Fine‐scale genetic structure and gene dispersal inferences in 10 Neotropical tree species

Abstract

Pollen dispersal was characterized within a population of the narrowly endemic perennial herb, Centaurea corymbosa, using exclusion-based and likelihood-based paternity analyses carried out on microsatellite data. Data were used to fit a model of pollen dispersal and to estimate the rates of pollen flow and mutation/genotyping error, by developing a new method. Selfing was rare (1.6%). Pollen dispersed isotropically around each flowering plant following a leptokurtic distribution, with 50% of mating pairs separated by less than 11 m, but 22% by more than 40 m. Estimates of pollen flow lacked precision (0-25%), partially because mutations and/or genotyping errors (0.03-1%) could also explain the occurrence of offspring without a compatible candidate father. However, the pollen pool that fertilized these offspring was little differentiated from the adults of the population whereas strongly differentiated from the other populations, suggesting that pollen flow rate among populations was low. Our results suggest that pollen dispersal is too extended to allow differentiation by local adaptation within a population. However, among populations, gene flow might be low enough for such processes to occur.

Joint analysis of spatial genetic structure and inbreeding in a managed population of Scots pine

“…The availability of highly variable molecular markers has facilitated the analysis of fine-scale genetic structure in natural tree populations. The fine-scale structure has been found in some forest tree species (Sork et al, 1993;Berg and Hamrick, 1995;Streiff et al, 1998;Dutech et al, 2002;Hardy et al, 2006). These tree species are characterized by either limited seed dispersal or restricted pollen and seed dispersal.…”

Fine-scale spatial genetic structure in a predominantly selfing plant: role of seed and pollen dispersal

“…where SE b was the standard error of the regression slope b (Hardy et al, 2006). We also calculated the 'Sp' statistic, which is the inverse of the neighborhood size Nb under IBD in the two-dimensional space (Vekemans and Hardy, 2004), that is, the ratio Àb/(1ÀF (1) ).…”

“…The effective density was estimated from the adult population density, D, using the approximation, D Â N e /N (the ratio of effective to census population size) (Hardy et al, 2006). Under self-fertilization, N e is predicted to equal N(2Às)/ 2 (Pollak, 1987).…”

“…In the past decade, several indirect methods to quantify gene dispersal in a continuously distributed population have been proposed (Epperson and Li, 1997;Hardy and Vekemans, 1999;Rousset, 2000;Hardy, 2003Hardy, , 2006Heuertz et al, 2003;Vekemans and Hardy, 2004). In these methods, gene dispersal distance among individuals is inferred through the usage of either inter-individual genetic distance (Rousset, 2000) or relatedness (Hardy and Vekemans, 1999).…”

The effect of segregation of flowering time on fine-scale spatial genetic structure in an alpine-snowbed herb Primula cuneifolia

“…Isolation by distance, that is, decreasing genetic relatedness among pairwise individuals with increasing physical distance (Wright, 1943), is a driving force that shapes local kinship structure, which in turn increases the likelihood of mating events between related individuals (Grifin and Eckert, 2003;Degen et al, 2004;Herlihy and Eckert, 2004). Some empirical studies have detected significant SGS when seed dispersal and/or pollen dispersal is restricted (for example, Hamrick et al, 1993;Epperson and Alvarez-Buylla, 1997;Hardy et al, 2006). In a simulation study, SGS was predicted to develop solely via a sufficient restriction of gene flow, without natural selection or other determinant forces (Turner et al, 1982).…”