BIOL 2P05 Lecture Notes - Lecture 27: Heterogametic Sex, Black Howler, Chromosomal Rearrangement
2 Apr 2018
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Document Summary
In animals, mating between individuals with different ploidy almost always produces infertile offspring. Ploidy in plants often associated with increased cell volume, larger pollen grains, larger seed sets, larger plants. Tetraploid plant reproducing with a diploid plant results in a triploid plant which my be infertile. However, triploid plants may be able to breed with other triploid plants. Isolation may be initiated when genes or clusters of genes become rearranged on a chromosome. Chromosomal inversions important in hybrid sterility in closely related species drosophila pseudoobsura and d. persimilis. A model for how hybrid incompatibility, might evolve as a result of epistatic interactions among loci. Epistatic interaction: the effect of one gene is dependent on another. Lower fitness of offspring because mutations are incompatible. In hybridizations, heterogametic sex is at a disadvantage. Among hybrid offspring (children from two different species), if one sex is absent, rare or sterile, that sex is heterogametic. Live in the same areas, and ocassionally socialize.
