Introduction to Evolution Biology 1-2

Introduction to Evolution Evolution-genetic change in a population over generations. Over time, genes (and the organisms themselves) change, based upon their traits and interactions with the environment. Explains both the diversity of life and similarities among species.

Evolution cont’d The theory of evolution explains a wide range of observations. Ties together observations from anatomy, embryology, molecular biology, biogeography and paleontology.

Evolution cont’d Paleontology-the study of fossils. Fossil-preserved remnant or impression of an organism that lived in the past. Shows how organisms and the environment have changed over time. Explains extinction events and the subsequent emergence of new groups.

Evolution cont’d Biogeography-the geographical distribution of species. Closely related species are found in the same geographic region. Descend from a common ancestor. Organisms living in similar conditions look alike even though they are not related. Evolve similar traits to deal with similar conditions.

Evolution cont’d Comparative anatomy-the study of the body structures in different organisms. Similarities point to common ancestry. Differences are the result of different environments.

Evolution cont’d Comparative embryology-the study of the formation, early growth and development of different organisms. Closely related organisms have many developmental stages in common.

Evolution cont’d Molecular biology-the study of the molecular basis of genes and gene expression. All organisms use DNA as their genetic material. Closely related organisms have many of the same genes and proteins. Differences in DNA and amino acid sequences are used to determine when the species split.

Populations A population is the smallest unit of evolution. Population-a group of individuals of the same species living in the same area. Species-a group of organisms that can successfully interbreed and produce fertile offspring.

Populations cont’d Evolution is the result of a population interacting with its environment. 1. Populations have the ability to reproduce exponentially. 2. Most populations are stable in size, with some seasonal fluctuations. 3. Resources are limited. More individuals are produced than survive.

Populations cont’d 4. Individuals in a population vary extensively, no two are identical. Individuals in a populations have different phenotypes. 5. Much of the variation in a population is inheritable. Mutations-a change in the base sequence of the DNA of a gene. Recombination-the combining of genes from two different parents through sexual reproduction, producing genetically different offspring.

Populations cont’d Individuals in a population have different rates of survival. Differences in phenotypes result in organisms having different chances of surviving and reproducing.