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Abstract Detail



Molecular Ecology and Evolution

Fonnemann, Brandon [1], Mason-Gamer, Roberta [2].

Molecular phylogenetic analysis of Coreopsis nuecensoides and C. nuecensis - a putative progenitor derivative species pair.

Coreopsis nuecensoides and C. nuecensis are narrowly distributed endemics of southeastern Texas with overlapping ranges but no observed incidences of co-occurrence. They are distinguished from one another by minor morphological and life history traits. Both exhibit a reduction in chromosomal numbers (Coreopsis nuecensoides, n=9 or 10 and C. nuecensis, n=6 or 7) with respect to other members of Coreopsis sect. Coreopsis (remaining species, n=13). Crosses between them yield largely sterile hybrids with an average pollen stainability of 2-5%. Coreopsis nuecensis is nearly endemic to a narrow strip (ca. 10 x 450 miles) of fine, porous sandy soil known as the Carrizo Sands Formation, which has different water retention properties than the neighboring soil types. The Carrizo Sands spans from northeast to southcentral Texas and has been characterized as an edaphic island, harboring ten or more endemic plant taxa. Coreopsis nuecensoides is restricted to neighboring soil types with no recorded incidences on the formation. It has been hypothesized that C. nuecensoides gave rise to C. nuecensis as peripheral populations of C. nuecensoides bordering the Carrizo Sands underwent rapid speciation on the formation due to a heightened intensity of selection and genetic drift. Past studies examining the distribution, cytogenetics, allozyme data, cpDNA restriction sites, and life history traits of C. nuecensoides and C. nuecensis were consistent with a progenitor-derivative relationship between them. However, preliminary data from a sample of 7-8 individuals/species, based on three nuclear markers - A25 (putative peroxisomal membrane protein, 400bp), A39 (putative glucose-6-phosphate/phosphate-translocator, 500bp), and A31 (unknown function, 500bp) - revealed considerable variation in C. nuecensis inconsistent with a predicted bottleneck associated with a karyotype change in a small population. Five populations (5 individuals/population) have been sampled from each species using nuclear markers A25, A39, C17 (unknown function, 500bp) along with cpDNA sequence data to see if (1) allelic diversity and phylogenetic relationships support a progenitor-derivative relationship between them, and (2) whether the origin of C. nuecensis was accompanied by a population bottleneck.

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1 - University of Illinois At Chicago, Biological Sciences, 845 West Taylor Street MC066, Chicago, IL, 60607-7060, USA
2 - University of Illinois Chicago, DEPT. OF BIOLOGICAL SCIENCES (M/C 066), 845 W. TAYLOR ST., CHICAGO, IL, 60607, USA

Keywords:
Asteraceae
Coreopsis
plant systematics
molecular phylogeny
Evolution
speciation.

Presentation Type: Oral Paper:Papers for Topics
Session: 46
Location: Newberry/Riverside Hilton
Date: Wednesday, July 31st, 2013
Time: 3:30 PM
Number: 46008
Abstract ID:484
Candidate for Awards:Margaret Menzel Award


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