Estimation of mating system parameters and the pollen dispersal kernel in Nothofagus nervosa

MARCHELLI, P.; SMOUSE, P.; GALLO, L.A.

Congreso; VI Southern Connection Congress “Gondwana Reunited: a Southern Perspective for a Changing World”.; 2010

The extent of pollen flow, along with mating system parameters such as inbreeding coefficients and correlated paternity among progeny, determine the genetic structure of plant populations and are crucial for the design of conservation strategies. The objective here is to estimate mating system parameters and to fit the pollen dispersal kernel in Nothofagus nervosa. We sampled 25 mothers and 372 progeny, distributed in two groups, from the Tromen Lake region in Argentina. We registered spatial position of the maternal trees, and genotyped mothers and offspring for five SSR markers. We estimated single locus (ts = 0.95) and multilocus (tm = 0.99) outcrossing rates, biparental inbreeding (tm – ts = 0.04), and correlated paternity within maternal sibships (rp = 0.10) with MLTR software (Ritland 2002). We used KINDIST software (Robledo-Arnuncio et al. 2006) to fit an exponential power dispersal kernel to the structure of pollen clouds sampled by different mothers. The effective number of pollen donors to a single mother is Nep = 9.6. The average pollination distance is 32.4m, but the dispersal kernel is leptokurtic (b = 0.36). The pollination pattern was bimodally distributed, in accord with the two subgroups. Nothofagus nervosa is strongly outcrossing, has short average pollen dispersal distance, but has a high probability of long distance dispersion.