BISC 102 Lecture Notes - Lecture 13: Living Fossil, Coevolution, Phylogenetics
21 Apr 2016
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Autopolyploidy: self chromosomes all from same species. New species can arise by unreduced gametes or mitosis. Many plant species have polyploidy in their history. Chromosome sets of 2 different species combined: An allopolyploid is a species with multiple sets of chromosomes derived from different species. Bread wheat (triticum aestivum) is an allohexaploid (6n), made up of chromosomes from 3 different parent species of wild grasses; On average, rates of speciation in many organism groups is greater than the rate of extinction, allowing biodiversity to increase over time. Adaptive radiation: rapid diversification of a phyletic line into several new lineages. Ecological opportunity: new habitat/resources, or reduced competition. Radiations of mammals and birds: fill niches vacated by dinosaurs. Adaptive radiation on islands is another example of ecological opportunity. Common on islands and archipelagos (island groups) because they provide many opportunities for reproductive isolation and speciation. The islands provided new habitat, including new resources (example: food sources).
