Population Genetics Dynamics
How would you describe what population genetics helps scientists understand about groups of organisms over time?
Population genetics describes how allele frequencies in a population change over time due to evolutionary forces (e.g., selection, drift, mutation, migration).
What do we call a variant form of a gene that contributes to variation in a trait?
An allele
Why might the Hardy-Weinberg model not perfectly reflect what actually happens in natural populations?
Because real populations experience mutation, selection, gene flow, genetic drift, and non-random mating, which violate Hardy-Weinberg assumptions.
How would you explain genetic drift as a mechanism of evolution?
Genetic drift is a random change in allele frequencies due to chance events, especially in small populations.
How is “fitness” defined in terms of evolutionary success?
Fitness is an organism’s ability to survive and reproduce, passing on its genes to the next generation.
What do we call the smaller group selected from a population that is used to represent the whole?
A sample.
How is tracking genotype frequencies different from tracking allele frequencies?
Genotype frequency refers to the proportion of individuals with a specific combination of alleles, while allele frequency refers to how common a specific allele is in the population overall.
Why is having a large population size important for maintaining Hardy-Weinberg conditions?
Large populations reduce the effects of genetic drift, making allele frequencies more stable and closer to Hardy-Weinberg expectations.
What is it called when one allele gets eliminated from a population?
Extinction
What are the two main factors that contribute to an organism’s fitness, and how do they influence survival?
Survival (viability): the ability to live long enough to reproduce
Reproductive success (fecundity): the ability to produce viable offspring
What term refers to the complete collection of all alleles present within a population?
Gene pool
In the Hardy-Weinberg model, what does the variable p tell us about a population?
The frequency of the dominant allele in the population.
What does it indicate about a population if it is in Hardy-Weinberg equilibrium?
It means allele and genotype frequencies remain constant across generations; no evolution is occurring.
What is the term for a situation where only one allele remains for a particular gene in a population?
Fixation
What does MRCA stand for, and what does this concept help scientists trace?
MRCA stands for Most Recent Common Ancestor, the most recent individual from which all members of a group are descended.
How do we describe genes that exist in multiple forms at a specific location in the DNA sequence?
Polymorphic genes
Homozygous dominant: p2
Homozygous recessive: q2
What are the 2 Hardy-Weinberg equations?
p + q = 1
p2 + 2pq + q2 = 1
Can you describe a real or hypothetical scenario that demonstrates the founder effect?
Example: A small group of individuals colonizes an island; their allele frequencies differ from the original population, leading to reduced genetic variation (founder effect).
How is genetic ancestry different from biological (or genealogical) ancestry?
Genetic ancestry is based on DNA inheritance, while biological (genealogical) ancestry includes all ancestors in a family tree, regardless of whether DNA was inherited from them.
How do allele frequency patterns differ between a real-world population and one that meets all conditions of Hardy-Weinberg equilibrium?
In real populations, allele frequencies often change due to evolutionary forces; in a Hardy-Weinberg population, allele frequencies remain constant across generations because no evolutionary forces are acting.
In the Hardy-Weinberg equation, how is the frequency of individuals with two different alleles represented?
2pq
How does a Hardy-Weinberg Punnett square differ in purpose or interpretation from a typical Punnett square used in Mendelian genetics?
A Hardy-Weinberg Punnett square models allele frequencies in a population (unequal probabilities are reflected by unequal box sizes), while a normal Punnett square reflects the same sizes boxes indicating a 50/50 chance of getting each allele.
What types of events can lead to a sudden and dramatic reduction in population size, resulting in a bottleneck?
Events like natural disasters, disease outbreaks, or human activities.
What biological mechanism allows scientists to estimate the timing of evolutionary events using DNA?
Mutation rates in DNA provide a molecular clock for estimating evolutionary timelines since they occur at a relatively consistent rate.