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Phylogeography and polyploid evolution of North American goldenrods ( Solidago subsect. Humiles , Asteraceae)
Author(s) -
Peirson Jess A.,
Dick Christopher W.,
Reznicek Anton A.
Publication year - 2013
Publication title -
journal of biogeography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 158
eISSN - 1365-2699
pISSN - 0305-0270
DOI - 10.1111/jbi.12136
Subject(s) - biology , glacial period , polyploid , phylogeography , chloroplast dna , range (aeronautics) , analysis of molecular variance , haplotype , ecology , genetic diversity , evolutionary biology , ploidy , genetic structure , genetic variation , population , phylogenetics , paleontology , genetics , allele , demography , materials science , composite material , gene , sociology
Aim We analysed range‐wide chloroplast DNA (cp DNA ) variation in a clade of N orth A merican goldenrods ( S olidago subsect. H umiles ) to infer its biogeographical history and evolution. Our objectives were to: (1) examine the structuring of cp DNA diversity in this widespread species complex, (2) reconstruct Pleistocene refugia and post‐glacial migration of the study species, and (3) test hypotheses relating to the frequency of polyploidization. We expected the glacial history of S olidago to differ markedly from that of temperate trees and forest understorey plants. Location N orth A merica ( C anada, continental USA , Mexico). Methods 1466 bp of chloroplast intergenic spacer DNA (cp DNA ) were sequenced from 368 individuals representing 72 populations of subsect. H umiles , which consists of the widespread S olidago simplex and four geographically restricted species. Estimates of N ST and G ST were compared as a test of phylogeographical structure, and spatial analysis of molecular variance ( SAMOVA ) was used to examine cp DNA variation. Rarified haplotype diversity and chromosome diversity (ploidy levels) were used to infer locations of glacial refugia and post‐glacial expansion, and to determine origins of polyploidy, respectively. Results A total of 46 haplotypes were recovered. While there was significant phylogeographical structure ( N ST > G ST ), cp DNA variation was not strongly partitioned across species boundaries, geography or ploidy levels, and six haplotypes were shared among species. The highest haplotype diversity was located in western North America, followed by the south‐eastern USA and the formerly glaciated Great Lakes region. Main conclusions S olidago simplex recolonized formerly glaciated eastern N orth A merica from refugia in western N orth A merica and near the perimeter of the ice margin. The south‐eastern USA had only limited involvement in recolonization of these northern regions. The geographical disjunction and scattered positions of polyploids in the haplotype network provide evidence of multiple polyploid origins within S . simplex , and the restriction of endemic, polyploid taxa to post‐glacial habitats provides evidence of Holocene polyploid speciation. The results highlight polyploidization as a source of adaptive genetic variation and speciation in novel and post‐glacial habitats.