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Population: Density = ________
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Distribution of population:
- Clumped: Plants near water source
- Uniform: Plants equally spread out
- Random
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Density Independent Inhibition:
External factors cause death
- Is weather caused
- High insects during summer months
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Density Dependent Inhibition:
Caused by resources being consumed; population levels too high
Logistic growth: graph that shows steady increase followed by flattened line (carrying capacity) which may or may not then lead to a drop
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Evidence for Evolution:
- Fossil records
- Comparative anatomy - homologous structures
- Comparative embryology - similarity in embryos between species
- Molecular biology
- Biogeography - similarity of species
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Natural Selection:
- Natural process
- Requires 100,000 yrs to occur
- Wolf-like:
- ↳Wolf
- ↳Coyote
- ↳Fox
- ↳Dog
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Artificial Selection:
- Humans serve as the environment
- Requires 1,000 yrs to occur
- Examples:
- Dog breeds
- Cat breeds
- Cattle breeds
- Plants
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Types of genetic drift:
- Bottleneck Effect
- Founder Effect
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Bottleneck effect
hunters kill genetic diversity
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Founder effect
a few leave population and start new population
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Gene flow
Isolated population; no migration
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Microevolution
Is the change in allele frequencies that occurs over time within a population.
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Microevolution is due to four different processes:
Mutation, selection (natural and artificial), gene flow, and genetic drift.
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Types of natural selection:
- Stabilizing
- Directional
- Disruptive
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Stabilizing natural selection
favors intermediates (the average)
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Directional natural selection
Favors one extreme (light vs dark)
Most common
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Disruptive natural selection
favors two extremes
diversifying
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Peppered Moth
- Smog from industrial revolution caused directional selection
- dark survived, light were killed
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Hardy-Weinberg Law
A principle stating that the genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors. When mating is random in a large population with no disruptive circumstances, the law predicts that both genotype and allele frequencies will remain constant because they are in equilibrium.
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Hardy-Weinberg Law assumes:
- Large population
- No natural selection
- No mutation
- Random mating
- No gene flow
- No genetic drift
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Hardy-Weinberg equation:
 - p+q=1
- P: Dominate gene
- q: Recessive gene
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Reproduction Barrier - Pre-zygotic:
- Temporal - time
- Habitat
- Mechanical - plants pollinated by birds
- Behavioral - mating rituals
- Gametic - sex cells incompatible (eggs/sperm)
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Reproductive Barriers - Post-zygotic:
- Hybrid sterility
- Hybrid inviability - aborts
- Hybrid breakdown - f1 ok, f2 breaks down (sterile)
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Hybrid animals:
- Mule - sterile
- Liger - female not sterile
- Leopon
- Cama - llama + camel
- Zorse
- Wholphin
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Types of Speciation:
- Allopatril - due to geography
- Sympatril - due to complete nondisjunction (polyploid)
- Adaptive radiation - traveling
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Allopatril speciation
due to geography
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Sympatril speciation
due to complete nondisjunction (polyploid)
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Adaptive radiation
- Species travel from different locations and turns into new species
- Birds w/ correct adaptations survive
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Polypliody
Polyploid cells and organisms are those containing more than two paired (homologous) sets of chromosomes. Most species whose cells have nuclei (Eukaryotes) are diploid, meaning they have two sets of chromosomes—one set inherited from each parent.
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Gradualist Theory of Evolution
Changes occur slowly
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Punctuated Theory of Evolution
Changes occur quickly
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Properties of a biological community:
- Species diversity
- Type of vegetation
- Stability - how fast does it recover from disaster
- Trophic structures - feeding levels
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Quaternary Consumer (hawk)
- ⇑⇑⇑⇑⇑
- Tertiary Consumer (snakes)
- ⇑⇑⇑⇑⇑
- Secondary Consumer (frogs)
- ⇑⇑⇑⇑⇑
- Primary Consumer (insects)
- ⇑⇑⇑⇑⇑
- Producer (plants)
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Niche
The specific area where an organism inhabits.
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Niche - Competitive Exclusion
+ Examples
- No 2 species can occupy the same niche
- Examples;
- Paramecia
- Dingo vs. Thylacine
- Homo Neaderthalensis vs. Homo Sapiens
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Ecological Relationships:
- Parasitism
- Commensalism
- Mutualism
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Parasitism
One benefits; Other is harmed
- Examples:
- Leeches
- Tapeworm
- Plasmodium (malaria)
- Ticks
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Commensalism
One benefits; other is unaffected
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Mutualism
Both benefit
- Examples:
- Ant/Acacia
- Flower/Bird
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Keystone Predator
Maintains ecosystem
- Examples:
- Starfish
- w/ starfish 16 species of shell fish w/o 1 species
- Wolf
- regulates Elk population in Yellowstone park w/o wolf little vegetation left
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Batesian Mimicry
Something harmless looks like something harmful
Moth looks like wasp
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Mullerian Mimicry
Two harmful things look like each other
Bee looks like wasp
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Object mimicry
Organism looks like object
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Types of Camouflage:
- Background shading
- Aposomatic Bright Coloration - colors
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Primary succession
- Bare rock
- ⇓
- Mosses
- ⇓
- Bushes
- ⇓
- Trees
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Secondary Sucession
- Disturbance (fire)
- ⇓
- Crab grass
- ⇓
- Bushes
- ⇓
- Trees
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