Microevolution I Flashcards
What is microevolution?
The evolutionary processes that occur rapidly within populations and change their genetic makeup from one generation to the next.
What is macroevolution?
The evolutionary processes that occur slowly, where the history of life is written both in the fossil record and in the relationship of living species.
What are jumping genes (transposable elements)?
They are a mobile segment of DNA that can change their position within the genome and alter the expression of those genes.
How were the jumping genes responsible for the dark coloration in moths studied?
Using fine scale linkage association mapping combined with DNA sequencing. And using statistical modeling, this mutation was dated to around 1819.
How were jumping genes responsible for the change in coloration in moths?
These genes were inserted within the moth cortex gene and were responsible for that color change.
How did the frequency of dark-colored moths change as natural selection acted upon them?
Initially, the pepper-colored moths were more prevalent because they blended in to the tree bark, but with the Industrial Revolution and large amount of pollutants on the trees, the dark variant was selected for and increased in frequency.
At the gene level, how is genetic variation quantified?
By the percentage of heterozygous loci in the population.
At the molecular level, how is genetic variation quantified?
By comparing nucleotide sequences of two or more individuals.
How does genetic variation originate?
When new genes or alleles arise by mutation, gene duplication, sexual reproduction, or other processes.
Why is there a disparity in evolution between viruses and mammals?
Viruses’ mutation rate is higher and their generation time is shorter.
What is a population?
A population is a group of organisms within the same species that live in the same area and interbreed with each other.
What does a gene pool consist of?
All the copies of every allele at every locus of all members of the population.
What does it mean to say a locus is fixed?
A locus is fixed if all individuals in that population are homozygous for the same allele. There will be no variation in that population unless there is a mutation or outside organism that brings with it variation.
What does p + q equal?
1
What do p^2, 2pq, and q^2 represent?
Genotype frequencies.
How do p, q, p^2, 2pq, and q^2 change throughout subsequent generations?
They don’t change; p^2 + 2pq + q^2 always equals 1.
What is the Hardy-Weinberg Principle?
Whatever the initial genotype frequencies for two alleles may be, after one generation of random mating, the genotype frequencies will be p^2 : 2pq : q^2
What does it mean for a locus to be in Hardy-Weinberg equilibrium?
The genotypes at the locus have the frequencies predicted by the Hardy-Weinberg principle.
What are the five assumptions of the Hardy-Weinberg principle?
- There is no mutation.
- The population is infinitely large (if not, random genetic drift)
- Mating among individuals is random (if not, assortative mating, inbreeding, etc)
- Individuals are not moved into or out of the population (if not, gene flow or migration)
- All individuals have equal probabilities of survival and reproduction (if not, natural selection)
What does it mean if any of the assumptions of the Hardy-Weinberg principle are violated?
It means that evolution is occurring and the null hypothesis of the H-W principle is overturned.
What happens in the absence of any evolutionary force?
Nothing. The population’s genotype and allele frequencies do not change.
What two reasons make the HW equation useful?
- It allows us to test whether evolution is occurring in a population.
- By assuming HWE, it allows us to estimate the percentage of a population carrying a disease allele.
Of the genotype numbers, what does D represent?
number of AA
Of the genotype numbers, what does H represent?
number of Aa
