Download Evolution

Biology
Evolution: A History &
a Process
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.
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• A niche is a habitat and the role a population plays in
that habitat.
– 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: Natural
Selection
• Theory based on observations made
when traveling on the Beagle around the
S. American coastline, specifically the
Galapagos Islands.
• Based theory on current thoughts of the
time
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Influences on Darwin
Evolution means change over time; process by
which populations change in response to their
environment
• Georges Buffon suggested the Earth was older
than originally believed (few thousand years).
• Jean-Baptiste Lamarck (1809) theorized that
fossils are extinct forms of living organisms
found today (in other words, evolution
occurred- the organisms today exist b/c of the
fossils; they are the ancestors). 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 use and
disuse.
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, On the Origin of
Species by Means of Natural
Selection, 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 (they
are ALREADY there).
– 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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• 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 are scientists who study
fossils.
• 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
• Homologous structures are
traits such as the human
arm and whale fin that are
similar in different species
b/c the 2 species share a
common ancestor.
– In this case, the arm and fin
have evolved from the
forelimb of a vertebrate
ancestor.
• Analogous structures are
characteristics that are
similar in function but are
different in structure in
distantly related organisms.
– Ex: wings of bats and wings
of insects.
http://www.citruscollege.edu/pic/46/0345l.jpg
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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://www.skullsunlimited.com/newsletter/oct2006/grap
hics/manatee-skeleton-lg.jpg
http://futurismic.com/wpcontent/uploads/2008/05/four-wisdom-teeth.jpg
http://www.google.com/imgres
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Structures
• Embryology is
the study of early
developmental
stages of
organisms.
– 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
• 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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WHY?
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• Heterozygous SCA
have resistance to
malaria
(plasmodium,
organism that
causes malaria,
does not reproduce
well w/in sickleshaped 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 1st round of
antibiotics to reproduce & pass on the
gene(s) for resistance.
• This is becoming a health concern.
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