Evolution descent with modification Descent the transmission of characteristics by inheritance o Characteristics change from one generation to the next Modification changing Phylogeny family tree of modification changing species Example 1 beetles on a diet vs normal beetles Environmental influences Example 2 brown beetles vs green beetles Evolution Gene a unit of heredity that is transferred from a parent to an Informal definition offspring and is held to determined some characteristic of the offspring Formal definition phenotypic effect the unit of heredity a region of DNA with a particular o Phenotype the observable physical or biochemical characteristics of an organism as determined by both genetic makeup and environmental influences Evolution a change in gene frequency overtime Mechanisms of Change 1 Mutation 2 Migration a A random odd occurrence of genetic mutation b Ex two green beetles have a brown beetle offspring a The combining of two different types of genes b Ex brown beetles joined a population of all green beetles so brown became part of the genetic code through reproduction 3 Genetic Drift changes 4 Natural Selection generations a One type of gene becomes more prevalent than another so the offspring b Ex the number of brown beetles was equal to the number of green beetles but after someone stepped on the green beetles the next generation would be more brown than green a Only genes that lead a species to better survival are passed down to further b Ex green beetles are seen more quickly by predators than brown beetles so after a while the brown beetles become more prolific while the green beetles dwindle to extinction