Speciation: within a population the individuals can make offspring with…
: within a population the individuals can make offspring with each other.
Selection : agents of evolution adopts population to their environments.
Selection: Intermediates chosen against.E.g. Finches, large and small beaks.
Selection: Eliminates one extreem in phenotype. E.g. flies
Selection: Eliminates both extremes from range or phenotypes. Favors Heterozygous.
Does not Change most common phenotype.
Human babies, birth weight.
: E.g. Sickle Cell Anemia.
Effects Phenotype directly and genotype indirectly.
Dogs, Horses and Corn.
Negative Frequency Dependent Selection:
Female chooses particular characteristics in males over others
Hardy Weinburg Assumptions
No Gene Flow
Equation: p^2+ 2pq +q^2 = 1
p^2 = homozygous dominant trait/ phenotype (
2pq = heterozygous trait/ phenotype (
q^2 = homozygous recessive trait/ phenotype (
p = dominant allele
q = recessive allele
Small Population Size
Random fluctuation in allele frequencies by chance.
: Loss of genetic variability; reduced population size due to natural disaster, disease or extinction.
: Rare alleles and combinations of alleles may be enhanced in new populations.
: producing viable offspring that survive and they produce viable offspring.
does not indicate health.
Re-infected by different HIV strains: Gene Flow
Multiple Sexual Encounters:Random Mating
Undergoing ant-viral Chemotherapy: Mutations occur and ossuary in HIV itself.
NO RANDOM MATING IS NOT BEING VIOLATED
Random mating is occurring.
Selection is Occurring
: the individual HIV strands survive the treatments because it contains different strains that resist environmental changes.
Infinite Population Size
: Hiv can infinitely multiply and mutate giving the number of individual strands to be quite high.
Generates genetic variation
Natural Selection acts on genetic variation.
Biological Species Concept
: produce viable offspring (if they come in contact).
Does not apply to Asexual Reproduction.
Morphology not part of species concept.
Types of Speciation:
speciate in different area, geologically isolated. (river divides land)
same area; species change and use different resources.
: most common speciation; how plants speciate.
: all chromosomes arise from same species
Tetrapods: four sets of chromosomes.
Triploids: Sterile, odd number
: hybrid; one chromosome from each. sterile, don't air right in meiosis.
Instantaneous Sympatric Speciation
: an individual is dorm reproductively isolated from its own species.
Sympatric Speciation via Destructive Selection - RARE
Speciation Increases; Gene Flow Decreases.
species occur with few competitors for resources. E.g. Diversification of Darwin's Finch's
Barriers that prevent the exchange of genetic information.
prevent the proper forming of zygotes.
same area, different habitats, rarely interact. E.g. lions and tigers; oak trees.
: Birds having unique mating songs. Pheromones: chemical signals.
: species produce at different times of day or year. E.g. Wild Lettuce and Frogs
Structural difference that prevents mating. E.g Bees and Pollen.
gametes form but can't function into the reproductive tract.
Post Zygotic Barriers:
prevents proper functioning of zygotes after they form.
Reduced Hybrid Viability
: zygotes fail to develop or fail to reach sexual maturity.
Reduced Hybrid Fertility
: Hybrid lives but is sterile.
Hybrid Break Down
: Offspring of hybrids have reduced viability and fertility.
: completely reproductively isolated.
The Pace of Evolution
: evolutionary change occurs slowly through time and is not linked to speciation.
requires that phenotype change occurs in bursts associated with speciation, separated by long periods of little to no change.
: No evolutionary change
Combination of oscillating and stabilizing selection
Species' ability to shift ranges. (ice age, move to water area)
: changes in the gene pool of a population over time which result in relatively small changes (smaller evolutionary changes in allele frequencies within a species) would not result in new species.
refers to changes (genetic, morphology, taxonomy, ecology, and behavior of organisms) in organisms, which is significant enough that over time new organisms will speciate. Ancestors can't meet with dependents.