Self-Fertilization

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Self-Fertilization

 

the merging of male and female sex cells belonging to a single bisexual individual (see HERMAPHRODITISM). Self-fertilization is rarely observed in nature. In the process of evolution, most organisms acquired adaptations that made self-fertilization impossible and ensured cross-fertilization. These adaptations increased the genetic variation of the off spring, promoting, in turn, the elaboration of new adaptations and the development of more viable offspring. Self-fertilization is sometimes observed in hydras, flatworms, certain annelids, mollusks, and fishes. Among plants it is observed in many algae, fungi, and flowering plants. In flowering plants self-fertilization is a result of self-pollination.

References in periodicals archive ?
Environmentally controlled induction of primary male gonochorists from eggs of the self-fertilizing hermaphroditic fish.
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 Plantago coronopus.
In 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 slugs.
Evolutionary rates in partially self-fertilizing species.
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 plants.
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".