Molecular evidence for genetic mixing of Arctic and Antarctic subpolar populations of planktonic foraminifers

• Published in: Nature (London) Vol. 405; no. 6782; pp. 43 - 47
• Main Authors: Darling, Kate F, Wade, Christopher M, Stewart, Iain A, Kroon, Dick, Dingle, Richard, Brown, Andrew J. Leigh
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 04.05.2000; Nature Publishing Group
• Subjects: Animals; Antarctic Regions; Antarctica; Arctic Circle; Arctic Regions; Base Sequence; Biological and medical sciences; Climate change; Cold Climate; DNA, Ribosomal - genetics; Evolution, Molecular; Foraminifera; Fundamental and applied biological sciences. Psychology; Genes; Genetic diversity; Genetics; Genetics of eukaryotes. Biological and molecular evolution; Genetics, Population; Genotype; Invertebrata; Latitude; Marine; Molecular biology; Molecular Sequence Data; Oceans and Seas; Phylogeny; Plankton; Plankton - classification; Plankton - genetics; Population genetics, reproduction patterns; RNA, Ribosomal - genetics; rRNA; Tropical environments; Antarctica; Arctic Region; Antarctic Regions; Arctic Regions; Arctic region; PN, Arctic Ocean; PS, Antarctic Ocean; PN, Arctic; Marine environment; Protozoa; Gene flow; Geographic distribution; Foraminifera; Paleoclimate; Subpolar zone; Population genetics; Zooplankton
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/35011002

Bipolarity, the presence of a species in the high latitudes separated by a gap in distribution across the tropics, is a well-known pattern of global species distribution. But the question of whether bipolar species have evolved independently at the poles since the establishment of the cold-water provinces 16-8 million years ago, or if genes have been transferred across the tropics since that time, has not been addressed. Here we examine genetic variation in the small subunit ribosomal RNA gene of three bipolar planktonic foraminiferal morphospecies. We identify at least one identical genotype in all three morphospecies in both the Arctic and Antarctic subpolar provinces, indicating that trans-tropical gene flow must have occurred. Our genetic analysis also reveals that foraminiferal morphospecies can consist of a complex of genetic types. Such occurrences of genetically distinct populations within one morphospecies may affect the use of planktonic foraminifers as a palaeoceanographic proxy for climate change and necessitate a reassessment of the species concept for the group.