ANT203H5 Lecture Notes - Lecture 18: Genetic Drift, Cladogenesis, Macroevolution
Document Summary
During this semester, we will focus on evolutionary change over long time periods: The word macroevolution was coined by t. dobzhansky, referring to evolution at levels higher than the population (species or higher): change of species through time. Macroevolution refers to evolutionary change over long periods of time. We will use here the biological species concept, which states that: Note that for different populations to belong to the same species, they must: be capable of interbreeding under natural conditions, and, be capable of producing fertile offspring. Problem: this concept of species can be applied (with some difficulties) to organisms with sexual reproduction but not to organisms with asexual reproduction. Example: horse and donkey: if they produce a mule; they cannot form viable offspring, by definition, donkey and horses cannot be classified as the same species. Macroevolution deals with evolution of species over time.
