Using Genetic Markers to Directly Estimate Gene Flow and Reproductive Success Parameters in Plants on the Basis of Naturally Regenerated Seedlings

Abstract

Estimating seed and pollen gene flow in plants on the basis of samples of naturally regenerated seedlings can provide much needed information about ''realized gene flow,'' but seems to be one of the greatest challenges in plant population biology. Traditional parentage methods, because of their inability to discriminate between male and female parentage of seedlings, unless supported by uniparentally inherited markers, are not capable of precisely describing seed and pollen aspects of gene flow realized in seedlings. Here, we describe a maximum-likelihood method for modeling female and male parentage in a local plant population on the basis of genotypic data from naturally established seedlings and when the location and genotypes of all potential parents within the population are known. The method models female and male reproductive success of individuals as a function of factors likely to influence reproductive success (e.g., distance of seed dispersal, distance between mates, and relative fecundity-i.e., female and male selection gradients). The method is designed to account for levels of seed and pollen gene flow into the local population from unsampled adults; therefore, it is well suited to isolated, but also wide-spread natural populations, where extensive seed and pollen dispersal complicates traditional parentage analyses. Computer simulations were performed to evaluate the utility and robustness of the model and estimation procedure and to assess how the exclusion power of genetic markers (isozymes or microsatellites) affects the accuracy of the parameter estimation. In addition, the method was applied to genotypic data collected in Scots pine (isozymes) and oak (microsatellites) populations to obtain preliminary estimates of long-distance seed and pollen gene flow and the patterns of local seed and pollen dispersal in these species.

Considering evolutionary processes in adaptive forestry

“…Using this approach in Quercus suber, Ramirez-Valiente et al (2011) detected significant heritability but nonsignificant selection gradient for carbon isotope discrimination, contrasting with very low heritability and significant selection gradient for specific leaf area. An alternative approach of selection gradients through the assessment of actual reproductive success in situ was recently developed (Oddou-Muratorio et al 2005;Burczyk et al 2006;Klein et al 2011). This method, based on the mixed-mating neighbourhood model, consists in estimating the reproductive success of individual adult trees using spatial genetic data of seedlings and their potential parents and then in relating this reproductive success to phenotypic traits.…”

Inferring contemporary dispersal processes in plant metapopulations: comparison of direct and indirect estimates of dispersal for the annual species Crepis sancta

“…In order to analyze our data, we used a slightly modified model developed by Burczyk et al (2006). In our analysis all individuals within a network can be encapsulated in a unique neighborhood (Oddou-Muratorio and Klein, 2008).…”

“…While previous methods performed parentage analysis and dispersal kernel estimates sequentially, recent methods allow joint parentage analysis and dispersal kernel estimation, which significantly improves statistical performance (Hadfield et al, 2006). The spatially explicit mating model (hereafter, SEMM) allows seed and pollen immigration rates from an unknown source to be estimated within a unique statistical framework and seed and pollen kernel dispersal (including self-fertilization) from viable established seedlings and potential parents to be fitted (Burczyk et al, 2006;Oddou-Muratorio and Klein, 2008). This method based on viable seedlings provides effective dispersal estimates that include all processes acting between dispersal and recruitment.…”

“…The method requires substantial sampling effort of potential parents coupled with an elevated recapture rate of seedlings/offspring. To our knowledge, it has mainly been used for trees (Burczyk et al, 2006;Oddou-Muratorio and Klein, 2008). Yet, inferring metapopulation processes requires rapid turnover of populations within a few years, which can be found in short-lived species.…”

Estimating Differential Reproductive Success From Nests of Related Individuals, With Application to a Study of the Mottled Sculpin,Cottus bairdi

“…Parentage studies also can be used to estimate reproductive success among potential parents (Smouse and Meagher 1994) and parameters such as the effective number of breeders within a population (Fiumera et al 2002), or they can be combined with quantitative genetic analyses to identify quantitative trait loci (QTL) in natural populations (Slate et al 2002) and to estimate heritabilities through analysis of wild-caught females and their progeny (King et al 2001). Parentage studies can also be applied to address questions relating to gene flow and dispersal (Burczyk et al 2006).…”