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Hybrid
The offspring of two different varieties
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Alleles
Genes that produce a feature
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Dominent
Fully expressed (visable)
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Recessive
No noticable effect on the organisms appearance
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Homozygous
Identical alleles
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Heterozygous
Two different allels for the same trait
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Incomplete Dominance
Hybrids appearence in intermediate between parental varieties
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Principle of Dominance
When parents differ in one characteristic, their hybrid offspring resemble one of the parents; not a blend of the two characteristics!
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Principle of Segregation
When hybrids reproduce they have two types of reproductive cells: 1/2transmitting the dominate characteristic, the other 1/2 transmitting the recessive characteristic of the other parent
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Principle of Independent Assortment
Dominence & segregation occur independently if there are two or more characteristics
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Phenotype
Physical (expressed) traits of an organism
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Blood type is determined by...?
A glycogen protien on the surface of the blood cell
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Type O Blood
- Can take transfusions from type O only!
- Geno Type = ii
- Antigens = A & B
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Type A Blood
- Can take transfussions from type O & type A
- Geno Type = iAiA; iAii
- Antigen = B
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Type B
- Can take transfusions from type O & type B
- Geno Type = iBiB; iBii
- Antigen = A
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Type AB
- Can take transfusions from any blood type!
- Geno Type = iAiB
- No antigens!
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Pleiotrophy
- Where a single gene affects more than one characteristic
- Ex. Sickle Cell gene, Marfan Syndrome
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Polygenic Inheritance
- When two or more genes affect a single characteristic
- Ex. Skin color
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Epistatic Genes
Mask the expression of other genes
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Monoecious
Plants that produce both egg & sperm
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Hermaphroditic
Animals that produce both egg & sperm
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Darwin's 4 Major Points
- 1. Individuals not alike (some differances inherited)
- 2. Individuals differ in reproductive sucess
- 3. Individuals chances for reproductive sucess partly dependent on heredity
- 4. Long time favoritism for more fit individuals over less fit individuals
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According to Darwin: The fittest individuals...
Are those that leave behind the most genes
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Species
A group of individuals with potential to interbreed and produce viable offspring
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5 Agents of Evolution
- 1. Genetic Drift
- 2. Gene Flow
- 3. Mutations
- 4. Non-Random Mating
- 5. Natural Selection
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Genetic Drift
- Agent of evolution
- Change in a gene pool of a small population due to chance
- Ex. Following a volcanic eruption
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Gene Flow
- Agent of evolution
- Gain of loss of different alleles due to movements of individuals
- Isolation reduces gene flow
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Mutations
- Agent of evolution
- Change in an organisms DNA that creates a new allele
- Very slow process
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Non-Random Mating
- Agent of evolution
- Ex. Feminine selection
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Natural Selection
- Agent of evolution
- Most likely to cause change in a gene pool
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Morph
When a population includes two or more forms of a phenotypic character
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Cline
A graded change in inherited characheristics over a geographic continuum
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Speciation
Evolution of a new species
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2 Randon Processes That Generate Variation
- 1. Mutations
- 2. Sexual recombiations (independent assortment & crossing over)
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Major Factor Affecting Endangered Populations
Reduced variation
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Reproductive Barriers
Prevents mating by the less able
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Pre-Zygotic Barriers
- Temporal Isolation
- Habitat Isolation
- Behavioral Isolation
- Mechanical Isolation
- Gametic Isolation
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Temporal Isolation
- Pre-zygotic barrier
- Breed at different seasons, times of day
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Habitat Isolation
- Pre-zygotic barrier
- Live in the same areas but not the same places
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Behavioral Isolation
- Pre-zygotic barrier
- No sexual attraction
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Mechanical Isolation
- Pre-zygotic barrier
- Sexual parts dont fit
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Gametic Isolation
- Pre-zygotic barrier
- Can mate, but no zygote is formed
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Post-Zygotic Barriers
- Hybrid Inviability
- Hybrid Sterility
- Hybrid Breakdown
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Hybrid Inviability
Hybrids don't survive
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Hybrid Sterility
Hybrids are viable & will mature, but cannot reproduce
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Hybrid Breakdown
First generation viable & fertile, but second generation feeble / sterile
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2 Requirements For "Adaptive Radiation" To Occur
- 1. New, different niche
- 2. Reproductive barriers
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250 Million Years Ago...
- Land masses convege , forming Pangea
- Reshaped biological diversity
- Massive extinctions!!
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180 Million Years Ago...
Pangea begins to break apart
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65 Million Years Ago...
- Modern continents begin to take shape
- Cool climate
- Seas receed from coastal lowlands
- Plants begin to die
- Massive extinctions!!
- Geologist find a thin layer of Iridium mixed with clay that corosponds to this date (common to asteroids / meteors)
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10 Million Years Ago...
India crunches into eurasia, beginning the formation of the Himalayan Mountains
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Urdovician Period
Marine algae
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Silurian Period
Plants appear on land
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Carboniferous Period
Forests
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Permian Period
- Massive extinctions!!
- Incects
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Triassic Period
First dinosaurs
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Jurassic Period
Dinosaurs rule
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Cretaceous Period
- Massive extinctions!!
- Dinosaurs go extinct
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Tertiary Period
Radiation of mammals
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Quaternary Period
Humans Appear
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Homologous Features
Similar structure due to common ancestry
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Non-Homologous Features
- Similarities due to convergent evolution
- Ex. Coral snake vs king snake
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How To Uncover Evolutionary Relationships
- Amino Acid sequencing
- DNA sequencing
- DNA - DNA hybridization
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Amino Acid Sequencing
- Compare amino acid sequences in a protien
- 104 amino acid positions
- Human vs chimp = 100% match
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DNA Sequencing
Measures nucleotide sequence of DNA segments
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DNA - DNA Hybridizaton
Ex. Wednesday's lab exercise
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