Evolution

• Biology Honors

• By Gail Mayes

• Foothill High School

Biology Honors Objectives

The Theory of Evolution

Click on Tortoise for Intro

Evolution

• A. The process by which modern organisms have descended from ancient organisms.

• 1. Charles Darwin (1809-1882) sailed on the HMS Beagle to the Galapagos Islands.

• 2. This voyage sparked a curiosity about how organisms came to be different and survive on each of the islands.

Darwin’s Journey

Darwin’s Studies

• A. Studied to find out why species change over time. Malthus stated that human populations tend to

grow faster than Earth’s food supply. Individuals struggle to compete in changing

environments.• Compete for food and space• Escape from predators• Find mates• Locate shelter

Natural Selection

Evidence for Evolution

• A. “Adaptation”=Species survived because they were better able to adapt to their environment.

• Mole rats that live underground their whole lives are blind. They have adapted to their environment.

Can you find the katydid?

Lizard AdaptationsVideo

• Lizards have adapted to their environment over time. Click on the lizard to find out how:

Mimicry- An adaptation that enables one species to resemble another.

Camouflage- Species blend with their environment. They can’t be easily seen by predators.

• CAMOUFLAGE

Find out more about snakes:

• Snakes

Click on the octopus to find out how long they have survived through

evolution:

Vestigial structures- A body structure in a present-day organism that no longer serves its original purpose, but was probably useful to an ancestor. (blind fish in the dark deep sea).

Population Genetics and Evolution

A. How can a population’s genes change over time?

1. Gene pool- All of the alleles of the population’s genes together on one pool.

2. Allelic frequency- The percentage of any specific allele in the gene pool.

3. Genetic equilibrium- Alleles remain over generations.

a. If a population is in equilibrium it is not evolving.

b. Mutations results in favorable changes in a species.

Hardy Weinberg Video

Evolution of Species

• A. Speciation- The evolution of new species is called speciation.– 1. Occurs when members of a similar

populations no longer interbreed to produce fertile offspring within their natural environment.

Speciation

• Convergent Evolution- Evolution in which distantly related organisms evolve similar traits.

• Different species can look alike:

Evolution Quiz Link

• http://www.unitedstreaming.com/studentCenter/index.cfm?cdCode=8518-D92B

Conclusion

• Evolution is a theory. There is evidence that evolution has occurred. Speciation occurs at a much quicker time scale and is evident in bacterial mutations.