A species flock driven by predation? Secondary metabolites support diversification of slugs in Antarctica

TitleA species flock driven by predation? Secondary metabolites support diversification of slugs in Antarctica
Publication TypeJournal Article
Year of Publication2013
AuthorsWilson NG, Maschek J.A, Baker BJ
JournalPlos One
Date Published2013/11
Type of ArticleArticle
ISBN Number1932-6203
Accession NumberWOS:000327546400018
Keywords1st insights; adaptive radiation; chemical; defense; diversity; ecology; gastropoda; invertebrates; mollusca; nudibranch austrodoris-kerguelenensis; opisthobranchia

Antarctica's rich marine animal biodiversity has been substantially influenced by a complex glacial history, but it is unclear why some taxa responded with diversification while others did not. Despite being considered a single endemic sea slug species in the Southern Ocean, mitochondrial DNA sequencing of Doris kerguelenensis (Bergh, 1884) revealed a multitude of highly divergent lineages. But because of the uniparental inheritance of mitochondria, it was unclear whether those lineages represented a radiation of cryptic species or simply stochastic sorting patterns of populations that rarely reach equilibrium. Here we demonstrate that the mitochondrial groups in D. kerguelenensis also correlate with nuclear DNA. Additionally, by extracting secondary metabolites from the same individuals we sequenced, we were also able to directly link the secondary metabolome to a mitochondrial lineage. These metabolites are not derived from the diet, but instead are synthesized de novo and implicated in an anti-predatory role. The strong linkage between these metabolites and the mitochondrial lineages strongly suggests that these lineages represent cryptic species in an adaptive radiation. Over millions of years, episodic glacial cycles reduced the distribution of a formerly widespread slug into a series of small vicariant refuges, vulnerable to genetic drift and predation pressure. The recognition of this marine invertebrate species flock implicates a strongly synergistic role for selection and allopatry driving speciation in this system.

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