MadSci Network: Genetics
Query:

Re: How do the outcomes of self-fertilization and asexual reproduction differ?

Date: Fri Mar 3 14:36:28 2000
Posted By: Michael Onken, MadSci Admin
Area of science: Genetics
ID: 950855288.Ge
Message:

It depends... The basic difference between self-fertilization and asexual reproduction in eukaryotes is that the former involves meiosis (as do all forms of sexual reproduction) and the latter is an extension of mitosis. In general, this means that self-fertilization involves chromosomal shuffling and redistributing the genome of the parent, while asexual reproduction is essentially cloning. I say "in general", because there are many organisms, mostly fungi, that have an asexual phase in which the mitotic production of offspring (spores) involves somatic recombination of the chromosomes. There is little difference between the genetic outcomes of asexual reproduction in these organisms and self-fertilization in other organisms.

Genomic rearrangements in the absence of sexual hybridization are the extreme form of inbreeding, and as such have positive and negative aspects compared to simple asexual reproduction. The biggest downside is that each rearrangement increases the chance of a detrimental, recessive gene surfacing. Thus, the offspring produced from self-fertilization are generally less fit than those produced by normal asexual reproduction, which have the same fitness as their parent. On the plus side, some recessive genes may be beneficial in certain environments, so the genomic shuffling during self-fertilization increases the variability of the offspring, possibly finding a new combination of alleles that can adapt to an environment inaccessible to the parent. So while standard asexual reproduction must rely on infrequent mutations to evolve a new genetic combination, self-fertilization (as well as several forms of eukaryotic asexual reproduction) allows constant recombination of the genome, placing each allele in dynamic relation with the environment.


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