BIOLOGY 1M03 Lecture Notes - Lecture 8: Species, Reproductive Isolation, Disruptive Selection
19 Mar 2013
School
Department
Course
Professor
Document Summary
Last time: biological species concept prezygotic barriers, post zygotic brriers: morphological species concept phylogenetic species concept allopatric speciation sympatric speciation via disruptive selection in the soapberry bug. Comes in two ways: spontaneous duplication, or autopolyploidisation and through interaction with another species, or allopolyploidisation. Tetraploids are the offspring of a parent that produced diploid gametes and then self fertilized. Tetraploid (4n) individuals can breed with other tetraploids but not with diploids. Tetraploid species are generated and these can undergo polyploidisation to generate octoploid species. can occur due to hybridisation, as pairing of homologous chromosomes require homology. The gametes of a triploid individual rarely contain the same number of each type of chromosome. When gametes combine, offspring almost always have an uneven and dysfunctional number of chromosomes. Genome duplication is an important phenomenon, humans came from a polyploid organism as well. By creating redundancy, we have the potential for crazy things to happen.
