Biology

Evolution: A History & a Process

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Terms:

• A

species

is a group of organisms, or population, that can be interbreed & produce fertile offspring

.

Variations

are the differences found within species

. Ex: eye color and hair color. – These

can be determined by the environment, genetics or both

. –

If inherited, it is the result of a random mutation or recombination

.

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Adaptations

are inherited traits that increase a population’s chances of survival and reproduction in a particular environment

.

http://www.google.com/imgres • A

niche

is a that habitat.

habitat and the role a population plays in

– This

includes where an organism lives, what & how it eats, how offspring are raised, where predators are, and space, light, moisture, & temperature

.

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Concept 14.1 Darwin’s Theory of Evolution

• •

Darwin wrote

The Origin of Species

Describes his idea of evolution:

Selection Natural

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Theory based on observations made when traveling on the Galapagos Islands

.

Beagle

around the S. American coastline, specifically the • Based theory on current thoughts of the time 4

Influences on Darwin

• •

Evolution

means change over time environment

;

process by which populations change in response to their Georges Buffon suggested the Earth was older than originally believed (few thousand years).

Jean-Baptiste Lamarck fossils are extinct forms of living organisms found today

(1809) (in other words,

evolution occurred- the organisms today exist b/c of the fossils; they are the ancestors theorized that

).

His theory includes 3 points.

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Lamarck’s Idea of Evolution:

1. Organisms were striving toward constant improvement

.

2. Body parts that were used in life continued to develop whereas unused body parts waste away . This is the idea of

disuse

.

use and

3. Once the structure is modified by use and disuse (#2), the modification is inherited by the offspring . This is called the

inheritance of acquired characteristics

. Think of Dobermans.

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Charles Darwin studied finches and many other organisms on the Galapagos Islands

. He studied many factors which influenced his

theory of evolution by natural selection

. –

Charles Lyell’s hypothesis about geological

change

:

it occurs extremely slowly & gradually but it can influence plant and animal life over long periods of time .

–

Thomas Malthus’s (an economist) idea of supply and demand and populations

:

Darwin believed this principle could be applied to the competition of food, water & space and the ability to survive allowed for reproduction.

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http://uk.gizmodo.com/charles_darwin_l.jpg

http://www.hras.org/sw/swnov04a.jpg

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Darwin’s Theory of Evolution by Natural Selection:

Darwin wrote a book,

Selection On the Origin of Species by Means of Natural

, which explains his theory.

His Theory involves: Descent with Modification: 1. Organisms descended from ancestral species & Descendants accumulated different modifications (or adaptations) 2. Natural Selection is the mechanism for evolution

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Descent with Modification & Natural Selection

•

This means: Variations occur within a population are ALREADY there).

(they

–

These are inherited

. – Understand, all of

Darwin’s knowledge was based on observations

.

He knew nothing of genetics.

Some variations are favorable

.

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Not all of the young produced in each generation survive

. – This

may be the result of disease, lack of food, or they may be the victims of predation.

•

Individuals that DO survive and have favorable variations WILL reproduce (and pass on those favorable variations to the next generation).

THEREFORE

,

the next generation will have a larger number of offspring with the favorable variations

.

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http://www.google.com/imgres •

Darwin stated ALL organisms were related.

•

He used a tree analogy.

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• •

Evidence of Evolution

Fossils

are preserved remains, or imprints, of ancient organisms found in rocks or sediments

.

Paleontologists

fossils

.

are scientists who study

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Biodiversity

is the variety & abundance of species that makeup a biological community

.

99% of all types of organisms that ever lived are now

extinct

( no longer exists )

.

•

Geographic distribution (patterns of life) has provided evidence as well.

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•

Structures

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Homologous structures

common ancestor

.

are traits such as the human arm and whale fin that are similar in different species b/c the 2 species share a

Analogous structures

are characteristics that are similar in function but are different in structure in distantly related organisms

. – In this case,

ancestor.

the arm and fin have evolved from the forelimb of a vertebrate

– Ex:

wings of bats and wings of insects

.

http://www.citruscollege.edu/pic/46/0345l.jpg

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http://img165.imageshack.u

s/img165/7901/homologym y6.jpg

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Structures

Vestigial structures

are structures that are often small or reduced in size and no longer used but inherited and still present in organisms

.

– Ex:

pythons have leg and hip bones, humans have an appendix, manatees have leg bones.

http://futurismic.com/wp content/uploads/2008/05/four-wisdom-teeth.jpg

http://www.skullsunlimited.com/newsletter/oct2006/grap hics/manatee-skeleton-lg.jpg

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Structures

Embryology

stages of organisms

.

is the study of early developmental

–

Scientists use this, along with biochemistry, to study and understand evolution

.

http://users.rcn.com/jkimball.m

a.ultranet/BiologyPages/R/Ro manes.jpg

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Other Evidence

Developmental

:

stages of embryonic devo are similar

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Molecular

:

similar DNA sequences

http://faculty.southwest.tn.edu/rburkett/GB%20Pro10.jpg

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• • • • •

Selective breeding to produce a desired trait is

artificial selection

(think dog breeding).

Example of Natural Selection in Action:

Pesticide resistance Pesticides

are poisons (kill insects that destroy crops & homes) Some insects are resistant to pesticides (have genes); they survive & reproduce (passing on this trait).

Understand, insects do not BECOME resistant; they already had the genes for resistance!

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NS & SCA

Sickle Cell Anemia (SCA)

is a

genetic disease affecting the shape of RBCs, creating symptoms of fatigue, body pain, organ damage & sometimes death.

• There is a

high frequency of SCA in Africa and even higher frequency of heterozygous individuals

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http://www.google.com/imgres •

WHY?

Heterozygous SCA have resistance to malaria (plasmodium, organism that causes malaria, does not reproduce well w/in sickle shaped RBCs); this is called the

heterozygote advantage

.

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Antibiotic Resistance

Antibiotics

are

medications that kill (or inhibit the reproduction of) bacteria

•

Some bacteria are resistant to antibiotics (again, this is b/c they contain genes for the resistance).

•

Antibiotic resistance

allows the bacteria that survive the 1 st round of antibiotics to reproduce & pass on the gene(s) for resistance.

•

This is becoming a health concern.

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