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Intraspecific variation in Podostemum ceratophyllum (Podostemaceae): evidence of refugia and colonization since the last glacial maximum
Author(s) -
Fehrmann Susie,
Philbrick C. Thomas,
Halliburton Richard
Publication year - 2012
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.1100275
Subject(s) - glacial period , biology , intraspecific competition , range (aeronautics) , ecology , last glacial maximum , population , colonization , genetic variation , biological dispersal , paleontology , demography , biochemistry , materials science , sociology , gene , composite material
• Premise of the Study: Intraspecific variation among 20 populations of Podostemum ceratophyllum Michx. was investigated to test the hypothesis of range expansion from southern refugia since the last glacial maximum. • Methods: Six noncoding regions of chloroplast DNA were sequenced in 60 individuals. Populations were divided into two groups, north and south of the glacial boundary, in addition to isolated populations in Arkansas and Honduras. Variation in populations north of the boundary was compared with variation in populations to the south and in the isolated populations. • Key Results: Nucleotide diversity was an order of magnitude lower in populations north of the glacial boundary than in those to the south. The Arkansas and Honduras populations showed no variation. The predominant haplotype in northern populations was also found in a Virginia population. • Conclusions: Reduced variation north of the glacial boundary suggests a founder event associated with range expansion since the last glacial maximum. Colonization probably occurred from populations in refugia located several hundred kilometers south of the glacial boundary. The results provide insight into the effects of past and current climate change on patterns of geographic distribution and genetic variation in aquatic plants.