Evolution Flashcards
What are the two major types of mutations?
- Point mutation
- Chromosomal mutations
What is a point mutation?
A point mutation happens at the level of the nucleotide, resulting from an error in replication.
What are the versions of point mutation?
a. Silent mutations
b. Missense mutations
c. Nonsense mutations
What is a silent mutation?
A silent mutation is a mutation that does not change the amino acid that is coded for.
What is a missense mutation?
A missense mutation is an error that changes the amino acid that is coded for.
i. Many may be neutral
ii. Can be negative and alter protein function
iii. Can be positive; increase shape & therefore function enhance protein function.
What is a nonsense mutation?
A nonsense mutation is an error that results in a stop codon, which in most cases results in nonfunctional proteins.
What is a frameshift mutation?
A frameshift mutation occurs when an extra nucleotide is added or deleted, leading to radically different protein sequences.
What are chromosomal mutations?
Chromosomal mutations involve changes in chromosomal number or structure.
What are examples of changes in chromosomal structure?
a. Translocation
b. Duplication
Changes can occur during crossing over but may not get assembled properly.
What is aneuploidy?
Aneuploidy is a chromosomal mutation involving an abnormal number of chromosomes.
What is polyploidy?
Polyploidy is a chromosomal mutation involving more than two complete sets of chromosomes, often due to nondisjunction.
What is evolution?
Change in allelic frequencies of a population over time.
What are Darwin’s 5 observations?
- In nature, there are more individuals born into a population than will survive to reproduce.
- Most populations tend to stay the same size year to year.
- Struggle for existence.
- Heritable variation in traits within populations.
- Some trait variants allow for organisms to be more successful at surviving and reproducing.
What is evolution by natural selection?
Change in allelic frequencies over time due to differential reproductive success that is based on heritable variation within a population.
What are the requirements for evolution by natural selection?
Requires heritable variation and differential reproductive success.
What are the mechanisms that contribute to heritable variation?
Mutations, sexual reproduction, crossing over, and independent assortment.
What is fitness in the context of natural selection?
The number of copies of an individual’s genes in future generations; a function of the number of offspring and their likelihood of survival.
What is stabilizing selection?
Where natural selection acts to maintain the allele frequencies in a population because the average phenotype is the most fit.
Example: Females with too small or large offspring have natural selection against them.
What is directional selection?
Natural selection acts to make one extreme of the phenotypic range more common because that portion of the range is more fit.
What is fitness in the context of natural selection?
The number of copies of an individual’s genes in future generations; a function of the number of offspring and their likelihood of survival.
What is stabilizing selection?
Where natural selection acts to maintain the allele frequencies in a population because the average phenotype is the most fit.
Example: Females with too small or large offspring have natural selection against them.
What is directional selection?
Natural selection acts to make one extreme of the phenotypic range more common because that portion of the range is more fit.
What is Disruptive Selection?
Disruptive Selection is where natural selection acts to divide a population into two genetically distinct races because the extreme phenotypes are more fitting than the mean.
What is Balancing Selection?
Balancing Selection is when natural selection acts to maintain genetic diversity in a population by:
- Heterozygotes being the most fit
- Frequency dependent selection.
What are the mechanisms of evolution?
The mechanisms of evolution include:
1. Mutations: Point mutations, missense.
2. Gene flow: Movement of alleles into or out of populations (immigration, emigration).
3. Genetic drift: Random events prevent some individuals in a population from reproducing, leading to a loss of genetic variation.
What is a genetic bottleneck?
A genetic bottleneck is a catastrophic event that wipes out a significant portion of a population, leading to a loss of genetic variation.
What is the founder effect?
The founder effect occurs when a small subset of a parent population emigrates and forms a new population, resulting in a genetic subset of the parent population.
What is fitness?
Fitness is the ability to get your genes into future generations.
What are the two mechanisms of non-random mating?
- Forced Inbreeding 2. Sexual Selection
What is forced inbreeding?
Forced inbreeding occurs due to a small, isolated population and low offspring dispersal, which can lead to inbreeding depression.
What is inbreeding depression?
Inbreeding depression is the reduction in fitness caused by mating with a close relative, leading to enhanced expression of negative recessive alleles.
What is sexual selection?
Sexual selection is directional selection that acts differently on the sexes due to differences in reproductive potential.
How is female reproductive potential (F-RP) determined?
F-RP is determined by how many eggs a female can make, which are limited because they cost energy and are large.
How is male reproductive potential (O-RP) determined?
O-RP is determined by how many eggs a male can fertilize, which involves finding mates.
What is the focus of female reproductive potential?
Female reproductive potential focuses on quantity over quality.
What traits enhance quantity in females?
Traits that enhance quantity include size and the ability to get energy, leading to strong natural selection.
What traits enhance quality in males?
Traits that enhance quality are those that attract females and competitive ability.
What is the quality aspect of male reproductive potential?
Quality in male reproductive potential involves mating with multiple females.
