Theory of Evolution

Charles Darwin Sailed on HMS Beagle The voyage lasted 5 years Gathered evidence about species and how they change

Evidence South America: Darwin found fossils of extinct armadillos that closely resembled the armadillos living in the area.

A collection of Glyptodons -- giant armadillo-like fossils

Evidence Galapagos Island and coast of South America had animals and plants that were similar to one another but also different in ways. Darwin surmised that S.A. animals migrated and then changed (over time).

Descent with Modification

Evolution: Descent with modification from a common ancestor. There must be a change in gene frequency OVER TIME. Time is KEY

Evolution??? Beetles on a diet Imagine a year or two of drought in which there are few plants that these beetles can eat. All the beetles have the same chances of survival and reproduction, but because of food restrictions, the beetles in the population are a little smaller than the preceding generation of beetles.

Evolution??? Beetles of a different color Most of the beetles in the population (say 90%) have the genes for bright green coloration and a few of them (10%) have a gene that makes them more brown. Some number of generations later, things have changed: brown beetles are more common than they used to be and make up 70% of the population.

Population: All the individuals of a species that live together in one place at one time. Ex: Alligators in the Everglades 1.jpg&imgrefurl= 4B4=&h=542&w=405&sz=73&hl=en&start=39&zoom=1&tbnid=RKtrpdVswhg5eM:&tbnh=169&tbnw=14 0&ei=NLSgTffMNKHE0QHqkfn_BA&prev=/search%3Fq%3Deverglade%2Balligator%26um%3D1%26 hl%3Den%26rlz%3D1G1GGLQ_ENUS398%26biw%3D1238%26bih%3D679%26tbm%3Disch0%2C96 3&um=1&itbs=1&iact=hc&vpx=885&vpy=253&dur=683&hovh=260&hovw=194&tx=129&ty=163&oei=L bSgTb-ZOYW_0QHVzcSWBQ&page=3&ndsp=15&ved=1t:429,r:3,s:39&biw=1238&bih=679

Process by which organisms change in response to their environment. Natural Selection:

Natural Selection cont’d Individuals that have physical or behavioral traits that are better suited their environment are more likely to survive and reproduce than those that do not have such traits.

Adaptation: The changing of a species that results in its being better suited to its environment.

List some examples of adaptations

On the Origin of Species Darwin did not publish his ideas on evolution until He published On the Origin of Species by Means of Natural Selection

Darwin’s ideas have been updated Genes are responsible for inherited traits.

Darwin’s ideas have been updated Isolation leads to species formation. Isolation: the condition in which two populations of the same species cannot breed with one another. Populations of the same species living in different locations tend to evolve differently.

Aberts SquirrelKaibab Squirrel

Species: Group of organisms that are genetically similar and can produce fertile offspring.

Darwin’s ideas have been updated Extinction leads to species replacement. Climate changes & natural disasters lead to extinction. Extinct: species disappears permanently. Species that are better suited to the new conditions replace the old species.

The Theory of Evolution is Supported by Four Points 1. Variation exists within the genes of every population or species. Some human examples: __________________ __________________ ______

The Theory of Evolution is Supported by Four Points 2. In a particular environment, some individuals of a population or species better suited to survive (as a result of variation) and have more offspring.

The Theory of Evolution is Supported by Four Points 3. Over time, the traits that make certain individuals of a population able to survive and reproduce tend to spread in that population.

The Theory of Evolution is Supported by Four Points 4. There is clear proof from fossils and many other sources that living species evolved from organisms that are extinct.

QUESTIONS?