Chapter 13: Processes of Evolution Flashcards
What is the hardy-weinberg equation?
p2 + 2pq + q2 = 1
What are the two equations that can be used to calculate allele frequencies?
p + q = 1
p = [2N(AA) + N(Aa)] / 2N
q = [2N(aa) + N(Aa)] / 2N
Allele frequencies(i.e. A or a) measure the amount of _________________(1) in a population.
(1) genetic variation
______________________(1) show how such variation is distributed among members of the population.
(1) genotype frequencies (i.e. Aa, aa, AA)
Allele and genotype frequencies provide information about _________________________(1).
(1) a population’s genetic structure
What is Hardy-Weinberg equilibrium? What are the five conditions of hardy Weinberg equilibrium?
hardy-weinberg equilibrium is a model in which allele frequencies do not change across generations.
5 requirements
1. Random mating
2. Large population size
3. No mutation
4. No gene flow
5. No selection of genotypes
Essentially, NO EVOLUTIOn
Since population in nature never meet the conditions of hardy-weinberg equilibrium, the model is only useful for _________________________(1)
(1) Predicting approximate genotype frequencies of a population
Hardy-weinberg equilibrium acts as a constant that we can constantly compare evolutionary changes to. This helps us identify mechanisms of evolutionary change
What is stabilizing selection?
Favours average individuals(steep curve in the middle)
What is directional selection?
favour individuals that vary in one direction from the mean, favours one extreme, entire bell curve shifts to the left or right(steepness does not change)
What is disruptive selection?
favours both extremes, bimodal
____________________(1) reduces variation in populations but does not change _________________(2). It is often called ________________(3) meaning selection against any __________________(4).
(1) Stabilizing selection
(2) the mean
(3) purifying selection
(4) deleterious mutations
For a single locus, _____________________(1) may favour a particular variant — __________________(2) for that variant
(1) directional selection
(2) positive selection
___________________(1) selection results in increased variation in the population.
(1) disruptive selection
What is a polymorphism?
the idea of having the same species start to have different phenotypes so that they can live in their individual niches/habitats
What is evolutionary theory?
A scientific body of work concerned with studying the mechanisms that cause evolutionary change in populations
What did Darwin do for evolutionary theory?
- The first person to articulate a theory of evolutionary change based on scientific study and observation
-Provoked by a 5-year voyage around the world on the HMS beagle
- Darwin studied the Galapagos islands, and found that many organisms living on the islands were unique from others in the world
- Organissms differed from island to island
What was Darwin’s hypothesis?
many organisms originally came to the islands from the mainland and each island presented a unique living environment to which organisms had to adapt in order to survive and reproduce.
What is sexual selection?
When individuals of one sex mate preferentially with particular individuals of the opposite sex rather than at random. There may be a trade-off between attracting mates(more likely to reproduce) and attracting predators(less likely to survive). this is an example of non-random mating
What is the founder effect?
A small group of population is speerated from the rest. Few individuals colonize a new area. Less genetic variation
What is a bottleneck?
a sharp reduction in the size of a population due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts; or human activities. Less genetic variation
What is genetic drift?
Changes in allele frequencies from one generation to the next due to random sampling, affects both large and small populations.
- Types of genetic drift are bottleneck and founder effect
What is an adaptation?
A favoured trait that spreads through a population by natural selection.
What were Darwin’s theories?
- Species change over time
- Divergent species share a common ancestor(descent with modification)
- the mechanism that produces change is natural selection.
Who was Alfred Russel Wallace?
Studied biodiversity in SE asia, wrote a paper and Charles Darwin agree with the ideas in this paper
What is natural selection?
Individuals best adapted to a given environment contribute more offspring to succeeding generations and survive better than others do. the differential survival and reproduction of individuals is due to variation of their traits. As more and more individuals of a population acquire new adaptive traits, the characteristics of the entire population evolve.
What is a gene pool?
Sum of all copies of all alleles at all loci in a population
What is allele frequency?
proportion of each allele in the gene pool
What is genotype frequency?
Proportion of each genotype among individuals in the population
Many of Darwin’s observation of variations and selection came from ____________________________(1). Darwin bred ________________________(2) and recognized similarities between selection by breeders and selection in nature. In both cases, selection simply increases the ________________________(3) from one generation to the next.
(1) domesticated plants and animals
(2) pigeons
(3) frequency of the favoured trait
