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Geographic structure of lineage associations in a plant‐bacterial mutualism
Author(s) -
Parker M. A.,
Spoerke J. M.
Publication year - 1998
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1046/j.1420-9101.1998.11050549.x
Subject(s) - biology , mutualism (biology) , lineage (genetic) , ecology , range (aeronautics) , evolutionary biology , population genetics , population , genetics , gene , materials science , demography , sociology , composite material
Two species linked by a mutualistic relationship may evolve correlated population differentiation if there is long‐term continuity of interactions between specific partners. This phenomenon was analyzed by multilocus enzyme electrophoresis on the annual legume Amphicarpaea bracteata and its nitrogen‐fixing bacterial symbionts ( Bradyrhizobium sp.) sampled from >20 sites over a 1000 km area. Three analyses indicated that genetic differentiation was correlated in the two organisms. First, the genetic distance between bacterial populations at each pair of sites was significantly positively related to the genetic distance between their host plant populations, as evaluated by the Mantel test. Second, a cluster analysis revealed that several divergent lineages were present both among plants and among bacteria. Bacterial lineages showed a highly nonrandom distribution across plant lineages that was consistent in each of two regions sampled. Finally, there were numerous cases where populations of the same plant lineage 1000 km apart harbored bacterial isolates with an identical multilocus genotype. Thus, despite recurrent opportunities for partner switching, particular genotypes of these two organisms associate consistently across multiple habitats throughout their geographic range.