Evolution can be tracked by changes in allele frequencies within populations. This lesson introduces the Hardy-Weinberg equilibrium principle and explains how natural selection and mutation can change a population's genetic makeup.
The Hardy-Weinberg equilibrium principle provides a reference point for understanding evolution. It states that allele frequencies in a population will remain constant from generation to generation when the evolutionary forces that can change them are absent.
All flashcards
What is Hardy-Weinberg equilibrium?
A condition in which allele frequencies remain constant across generations when evolutionary forces that change them are absent.
How can natural selection affect allele frequency?
When a phenotype associated with an allele improves reproductive success, carriers may leave more offspring, making the allele more common in later generations.
What is a mutation?
A change in a gene's DNA sequence that can alter an allele and is the ultimate source of new alleles and genetic variation.
How can beneficial and harmful mutations differ in their outcomes?
Selection may favor and spread a beneficial mutation, while it may remove a harmful mutation, which is generally maintained at a low frequency related to the mutation rate.
What determines whether a mutation is beneficial, harmful, or neutral?
Its effects on survival to sexual maturity and reproduction in the relevant environmental conditions determine its selective effect.
Quiz questions
What does the Hardy-Weinberg equilibrium principle predict when evolutionary forces are absent?Answer: Allele frequencies remain constant across generations.
How can natural selection increase the frequency of an allele?Answer: Carriers with an associated reproductive advantage may leave more offspring.
Why is mutation considered the ultimate source of new alleles?Answer: Changes in DNA sequence can produce alleles that were not previously present.
What causes genetic drift?Answer: Chance changes in which alleles are passed between generations.
Why does genetic drift generally have a stronger effect in small populations?Answer: A chance event can affect a larger proportion of the population's gene pool.
Based on Concepts of Biology by Samantha Fowler, Rebecca Roush, James Wise (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.