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Fine‐scale geographical structure of genetic diversity in inland wild beet populations
Author(s) -
ARNAUD JEANFRANÇOIS,
FÉNART STÉPHANE,
GODÉ CÉCILE,
DELEDICQUE SYLVIE,
TOUZET PASCAL,
CUGUEN JOËL
Publication year - 2009
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/j.1365-294x.2009.04279.x
Subject(s) - biology , ruderal species , introgression , gene flow , gene pool , genetic diversity , polyploid , cultivated plant taxonomy , pollen , botany , genetic variation , population , ecology , genetics , gene , habitat , demography , genome , sociology
Introgression arising from crop‐to‐wild gene flow provides novel sources of genetic variation in plant species complexes. Hybridization within the Beta vulgaris species complex is of immediate concern; crop lineages ( B . vulgaris ssp. vulgaris ) hybridize easily with their wild relatives ( B . vulgaris ssp. maritima ) thereby threatening wild beet gene diversity with genetic swamping. Hybridization ‘hotspots’ occur in European seed production areas because inland ruderal wild beets occur and reproduce in sympatry with cultivated beets. We studied gene flow occurring between seed‐producing cultivars and ruderal wild B . vulgaris in southwestern France to determine whether feral beets, arising from unharvested cultivated seed, represent an opportunity for crop‐to‐wild gene flow. We surveyed 42 inland ruderal beet populations located near seed production fields for nucleo‐cytoplasmic variation and used a cytoplasmic marker diagnostic of cultivated lines. Occurrence of cultivated‐type cytoplasm within ruderal populations clearly reflected events of crop seed escape. However, we found no genetic signatures of nuclear cultivated gene introgression, which suggests past introgression of cultivated cytoplasm into a wild nuclear background through seed escape rather than recent direct pollen flow. Overall, patterns of genetic structure suggested that inland ruderal wild beet populations act as a metapopulation, with founding events involving a few sib groups, followed by low rates of seed or pollen gene flow after populations are established. Altogether, our results indicate that a long‐lived seed bank plays a key role in maintaining cultivated‐type cytoplasm in the wild and highlight the need for careful management of seed production areas where wild and cultivated relatives co‐occur.