GENE FLOW IN CHAMAECRISTA FASCICULATA (LEGUMINOSAE) II. GENE ESTABLISHMENT

Abstract

The role of gene establishment in gene flow was investigated in a population of the annual legume Chamaecrista fasciculata by determining the effect of interparent distance on progeny fitness throughout the entire life history. A decelerating gain in progeny fitness with increasing interparent distance was observed. Selfed progeny suffered a 2‐fold fitness disadvantage compared to progeny derived from mating events between individuals in the same neighborhood. Progeny derived from within neighborhood crosses had lower fitness than progeny from crosses between neighborhoods. Coupling the effect of interparent distance on gene establishment with information on gene dispersal resulted in a considerable increase in estimated gene flow. However, gene flow was still limited, as the average neighborhood area corresponded to a circle with radius of approximately 3.0 m. Yearly fluctuations in population size and variation in reproductive output lowered the estimate of Ne below the census estimate to approximately 100 individuals. The role of a seed bank in increasing the estimate of Ne was found to be insignificant. It is likely that genetic drift plays a major role in determining the distribution of genetic variation in this population.

Inbreeding depression under a competitive regime in Mimulus guttatus: consequences for potential male and female function

“…Many researchers have quantified inbreeding depression in individual flower production, fruit production, and adult above-ground biomass (e.g. Schemske, 1983;Schoen, 1983;Dudash, 1990;Fenster, 1991b;Johnston, 1992), but few studies have examined allocation to potential male and female reproduction within a flower by quantifying pollen and ovule production (but see Karoly, 1991Karoly, , 1994. We documented a 28-33 per cent reduction in pollen number and a 14-30 per cent reduction in ovule number.…”

“…Sobrevila, 1988;Waser & Price, 1989;Fenster, 1991b;van Treuren et a!., 1993). If plants within populations share deleterious alleles because of common ancestry, crosses made between populations can show greater heterosis than those made within populations.…”

“…Schemske & Pautler, 1984;Dudash, 1990;Fenster, 1991b;van Treuren et a!., 1993). We included seed mass, the probability of germination, adult above-ground biomass, and pollen and ovule numbers in our multiplicative fitness function (MFF).…”

“…Schemske, 1983;Schoen, 1983; reviewed by Charlesworth & Charlesworth, 1987;Ritland & Ganders, 1987;Svensson, 1988;Griffing, 1989;Levin, 1989;Dudash, 1990; Holtsford & Elistrand, 1990;Fenster, 1991b;Johnston, .1992;Agren & Schemske, 1993) more information is needed on how the genetic makeup of immediate neighbours can affect the relative performance of self and outcross progeny and how the expression of inbreeding depression varies across life history traits.…”

Heterosis and outbreeding depression in crosses between natural populations of Arabidopsis thaliana

“…Many mildly deleterious recessive or nearly recessive mutations are predicted to become fixed when effective population sizes are modest and gene flow is limited (Whitlock et al, 2000). Heterosis in F 1 crosses between natural populations is ubiquitous (for example, Fenster, 1991;Armbruster et al, 1997;Edmands, 1999;Oakley and Winn, 2012).…”