Changes in a population of organisms over time. Evolution

Charles Darwin A. Born 1809 B. Took a trip around the world on the HMS Beagle – Acted as the ship’s naturalist C. Came up with the Theory of Evolution D. He traveled to the Galapagos Islands 1. Where Darwin did his most persuasive studies 2. Discovered an example of: speciation : members of a species stop breeding with one another until two separate species are formed.

How It Happens Geographic Isolation: Two populations within a species are separated by some natural barrier.

Temporal Isolation: populations within a species mate at different times. Behavioral Isolation: Members of one sex no longer find certain varieties of the other sex suitable for mating. http://www.youtube.com/watch?v=A-05Z- GsGfI

Introduction of Adverse Environmental Conditions Could be a predator, new landscape, climate or anything else that changes the requirements for survival. Disruptive Selection: Something is causing the death of part of the mean of the population. Can cause speciation

Directional Selection: One characteristic is being reduced and another type is more successful. Results in a population that would be more like those with the favorable trait. Stabilizing Selection: The outliers have trouble surviving Results in a population that has DNA (traits) like the average of past generation

Artificial Selection: Man chooses which specimens will pass their genes on to the next generation.

More Evidence for Evolution Homologous Structures: Structures that arise from the same tissue but have different functions.

Analogous Structures: Structures that arise from different tissues but have the same function.

Vestigial Structures: The reduced form of a structure that is no longer providing a reproductive advantage.

Dating Techniques DNA Molecular Clock: A technique that uses fossils and rates of molecular change to deduce the time in geologic history when two species diverged. Other Absolute and Relative Dating Methods…

Evolution: An Overview “Survival of the Fittest” Fitness is a NUMBER = How many kids did you have that survived to reproductive maturity. The TRAITS that survive are the ones that were passed on to the next generation. If a trait helps you to have more kids  more individuals in the next generation have the DNA for that trait