Ditch network sustains functional connectivity and influences patterns of gene flow in an intensive agricultural landscape.
In intensive agricultural landscapes, plant species previously relying on semi-natural habitats may persist as metapopulations within landscape linear elements. Maintenance of populations' connectivity through pollen and seed dispersal is a key factor in species persistence in the face of substantial habitat loss. The goals of this study were to investigate the potential corridor role of ditches and to identify the landscape components that significantly impact patterns of gene flow among remnant populations. Using microsatellite loci, we explored the spatial genetic structure of two hydrochorous wetland plants exhibiting contrasting local abundance and different habitat requirements: the rare and regionally protected Oenanthe aquatica and the more commonly distributed Lycopus europaeus, in an 83 km(2) agricultural lowland located in northern France. Both species exhibited a significant spatial genetic structure, along with substantial levels of genetic differentiation, especially for L. europaeus, which also expressed high levels of inbreeding. Isolation-by-distance analysis revealed enhanced gene flow along ditches, indicating their key role in effective seed and pollen dispersal. Our data also suggested that the configuration of the ditch network and the landscape elements significantly affected population genetic structure, with (i) species-specific scale effects on the genetic neighborhood and (ii) detrimental impact of human ditch management on genetic diversity, especially for O. aquatica. Altogether, these findings highlighted the key role of ditches in the maintenance of plant biodiversity in intensive agricultural landscapes with few remnant wetland habitats.
UMR CNRS 6553 ECOBIO, Université de Rennes 1, Campus de Beaulieu, Rennes Cedex, France.
L
http://orcid.org/0000-0002-1712-9711
L
Favre-Bac
UMR CNRS 6553 ECOBIO, Université de Rennes 1, Campus de Beaulieu, Rennes Cedex, France.
C
C
Mony
UMR CNRS 6553 ECOBIO, Université de Rennes 1, Campus de Beaulieu, Rennes Cedex, France.
A
A
Ernoult
UMR CNRS 6553 ECOBIO, Université de Rennes 1, Campus de Beaulieu, Rennes Cedex, France.
F
F
Burel
Unité Évolution, Écologie, Paléontologie, UMR CNRS 8198, Université de Lille 1-Sciences et Technologies, Villeneuve d'Ascq, France.
J-F
JF
Arnaud
D000383:Agriculture; D017753:Ecosystem; D005602:France; D051456:Gene Flow; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D005843:Geography; D015810:Linkage Disequilibrium; D031333:Lycopus / Q000235:genetics*; D018895:Microsatellite Repeats; D031050:Oenanthe / Q000235:genetics*; D062206:Spatial Analysis; D053833:Wetlands