Populations & Gene Pools and Genetic Variation

Vocab. To Know -Microevolution: change within species; can occur over dozens or hundreds of years -Macroevolution: change that results in the origin of new species; involves much longer periods of time than microevolution -Population Genetics: the field of biology that studies microevolution -Gene Pool: consists of all the genes of a local population of organisms -Polymorphic: when two or more alleles of a gene for a trait are present in a gene pool

Populations and Gene Pools Evolution: a change in populations though time Two time scales: – Microevolution – Macroevolution

Microevolution It’s the change in the genetic composition of populations – This study is called population genetics

Gene Pools A central concept in population genetics is the gene pool Example: if a population consists of white flowers and purple flowers, then the frequencies of alleles in their gene pool could be 40% white and 60% purple Remember a gene pool refers to one population

Genetic Variation Among a species there are genetic difference in some traits – Ex. eye color and blood type Genetic variation has also been found in the amino-acid sequences of proteins and the nucleotide sequence of DNA

When Does Genetic Variation Occur? Genetic variation can occur if a trait is polymorphic The recombination of alleles during meiosis, crossing over, and independent assortment