The Evolution Of Populations Flashcards
What are population genetics and how do scientists use it to study population evolution?
Population genetics is the study of what changes allele frequencies in populations overtime.
Scientist study how selective forces change a population through changes in alleles and genotypic frequencies
What is modern synthesis? Why is Mendelian genetics important?
Modern synthesis is a coherent understanding of the relationship between natural selection and genetics.
Mendel demonstrated that traits are discrete and keep their properties through generations.
What is Microevolution?
Population change overtime.
What is Macroevolution?
Processes that give rise to new species and higher taxonomic groups with widely divergent characteristics.
Example: loss of limb or emergence of tetrapods
What is Allele frequency? How is it related to evolution?
The frequency in which a specific gene or allele appears within a population, usually expressed as a decimal fraction or a percentage.
(Note: changes in frequencies over time is called micro evolution )
What is a gene pool?
The sum of all alleles in a population
What is genetic drift? What is the founder effect?
Random change in population with no advantage to the population over existing allele frequencies is called genetic drift, and this usually occurs in smaller populations.
If the subset of the original population is used to establish a new population, then this new population may have an allele frequency which is not typical of the original population; this is called the founder effect.
What is the hardy Weinberg principle of equilibrium? What is the hardy Weinberg equation?
This principal states that a population’s allele and genotype frequencies are inherently stable, and that unless some kind of evolutionary force is acting upon the population, neither the allele nor the genotypic frequencies would change.
While no population can satisfy these conditions, the principal offers a useful model against which to compare real population changes.
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Hardy-Weinberg Equation: P^2 + 2pq + q^2 = 1
P = frequency of dominant alleles
Q = frequency of recessive alleles
P + q = 1
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P^2 = frequency of homozygous dominants
2pq = frequency of heterozygotes
Q^2 = frequency of homozygous recessives
What is heritability and genetic variance? How do these affect the health of a population?
Heritability is the fraction of the phenotype variation that we can attribute to genetic differences among individuals in a population
The diversity of alleles and genotypes within a population is called genetic variance.
The inbreeding or mating of closely related individuals can result in the increased likelihood of recessive mutations that cause abnormalities and disease. Whereas in a healthy population, the chance the two carriers will make is low and even then only 25% of their offspring will inherit the disease allele from both parents.
What are the evolutionary forces that apply selection pressure?
Natural selection: survival of the fittest (best traits suited for survival in particular environmental conditions as passed)
Genetic drift : random or chance events that can lead to the elimination of allele from a population.
Gene flow : the flow alleles in and out of a population due to my migration of individuals or gametes
Mutation : changes to an organisms DNA (note: Species evolved because of mutations accumulating over time)
Non-random mating: exactly how it sounds. (Reasons - phenotype preference, geographical distance, etc.)
What are the ways that selection pressures can affect population variation?
Stabilizing selection: an average phenotype is favored
Directional selection : A change in the environment shifts the spectrum of phenotypes of observed
Diversifying (disruptive) selection : Two or more extreme phenotypes are selected, while the average phenotype is selected against
Sexual selection : male and females differ because potential mates prefer a certain phenotype.
Artificial selection (selective breeding): your process by which humans use animal implant breeding to develop particular phenotypic traits or characteristics by choosing which males and females will sexually reproduce and have offspring.
What is polymorphic?
An organism with two or more particular characteristics
