Evolution and Classification Spring 2018

Evolution of Populations Evolution is a change in the frequency of alleles in a population over time. 3 sources of genetic variation Mutations- Change in genetic material of a cell Genetic Recombination- During sexual reproduction, each chromosome in a pair moves independently during meiosis Lateral Gene Transfer- passing of genes from one organism to another (not including offspring)

Hardy-Weinberg Principle Allele frequencies will remain constant, or have genetic equilibrium Unless factors cause those frequencies to change. The Hardy-Weinberg Principle holds under these conditions: Random Mating Very Large Population No movement in or out of a population No mutations No natural selection

The Fossil Record The Fossil Record- Collections of fossils Organized to provide evidence about the history of life on Earth Includes how organisms have changed over time

Classification In the 1730’s, Carlos Linnaeus, a Swedish botanist, developed a two word naming system called binomial nomenclature- First part of the name is the genus Second part of the name is referring to the species

Classification Linnaeus also developed a classification system It included seven hierarchical taxa: Kingdom Phylum Class Order Family Genus Species

Classification Sometimes classification keys are used to identify organisms by traits that are visible However, scientists today now look at how closely members of groups are related. Phylogeny- the study of how living and extinct organisms are related to one another. Clade- A group of species that includes a single common ancestor and all descendants of that ancestor.

Classification Cladogram- Derived character- descendants Cladogram- A diagram that links groups of organisms by showing evolutionary lines Aka lineages Branches from common ancestors Derived character- A trait that arose in the most recent common ancestor of a particular lineage and passed to its descendants. Splitting events Ancestral lineage