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Evidence of hidden biodiversity, ongoing speciation and diverse patterns of genetic structure in giant Antarctic amphipods

journal contribution
posted on 2023-05-17, 10:34 authored by Helen BairdHelen Baird, Miller, KJ, Start, JS
Recent molecular research on Antarctic benthic organisms has challenged traditional taxonomic classifications, suggesting that our current perceptions of Antarctic biodiversity and species distributions must be thoroughly revised. Furthermore, genetic differentiation at the intraspecific level remains poorly understood, particularly in eastern Antarctica. We addressed these issues using DNA sequence data for two sibling amphipod species that could be collected on a circum-Antarctic scale: Eusirus perdentatus and Eusirus giganteus. Haplotype networks and Bayesian phylogenies based on mitochondrial (COI, CytB) and nuclear (ITS2) DNA provided strong evidence of multiple cryptic species of Eusirus, with several occurring in sympatry and at least one likely to have a true circum-Antarctic distribution. Within species, gene flow was often highly restricted, consistent with a brooding life history and in some cases suggestive of current or future allopatric speciation. Patterns of genetic structure were not always predictable: one cryptic species showed preliminary evidence of high genetic differentiation across ~150 km in eastern Antarctica (FST > 0.47, P < 0.01), yet another was remarkably homogenous across ~5000 km (FST = 0.00, P = 1.00). Genetic diversity also varied among cryptic species, independent of sample size (p = 0.00-0.99). These results indicate several hidden levels of genetic complexity in these Antarctic amphipods that are neither apparent from previous taxonomic or ecological studies nor predictable from their life history. Such genetic diversity and structure may reflect different modes of survival for Antarctic benthic organisms during historic glacial cycles, and ⁄ or subsequent re-establishment of populations on the shelf, and highlight our misunderstanding of Antarctic marine species diversity.

History

Publication title

Molecular Ecology

Volume

20

Issue

16

Pagination

3439-3454

ISSN

0962-1083

Department/School

Institute for Marine and Antarctic Studies

Publisher

Blackwell Publishing Ltd

Place of publication

9600 Garsington Rd, Oxford, England, Oxon, Ox4 2Dg

Rights statement

The definitive published version is available online at: http://www3.interscience.wiley.com/

Repository Status

  • Restricted

Socio-economic Objectives

Biodiversity in Antarctic and Southern Ocean environments

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