Title
Molecular evidence for distinct Antarctic lineages in the cosmopolitan terrestrial diatoms **Pinnularia borealis** and **Hantzschia amphioxys** Molecular evidence for distinct Antarctic lineages in the cosmopolitan terrestrial diatoms **Pinnularia borealis** and **Hantzschia amphioxys**
Author
Faculty/Department
Faculty of Sciences. Biology
Publication type
article
Publication
Jena ,
Subject
Biology
Source (journal)
Protist. - Jena
Volume/pages
164(2013) :1 , p. 101-115
ISSN
1434-4610
ISI
000312188500010
Carrier
E
Target language
English (eng)
Full text (Publishers DOI)
Abstract
Recent morphology-based studies indicate that freshwater diatom floras in the Antarctic comprise a significant share of endemics among a majority of apparently cosmopolitan species. Given the widespread (pseudo)cryptic species diversity in diatoms, we assessed the molecular divergence and temperature-dependent growth characteristics between Antarctic and non-Antarctic strains for two presumed species with a cosmopolitan distribution, namely Pinnularia borealis and Hantzschia amphioxys. Molecular phylogenies based on the plastid gene rbcL and the nuclear 28S rDNA (D1-D3 region) revealed that both taxa consist of multiple lineages, each including a distinct Antarctic lineage. A molecular clock estimates the origin of P. borealis at 35.8 (30-47) million years (Ma) ago, making this the oldest known diatom species complex. The Antarctic P. borealis lineage is estimated to have diverged 7.8 (2-15) Ma ago, after the geographical and thermal isolation of the Antarctic continent. Despite not being psychrophilic, the Antarctic lineages of P. borealis and H. amphioxys have a lower optimal growth temperature and upper lethal temperature than most lineages from more temperate regions, indicating niche differentiation. Together, this suggests that many presumed cosmopolitan Antarctic diatom species are in fact species complexes, possibly containing Antarctic endemics with low temperature preferences.
E-info
https://repository.uantwerpen.be/docman/iruaauth/b56c2a/2612c9c1dbc.pdf
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