BIOLOGY 1M03 Lecture Notes - Lecture 9: Species Problem, Genetic Recombination, Genetic Drift
6 May 2019
School
Department
Course
Professor
Document Summary
Sexual species need to make males that do not reproduce themselves: have to find someone to have sex with, especially hard in sparsely distributed species, may disrupt advantageous combinations of alleles. How are species defined and identified: a species is defined as an evolutionarily independent population or group of populations, gene flow homogenizes genetic variation among populations, so evolutionary independence starts with a reduction or cessation of gene flow. If gene flow between populations stops, natural selection, genetic drift, and mutation begin to act on populations, independently: allele frequencies and other characteristics of these independent populations diverge, and over time the populations can become distinct species. Species are distinguished by differences in size, shape or other morphological features: based on the idea that distinguishing features are most likely to arise if evolutionary lineages do not have gene flow. Features used to distinguish species are rather subjective.
