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93 Cards in this Set

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Evolution
A change in population of organisms with time
Population
An interbreeding group of individuals sharing a common geographic area
Charles Darwin

What did he discover?
Didn't discover evolution
Discovered a mechanism by which evolution works--natural selection
Charles Darwin

What did he realize?
Like begets like (offspring resemble parent)
Within a population, variations exist, and some of theses variation can be inhertied
In most species, the number of individuals that survive and reproduce is small compared to the number born
Reproductive success (fitness) is often determines by the variations within a population
Since the individual has more reproductive success, it will contribute more offspring with the successful gene, and eventually it will become a common variation (this is natural selection)
Phenotype is determined by genotype, and if a phenotype gives an organism an advantage with reproduction, then the odds of that genotype being passed on are increased
Evolutionary adaption
The environment acts as a selective factor allowing some to reproduce and not allowing others
Natural selection is always at work because the environment is alway changing
A rabbit may have a phenotype hard-wired into its brain to backtrack it's path to escape hunting dogs
However, this phenotype isn't a good thing if the rabbit is running across the road and decides to backtrack
Artificial Selection
Intentional breeding of certain traits or combination of traits
Biogeography
Study of the distribution of species
An organism is always more closely related to other organisms within its relative area, as opposed to organisms on the other side of the world
Ex: Tasmanian wolf looks like a wolf. But its most closely related to kangaroos and wallabies than an American wolf
Niche
The organism's "profession;" the organism's role within its community
Law of Super Position
The lowest sedimentary layer is the oldest, while the highest is the youngest
The fossils in the higher levels would be more similar to today's organisms than the fossils in the lower levels
Comparative anatomy
Compares the structure of different organisms
Homologous structure
Structures that have a common origin but not necessarily a common function

Ex. Forelimbs of humans, cats, whales, and bats
The bony anatomy is basically the same, even if they aren't used in the same way
This is evidence of a common ancestor
Vestigial organs
Organs that in some past ancestor had a function, but now no longer serve a useful purpose
Ex. Whales have vestigial pelvic bones
Ex. Human appendix: extension of the cecum; in plant-eating animals, it is full of cellulose-digesting bacteria' humans don't have any cellulose-digesting bacteria in their appendix, but it indicates that an ancestor of modern man could digest grass
What is the state fossil of Alabama?
Whale

Basilosaurus cetoides
Morphological criteria
Deals with structure or form, such as vestigial organs or locations of fossils
Embryonic criteria
The embryos of various groups of vertebrae animals show the features they all have in early development, such as gill slits and a tail
Synthetic Theory of Evolution
The use of genetics to explain evolution (population genetics)
Gene pool
If you have both recessive and dominant alleles, why is it that dominant alleles don't take over within a few generations?
Gene pool
The total number of all the alleles of all the genes of all the individuals in a population
Genetic equilibrium
Aniridia
Disease in humans
Is a dominant disease
Causes blindness (You have to be homozygous recessive to not have it)
Hardy-Weinberg Law
Basic law of population genetics
Hypothetical population of squirrels
Assume:
Random mating
All alleles are equally viable
No entry or exit of alleles into/out of the population
No mutation
Large population

p = frequency of dominant allele
q = frequency of recessive allele
p^2 = frequency of homozygous dominant
q^2 = frequency of homozygous recessive
2pq = Frequency of heterozygous

p^2 +2pq + q^2 = 1(genotypic frequency equation)
Genetic equilibrium
If the assumptions are correct, then the population will not evolve
Hardy-Weinberg Law

Example--Drosophila
7000 AA in one bottle and 3000 aa in another
Random matin when the flies are combined in a single bottle
Parents: p = 0.7 and q = 0.3
Offspring: p^2 = 0.49 q^2 = 0.09 and 2pq = 0.42
So the offspring are 49% AA, 9% aa, and 42% Aa
Hardy-Weinberg Law

Example--Sickle Cell Anemia
q^2 = 0.025; what is the frequency of the heterozygotes?
q = 0.05 (square root) so p = 0.95
Heterozygotes = 2pq = 2(0.95)(0.05) = 0.095
Agents of evolution
Mutation
Gene flow (individuals moving in and out of population(s))
Genetic drift
Natural selection
Nonrandom mating

**Change caused by these agents is so slow that the Hardy-Weinberg Law can still be used
Mutations
Inheritable changes in the genotype
The odds of mutations are high simply because of the huge number of gene loci within a single sperm or egg
Increase genetic variability in a population (the more genetic variability a population has, the healthier it is going to be)
Non-radom mating
Animals, not just humans, participate in non-random mating
With inbreeding, p^2 and q^2 increase while 2pq decreases
Inbreeding depression
Manifests itself with high juvenile mortality, poor health, shorter lifespan, and low fertility
The invention of the bicycle helped the old English population decrease inbreeding because it allowed young people to meet other young people outside their village
Gene flow

Immigration vs emigration
Immigration: Entering a population (increases genetic diversity)

Emigration: Leaving a population
Genetic drift
A change in the allelic frequencies as a result of chance
Allelic frequencies in a small population can fluctuate dramatically in a short amount of time
It ultimately leads to the loss of one or more alleles in a population
Genetic drift:

Bottle neck effect
A population is dramatically lowered by change (disaster, cataclysmic event, etc.)
The remaining individuals mate, and the frequencies of alleles are changed
Lowers genetic diversity

**See examples in notes now**
Founders effect
When a new population is established by a very small number of individuals from a larger population (on purpose)
Resulting population is determined by the genetics of the founders
It's possible that a founder could have an incredibly rare allele from the main population, but since the smaller population is based on this founder, it would be common in the small population
Ellis-van Creveld (EVC) syndrome
Symptoms
Six digits on hands and feet
Long limbed dwarfism
Possible congenital heart failure
Common with the Lancaster County Amish because they're a closed population (1 in 200, but 1 in 60,000 in the US as a whole)
Consanguinity: Inbreeding
High birth rate
Founded by a handful of couple, and EVC was traced back to one of these couples
Natural selection
A population is adaptive to its environment

Stabilizing natural selection
Disrupting natural selection
Directional natural selection
Stabilizing natural selection
The environment stresses select against extreme phenotypes
Makes the population more uniform (skinnier bell-shaped curve)
Disruptive natural selection
Environmental changes favor phenotypes at both extremes to the normal distribution
Causes split in the population (double bell-curve)
Directional natural selection
Environmental changes favor phenotypes at one extreme
Normal distribution shifts (bell-curve retains its shape but shifts in the direction of the favored extreme)
Genetic variability

Increased/decreased by what?
Increased by:
Mutation
Recombination (crossing-over)
Immigration
Maintained by:
Diploidy (recessive allele never actually lost)
Balanced polymorphism
Genetic variability

Balanced polymorphism
The ability of natural selection to maintain diversity with a population
Heterozygote superiority/advantage
Frequency-dependent selection
Heterozygote superiority/advantage
Example sickle cell anemia in Africa; those with Hh didn't die from sickle cell, but weren't as badly affected by malaria as homozygous dominant
Frequency dependent selection
The fitness of any one phenotype declines if it becomes too common in the population
Example: water boatmen (bugs)
Come in different colors, and the least camouflaged water boatmen will be the ones eaten by fish
however, if a color becomes too common, the fish turns their attention to that color that way none of the three phenotypes are driven to extinction
Species
Group of interbreeding organisms reproductively isolated from other groups
Taxonomists
Specialize in the classification of organisms
Species are named by giving them a binomial (two names)
Classifications
Species are named by giving them a binomial (two names)
Ex. Felis catus L. (domestic house cat)
First name is the organism's genus
Second name is the organism's specific epithet
The letter is the authority (abbreviation of the name of the person who named that particular species) in this case Linnaeus, one of the founders of classification
Classifications
Domain, kingdom, phylum, class, order, family, genus, specific epithet
Speciation

What are the two types?
Creation of a new species through genetic divergence leading to reproductive isolation

Two types:
Allopatris speciation
Sympatric speciation
Allopatric speciation
Geographic isolation or separation
There is already variety within a species if it's spread out over a large geographic are
If a small group is suddenly separated, over a long period of time it would eventually diverge genetically so much that the two groups would no longer be able to interbreed
Sympatric speciation
Does not involve geographic isolation or separation
Hybrids-an offspring of parents of different species
More common in plants than animals
Ex. One organism has a diploid number of 6 and another has a diploid number of 4
Hybrid is made with 5 chromosomes
The odds are it is infertile and cannot produce offspring with either of the parents
However, in plants sometimes they will spontaneously double their chromosomes and pairing is now possible during meiosis
Sexual reproduction is now possible in an asexual reproduction and in a new species
Isolating mechanisms (allopatris speciation)
Keep two closely related species from interbreeding
Post-zygotic mechanisms: see notecard
Pre-zygotic mechanisms:
Habitat or ecological isolation
Behavioral isolation
Temporal isolation
Gamete isolation
Pre-zygotic isolation
Habitat or ecological: physical boundaries that prevent interbreeding

Behavioral: differencing in behavior that keep species from interbreeding

Temporal: differences in time (flower that blooms in spring won't breed with flower that blooms in fall)

Gamete: the egg and sperm of two species won't fuse or the sperm can't survive in the female's reproductive tract
Post-zygotic isolation
The egg and sperm have fused
Sometimes the zygote won't grow or will be spontaneously aborted
Offspring can also be sterile
Hybrid breakdown: The first generation hybrids are viable and fertile, but when the hybrids mate with one another or with one of the parents, the second generation are feeble or sterile
Ecosystem
All the organisms within an geographic area plus their abiotic (nonliving) environment (such as sunlight, rain, etc.)
Ellis-van Creveld (EVC) syndrome
Symptoms
Six digits on hands and feet
Long limbed dwarfism
Possible congenital heart failure
Common with the Lancaster County Amish because they're a closed population (1 in 200, but 1 in 60,000 in the US as a whole)
Consanguinity: Inbreeding
High birth rate
Founded by a handful of couple, and EVC was traced back to one of these couples
Natural selection
A population is adaptive to its environment

Stabilizing natural selection
Disrupting natural selection
Directional natural selection
Stabilizing natural selection
The environment stresses select against extreme phenotypes
Makes the population more uniform (skinnier bell-shaped curve)
Disruptive natural selection
Environmental changes favor phenotypes at both extremes to the normal distribution
Causes split in the population (double bell-curve)
Directional natural selection
Environmental changes favor phenotypes at one extreme
Normal distribution shifts (bell-curve retains its shape but shifts in the direction of the favored extreme)
Genetic variability

Increased/maintained by what?
Increased by:
Mutation
Recombination (crossing-over)
Immigration
Maintained by:
Diploidy (recessive allele never actually lost)
Balanced polymorphism
Genetic variability

Balanced polymorphism
The ability of natural selection to maintain diversity with a population
Heterozygote superiority/advantage
Frequency-dependent selection
Heterozygote superiority/advantage
Example sickle cell anemia in Africa; those with Hh didn't die from sickle cell, but weren't as badly affected by malaria as homozygous dominant
Frequency dependent selection
The fitness of any one phenotype declines if it becomes too common in the population
Example: water boatmen (bugs)
Come in different colors, and the least camouflaged water boatmen will be the ones eaten by fish
however, if a color becomes too common, the fish turns their attention to that color that way none of the three phenotypes are driven to extinction
Species
Group of interbreeding organisms reproductively isolated from other groups
Taxonomists
Specialize in the classification of organisms
Species are named by giving them a binomial (two names)
Classifications
Species are named by giving them a binomial (two names)
Ex. Felis catus L. (domestic house cat)
First name is the organism's genus
Second name is the organism's specific epithet
The letter is the authority (abbreviation of the name of the person who named that particular species) in this case Linnaeus, one of the founders of classification
Classifications
Domain, kingdom, phylum, class, order, family, genus, specific epithet
Speciation

What are the two types?
Creation of a new species through genetic divergence leading to reproductive isolation

Two types:
Allopatris speciation
Sympatric speciation
Allopatris speciation
Geographic isolation or separation
There is already variety within a species if it's spread out over a large geographic are
If a small group is suddenly separated, over a long period of time it would eventually diverge genetically so much that the two groups would no longer be able to interbreed
Sympatric speciation
Does not involve geographic isolation or separation
Hybrids-an offspring of parents of different species
More common in plants than animals
Ex. One organism has a diploid number of 6 and another has a diploid number of 4
Hybrid is made with 5 chromosomes
The odds are it is infertile and cannot produce offspring with either of the parents
However, in plants sometimes they will spontaneously double their chromosomes and pairing is now possible during meiosis
Sexual reproduction is now possible in an asexual reproduction and in a new species
Isolating mechanisms (allopatris speciation)
Keep two closely related species from interbreeding
Post-zygotic mechanisms: see notecard
Pre-zygotic mechanisms:
Habitat or ecological isolation
Behavioral isolation
Temporal isolation
Gamete isolation
Pre-zygotic isolation
Habitat or ecological: physical boundaries that prevent interbreeding

Behavioral: differencing in behavior that keep species from interbreeding

Temporal: differences in time (flower that blooms in spring won't breed with flower that blooms in fall)

Gamete: the egg and sperm of two species won't fuse or the sperm can't survive in the female's reproductive tract
Post-zygotic isolation
The egg and sperm have fused
Sometimes the zygote won't grow or will be spontaneously aborted
Offspring can also be sterile
Hybrid breakdown: The first generation hybrids are viable and fertile, but when the hybrids mate with one another or with one of the parents, the second generation are feeble or sterile
Ecosystem
All the organisms within an geographic area plus their abiotic (nonliving) environment (such as sunlight, rain, etc.)
Community
All populations of organisms inhabiting a common environment and interaction with one another
Predation
The consumption of one species (the prey) by another (the predator)
The predator population controls the size of the prey population and **vice verse***
Predators tend to cull (select) the old and the sick out of the prey population
Has predation been shown to increase or decrease genetic diversity?
May actually increase it
In England there are a lot of chalk soils
Grass and flowers compete to grow
However, the rabbits will eat the grass, and keep it in check
Co-evolution
An arms race between prey and predator population
Predators
Pursuit, ambush

Go after prey
Herbivory
Eating plants (a type of predation since both the plants and animals have been living organisms)
Defense mechanisms for plants (prey)
Trichomes: small hairs on plant leaves; can be chemical or physical deterrents
Resins: secreted from special channels; can deter anything from bugs to people (ex. poison ivy)
Spines
Defense mechanisms for animals (prey)
Warning coloration: or aposematic coloration; ex: a skunk's stripe
Cryptic coloration: or camouflage; ex: a moth that's colors help it blend into tree branches
Mimicry: When one species has evolved to look like another
Example:
Batesian: the model is dangerous while the mimic is not; ex: harmless king snake vs. poison coral snake

Mullerian: All of the species that look alike are dangerous; ex: a cuckoo bee and a yellow jacket
Batesian vs Mullerian mimicry
Batesian: One species is harmful while the mimic is not

Mullerian: Both species are harmful
Symbiosis
A close and long-term association between organisms of two different species

Ex: mutualism, commensalism, parasitism, and competition
Mutualism
When both species benefit from the association

Ex. Acacia (tropical tree) and ants (pseudomrymex)
Ants get a protein sources and other things, while they viciously attach anything else that tries to eat the leaves of the trees (protecting it)
Commensalism
One species benefits, but the other is neither helped nor harmed

Ex. orchids and trees
Orchids anchor themselves to the tree and can get water, nutrients, etc.
The tree gets nothing, but it isn't harmed
Parasitism
One species benefits, and the other is harmed

Ex. Tick and host
Tick attaches to host and gain nutrients
While the host loses nutrients (therefore is harmed)
Competition
The interaction between organisms using the same resource present in limited supply

Ex: intraspecific & interspecific
Intraspecific competition
Competition between members of the same species
Interspecific competition
Competition between members of different species
Gause's Principle of Competitive Exclusion
Two species cannot fill the same niche within a same ecosystem
Results: extinction, resource partitioning (subdivided niche), and character displacement (evolution causes increased diversity between the two species)
Trophic levels
Feeding levels in an ecosystem
Trophic levels

Terrestrial ecosystem
First: primary producers (autotrophs)
Second: primary consumers (herbivores)
Third: secondary consumers (carnivores)
Fourth: tertiary consumers (carnivores)

Example: (1) plant, (2) insect, (3) bird, (4) cat
Omnivore
Can digest both plants and animals
Second Law of Thermodynamics
Energy goes from useful to useless, usually in the form of heat

As food is transferred from one trophic level to the next, most of the energy from the food is lost as heat
This loss can be represented by a biomass pyramid
This is why organisms get larger and larger the higher they are on the food chain
Biological magnification
A substance is introduced at a low level of the food chain (such as a DDT to kill mosquitos)
The substance moves up the food chain, where it can have a negative effect (such as pelicans not being able to reproduce from their eggs being too thin due to (mosquitoes) DDT poisoning
Water and mineral cycle

Biogeochemical cycle
Biogeochemical cycles
Water and minerals can cycle through the atmosphere, earth, and hydrosphere (water)
These things cycle continuously, unlike food
Ex. you could have a phosphorous atom in your body that used to be in a dinosaur