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93 Cards in this Set
- Front
- Back
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Evolution
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A change in population of organisms with time
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Population
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An interbreeding group of individuals sharing a common geographic area
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Charles Darwin
What did he discover? |
Didn't discover evolution
Discovered a mechanism by which evolution works--natural selection |
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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 |
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Evolutionary adaption
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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 |
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Artificial Selection
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Intentional breeding of certain traits or combination of traits
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Biogeography
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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 |
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Niche
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The organism's "profession;" the organism's role within its community
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Law of Super Position
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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 |
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Comparative anatomy
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Compares the structure of different organisms
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Homologous structure
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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 |
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Vestigial organs
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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 |
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What is the state fossil of Alabama?
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Whale
Basilosaurus cetoides |
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Morphological criteria
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Deals with structure or form, such as vestigial organs or locations of fossils
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Embryonic criteria
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The embryos of various groups of vertebrae animals show the features they all have in early development, such as gill slits and a tail
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Synthetic Theory of Evolution
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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? |
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Gene pool
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The total number of all the alleles of all the genes of all the individuals in a population
Genetic equilibrium |
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Aniridia
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Disease in humans
Is a dominant disease Causes blindness (You have to be homozygous recessive to not have it) |
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Hardy-Weinberg Law
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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) |
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Genetic equilibrium
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If the assumptions are correct, then the population will not evolve
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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 |
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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 |
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Agents of evolution
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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 |
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Mutations
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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) |
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Non-radom mating
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Animals, not just humans, participate in non-random mating
With inbreeding, p^2 and q^2 increase while 2pq decreases |
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Inbreeding depression
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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 |
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Gene flow
Immigration vs emigration |
Immigration: Entering a population (increases genetic diversity)
Emigration: Leaving a population |
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Genetic drift
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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 |
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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** |
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Founders effect
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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 |
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Ellis-van Creveld (EVC) syndrome
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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 |
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Natural selection
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A population is adaptive to its environment
Stabilizing natural selection Disrupting natural selection Directional natural selection |
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Stabilizing natural selection
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The environment stresses select against extreme phenotypes
Makes the population more uniform (skinnier bell-shaped curve) |
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Disruptive natural selection
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Environmental changes favor phenotypes at both extremes to the normal distribution
Causes split in the population (double bell-curve) |
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Directional natural selection
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Environmental changes favor phenotypes at one extreme
Normal distribution shifts (bell-curve retains its shape but shifts in the direction of the favored extreme) |
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Genetic variability
Increased/decreased by what? |
Increased by:
Mutation Recombination (crossing-over) Immigration Maintained by: Diploidy (recessive allele never actually lost) Balanced polymorphism |
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Genetic variability
Balanced polymorphism |
The ability of natural selection to maintain diversity with a population
Heterozygote superiority/advantage Frequency-dependent selection |
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Heterozygote superiority/advantage
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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
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Frequency dependent selection
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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 |
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Species
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Group of interbreeding organisms reproductively isolated from other groups
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Taxonomists
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Specialize in the classification of organisms
Species are named by giving them a binomial (two names) Classifications |
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Species are named by giving them a binomial (two names)
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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 |
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Classifications
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Domain, kingdom, phylum, class, order, family, genus, specific epithet
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Speciation
What are the two types? |
Creation of a new species through genetic divergence leading to reproductive isolation
Two types: Allopatris speciation Sympatric speciation |
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Allopatric speciation
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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 |
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Sympatric speciation
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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 |
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Isolating mechanisms (allopatris speciation)
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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 |
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Pre-zygotic isolation
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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 |
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Post-zygotic isolation
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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 |
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Ecosystem
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All the organisms within an geographic area plus their abiotic (nonliving) environment (such as sunlight, rain, etc.)
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Ellis-van Creveld (EVC) syndrome
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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 |
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Natural selection
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A population is adaptive to its environment
Stabilizing natural selection Disrupting natural selection Directional natural selection |
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Stabilizing natural selection
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The environment stresses select against extreme phenotypes
Makes the population more uniform (skinnier bell-shaped curve) |
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Disruptive natural selection
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Environmental changes favor phenotypes at both extremes to the normal distribution
Causes split in the population (double bell-curve) |
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Directional natural selection
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Environmental changes favor phenotypes at one extreme
Normal distribution shifts (bell-curve retains its shape but shifts in the direction of the favored extreme) |
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Genetic variability
Increased/maintained by what? |
Increased by:
Mutation Recombination (crossing-over) Immigration Maintained by: Diploidy (recessive allele never actually lost) Balanced polymorphism |
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Genetic variability
Balanced polymorphism |
The ability of natural selection to maintain diversity with a population
Heterozygote superiority/advantage Frequency-dependent selection |
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Heterozygote superiority/advantage
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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
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Frequency dependent selection
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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 |
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Species
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Group of interbreeding organisms reproductively isolated from other groups
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Taxonomists
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Specialize in the classification of organisms
Species are named by giving them a binomial (two names) Classifications |
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Species are named by giving them a binomial (two names)
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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 |
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Classifications
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Domain, kingdom, phylum, class, order, family, genus, specific epithet
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Speciation
What are the two types? |
Creation of a new species through genetic divergence leading to reproductive isolation
Two types: Allopatris speciation Sympatric speciation |
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Allopatris speciation
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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 |
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Sympatric speciation
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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 |
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Isolating mechanisms (allopatris speciation)
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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 |
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Pre-zygotic isolation
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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 |
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Post-zygotic isolation
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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 |
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Ecosystem
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All the organisms within an geographic area plus their abiotic (nonliving) environment (such as sunlight, rain, etc.)
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Community
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All populations of organisms inhabiting a common environment and interaction with one another
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Predation
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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 |
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Has predation been shown to increase or decrease genetic diversity?
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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 |
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Co-evolution
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An arms race between prey and predator population
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Predators
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Pursuit, ambush
Go after prey |
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Herbivory
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Eating plants (a type of predation since both the plants and animals have been living organisms)
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Defense mechanisms for plants (prey)
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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 |
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Defense mechanisms for animals (prey)
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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 |
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Batesian vs Mullerian mimicry
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Batesian: One species is harmful while the mimic is not
Mullerian: Both species are harmful |
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Symbiosis
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A close and long-term association between organisms of two different species
Ex: mutualism, commensalism, parasitism, and competition |
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Mutualism
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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) |
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Commensalism
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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 |
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Parasitism
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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) |
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Competition
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The interaction between organisms using the same resource present in limited supply
Ex: intraspecific & interspecific |
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Intraspecific competition
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Competition between members of the same species
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Interspecific competition
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Competition between members of different species
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Gause's Principle of Competitive Exclusion
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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) |
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Trophic levels
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Feeding levels in an ecosystem
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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 |
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Omnivore
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Can digest both plants and animals
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Second Law of Thermodynamics
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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 |
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Biological magnification
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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 |
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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 |
