Journal Article

Origin and Dispersal History of Two Colonial Ascidian Clades in the Botryllus schlosseri Species Complex

Giesbrecht, Kirsten B., Nydam, Marie L., Stephenson, Emily E.

2017

Overview

Human-induced global warming and species introductions are rapidly altering the composition and functioning of Earth's marine ecosystems. Ascidians (Phylum Chordata, Subphylum Tunicata, Class Ascidiacea) are likely to play an increasingly greater role in marine communities. The colonial ascidian B. schlosseri is a cryptic species complex comprising five genetically divergent clades (A-E). Clade A is a global species, and Clade E has so far been identified in European waters only. Using the largest mitochondrial cytochrome oxidase I datasets yet assembled, we determine the origin and dispersal history of these species. Nucleotide diversity and Approximate Bayesian Computation analyses support a Pacific origin for Clade A, with two likely dispersal scenarios that both show the northwestern Atlantic populations establishing early in the history of the species. Both Discrete Phylogeographic Analysis and Approximate Bayesian Computation support an origin of Clade E on the French side of the English Channel. An unsampled lineage evolved from the French lineage, which reflects the conclusion from the median joining network that not all Clade E lineages have been sampled. This unsampled lineage gave rise to the haplotypes on the English side of the English Channel, which were the ancestors to the Mediterranean and Bay of Biscay populations. Clade E has a wider geographic range than previously thought, and shows evidence of recent range expansion. Both Clade A and Clade E should be considered widespread species: Clade A globally and Clade E within Europe.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Analysis / Animals / Ascidiacea / Bayes Theorem / Bayesian analysis / Biodiversity / Bioinformatics / Biology and Life Sciences / Botryllus schlosseri / Chordata / Climate change / Computation / Cryptic species / Cytochrome / Cytochrome oxidase I / Deoxyribonucleic acid / Dispersal / Dispersal (Ecology) / Dispersion / Divergence / DNA / Earth Sciences / Ecology and Environmental Sciences / Genetics / Global warming / Haplotypes / Human influences / Introduced species / Marine ecosystems / Mathematics / Mitochondria / Morphology / Mutation / Natural history / People and Places / Phylogeny / Phylogeography / Polymorphism, Genetic / Population growth / Populations / Range extension / Sea squirts / Species / Species diversity / Statistical analysis / Studies / Tunicata / Urochordata - classification / Urochordata - genetics