BIOL 1108 Lecture Notes - Lecture 19: Species Complex, Great Dane, Genetic Drift
Document Summary
Species concepts: the world species has two overlapping but distinct meanings. The older meaning- a species is a taxonomic category, like genus or family. Species attempts to describe the biological cohesiveness and relatedness of the members of that group: various specific goals of species definitions are. To enable us to classify organisms systematically. That a species corresponds to discrete groups of similar, closely related organisms. To help us understand how these discrete clusters of organisms arise in nature. To apply to the largest possible variety of organisms. However, no single species definition satisfies all these goals: species is the smallest independently evolving unit- the essence of speciation is the lack of gene flow. Independent evolution occurs when mutation, selection, and genetic drift operate independently in different groups of organisms. Therefore these species will follow independent trajectories. The type specimen may not truly represent the whole species. Morphological variation exists within species (chiwuawua and great dane)
