Genetic affinities between trans-oceanic populations of non-buoyant macroalgae in the high latitudes of the Southern Hemisphere

• Main Authors: Fraser, Ceridwen I., Zuccarello, Giuseppe C., Spencer, Hamish G., Salvatore, Laura C., Garcia, Gabriella R., Waters, Jonathan M.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Public Library of Science 2015
• Subjects: phylogeography; seaweed; ecological and environmental processes; oceans and seas; phylogeny; Antarctic; The Antarctic; Shackleton; New Zealand; Marsden; Antarc*; Australian Antarctic Division
• Online Access: http://hdl.handle.net/1885/16501

Marine biologists and biogeographers have long been puzzled by apparently non-dispersive coastal taxa that nonetheless have extensive transoceanic distributions. We here carried out a broad-scale phylogeographic study to test whether two widespread Southern Hemisphere species of non-buoyant littoral macroalgae are capable of long-distance dispersal. Samples were collected from along the coasts of southern Chile, New Zealand and several subAntarctic islands, with the focus on high latitude populations in the path of the Antarctic Circumpolar Current or West Wind Drift. We targeted two widespread littoral macroalgal species: the brown alga Adenocystisutricularis (Ectocarpales, Heterokontophyta) and the red alga Bostrychiaintricata (Ceramiales, Rhodophyta). Phylogenetic analyses were performed using partial mitochondrial (COI), chloroplast (rbcL) and ribosomal nuclear (LSU / 28S) DNA sequence data. Numerous deeply-divergent clades were resolved across all markers in each of the target species, but close phylogenetic relationships - even shared haplotypes - were observed among some populations separated by large oceanic distances. Despite not being particularly buoyant, both Adenocystisutricularis and Bostrychiaintricata thus show genetic signatures of recent dispersal across vast oceanic distances, presumably by attachment to floating substrata such as wood or buoyant macroalgae. This work was funded by New Zealand Marsden contract 07-UOO-099, Department of Zoology and University of Otago Research grants to JMW and CIF; a Shackleton Scholarship to CIF; an Allan Wilson Centre for Molecular Ecology and Evolution postdoctoral grant to CIF; Australian Antarctic Division AAS project #2914.