Chapter 16.4 (Pgs. 465-473): Evidence of Evolution

Biogeography Is the study of where organisms live, now and historically Patterns in distribution of living and fossil species can show evolutionary patterns Two patterns: Closely related but different species live in slightly different habitats Distantly related but similar species live in similar habitats around the world

Age of the Earth Was proposed by geologists to be much older than 6000 yrs old In 1860s, radioactivity was discovered Used to determine age of rocks and fossils Is 4.5 billion years old This provided enough time for evolutionary change to occur

Fossils Show the record of extinct species Show how intermediate forms connect extinct and living species

Anatomy and Physiology

Anatomy and Physiology Can show relationships to a common ancestor Homologous Structures Are similar structures Can be used for different functions Come from a common ancestor Analogous Structures Are used for the same function Are found in unrelated organisms

Homologous structures show how closely related organisms are

Anatomy and Physiology Vestigial Structures Are inherited from ancestors Have lost most of their function Embryology Similar patterns of development show that organisms are related to a common ancestor

Genetics and Molecular Biology Common Genetic Code DNA is universal among all organisms, which indicates a common ancestor Homologous Molecules Enzymes, hormones, and other important molecules are similar between organisms, which indicates a common ancestor

Testing Natural Selection Has been shown in Galapagos finches They gave beaks with different sizes and shapes Changes in the food supply creates selection pressure on beak size Only larger seeds are available during a drought, and only birds with larger beaks can eat them Birds with smaller beaks starve during a drought