Download Patterns of Evolution

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 Naturalist
 Credited
for the
concept of Evolution
 “Father of Evolution”
 Darwin
is invited on an epic journey
 1831: HMS Beagle sets sail from England to
survey the coast of South America
 5 year voyage
 His job was to collect biological and
geological specimens during the ship’s travel.
 He noticed many plants & animals were well
suited to their environment.

1835: The Beagle stops
at the Galápagos Islands,
recently formed volcanic
islands
• Located 500 miles off the
coast of Ecuador
Each island has a very
unique climate
 The animals on the
islands lived nowhere
else in the world, but,
looked like species from
South America, but these
two places have different
environments

 Darwin
found many
different birds on the
Islands, thinking each
one was a different
type of bird
 He was amazed to
learn that all 14
species were finches
 THERE WAS ONLY 1
SPECIES ON THE
MAINLAND
 Darwin
wondered - If the finches came
from the mainland, why were they so
different now?
 He suspected that populations from the
mainland changed after reaching the
islands
 Hypothesis: New species could appear
through small changes in ancestral
species – but how does this process
work?
 Turned to pigeon breeders
 Previously
referred to as selective
breeding
 He learned that breeders could produce
certain traits through directed breeding
 Darwin thought that if humans could
change a species through artificial
selection, then perhaps the same process
could happen in nature
 Theory
developed by Darwin
 Explanation of how evolution works, NOT
a synonym
 Based on 4 principles that explain how
traits change over time:
• Variations
• Inheritance
• Overproduction
• Reproductive Advantage
 Individuals
in a
population show
differences – or
variations
 Variations
are
inherited,
meaning they
are passed
down from
parent to
offspring
 Organisms
have
more offspring than
can survive on
available resources
• This creates
competition, and a
struggle to survive
MMMMM
Bunny
 Variations
that increase reproductive
success will have a greater chance of
being passed on than those that do not
increase reproductive success –
SURVIVAL OF THE FITTEST!
• Faster predator – more food, survives longer
• Camouflaged prey – better protection, survives
longer
 Adaptations
are central to this principal

Given
enough
time,
natural
selection
modifies a
population
enough,
and
through
evolution
produces a
new
species
Natural selection is ALWAYS HAPPENING!
 He
concluded that
the different beaks of
each finch were
inherited variations
(changes)
 These different beaks
helped the birds
compete for food,
survive, and
reproduce
 Darwin
was extremely nervous about
publishing his findings, so he continued to
collect evidence for his theories for many
years
 In 1859, after 23 years, he published On the
Origin of Species by Means of Natural
Selection
 He used the term “Evolution” on the last
page only
 This term is what biologists use today to
define the changes in groups of organisms
through time
 The
changes
that occur over
time in the
hereditary
features of a
species.
Remember, the theory
of evolution states that
we all descended from
a common ancestor
 How do we know
evolution has
happened on our
planet?

• Fossils
• Anatomy
 Homologous, Analogous,
Vestigial
• Embryology
• Adaptations
 Fossil: remains
of
once-living things
from the past
 Comparing fossils
from older & younger
rock layers
documents the fact
that evolution has
occurred; it is a
detailed record of
evolution.
 Fossils
provide a
record of species that
lived long ago
 They show that ancient
species share
similarities with
species that live on
Earth now
 Some show that some
species have changed,
and that some species
have not changed at all
HOMOLOGOUS STRUCTURE



Similar structure
Different forms and
functions
Inherited from a common
ancestor
ANALOGOUS STRUCTURE



Different in structure and
form
Similar in function
NOT inherited from a
common ancestor
 Type
of homologous
structure
 Shared structure that
has reduced function
or no function in
some organisms
 Evolution suggests
that over time these
structures will be lost
 Human
appendix
 Wisdom teeth
 Tailbone (coccyx)
 If
you look at
different
animals during
stages of
embryonic
development
you can see
common traits.
 This shows a
common
ancestry
 Adaptation: a
trait shaped by natural
selection, increases an organism’s
reproductive success
 Fitness: how
much a trait contributes to
the next generation
• How necessary a trait is to survival will
determine if it is passed on
 There
are many kinds
of adaptations, they
can be physical or
behavioral
 Some adaptations are
the consequences of
other evolved
characteristics,
however, these
adaptations will not
increase reproductive
success
 The
better adapted
an organism is, the
higher its chances of
survival are
 Adaptations are at the
heart of Darwin’s
theory!
 Adaptations
that allow
organisms to blend in
with their surroundings
 Camouflage varies by
species, but their
environment is often
the most important
factor in how they
appear
 Become almost
invisible to predators
and prey
 One
species evolving
to resemble another
species
White-tailed Deer Fake Death
When a predator approaches,
their heart rate is
programmed to drop so low
that they enter a state of tonic
immobility. The result is that
the look dead, which, coupled
with its involuntary peeing
and pooping that
accompanies the heart rate
drop, will look pretty
unappealing, even to a hungry
animal.
Bloody Hippo Sweat
It contains zero blood
and zero sweat and
yet, hippopotamuses
secrete what we know
as "blood sweat." This
keeps their skin moist
and protects it from
sunburns, as well as
many infections.
Exploding Malaysian
Ant
This adaptation is
perhaps the most
intense defense
mechanism: suicide.
When the ant senses
its life is at risk, it will
often click its own
self-destruct button
and explode
Northern Fulmar
Projectile Vomit
All it takes is a tiny
confrontation for a
fulmar chick to
literally throw up
chunks of orange
puke that is so nasty
and sticky, it
becomes the foulest
prey of all time
Great Transformations
 Natural
selection is not the only way to
explain how evolution works
LICE
 Every
population of a species has a variety of
genes, and each gene can have multiple
alleles.
 Gene Pool: All the available genetic
information within a population
 When life is thriving in a population and
there is genetic equilibrium, then these
alleles are not changing in frequency. There
is no selection. There is no evolution.
Everything is calm. Like a pool…before the
cannon ball.
 Hardy-Weinberg
Principle: when allele
frequencies remain constant, a population is
in genetic equilibrium. In other words when the dominant genes and recessive
genes are constant, the POPULATION is in
equilibrium
 Evolution
cannot occur if alleles in the population
are not acted on by forces that cause change!
Consider these forces the CANNON BALL!
• Genetic drift
• Gene flow
• Mutation
• Random mating
• Natural selection
 When
these things are happening, evolution is
happening, and Hardy-Weinberg is null and void
 Change
in the allele frequency due to
chance
• Founder effect, Bottleneck effect
• An ant gets stepped on, a rabbit gets swept up by a
tornado, an elephant drinks up a protozoa living in a
puddle, a plane crashes killing a Nobel Laureate.
 The
above events have nothing to do with
genotype or phenotype--they occurred
purely by chance.
 Founder
Effect: Occurs when a small
sample of a population settles in a
location separated from the rest of the
population
• Alleles that were uncommon in the original
population might be common in the new
population. (so the recessives might start
showing up, this happens in populations like the
Amish)
 Bottleneck
Effect: Occurs when a
population declines to a very low
number and then rebounds
 New
genes entering the population, and
genes leaving the population
• The movement of individuals in and out of
populations increases variation within a population,
and decreases differences between populations
A
change in the original DNA sequence
of an organism
 Some have no effect, however others can
lead to the creation of a different protein,
which will change the phenotype
 Variation
of traits
 Inheritance
 Overproduction
 Survival of fittest
 The
formation of two species from a
common ancestor
• A species is a group of living things that can
breed with others of the same species and form
FERTILE offspring.
• Allopatric, sympatric
A
physical barrier divides one population into
two or more populations.
• Ocean, river, mountain, glacier, lava, etc.
Abert squirrel
Kaibab
squirrel
 During
the time of their separation,
evolution continues to take place in each
group.
 However, the
changes that occur in one
group are not the same as the changes
that occur in the other – they both evolve,
but evolve differently
 The
two groups gradually become
different because their environments are
different.
 In
time each group may become a
different species.
 As
a result – they would not be able to
produce fertile offspring if brought back
together
A
species evolves into a new species
without a physical barrier.
 The ancestor species and the new
species live side by side during the
speciation process.
 Speciation
is a long, gradual process
 Scientists know it happens because of
patterns in evolution
• Coevolution
• Convergent evolution
 Sometimes
species evolve together!
 Coevolution: The relationship between
two species might be so close that the
evolution of one species affects the
evolution of the other species
 Coevolutionary arms race – antibiotic
resistant bacteria
• Adaptations and counter-adaptations
 Unrelated
species evolve similar traits because
they live in similar climates, even though they
live in different parts of the world.
 The
Evolutionary Arms Race
 The Mind’s Big Bang