Charles Darwin: Father of Evolution

EVOLUTION Charles Darwin 1809-1882 Evolution Very important Biologist!!! (Father of Evolution) Responsible for the Theory of Natural Selection Wrote book: The Origin of Species Evolution is supported by fossil evidence happens when species change over a long period of time in response to their environment only occurs when the gene pool changes is influenced by the mechanism of Natural Selection

4 Principles for the Theory of Natural Selection 1. Organisms produce more offspring than can survive 2. In any population, individuals have variations of traits 3. Individuals with certain favorable traits survive in the envrironment and pass those traits on. 4. Over time, offspring with certain favorable traits (variations) will make up most of the population and ultimately look different from their ancestors.

Review of Terms Artificial Selection- breeding of organisms with specific favorable traits to produce offspring with those traits. (ex: show dogs and race horses) Species- a group of interbreeding organisms that can produce healthy, fertile offspring Population- a group of a species living together in one location

Adaptations- inherited characteristic that aids an organism's chance of survival in its environment. 3 types: Structural adaptation, Mimicry, Camouflage Physiological adaptations – can occur in only some individuals and occurs more quickly. (resistant bacteria, roaches, weeds)

Mechanisms of Evolution Populations, NOT individuals evolve Natural Selection acts on the phenotypes in a population Evolution occurs as a population’s genes and the allelic frequency changes. gene pool- all the genes in the population allelic frequency- percentage of each allele

Populations in genetic equilibrium are not evolving Populations in genetic equilibrium are not evolving. Any factor that affects the genes in the gene pool can change the allelic frequency and cause evolution.

Mechanisms for Genetic Change: 1. Mutation- a change in hereditary information caused by radiation, chemicals, or simply by chance 2. Gene flow- change in the gene pool due to migration

Mechanisms for Genetic Change: 3. Genetic Drift- alteration of allelic frequency by chance 4. Natural Selection- changes in allelic frequencies due to inherited variations

Mutation, Gene Flow and Genetic Drift have a greater effect if the population is small. If the population is large, these have minimal effect.

Three Types of Evolution Convergent Divergent Adaptive

Convergent Evolution Occurs when distantly related species look alike because they occupy similar environments in different parts of the world.

Divergent Evolution Occurs when closely related species have evolved to look different due to adaptations to a changing environment.

Divergent Evolution

Adaptive Radiation When an ancient species evolves into many different species in order to fit into several diverse habitats.