Transcript Regents Biology

What is Evolution?

changes in living organisms and their
genes over time
 We KNOW based on evidence and observations

explains how modern organisms have
descended from ancient organisms
 Evolution explains BOTH

unity of life - similarities between all living things


AND
diversity of life - wide variety of different creatures
on Earth
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 UNITY:
All creatures have common
characteristics
How did we get GRSNERRT?
 DNA – codes for _______________
 Proteins are made of _______________
 Amino acids are coded for by ________
 The 3 bases are called _________
 Codons are translated using the “Universal”
code - works for ALL living things!!!!!!!
Determines ADAPTATIONS
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DIVERSITY - variation BOTH within a
population and the wide variety of living
things (remember classification – 6 Kingdoms)
 Sexual Reproduction

Two parents contributing genes
 In Meiosis – crossing over

New combinations of parents genes
 Mutation, mutation, mutation

sometimes beneficial -
determines Adaptations
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Adaptations
 Traits that help an individual survive –
may not know it’s beneficial
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Physical – color, structure
Behavioral – instincts, courtship
Biochemical/physiological – enzymes, sweating,
internal characteristics
 Born with adaptations – are NOT chosen
 GENES determine adaptations
(remember genotype determines
phenotype)
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Adaptations
NO organisms BECOME
adapted
They are either born
adapted or they are not.
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What determines survival?
 Natural Selection

traits that help individuals survive
 survive predators
 survive disease
 compete for food
 compete for territory

Adaptations
traits that help individuals reproduce
 attracting a mate
 compete for nesting sites
 successfully raise young
Survival
& Reproduction of the Fittest
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Earlier ideas on Evolution
 LaMarck

evolution by acquired
traits
 creatures developed
traits during their lifetime
 give those traits to their
offspring

example
 in reaching higher
leaves giraffes stretch
their necks & give the
acquired longer neck to
offspring

not accepted as valid
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Charles Darwin
1809-1882
 British naturalist
 Voyage of the HMS Beagle
 Stopped in the
Galapagos Islands

 Proposed a way how
evolution works

natural selection
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Voyage of the HMS Beagle
 Stopped in Galapagos Islands

500 miles off coast of Ecuador
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Darwin found: many unique species
Different shells on tortoises on different islands
Darwin asked:
Is there a relationship
between the environment
& what an animal
looks like?
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The finches cinched
it!
 different beaks are
Darwin found:
The differences
between species of
finches were
associated with the
different food they
ate.
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inherited variations
 serve as adaptations
that help
birds said:
compete
Darwin
for food
Ahaaaa!
 these birds survive &
Aeater
flock of South
Big
Large
seed
ground
Small
Small
seed
ground
eater
Finch?
Sparrow?
reproduce
finch
finch
American finches
 pass on the genes for
were stranded on the
those more fit beaks
Galapagos…
 over time nature selected
for different species with
different beaks
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Warbler
Insect eater
finch
Woodpecker?
Leaf
Tree
& bud
finch
eater
Warbler?
Darwin’s finches
 Darwin’s conclusions

variations in beaks
 differences in beaks in the original flock
 adaptations to foods available on islands

natural selection for most fit
 over many generations, the finches were
selected for specific beaks & behaviors

offspring inherit successful traits
 accumulation of winning traits:
both beaks & behaviors
separate into different species(speciation)

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Modern Natural Selection
 Overproduction – not all offspring will
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
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survive
Variation – (3 sources) differences in
adaptations (3 types)
Competition – “struggle for survival”
Environment (nature) determines which
adaptations are the “fittest”
Best adapted survive and reproduce – pass
on the “fit” genes to next generation
 The gene pool changes =
EVOLUTION – Not the individual
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3 Types of Selection
 1. Stabilizing
 2. Directional
 3. Disruptive
Niche – organism’s role or “job” in an ecosystem
ex: predator/prey, habitat, relationships
with other organisms, when it is “active”
ONLY ONE (1) species may occupy a
niche at a time - total overlap results in
“extinction” of the less fit from that ecosystem
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Stabilizing Selection
 Favors the average – decreases variation
 Extremes are selected against
 Example – spiders - too big: can be easily
seen by predators; too small: can’t
compete for web building sites
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Directional Selection
 Favors one extreme or the other
 Example – finch beaks – small or large
food; also peppered moths
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Witness to Evolution
 Peppered Moth

2 types: dark vs. light
Peppered moth
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Peppered moth
 Why did the population change?

early 1800s = pre-industrial England
 low pollution
 lichen on trees = light colored bark
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late 1800s = industrial
 factories = soot coated trees
 killed lichen = dark colored bark
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mid 1900s = pollution controls
 clean air laws
 return of lichen = light colored
bark
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Disruptive Selection
 Favors BOTH extremes at the same time
 Leads to speciation – two separate species
forming to fill different niches
 ONLY one species can occupy a given niche
in an ecosystem (increased competition leads
to narrower niches)
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Relationship between species (beaks) & food
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Other Evidence supporting evolution
 1. Fossil record

shows change over time
 2. Anatomical record

comparing body structures
 homology & vestigial structures
 embryology & development
 3. Molecular record

comparing protein & DNA
sequences
 4. Artificial selection
human caused evolution
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1. Fossil record
 Layers of rock contain fossils

new layers cover older ones
 creates a record over time

fossils show a series of organisms have
lived on Earth
 Link between birds and reptiles
 Link between land and sea animals
→ supports the idea of a common
ancestor
 Types:
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What do we know?
 Creatures have changed over time
Fossil Record
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2. Homologous structures
 Structures that come from the same origin
 homo- = same
 -logous = information
 Forelimbs of human, cats, whales, & bats

same structure
 on the inside
same development in embryo
 different functions

 on the outside
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evidence of common ancestor
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2. Anatomical strucures
 The same bones under the skin

limbs that perform different functions
are built from the same bones
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Vestigial organs
 Structures on modern animals that have
no function
remains of structures that were functional
in ancestors
 evidence of change over time
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 some snakes & whales have pelvis bones &
leg bones of walking ancestors
 eyes on blind
cave fish
 human tail bone
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Human vestigial organs
 1. a_________________
 2. t________ b_______
 3. w_______ t_________
 No longer have a function or are
necessary – may have had a function at
one time
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Comparative embryology
 Development of embryo tells an
evolutionary story

similar structures during development
all vertebrate embryos have a “gill
pouch” at one stage of development
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3. Biochemical Evidence
 Compare DNA base sequences and
chromosome banding patterns
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Biology
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Biology
3. Biochemical Evidence
 Compare amino acid sequences and 3-D
structure in proteins
number of amino acids different from human
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4. Artificial selection
 We know natural selection can change
a population?
we can recreate a similar process
 “evolution by human selection”
“descendants”
Humans create the
of the wolf

change over time
Video – Evolution
in Action – Silver
Foxes
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But don’t be fooled by these…
 Analogous structures

look similar
 on the outside
same function
 different structure & development

 on the inside
different origin
 no evolutionary relationship

Solving a similar problem with a similar solution
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Convergent evolution led to mimicry
 Why do these pairs look so similar?
Monarch male
Viceroy male
poisonous
edible
Which is the moth
vs.
the
bee?
fly vs. the bee?
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fly
bee
moth
bee
For examples of Natural Selection –
1. ID variation in the population
2. ID type of variation (adaptation)
3. ID source of variation
4. ID selecting agent (e___________)
5. individuals with advantageous
variations – survive;
6. THEN they get to reproduce
7. State which variation increases and
which variation decreases
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Artificial Selection gone bad!
 Unexpected and often dangerous
consequences of artificial
selection
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Antibiotic resistance
Bacteria
Pesticide
(and herbicide)
resistance
Insects
And
Weeds
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Insecticide resistance
 Spray the field, but…
insecticide didn’t kill all individuals
 variation
Insecticide did NOT cause the
resistance – it’s the selecting agent
 resistant survivors reproduce
 resistance is inherited
 insecticide becomes less & less
effective

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Antibiotic Resistance
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REVIEW - Evidence of Evolution
 1. Fossils
 2. Comparative Anatomy



h______________ structures
v____________
e________________
 3. Comparative Biochemistry

________ and p___________
 4. Artificial Selection
b________________
 i____________ and a_______________
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
Time Frame for Evolution
 Punctuated Equilibrium
 Periods of stability followed by periods of
rapid change (speciation) OR extinction due
to rapidly changing environment
 Adaptations must already exist in population
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Time Frame for Evolution
 Gradualism
 Slow, continual change due to a more
stable environment
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Current Theory
Recent or
now
Species
Alive
today
Extinct
Period of
stability
Change in
environment
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Common Ancestor
Oldest
Evolutionary Time Frame
 Evolution is caused by changes in the
environment
Natural – caused by nature
 Artificial – caused by humans
 Ex: pesticide and antibiotics

 Evolution is faster with organisms with
short life cycles AND lots of offspring

Examples – insects and bacteria
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Natural Selection - Summary
Adaptations – 3 types: p_________, b________,
ph________________
 Born with – determined by genes
Variation – 3 sources: s____, c_______ o____,
m________; NOT e___________
Competition – struggle for resources (food,
shelter, mates) to s_________________
“Fittest” or best adapted are selected for by
s___________ a_________ in the
e_______________
If “fit” – reproduce and pass on g______
Gene pool evolves (NOT the individual) from
selection – 3 types: s___________,
d_____________, d____________
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Summary – One more time
 1. Overproduction –
WAY too many offspring are
produced
 2. Variation –
 3 sources  Adaptations – DO NOT get to Choose
 3 types 
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Summary - Continued
 3. Selection – selecting agent
Natural – environment
 Artificial – human
 → “fittest” survive

 4. Reproduction
Pass on “fit” genes
→Over time “fit” genes increase
→ gene pool of a population changes

That is EVOLUTION!!!!!
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Study Guide
Vocab, vocab, vocab!!!!!!!
Evolution – unity and diversity – p.___
Darwin – Galapagos – p.____
Natural Selection – p. ____
Overproduction
Variation in adaptations – 3 types, 3 sources
Competition
Survival of fittest – 3 types of selection – p._
Evidence of Evolution – 4 pieces – p. ____
Time Frame for Evolution – 3 theories – p. ____
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