Hardy-Weinberg
What does the Hardy-Weinberg principle predict?
Allele and genotype frequencies will remain constant in a population if no evolutionary forces act on it.
Which type of selection favors the average phenotype?
Stabilizing selection
What is genetic drift?
A change in allele frequencies due to random chance
What is speciation?
The formation of new species
What is evolution defined as?
Change in a population’s characteristics over time
What are the five conditions required for Hardy-Weinberg equilibrium?
Large population, random mating, no mutations, no gene flow, no natural selection
Which type of selection favors one extreme phenotype?
Directional selection
What is the founder effect?
Genetic drift that occurs when a small group colonizes a new area
Name one post-zygotic barrier
Hybrid sterility/death
Why can't populations grow exponentially?
Carrying capacity- only so many organisms can exist in one environment at a time
Which Hardy-Weinberg condition would be the most difficult to maintain when studying a large population of worms in a lab?
No mutations
Which type of selection favors both extreme phenotypes over the average?
Disruptive selection
What is the bottleneck effect?
A sudden population reduction that changes allele frequencies
Name two prezygotic isolation barriers.
Temporal, behavioral, mechanical, habitat
What helps preserve genetic diversity in a population?
Heterozygote advantage, gene flow, mutations, frequency-dependent selection
Is it ever possible for a population to be in Hardy-Weinberg equilibrium? Why/why not?
Not really, impossible to prevent mutations
Give an example of directional selection in nature.
Ex: Beak size in Darwin’s finches during drought
What is assortative mating?
Mating between individuals with similar phenotypes
What is hybrid sterility?
A postzygotic barrier where offspring cannot reproduce
If a pesticide kills 90% of insects but 10% survive, what happens to the population over time?
It becomes mostly pesticide-resistant
Why does non-random mating violate Hardy-Weinberg?
Leads to sexual selection
What type of selection may lead to speciation by splitting a population into two phenotypic groups?
Disruptive selection
In a small population of lizards, a hurricane kills most of the individuals, leaving only a few survivors whose allele frequencies differ from the original population. Over generations, this leads to a significant reduction in genetic variation. What kind of genetic drift is this?
Bottleneck effect
What is the difference between prezygotic and postzygotic barriers?
Prezygotic prevents mating or fertilization; postzygotic affects offspring viability or fertility
How can species be identified? (2 ways)
Biological, morphological, ecological, phylogenetic species concepts