A morphologically intergrading population facilitates plastid introgression from diploid to tetraploid Dodecatheon (Primulaceae).

OBERLE, BRAD; MONTGOMERY, ROBERT A.; BECK, JAMES B.; ESSELMAN, ELIZABETH J.

Polyploidy may promote diversification by generating reproductive isolation between ploidy levels, but this reproductive barrier may not be absolute. Several recent analyses of diploid-tetraploid contact zones have found evidence for hybridization. In these cases, inter-cytotype gene flow is often associated with morphologically intergrading populations. In this study, we combine cytological, fitness and population genetic data to examine the evolutionary role of a morphologically intergrading population at a contact zone between species with different ploidy levels in Dodecatheon. Diploid D. frenchii and tetraploid D. meadia are usually distinguished by leaf-shape characters. In southern Illinois, where these taxa occur in parapatry, a morphologically intergrading population includes the first documented tetraploid with D. frenchii morphology. Most plants in this intergrading population are fertile, and a nearby typical population of D. meadia has plastid DNA haplotypes that only occur in D. frenchii elsewhere in southern Illinois. These results suggest that fit neo-tetraploids in this intergrading population have facilitated local introgression between ploidy levels. Similar patterns in other regions where these taxa co-occur may explain weak range-wide genetic differentiation between these species. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 168, 91-100.

PRIMULACEAE; REPRODUCTIVE isolation; PLANT reproduction; PLANT morphology; PLASTIDS; POLYPLOIDY in plant chromosomes; PLANT hybridization

Botanical Journal of the Linnean Society, 2012, Vol 168, Issue 1, p91

0024-4074

Academic Journal

10.1111/j.1095-8339.2011.01191.x