Fat‐tailed gene flow in the dioecious canopy tree species Fraxinus mandshurica var. japonica revealed by microsatellites

Abstract

Pollen flow, seed dispersal and individual reproductive success can be simultaneously estimated from the genotypes of adults and offspring using stochastic models. Using four polymorphic microsatellite loci, gene flow of the wind-pollinated and wind-seed-dispersed dioecious tree species, Fraxinus mandshurica var. japonica, was quantified in a riparian forest, in northern Japan. In a 10.5-ha plot, 74 female adults, 76 male adults and 292 current-year seedlings were mapped and genotyped, together with 200 seeds. To estimate dispersal kernels of pollen and seeds, we applied normal, exponential power, Weibull, bivariate t-distribution kernels, and two-component models consisting of two normal distribution functions, one with a small and one with a large variance. A two-component pollen flow model with a small contribution (26.1%) from short-distance dispersal (sigma = 7.2 m), and the rest from long-distance flow (sigma = 209.9 m), was chosen for the best-fitting model. The average distance that integrated pollen flows inside and outside the study plot was estimated to be 196.8 m. Tree size and flowering intensity affected reproduction, and there appeared to be critical values that distinguished reproductively successful and unsuccessful adults. In contrast, the gene flow model that estimated both pollen and seed dispersal from established seedlings resulted in extensive seed dispersal, and the expected spatial genetic structures did not satisfactorily fit with the observations, even for the selected model. Our results advanced small-scale individual-based parentage analysis for quantifying fat-tailed gene flow in wind-mediated species, but also clarified its limitations and suggested future possibilities for gene flow studies.

Spruce colonization at treeline: where do those seeds come from?

“…By means of parentage analysis on established juveniles, Troupin (2005) found in Pinus halepensis colonization events over 500 m long, and Bacles et al (2006) recorded individuals established up to 1.4 Km from their mother tree in a fragmented population of F. excelsior. Long-distance dispersal and establishment events were also detected in other tree species by Goto et al (2006) and Hardesty et al (2006) using the same approach. We found that the probability of reaching distances as long as 2 Km is still high, especially considering the large reproductive output of conifers, and how taking into account MDDs provides a better estimation of the tail of the curve, reducing underestimation errors.…”

Limiting inbreeding in disjunct and isolated populations of a woody shrub

“…Immigration rates estimated using the neighborhood model are a function of the dispersal kernel and are based on the assumption that the neighborhood is circular (Goto et al. 2006) resulting in a bias when the populations are linear.…”

“…Inferences about mating patterns and their association with ecological parameters such as distance, density, flowering and fragmentation are often reported in the literature based on single populations or multiple populations of different size, condition and level of genetic isolation (Goto et al. 2006; Geng et al. 2008; Llaurens et al.…”

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

“…With a neighborhood size of N, we can consider that a fraction a ¼ R N 0 f ðrÞ2pr@r of dispersal events occurs inside the neighborhood whereas the complementary fraction 1 À a ¼ R 1 N f ðrÞ2pr@r occurs outside the neighborhood (Goto et al, 2006). With an infinite neighborhood size, we consider that N is half of the maximum distance between potential parents in a patch network in order to ensure that all individuals are included in the neighborhood.…”

“…With an infinite neighborhood size, we consider that N is half of the maximum distance between potential parents in a patch network in order to ensure that all individuals are included in the neighborhood. The fraction 1 À a can be considered as the expected immigration rate-of seed or pollen-if the dispersal kernel is the only dispersal source (Goto et al, 2006). Comparison of these expected and estimated rates (ms and mp) allows an estimate of all random processes (for example, long-distance dispersal) that are not captured by the kernels (Goto et al, 2006).…”