Environmentally controlled induction of primary male gonochorists from eggs of the self-fertilizing
Here I present results of a study designed to estimate the mating system, magnitude of inbreeding depression, the relationship between fitness and inbreeding level, and the variation among maternal plants in inbreeding depression in one population of partially self-fertilizing
species, isozyme variation within populations is lower than that among populations (Hamrick, 1989).
We first tested the hypothesis that rate of egg production would be higher for isolated slugs producing unfertilized eggs than for isolated but self-fertilizing
Evolutionary rates in partially self-fertilizing
In contrast, Johnston and Schoen (1996) found that inbreeding depression in the highly self-fertilizing
tetraploid Amsinckia gloriosa was higher than that in selfing populations of the diploid A.
Similar levels of genetic variation to those we found in Echinococcus, however, have been reported for self-fertilizing
invertebrates (Jarne 1995).
On average, self-fertilizing
populations had significantly less inbreeding depression than outcrossers at seed production, germination, and survival but statistically similar inbreeding depression at growth/reproduction (Tables 3-4; [ILLUSTRATION FOR FIGURE 3 OMITTED]).
The amazingly high level of inbreeding depression found in many partially self-fertilizing
conifer species (Namkoong and Bishir 1987; Muona 1989; but see, for example, Kuittinen and Savolainen 1992) can be explained by mutation-selection balance only if the mutation rate in conifers is very high.
Allocations to pollen, seeds, and pollination mechanisms in self-fertilizing
The average genotypic correlation between self-fertilizing
mates caused by their common ancestry is [r.sub.x].
He was also well aware that some species of plants are habitually self-fertilizing
, and that there must therefore be a conflict between factors favoring the evolution of self-fertilization (attributed to the assurance of higher reproductive output by selfing), and of outcrossing (the avoidance of inbreeding depression): "Under these extremely complex and fluctuating conditions, with two somewhat opposed ends to be gained, namely, the safe propagation of the species and the production of cross-fertilised, vigorous offspring, it is not surprising that allied forms should exhibit an extreme diversity in the means which favour either end".