History of Evolution

EQ: How do we know when organisms have evolved?

History of Evolution

Important Scientists:• Jean-Baptiste Lamarck• Thomas Malthus• Alfred Russel Wallace• Charles Darwin

Jean-Baptiste Lamarck(1744-1829)

• Zoologist, forerunner of evolution

INCORRECT theories:1. Simple life forms continually come into

existence from dead matter.2. Life forms continually become more

complex or more “perfect” as they transform into new species.

Examples:

• Lamarck thought that giraffes evolved their long necks by each generation stretching further to get leaves in trees and that this change in body shape was then inherited.  Likewise, he believed that wading birds, such as herons and egrets, evolved their long legs by stretching them to remain dry. 

• Lamarck also believed that creatures could develop new organs or change the structure and function of old ones as a result of their use or disuse.

CORRECT Theory:3. Change in species is linked to an organism’s

environment.

Thomas Malthus(1766-1834)

• Realized that producing more offspring than can survive establishes competition among a species.

• Populations grow as much as the environment allows.

• Influenced Darwin & Wallace’s theory of natural selection and Survival of the fittest.

Alfred Russel Wallace(1823-1913)

• Came to same conclusions as Darwin during same time frame.

• Co-published theory of natural selection/evolution with Darwin.

Who Was Charles Darwin(1809-1882)

Label your paper :1. 2. 3. 4. 5. Write 5 facts from the short video

clip on Darwin…

http://www.pbs.org/wgbh/evolution/library/11/2/e_s_2.html

• Darwin made observations & collected data during his Voyage of the Beagle through South America and across the Pacific Ocean.

• Spent much time on Galapagos Islands collecting information about species that inhabitated each island.

• 1859: Published the “Origin of Species”

Darwin’s Observations on Galapagos Islands:• Species resembled those of the nearby islands but

had evolved differences• He called this descent with modification after

separating from a common ancestor

Darwin’s Ideas:• Natural Selection states that a struggle for life

exists causing individuals with favorable characteristics to survive while the other would become extinct (“Survival of the Fittest”)

Newsworthy Events• 1925: John Scopes Trial

– Teacher violates anti-evolution law in Tennessee by teaching evolution to students

• 2005: “Intelligent Design” mandatory to be taught in public schools

• Darwin explained the theory of evolution by Natural Selection.

• “Survival of the Fittest” means organisms that adapt to their environment survive, while organisms that do not adapt disappear.

• Natural selection leads to adaptations within a population.

Types of Evolution• Microevolution- the change of allele frequencies

within a population

• Macroevolution- large-scale evolutionary changes : 5 patternsl. Mass extinctions2. Adaptive Radiation3. Convergent Evolution4. Coevolution5. Punctuated Equilibrium (and gradualism)

Mass extinctions

• More than 99% of all species that ever lived are now extinct

• Mass extinctions wiped out food webs & ecosystems

• Example: Dinosaurs- asteroid but could have been many factors (volcanoes & continents drifting)

Adaptive Radiation• A species or group of species evolves into

many new species

Convergent Evolution

bird

fish

mammal

• Unrelated organisms come to resemble one another

Coevolution• 2 species evolve in response to changes in each

other over time

Central American Swollen-Thorn Acacias

Acacia ants and acacia trees Acacias are small, Central American trees in the Leguminosae. They have large, hollow thorns. The acacia ants live in the thorns. On the tips of its leaflets, the plant makes a substance used by the ants as food. The ants defend the tree from herbivores by attacking/stinging any animal that even accidentally brushes up against the plant. The ants also prune off seedlings of any other plants that sprout under “their” tree

Acacia ants and tree video

• http://video.nationalgeographic.com/video/player/animals/bugs-animals/ants-and-termites/ant_acaciatree.html

• click here

Punctuated Equilibrium• Rapid evolution after long periods of equilibrium

(balance)• Why? Migration, mass extinctions, isolation

How does it appear that GRADUALISM is different?

Label Paper:( Page 42)

1. Genetic Variationa.

b.

2. Overproduction of Offspring a.

b.

3. Struggle for Existence a.

b.

4. Differential Survival & Reproduction a.

b.

Natural Selection Video

http://www.pbs.org/wgbh/evolution/library/11/2/e_s_4.html

6 min 39 sec