RT Journal Article
SR Electronic
T1 Geographically structured genetic variation in the <em>Medicago lupulina</em> – <em>Ensifer</em> mutualism
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 117192
DO 10.1101/117192
A1 Tia L. Harrison
A1 Corlett W. Wood
A1 Katy D. Heath
A1 John R. Stinchcombe
YR 2017
UL http://biorxiv.org/content/early/2017/03/15/117192.abstract
AB Mutualisms are interspecific interactions affecting the ecology and evolution of species. Patterns of geographic variation in interacting species may play an important role in understanding how variation is maintained in mutualisms, particularly in introduced ranges. One agriculturally and ecologically important mutualism is the partnership between legume plants and rhizobia. Through characterizing and comparing the population genomic structure of the legume Medicago lupulina and two rhizobial species (Ensifer medicae and E. meliloti), we explored the spatial scale of population differentiation between interacting partners in their introduced range in North America. We found high proportions of E. meliloti in southeastern populations and high proportions of E. medicae in northwestern populations. Medicago lupulina and the Ensifer genus showed similar patterns of spatial genetic structure (isolation by distance). However, we detected no evidence of isolation by distance or population structure within either species of bacteria. Genome-wide nucleotide diversity within each of the two Ensifer species was low, suggesting limited introduction of strains, founder events, or severe bottlenecks. Our results suggest that there is potential for geographically structured coevolution between M. lupulina and the Ensifer genus, but not between M. lupulina and either Ensifer species.