EAS230 Lecture Notes - Lecture 28: Speciation, Mutation, Genetic Variation

• School: University of Alberta
• Department: Earth and Atmospheric Sciences
• Course: EAS230
• Professor: Lindsey Leighton

Document Summary

Within a species, individuals vary in their traits - shape, size, etc. These traits (as a whole, the phenotype) are largely an expression of the genes of the organism (the genotype). Thus some traits are heritable - can be passed down onto descendants. Selection can act only on heritable traits. Differential mortality - individuals with particular traits may have greater survivorship - they are selected. Surviving individuals have greater tness - they will have more offspring and pass on their genes. An agency of selection - predation, competition, physical environment, etc. causes differential mortality. Thus the species adapts to its environment. Selection can work only on existing genetic variation. Although selection may be directed,mutations etc. are random, and develop independently of selection. Mutations and recombinations are often lethal or neutral. Populations of a species become suf ciently distinct that they can no longer reproduce viable offspring. Two primary mechanisms: allopatric speciation - geographic separation.