Connect!

• Who was Gregor Mendel?

• What contributions did Mendel make to

the science of biology?

• Give 5 facts about Charles Darwin.

B. THEORIES OF EVOLUTION• Theories of evolution attempt to explain the

diversity among species.• A major part of these theories are adaptations.

Adaptations are features (structure, function, or behavior) which make a species better suited to live and reproduce in its environment.

Darwin’s Theory

• is based on variation and natural selection• developed after he observed variations in

species. • According to Darwin, evolution occurs because

of natural selection; organisms better adapted to the environment survive and reproduce while others do not.

Chunk!

• What does the Theory of Evolution attempt to explain?

• Define adaptation, and give an example.

• What did Darwin base his theory on?

• Explain evolution in terms of variations, adaptations, and natural selection.

Ideas in Darwin’s Theory:

1. Overproduction – Within a population,

more offspirng are born than can possibly survive.

2. Competition – Because of overproduction,

there is a competition of a “struggle for

existence” between organisms for space,

food, water, or other limited resources.

Competition limits population size.

3. Variation – Members of a population

show variations or differences in traits

that make certain individuals better

adapted to survive (usually a structure,

function, or behavior)

4. Natural Selection – Since some

variations are more beneficial than others,

there is natural selection against organisms

that cannot adapt and they die off. “Survival

of the fittest” applies to the individuals who have

variations that enable them to survive.

5. Transmission of Variations – Organisms

with helpful variations are more likely to

survive and reproduce, passing on these

variations to their offspring.

6. Speciation – Over long periods of time,

variations accumulate in a population.

Eventually, the variations are so numerous

that the population is different from the original,

and represents a new species.

Chunk!

• Name the 6 parts to Darwin’s Theory.

• Give an example of each.

Darwin’s Finches

• How did all these species of finch come to exist on the tiny Galapagos Islands?

Adaptive Radiation in Galapagos Finches

• THINK…why do you think this is called “adaptive radiation”?

Learn how to read this chart…

• Name two species that do not have to compete for their food.

• Which species does the warbler finch have to compete with?

• Why doesn’t the small ground finch compete with the small tree finch?

• What species does the large ground finch have to compete with? Why?

• What do the woodpecker finch, warbler finch and cactus finch have in common?

• Although variations were a major part of Darwin’s Theory, he did NOT understand the basis for variations.

Inherited factors can make offspring different!

Some variations help in survival, and are passed on to offspring!

• Explain the science behind this cartoon.

DYGI?(Do Ya Get IT?!)

Image Sources

• Darwin - selfexpressions.net/.../CharlesDarwin.jpg• Bird adaptations - animals.howstuffworks.com/.../printable • Baby snakes - fohn.net/.../baby-corn-snakes.jpg • Two snakes, winning snake - static.flickr.com/67/188076925_0c695850e3.jpg• Color variations - aqualandpetsplus.com/Snake94.jpg • Albino - grandpacliff.com/.../albino-snake-pine-b.jpg • Snake species - www.scielo.br/.../jvatitd/v15n4/a06fig02.jpg• Photos of Darwin’s finches - www.galapagoscruises.be/darwins-finches.jpg • Adaptive radiation - media-2.web.britannica.com/eb-media/11/54911-. • Chart - www.pbs.org/.../01/6/images/l_016_02_l.gif • Darwin clip art (modified from) - evolution.berkeley.edu/.../darwin_cartoon.gif • Mendel redwood cartoon - members.pioneer.net/~mchumor/00images/1818_fo. • Mendel clipart - www.larrygonick.com/images/sch/mendel.gif