Day 5: Evolution

 Traveled on the Beagle to the Galapagos Islands  Studied 13 species of finches on the islands  Hypothesized that all originated from 1 ancestor  Explained his theory of NATURAL SELECTION  Published in On the Origin of Species  Influenced by Lyell and Wallace  Strayed from Lamarck’s “inherited traits” theory

 Survival of the Fittest  Fit = best adapted to environment for survival Mice will display gray coloring rather than white

 Adaptations  Changes in response to the environment and becomes a new species  Required to survive in the changing world  Reproductive Isolation  A species is separated and becomes two separate species

 Speciation  Creation of a new species  A species can mate and produce viable offspring  Extinction  A species ceases to exist  Can occur gradually (rainforest plants) or as a mass extinction (dinosaurs)  Biodiversity  Number of different species/organisms  Biodiversity inside a classroom is much lower than the biodiversity outside  Inside: humans, insects  Outside: humans, insects, plants, animals, etc.

 Gene Pool  Genes available for reproducing  Gene Flow  Introducing genes from one gene pool into another gene pool

 Gradualism  Punctuated Equilibrium

 Radioisotope Dating  Provides EXACT age of fossils  Uses the half-lifes of radioactive isotopes (Carbon-14)  Relative Dating  Provides APPROXIMATE age of fossils  Generally, older fossils are found in rock layers beneath younger fossils

 Analogous Structures  Vestigial Structures  Used by common ancestor but no longer necessary  Homologous Structures

 Stabilizing Selection  Selects for the central trait  Directional Selection  Selects for one extreme trait  Disruptive Selection  Selects for both extreme traits

 Variations exists within populations.  Organisms compete for limited natural resources.  Organisms produce more offspring than can survive.  Individuals with variations suitable for their habitat survive and reproduce.

 Natural selection allows for the resistant bacteria and pests to survive and reproduce offspring that are also resistant  Antibiotic resistance  The overuse of antibiotics leads to “superbugs”  Pesticide resistance  Farmers must increase the use of pesticides on crops as pests become immune/resistant to doses