BIO 122 Lecture Notes - Lecture 10: Inbreeding Depression, Polyploid, Zygosity
15 Apr 2019
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Document Summary
Polyploidy occurs when an error in meiosis or mitosis doubles the chromosome number ] Autopolyploid individuals produced when a mutation results in a doubling of the chromosome number. Chromosomes all come from the same species . Allopolyploid individuals are created when parents that belong to different species mate. Produces offspring with two different sets of chromosomes. Tetraploid maidenhair ferns: parents produced diploid gametes and self fertilized. Can breed with tetraploids but not diploids. If they breed w diploids = sterile offspring. New tetraploid species may be created when two diploid species hybridize. When diploid gametes fuse during self-fertilization, a tetraploid individual results. Allopolyploid offspring have two copies each of two sets of chromosomes. Speciation by polyploidy is important in plants bc many diploid plant species have closely related polyploid species. Polyploids have higher levels of heterozygosity than do diploids. Polyploids can tolerate higher levels of self-fertilization because they are not as affected by inbreeding depression as are diploids.
