The influence of pleistocene climatic changes and ocean currents on the phylogeography of the Southern African Barnacle, Tetraclita serrata (Thoracica; Cirripedia)
Date
2014-07
Journal Title
Journal ISSN
Volume Title
Publisher
Public Library of Science
Abstract
Abstract
The evolutionary effects of glacial periods are poorly understood for Southern Hemisphere marine intertidal species,
particularly obligatory sessile organisms. We examined this by assessing the phylogeographic patterns of the southern
African volcano barnacle, Tetraclita serrata, a dominant species on rocky intertidal shores. Restricted gene flow in some
geographical areas was hypothesized based on oceanic circulation patterns and known biogeographic regions. Barnacle
population genetic structure was investigated using the mitochondrial cytochrome oxidase subunit 1 (COI) region for 410
individuals sampled from 20 localities spanning the South African coast. The mtDNA data were augmented by generating
nuclear internal transcribed spacer 1 (ITS1) sequences from a subset of samples. Phylogenetic and population genetic
analyses of mitochondrial DNA data reveal two distinct clades with mostly sympatric distributions, whereas nuclear analyses
reveal only a single lineage. Shallow, but significant structure (0.0041–0.0065, P,0.01) was detected for the mtDNA data set,
with the south-west African region identified as harbouring the highest levels of genetic diversity. Gene flow analyses on
the mtDNA data show that individuals sampled in south-western localities experience gene flow primarily in the direction of
the Benguela Current, while south and eastern localities experience bi-directional gene flow, suggesting an influence of
both the inshore currents and the offshore Agulhas Current in the larval distribution of T. serrata. The mtDNA haplotype
network, Bayesian Skyline Plots, mismatch distributions and time since expansion indicate that T. serrata population
numbers were not severely affected by the Last Glacial Maximum (LGM), unlike other southern African marine species. The
processes resulting in the two morphologically cryptic mtDNA lineages may be the result of a recent historical allopatric
event followed by secondary contact or could reflect selective pressures due to differing environmental conditions.
Description
Publication of this article was funded by the Stellenbosch University Open Access Fund.
The original publication is available at www.plosone.org
Please cite as follows:
Reynolds, T. V., Matthee, C. A., & Von der Heyden, S. 2014. The Influence of pleistocene climatic changes and ocean currents on the phylogeography of the Southern African Barnacle, Tetraclita serrata (Thoracica; Cirripedia). PLoS ONE, 9(7): e102115, doi:10.1371/journal.pone.0102115.
The original publication is available at www.plosone.org
Please cite as follows:
Reynolds, T. V., Matthee, C. A., & Von der Heyden, S. 2014. The Influence of pleistocene climatic changes and ocean currents on the phylogeography of the Southern African Barnacle, Tetraclita serrata (Thoracica; Cirripedia). PLoS ONE, 9(7): e102115, doi:10.1371/journal.pone.0102115.
Keywords
Pleistocene climatic changes, Barnacle -- Phylogeography, Tetraclita serrata
Citation
Reynolds, T. V., Matthee, C. A., & Von der Heyden, S. 2014. The Influence of pleistocene climatic changes and ocean currents on the phylogeography of the Southern African Barnacle, Tetraclita serrata (Thoracica; Cirripedia). PLoS ONE, 9(7): e102115, doi:10.1371/journal.pone.0102115.