title: Limits to gene flow in a cosmopolitan marine planktonic diatom.
abstract: The role of geographic isolation in marine microbial speciation is hotly debated because of the high dispersal potential and large population sizes of planktonic microorganisms and the apparent lack of strong dispersal barriers in the open sea. Here, we show that gene flow between distant populations of the globally distributed, bloom-forming diatom species Pseudo-nitzschia pungens (clade I) is limited and follows a strong isolation by distance pattern. Furthermore, phylogenetic analysis implies that under appropriate geographic and environmental circumstances, like the pronounced climatic changes in the Pleistocene, population structuring may lead to speciation and hence may play an important role in diversification of marine planktonic microorganisms. A better understanding of the factors that control population structuring is thus essential to reveal the role of allopatric speciation in marine microorganisms.
authors.affiliation: Laboratory of Protistology and Aquatic Ecology, Biology Department, Ghent University, B-9000 Ghent, Belgium.
authors.forename: Griet
authors.initials: G
authors.lastname: Casteleyn
authors.forename: Frederik
authors.initials: F
authors.lastname: Leliaert
authors.forename: Thierry
authors.initials: T
authors.lastname: Backeljau
authors.forename: Ann-Eline
authors.initials: AE
authors.lastname: Debeer
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kotaki
authors.forename: Lesley
authors.initials: L
authors.lastname: Rhodes
authors.forename: Nina
authors.initials: N
authors.lastname: Lundholm
authors.forename: Koen
authors.initials: K
authors.lastname: Sabbe
authors.forename: Wim
authors.initials: W
authors.lastname: Vyverman
mesh_terms: D000483:Alleles; D017377:Diatoms / Q000235:genetics*; D051456:Gene Flow / Q000235:genetics*; D056426:Genetic Loci / Q000235:genetics; D005843:Geography; D038622:Internationality; D010802:Phylogeny; D010933:Plankton / Q000235:genetics*; D025341:Principal Component Analysis; D012623:Seawater; D013997:Time Factors