A trait that improves a populations reproductive success is an adaptation An individualpopulation that is adapted is successful at producing grandchildren in its environment Adaptation ID: 933480
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Slide1
ADAPTATION
Slide2Terms related to Adaptation
A trait that improves a population’s reproductive success is
an adaptation
.
An individual/population that is
adapted
is successful at producing grandchildren in its environment.
Adaptation
is the process by which a population becomes more adapted to its environment.
The process of adaptation includes changes in the genes of the population.
All the genes (and their proportions) in a population is the
gene pool
.
Slide3Adaptations
Adaptations are
traits
that help the individual, population, and species survive and reproduce in their environment.
Traits may be physical, metabolic, and developmental.
Examples?
Slide4Traits
Traits are passed from one generation to the next
That means that all the information to produce all of your traits was contained within the single cell that was you when you were conceived.
What determines your traits?
Slide5Proteins
Proteins
determine our traits
Each protein is a sequence of
amino acids
. The length of the amino acid chain and the sequence of amino acids in the chain determine the structure and function of the protein and thus the trait.Hemoglobin is an example of a protein.
Val
His
Leu
Thr
Pro
Glu
Lys
… 139 more
Hemoglobin: a protein that is 146 amino acids long
Slide6DNA
DNA
is the recipe book for making proteins (and therefore traits). This is what is passed on from one generation to the next.
How does DNA code for proteins, thus traits?
Proteins
DNA
Traits
Slide7It is composed of four types of nucleotides:
A
Adenine
T Thymine
G Guanine
C Cytosine
DNA is arranged as a
double helix
Slide8The sequence of nucleotides along the DNA molecule provides the recipe specifying the sequence of amino acids to put together to make each type protein.
This is like the sequence of letters in a recipe specifying the ingredients to put together to make the final dish.
Slide9More on DNA
A - T every three nucleotides
A - T (codon) codes for one of the
T - A 20 amino acids
C - G (and there are 1000s
G - C of nucleotides in aT - A strand of DNA)
Slide10Translation (from DNA to mRNA to Protein
A copy of the DNA is made (called mRNA) so that the original isn’t messed with. The mRNA is like the DNA except the T nucleotide is replaced with a U nucleotide.
Readers go along the mRNA and when they find a particular sequence of nucleotides (the start codon), they begin to read each codon and put together the specified amino acids until they hit a stop codon which causes the protein to break off.
Video2 on DNA translation
Slide11THE GENETIC CODE
Thymine (T) is replaced with Uracil (U) in messenger RNA.
Slide12Genes are translated into proteins based on a triplet code
Transcription
Codon = 3 bases
Translation
Amino acid
Protein = many amino acids strung together
Slide13Recap
DNA is composed of nucleotides
There are only 4 types of nucleotides
Every 3 nucleotides codes for an amino acid
There are 20 different amino acids
Strands of amino acids form proteins
Proteins are responsible for traits and adaptations…
Video2 on DNA translation
Slide14Chromosomes
So what is a chromosome?
Slide15Chromosomes
Strands of DNA, all tightly wrapped up and existing in a cell’s nucleus
[Humans have 46 chromosomes, 23 from each parent]
Slide16Genes
So what is a gene?
Slide17Genes are a particular segment of DNA, that code for a protein (usually).
Junk DNA
Slide18Genes
Genes are
A section of DNA that encodes information for building a protein (or RNA molecule)
Each chromosome can have thousands of genes on it.
Slide19Mutations
What is a mutation?
Slide20Mutations
Mutations are a change in the sequence of nucleotides in a gene.
Mutations are random, caused by
Chemicals, radiation, copying errors
Mutations change the protein that is specified
Mutations may be beneficial, neutral, harmful, or lethal
Slide21Alleles are variants of genes
Slide22Sickle cell disease
Occurs due to a mutation in the gene that codes for the hemoglobin protein. protein that carries oxygen in red blood cells.
Causes the normally round red blood cell to change into a sickle shape that no longer carries oxygen as well. This can be lethal. Red blood cells of affected individuals distort in shape, break down or clog blood vessels and cause pain, poor circulation, etc
Val
His
Leu
Thr
Pro
Glu
Lys
… 139 more
Val
His
Leu
Thr
Pro
Val
Lys
… 139 more
Slide23Sickle cell disease
Alleles
: different versions of genes.
Sickle cell allele (h)
“normal” allele (H)
Sickle Cell Anemia (hh): often lethalSickle Cell Trait (Hh): symptoms vary, usually very little effects.
H
h
H
HH
Hh
h
Hh
hh
Mom
Dad
Slide24Sickle cell disease
Is having the sickle cell allele good or bad?
Slide25Sickle cell disease
Is having the sickle cell allele good or bad?
It depends on the environment!!
The sickle cell allele confers genetic resistance to malaria, one of the biggest killers of infants in areas with malaria.
So, where do you think you find populations with the highest incidence of the sickle cell allele? Areas with Malaria.
PBS Video
Slide26Gene pool
Gene Pool
: all of the alleles and their proportions in a population.
Slide27Gene pool
Gene pools change over time.
0%
100%
80%
20%
Environmental Change – Pesticide introduced
Resistant Gene
Slide28Gene pool
A change in a gene pool over time is called what?
Slide29Evolution
Genetic Evolution
: a change in a gene pool
Note: this operates at the population level! Another definition is a
genetic
change in a population.
Slide30What causes gene pools to change?
Mechanisms of evolution
Mutation
Migration (Gene Flow)
Chance (Genetic Drift)
Natural Selection
Slide31Mechanisms of evolution
1.
Mutations
: produce new alleles and new genes.
are random
cannot be predicted ahead of timecreate genetic variety
may be beneficial, neutral, or harmful to the individuals that inherit them
Slide32Mechanisms of evolution
2.
Migration
(immigration/emigration).
Technical term is
gene flow.The movement of alleles between populations as a result of movement of individuals from one population to another.
Slide33Mechanisms of evolution
3.
Chance
: when chance, rather than traits determine reproductive success. Example: disaster that kills part of a population. Small populations are more susceptible to big evolutionary change due to chance. Technical term is
Genetic Drift
.
Slide34Mechanisms of evolution
4.
Natural Selection
: When traits determine reproductive success; traits in more reproductively successful individuals get passed on more into the next generation.
Slide35Natural Selection
Natural Selection
: Alleles that confer “success” are more likely to be passed on to future generations and will increase their % relative to other alleles over time. Technical term for “success” is
differential reproductive success.
Slide36Example of Natural Selection
Gene pools change over time.
0%
100%
80%
20%
Environmental Change – Pesticide introduced
Resistant Allele
Non-Resistant Allele
Alleles
Slide37Example of natural selection
Beetles and pesticide resistance
The resistant and non-resistant alleles were due to
past
mutations that created genetic variety in the beetles but were neutral until now (pesticide spraying time).
The pesticide acted as a new environmental selection pressure that selected for the resistant allele.
This selection pressure, causing individuals with the resistant allele to out-survive and out-reproduce individuals without the resistant allele, resulting in an increase in individuals with the resistant allele in the next generation.
Slide38Natural Selection
http://evolution.berkeley.edu/evolibrary/article/0_0_0/evo_14
Slide39Natural Selection
http://faculty.etsu.edu/jonestc/Virtualecology/Models/Moths.html
Peppered Moth Simulation
With lichens on tree before pollution
Without lichens on tree because pollution killed them
Slide40Natural selection flowchart
Mutation
New Genes
Random
Recombination
New combinations of existing genes
Sexual reproduction
Genetic Variability—Gene Pool
Current mix of genes in population
Environmental Selection Pressures
Examples: climate, predation, mate selection
Differential Survival
Some genes and gene combinations help the individual survive better than other individuals.
Differential Reproduction
Some genes and gene combinations help the individual reproduce better than other individuals
Reproduced Genes
Slide41Natural selection flowchart
Mutation and recombination create genetic variety in gene pool of a population.
Mutations
: create new alleles/genes.
Recombination
: sexual reproduction mixes alleles and creates new combinations of alleles.
Slide42Variationarises from
Mutation:
new genes
Sexual Recombination: new gene combinations
Slide43Natural selection flowchart
Environmental selection pressure
: affects the survival and reproduction of individuals in a population differently (think back to the beetles)
Slide44Natural selection flowchart
Environmental selection pressure leads to differential survival and differential reproduction of individuals with more successful alleles. This is passed on to future generations and changes the gene pool through time.
Slide45“evolution: survival of the fittest”
Isn’t that what we were taught in school? Well, its wrong.
This is an example of science being misinterpreted by the public.
Slide46“evolution: survival of the fittest”
What does fittest mean?
To a biologist?
To the public?
Slide47“evolution: survival of the fittest”
What does fittest mean?
To a biologist?
= differential reproductive success
To the public?
= biggest, strongest, ….
Slide48“evolution: survival of the fittest”
What does fittest mean?
To a biologist?
= differential reproductive success
To the public?
= biggest, strongest, ….ALL that really matters is whether or not your genes are passed on to future generations ….
Slide49Artificial Selection
Slide50Types of evolution
1. Divergent evolution
2. Convergent evolution
3. Co-evolution
Slide51Divergent Evolution
1.
Divergent evolution
Two different populations of a species that experience
different selection pressures
may as a result become genetically different from one another
Once in a very great while, the two populations will become so different that they cannot reproduce together anymore (this then becomes speciation).
Slide52Divergent Evolution
Slide53Divergent Evolution
Slide54Divergent Evolution
Slide55Divergent Evolution
http://www.biology-online.org/images/darwin_finches.jpg
Slide56Divergent Evolution
Slide572.
Convergent evolution
Start with two very different species; they experience
similar selection pressures
and through time come to look and/or behave similarly.
Convergent Evolution
Slide58Convergent Evolution
Fish
Reptile
Mammal
What is the similar selection pressure?
Slide59Convergent Evolution
Slide60Convergent Evolution
What is the similar selection pressure?
http://www.votawphotography.com
/photo/Animals/animals.htm
http://www.hundekosmos.de/images/greyhound_517.jpg
Speed to catch prey (cheetah) and speed to win races and be bred.
Slide61Convergent Evolution
Marsupial
Mammals
Placental Mammals
Slide62Convergent Evolution
“Ant eaters” of the world
Slide63Convergent Evolution
Many plants look like cacti because they also have evolved to store and defend water but they are not cacti – for example, the ocotillo is not a cactus, it is a shrub in a different plant family.
Slide64Types of evolution
3.
Co-evolution
Two species that interact with each other (predator/prey; mutualistic; parasite/host; …) and
act as selection pressures on one another
“Evolutionary Arms Race”
Long legs
Good hearing
Sharp eyesight
Slide65Coevolution