The concept of population in clonal organisms: mosaics of temporally colonized patches are forming highly diverse meadows of Zostera marina in Brittany

Type Article
Date 2010-06
Language English
Author(s) Becheler Ronan1, Diekmann O.2, Hily Christian3, Moalic Yann1, Arnaud-Haond SophieORCID1, 2
Affiliation(s) 1 : IFREMER, Lab Environm Profond, Ctr Brest, F-29280 Plouzane, France.
2 : Univ Algarve, CCMAR, CIMAR Lab Associado, P-8005139 Faro, Portugal.
3 : Univ Bretagne Occidentale, Inst Univ Europeen Mer, LEMAR, F-29280 Plouzane, France.
Source Molecular Ecology (0962-1083) (Wiley-blackwell Publishing, Inc), 2010-06 , Vol. 19 , N. 12 , P. 2394-2407
DOI 10.1111/j.1365-294X.2010.04649.x
WOS© Times Cited 55
Keyword(s) clonality, dispersal, ecotype, network analysis, population, Zostera marina
Abstract Seagrasses structure some of the world's key coastal ecosystems presently in decline due to human activities and global change. The ability to cope with environmental changes and the possibilities for shifts in distribution range depend largely on their evolvability and dispersal potential. As large-scale data usually show strong genetic structure for seagrasses, finer-grained work is needed to understand the local processes of dispersal, recruitment and colonization that could explain the apparent lack of exchange across large distances. We aimed to assess the fine-grained genetic structure of one of the most important and widely distributed seagrasses, Zostera marina, from seven meadows in Brittany, France. Both classic population genetics and network analysis confirmed a pattern of spatial segregation of polymorphism at both regional and local scales. One location exhibiting exclusively the variety 'angustifolia' did not appear more differentiated than the others, but instead showed a central position in the network analysis, confirming the status of this variety as an ecotype. This phenotypic diversity and the high allelic richness at nine microsatellites (2.33-9.67 alleles/locus) compared to levels previously reported across the distribution range, points to Brittany as a centre of diversity for Z. marina at both genetic and phenotypic levels. Despite dispersal potential of several 100 m, a significant pattern of genetic differentiation, even at fine-grained scale, revealed 'genetic patchiness'. Meadows seem to be composed of a mosaic of clones with distinct origins in space and time, a result that calls into question the accuracy of the concept of populations for such partially clonal species.
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