The Influence of Pleistocene Climatic Changes and Ocean Currents on the Phylogeography of the Southern African Barnacle, Tetraclita serrata (Thoracica; Cirripedia)

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.

Genetic isolation by distance reveals restricted dispersal across a range of life histories: implications for biodiversity conservation planning across highly variable marine environments

“…This can be particularly pronounced in populations which undergo fluctuations in population sizes, which influences population bottlenecks and even extinctions. In South Africa, reduced gene flow occurs around Cape Point, a biogeographic barrier which separates the west from the south‐west coast, for some species (von der Heyden et al ., ; Muller et al ., ; Reynolds et al ., ). This may well be a factor in separating populations on either side of Cape Point and contribute to reduced levels of genetic diversity for some species.…”

“…DNA sequence data on 11 intertidal marine species were taken from published works (Neethling et al ., ; Teske et al ., ; von der Heyden et al ., , ; Muller et al ., ; Reynolds et al ., ), as well as unpublished data (Muteveri, ); two new data sets ( Acanthochiton garnoti and Cyclograpsus punctatus ; Appendix S1 in Supporting Information) were generated for this study (Table ; Appendix S1). Sampling sizes for each species and locality are given in Appendix S2.…”

Genetic differentiation of the soft shore barnacle Fistulobalanus albicostatus (Cirripedia: Thoracica: Balanomorpha) in the West Pacific

“…albicostatus . Species exhibiting pre‐LGM population expansions include tubeworms (Jolly, Viard, Gentil, Thiebaut, & Jollivet, ) and the brown algae Fucus (Hoarau, Coyer, Veldsink, Stam, & Olsen, ) in the Northeast Atlantic, as well as the barnacles Tetraclita serrata (Reynolds, Matthee, & von der Heyden, ) in South African waters and Chthamalus challengeri and Chthamalus moro in the West Pacific (Cheang et al., ; Wu et al., ). By contrast, the sea bass and redlip mullet (Liu, Gao, Wu, & Zhang, ; Liu, Gao, Yokogawa, & Zhang, ), mitten crab (Xu et al., ) and mud crab (He et al., ) exhibit post‐LGM expansion.…”

Molecular approaches uncover cryptic diversity in intertidalLigiaisopods (Crustacea, Isopoda, Ligiidae) across the southern Africa coastline

“…Recent phylogeographic work on coastal invertebrate species has led to the discovery of cryptic diversity in poorly dispersing species around the world (e.g., Chan, Tsang & Chu, 2007 ; Hurtado, Lee & Mateos, 2013 ; Radulovici, Sainte-Marie & Dufresne, 2009 ; Santamaria et al, 2017 ; Santamaria et al, 2016 ; Santamaria, Mateos & Hurtado, 2014 ; Santamaria et al, 2013 ; Varela & Haye, 2012 ). In South Africa, cryptic diversity has been reported for several coastal invertebrate taxa ( Evans et al, 2004 ; Mmonwa et al, 2015 ; Reynolds, Matthee & Von der Heyden, 2014 ; Ridgway et al, 2001 ; Teske et al, 2007 ; Zardi et al, 2007 ), including direct-developing crustacean peracarids. Teske et al (2006) reported the presence of multiple deeply-divergent lineages for Exosphaeroma hylecoetes and Iphinoe truncata , with Baldanzi et al (2016) reporting the presence of multiple evolutionary lineages within the amphipod Talorchestia capensis .…”