Int. J. Mol. Sci. 2010, 11(2), 492-506; doi:10.3390/ijms11020492
Article

Effective Population Size, Gene Flow, and Species Status in a Narrow Endemic Sunflower, Helianthus neglectus, Compared to Its Widespread Sister Species, H. petiolaris

1,†email, 2email and 1,* email
Received: 25 November 2009; in revised form: 17 January 2010 / Accepted: 21 January 2010 / Published: 2 February 2010
(This article belongs to the Special Issue Cladistic Analysis and Molecular Evolution)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: Species delimitation has long been a difficult and controversial process, and different operational criteria often lead to different results. In particular, investigators using phenotypic vs. molecular data to delineate species may recognize different boundaries, especially if morphologically or ecologically differentiated populations have only recently diverged. Here we examine the genetic relationship between the widespread sunflower species Helianthus petiolaris and its narrowly distributed sand dune endemic sister species H. neglectus using sequence data from nine nuclear loci. The two species were initially described as distinct based on a number of minor morphological differences, somewhat different ecological tolerances, and at least one chromosomal rearrangement distinguishing them; but detailed molecular data has not been available until now. We find that, consistent with previous work, H. petiolaris is exceptionally genetically diverse. Surprisingly, H. neglectus harbors very similar levels of genetic diversity (average diversity across loci is actually slightly higher in H. neglectus). It is extremely unlikely that such a geographically restricted species could maintain these levels of genetic variation in isolation. In addition, the two species show very little evidence of any genetic divergence, and estimates of interspecific gene flow are comparable to gene flow estimates among regions within H. petiolaris. These results indicate that H. petiolaris and H. neglectus likely do not represent two distinct, isolated gene pools; H. neglectus is probably more accurately thought of as a geographically restricted, morphologically and ecologically distinct subspecies of H. petiolaris rather than a separate species.
Keywords: gene flow; species delimitation; genetic variation; reproductive barriers; endemism
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MDPI and ACS Style

Raduski, A.R.; Rieseberg, L.H.; Strasburg, J.L. Effective Population Size, Gene Flow, and Species Status in a Narrow Endemic Sunflower, Helianthus neglectus, Compared to Its Widespread Sister Species, H. petiolaris. Int. J. Mol. Sci. 2010, 11, 492-506.

AMA Style

Raduski AR, Rieseberg LH, Strasburg JL. Effective Population Size, Gene Flow, and Species Status in a Narrow Endemic Sunflower, Helianthus neglectus, Compared to Its Widespread Sister Species, H. petiolaris. International Journal of Molecular Sciences. 2010; 11(2):492-506.

Chicago/Turabian Style

Raduski, Andrew R.; Rieseberg, Loren H.; Strasburg, Jared L. 2010. "Effective Population Size, Gene Flow, and Species Status in a Narrow Endemic Sunflower, Helianthus neglectus, Compared to Its Widespread Sister Species, H. petiolaris." Int. J. Mol. Sci. 11, no. 2: 492-506.

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