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Genetic variation and reproductive system among North American species of Nuttallanthus (Plantaginaceae)
Author(s) -
Crawford Phillip T.,
Elisens Wayne J.
Publication year - 2006
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.93.4.582
Subject(s) - biology , reproductive isolation , outbreeding depression , genetic variation , outcrossing , genetic diversity , inbreeding , inbreeding depression , genetic divergence , genetic variability , zoology , ecology , population , genetics , gene , sociology , genotype , pollen , demography
We examined 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. 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 (0.819–0.936), but interspecific comparisons indicated many qualitative allelic differences and correspondingly low I values (0.516–0.623). 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.