mechanics of evolution Flashcards
What is a gene pool?
All of the genes of a population
The gene pool represents the genetic diversity available within a population.
Define allele frequency.
The percentage of any particular allele in a gene pool
Allele frequency is crucial in understanding genetic variation and evolution.
What does genetic equilibrium indicate?
A population in which an allele frequency remains the same over many generations is stable and is NOT evolving
Genetic equilibrium is a theoretical state where the gene pool is stable.
What is the effect of microevolution?
Any factor affecting the genes in a gene pool will result in microevolution
Microevolution refers to small changes in allele frequencies within a population.
List the five major factors that can cause evolutionary change.
- Mutation
- Natural Selection
- Gene flow
- Genetic Drift
- Non-random mating / Artificial selection
These factors can influence the genetic composition of populations over time.
What is a mutation?
A change in the DNA
Mutations are essential as they introduce new alleles into the gene pool.
What are harmful mutations?
Most common type, nature selects against them, rare in the gene pool
Harmful mutations often decrease an organism’s fitness.
What are beneficial mutations?
Occur rarely, nature selects for them, accumulate in gene pool
Beneficial mutations can enhance survival and reproduction.
What are neutral mutations?
Nature selects neither for or against
Neutral mutations do not affect an organism’s fitness.
What is natural selection?
According to the survival of the fittest, the best adapted phenotype is ‘selected’
Natural selection is a key mechanism of evolution.
What are selective pressures?
- Disease
- Climate conditions
- Food availability
- Predators
- Choice of mate
Selective pressures influence which traits are favored in a population.
What is stabilizing selection?
Limits evolutionary change by favouring the current population norm (the average)
Examples include human birth weights and ideal bill lengths in hummingbirds.
What is directional selection?
Favors individuals that differ from the population norm in one direction
Common in artificial breeding, it can result from sudden environmental changes.
What is disruptive selection?
Favors more than one trait (two directions) – both extremes
An example is finches in Africa that eat both soft and hard seeds.
What is sexual selection?
Selection favours individuals with variation of a trait that aids in mating success
Common forms include female mate choice and male vs. male competition.
What is gene flow?
Transfer of alleles from one population to another via migration
Gene flow can change allele frequencies in either or both populations.
What is genetic drift?
Changes to allele frequency by chance events or disasters
Genetic drift is particularly significant in small populations.
What is a genetic bottleneck?
Loss of genetic diversity following an extreme reduction in population size
It can result from starvation, disease, or natural disasters.
What is the founder effect?
Small number of individuals leave a population and establish a new population
The new population may have limited genetic diversity.
What is non-random mating?
Occurs when individuals select mates based on their phenotypes
Inbreeding and artificial selection are examples of non-random mating.
What is artificial selection?
Changes to a population caused by deliberate, selective breeding by humans
It can lead to reduced genetic diversity and increased vulnerability to diseases.
What does the Hardy-Weinberg principle describe?
The relationship between allele frequency and chances of those frequencies remaining constant
It provides a mathematical framework for studying genetic variation.
Fill in the blank: The equation representing the Hardy-Weinberg principle is _______.
A^2 + 2Aa + a^2 = 1
A = dominant allele, a = recessive allele.
What impact do human actions have on evolution?
Widespread effects on all species, influencing evolution through both intentional and unintentional means
Habitat loss and artificial selection are examples of human impacts on evolution.
