Evolution NotesBiology

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 extinctions

2. Adaptive Radiation

3. Convergent Evolution

4. Coevolution

5. 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• Unrelated organisms come to resemble one another

bird

fish

mammal

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

Punctuated Equilibrium• Rapid evolution after long periods of equilibrium

(balance)

• Why? Migration, mass extinctions, isolation

How does it appear that GRADUALISM is different?

Acacia ants and tree video

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

• click here

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

Evidence for EvolutionThe fossil record gave

us:

1.1. Descent with Descent with modificationmodification

2. Homologous 2. Homologous StructuresStructures

3. Transitional 3. Transitional FossilsFossils

Descent with Modification• All living organisms are related to one another-

common descent

• Speciation-new species can arise

Homologous Structures

• structures in different species that may perform different functions but are similar in structure because of their common ancestry

• Examples: bat wing,

whale flipper, cat claw,

Human hand

Vestigial Organs

– structures of no apparent function to an organism; leftover from ancestry

– Examples: snakes have leg & pelvis bones; whale rear limbs

http://www.pbs.org/wgbh/evolution/library/03/4/l_034_05.html

5 min, 9 sec

Whale Evolution

Video

Label Paper Left Page

# 1-5

Examples of Evolution• Antibiotic Resistance: natural

selection has occurred within populations of bacteria

• Mutations cause bacteria to change their structure…antibiotics cannot bind to cell surface

• Acquiring new genes…bacteria have new enzymes that can deactivate or destroy antibiotic

• Ex:Tuberculosis bacteria

Examples of Evolution• Darwin’s Finches: Natural selection has

occurred in beak size

Examples of Evolution• Speciation: begins as a population adapts to its

environment.

Biological ResistanceAntibiotic Resistance• Tremendous quantities of antibiotics are released and used

in the environment daily.• Bacteria become resistant through:

– Adaptations (natural selection)– Acquiring mutated genes that make them resistant.

**Evolution through natural selection can occur remarkably quickly when natural selection pressures are very strong and reproduction rates are very fast (some bacteria reproduce in 10-15 minutes!)

What does this mean for us?• Antibiotics will be ineffective against bacterial diseases

or infections.• The drug will not longer bind to the target therefore not

killing off harmful bacteria.

Pesticide Resistance• The natural occurrence in which the ability of

individuals in a population to survive a plant protection product treatment that would normally give effective control is passed on to future generations

• Insects are among most adaptable organisms on Earth

• For the past 400 million years they have managed to survive by adjusting to changes in their environment, so it should come as no surprise that they can also adapt to chemical pesticides.

• Example: Colorado potato beetles on Long Island, N.Y.

Why does Evolution Matter Now?

View the video and take notes on your notesheet.

http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html

Primate & Human Evolution

• The fossil record has allowed scientists to study how humans have changed over time

• Monkeys, apes and humans are classified as primates

• Primates are mammals that have eyes that face forward, a well-developed cerebrum, and opposable thumbs that can be used for grasping

• About 45 million years ago, primates divided into 2 main groups

Common Ancestors

Primates

New world monkeys Second group of primates

Old world monkeys apes Human ancestor

New World VS Old World Monkeys

• New world monkeys– Have a tail that can grasp like a hand

and nostrils that open upward• Howler and spider monkeys

• Old world monkeys– Cannot grasp with tails (if they have

one) and nostrils that open downward• baboons

Evolution

• Apes– Do not have tails– Gorillas and chimpanzees

• Human ancestors– Appeared around 3 million years ago– Walked upright– Shorter than modern humans– Several groups evolved, but all became

extinct

Early Humana-Like Forms

• Early human-like forms– Australopithecus

• Several different genii appeared

– Ramapithecu – Homo habilis

• First to use tools, “handy man”

– Homo erectus– Homo erectus

• First to walk completely upright

Human Ancestors

• Two groups of homo sapiens have lived on Earth

• Only one form is alive today• Homo sapiens means “thinking man”• Homo sapiens neandertalensis is better

known as Neanderthal Man– Shorter than modern man– Thicker bones than modern man– Became extinct

• The second Homo sapiens evolved into modern man

Current Event• Homo floresiensis (The

hobbit)– This much debated about

hominid is a mini-human like organism that is believed to have lived with humans at one point.

– Believed to be present about 18,000 years ago.

– Only 40 inches tall!!