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Abstract Detail

Systematics Section / ASPT

Crawford, Phillip [1], Elisens, Wayne [2].

North American species of Nuttallanthus (Plantaginaceae) are reproductively isolated and predominantly inbreeding.

WE examined the extent of reproductive isolation and the effect of reproductive and life history strategies on the amount and partitioning of genetic variation in three annual species of Nuttallanthus. The North American species N. canadensis, N. floridanus, and N. texanus have regional to widespread ranges that overlap in the southeastern USA, are characterized by homogeneous populations and high fecundity, and possess showy, fragrant flowers seemingly adapted for insect pollination and outbreeding. Purported intergradation of floral characters resulted in prior hypotheses of interspecific hybridization. Field and greenhouse studies on plants from 25 populations indicated that reproductive strategies were similar among species and showed predominant self-fertilization via cleistogamy and self-pollination prior to anthesis in chasmogamous flowers. Species were reproductively isolated and demonstrated complete cross-incompatibility after experimental crosses and no evidence for hybridization in mixed populations. Genetic variation was assessed using starch gel electrophoresis to resolve 15 isozyme loci in 50 populations. Conspecific genetic identity (I) values were high (0.819 to 0.936), but interspecific comparisons indicated many qualitative allelic differences and correspondingly low I values (0.516 to 0.623). Low levels of polymorphism and observed heterozygosity within populations and the disproportionate amount of gene diversity distributed among populations were concordant with reproductive data. The pattern of genetic differentiation was most similar to that observed in species with a predominantly inbreeding mating system.

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1 - University of Oklahoma, Oklahoma Biological Survey, 111 E Chesapeake St., Norman, Oklahoma, 73019-5112, USA
2 - University of Oklahoma, Botany & Microbiology and Oklahoma Biological Survey, 770 Van Vleet Oval, Norman, Oklahoma, 73019, USA


Presentation Type: Oral Paper:Papers for Sections
Session: 8-5
Location: 120/Ayres
Date: Monday, July 31st, 2006
Time: 9:30 AM
Abstract ID:152

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