Genetic Fingerprint-Inferred Population Subdivision and Spatial Genetic Tests for Isolation by Distance and Adaptation in the Coastal Plant Limonium carolinianum

Abstract

This paper examines two wild populations of Limonium carolinianum for population genetic subdivision and spatial patterns of genetic variation in an attempt to simultaneously test for both the action of local adaptation to tidal gradients and isolation by distance (IBD). A VNTR (variable number of tandem repeats) genetic "fingerprinting" marker was used to infer relatedness among mapped plants in two populations. Band sharing within and between populations estimated F'ST, an approximate measure of F ST' Regression models were used to analyze the relationship between band sharing and spatial separation in tidal elevation and horizontal distance, as well as the relationship of fecundity differences with band sharing and spatial distance. Populations differed in band size frequency distributions and mean number of bands per profile and, therefore, likely differed in effective population size. F'ST was estimated at 0.0678 and was significantly greater than F'ST among randomly constructed subpopulations. Band sharing decreased 0.13% per meter in one population but showed no significant relation to distance in the other. In the population with significant IBD band sharing increased with increasingly different tidal elevation, contrary to an adaptive hypothesis, possibly due to directional gene flow or drift. Deme sizes were approximately 25 meters and greater than 100 meters, spanning larger areas than the entire environmental gradient. Fecundity differences were not associated with spatial parameters or band sharing. Unequal potential maternal fecundity measured as variance in number of seeds per maternal family was a significant source of genetic sampling variance. The VNTR marker employed is capable of detecting adaptation as identity by descent in ecological time and is an appropriate method for estimating the net evolutionary fate of polygenic traits. The results show that the net balance between selection along an environmental gradient and the effects of IBD and unequal maternal fecundity favor genetic differentiation by random processes in populations of Limonium,

Reconciling nuclear microsatellite and mitochondrial marker estimates of population structure: breeding population structure of Chesapeake Bay striped bass (Morone saxatilis)

“…Their data suggested little population genetic differentiation based on a sample of YOY fish and highly variable multilocus DNA 'fingerprint' genetic markers. Although highly variable, VNTR markers can produce biased estimates of population structure since differences in band sizes are not equivalent to Mendelian alleles and using band sharing among VNTR profiles to estimate heterozygosity leads to downward bias in estimates of fixation indices (see Hamilton, 1997). However, the results presented here (based on microsatellite loci that exhibit strictly Mendelian alleles) are in qualitative agreement that very little genetic variation is found among populations within Chesapeake Bay.…”

Habitat requirements and population structure of the rare endangered Limonium girardianum in Mediterranean salt marshes

“…As has been observed for other Limonium species (Hamilton, 1997;Palacios and González-Candelas, 1997a), L. girardianum does not present any specialized morphological features for dispersal, either on floral parts or on fruits or seeds. Previous studies showed that the distribution of most plant species is often limited by their capacity to disperse (Primack and Miao, 1992;Turnbull et al, 2000) as, in the case of salt marshes, by the heterogeneous spatial distribution of seed rain (Erfanzadeh et al, 2010;Rand, 2000).…”

Genetic diversity of Typha latifolia (Typhaceae) and the impact of pollutants examined with tandem‐repetitive DNA probes

“…A survey of 25 studies examining allozyme polymorphisms in long-lived herbaceous perennials found that F st averaged [Vol. 86 AMERICAN JOURNAL OF BOTANY Alberte et al, 1994Hamilton, 1997Busemeyer et al, 1997Kumar and Rogstad, 1998Keane, Smith, and Rogstad, 1998 0.29 (Hamrick, Godt, and Sherman-Broyles, 1992). Our estimates of F st for T. latifolia suggest that gene flow is lower in this species than on average for other long-lived herbaceous perennials, especially given the relatively small area of this study.…”