Download FINAL Honors Evolution and Ecology Review for spring 2014 final

Evolution and Ecology Review
Thomas Malthus
• In 1800s, he thought food supply was not going to keep
up with rapid population growth. He thought this
would lead to disease, starvation, and mass death.
Resources would be limited, and there would be a
struggle for survival.
• Darwin realized from reading Malthus that this struggle
occurs in populations of all living things, not just
humans. ALL populations produce more offspring than
can survive, so there is a struggle for survival. Those
who have the most fitness survive and reproduce.
Natural selection
• Organisms with traits best suited to their
environment are more likely to survive and
reproduce
• ie bunnies on pHET simulation in class. White
bunnies succeed in white arctic environment.
Mutated brown bunnies are less successful. If ,
over many generations of bunnies, the
environment warms and snow melts, the
mutated brown bunnies will be more successful.
Alfred Wallace
• Came up with the idea of natural selection at
about the same time as Darwin
• Wallace
Darwin
Evidence for Evolution
•
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Fossils
Vestigial structures
DNA similar
And more…
Fossils – strata, relative dating
Fossils
• Preserved remains or traces of organisms long
dead. Not alive today but any similarity to us?
Vestigial Structures
• Structures on organism that have no apparent
use. Idea is that they were once useful and
are slowly becoming smaller over generations.
• EX: mole rat eyes, whale hips, snake hips,
tailbone, ear muscles, dewclaw (dog thumb),
etc…
Selection: Stabilizing, Directional, Disruptive
If light
and dark
trees die
If light
and medium
trees die
If medium
trees die
Selection: Stabilizing, Directional,
Disruptive
• Stabilizing: population shifts to middle
(intermediate) phenotype
• Directional: population shifts away from one
extreme phenotype toward intermediate and
the other extreme phenotype
• Disruptive: shift to both extreme phenotypes,
decrease in intermediate phenotype
Homologous structures /divergance
• Similar structures that have evolved over time
From the same ancestral structure. Can have
very different functions, but similarity suggests a
shared ancestry /evolutionary relationship.
Analogous Structures/convergence
• Structures that have similar function but did
NOT evolve from the same ancestral structure.
Dragonfly wings also analogous to these.
Homologous vs. analogous structures
Founder effect
Hardy Weinberg Formula
To determine a shift in allele frequencies within a population
(determine if evolution is happening in a population. )
p2 + 2pq + q2 = 1 and p + q = 1
• p= frequency of DOMINANT brown bunny allele (B)=??%
• q=frequency of RECESSIVE white bunny allele (b)= ??%
• p2 = % of BB genotype (homozygous dominant)
• q2 = % of bb genotype (homozygous recessive)
• 2pq = % of Bb genotype (heterozygous)
• Count homozygous recessive individuals (bb) and you get q2.
Take square root and you get q, so do 1-q to get p.
• Now you have BOTH p and q, or the allele frequencies for first
generation. Now wait and do the same thing for the second
generation to see if there has been a shift in allele frequency.
Sexual vs. Asexual reproduction
• Sexual involves two parents whereas asexual
involves one.
• In sexual reproduction, the genetic
information of the two parents can be
combined in nearly infinite ways to produce
highly diverse offspring – more diverse than
offspring produced by asexual reproduction.
Sexual selection
• An example of natural selection. EX: female
attracted to peacock (male peafowl). The
brighter, the higher the male’s fitness and chance
of reproductive success.
Carbon 14 dating
-radioactive dating
Carbon 14 dating
-radioactive dating
Carbon-14 dating
(Radioactive decay)
C 14 half life
• Every 5730 yrs, ½ of the mass of a sample of
carbon-14 decays to nitrogen-14.
• The percent of carbon 14 is maintained in the
environment through ionizing radiation.
• When you die you stop taking up NEW Carbon
14, and the Carbon 14 you have continues to
decay.
Half-life
• This the the amount of time it takes for ½ the
mass of a sample of a radioactive substance to
decay
• In Carbon 14, this time is 5730 yrs.
C 14 half life
• Because we know how much carbon-14, by
mass, should be in a sample of bone at the
time of death, we can determine how long
ago death occurred based on what fraction of
c-14 remains in the bone.
If half remains, it has gone through 1 half life
(5730 yrs.)
If a ¼ remains, then it has gone through 2 half
lives (11000 yrs)
Variation in populations
Darwin said very important for natural
selection
Not so much 
Period of recovery and adaptive
radiation (after mass extinction or
inhabiting new area)
• an event in which a lineage rapidly diversifies, with the
newly formed lineages evolving different adaptations.
Ecology
• Successional change
Successional change-pioneer species
and climax community
• Build soil where there is none (new volcanic
islands)
Climax community (see picture in
previous slide)
• It represents a self-perpetuating, stable
assembly of organisms, and undergoes little
change over long periods of time. The species
assembled together are very complimentary,
they do not directly compete for same
resource at same time. The degree of their
niche overlap is minimized.
Lichen on rock
Niche
• What’s eating you?
• What are you eating?
• Who gets affected if you and your whole
population were to disappear?
Carrying capacity
• maximum number of individuals of a given
species that an area's resources can sustain
indefinitely without significantly depleting or
degrading those resources
Carbon cycle – carbon flow
• Biological and non-biological reservoirs
Acid rain
Energy flow in ecosystems – not a
cycle since not return to sun
Global warming
• Arctic sea ice and polar bears
• Less able to hunt due to decreasing ice floes,
and which could move too far away from land.
Eutrophication
Eutrophication
• The process by which a body of water acquires a
high concentration of nutrients, especially
phosphates and nitrates. These typically promote
excessive growth of algae. As the algae die and
decompose, high levels of organic matter and the
decomposing organisms deplete the water of
available oxygen, causing the death of other
organisms, such as fish. Eutrophication is a
natural, slow-aging process for a water body, but
human activity greatly speeds up the process.”
Causes of extinction
• http://www.uwec.edu/jolhm/eh4/extinction/
CausesLink.html
Species definition
• 2 organisms are from the same species if they
can mate and produce fertile offspring.
Dihybrid crosses
• Practice them
Increase or decrease in complexity as
you dig down?
Why similar? CH 16.2
Mechanisms of Control
• All cells in an embryo inherit the same genes, but
they start using different subsets of those genes
during development
• The orderly, localized expression of master genes
gives rise to the body plan of complex multicelled
organisms
Population
• # of individuals in a species that occupy a
given region at the same time.
• ie students at ghchs = 4400