online)
dc.identifier.other	doi:10.1371/journal.pone.010462
dc.identifier.uri	http://hdl.handle.net/10019.1/99507
dc.language.iso	en_ZA	en_ZA
dc.publisher	Public Library of Science
dc.rights.holder	Authors retain copyright
dc.subject	Ecological
dc.subject	Evolutionary
dc.title	Population genetics of the Sao Tome caecilian (gymnophiona: dermophiidae: schistometopum thomense) reveals strong geographic structuring	en_ZA
dc.type	Article	en_ZA