Genetic Diversity and Evolution Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which process is specifically known to decrease genetic diversity within populations?

Recombination

Natural selection

Genetic drift (correct)

Mutation

What metric measures the fraction of individuals that are heterozygous across gene loci?

Polymorphism (P)

Allelic diversity (A)

Heterozygosity (H) (correct)

Genetic variance (G)

Which factor maintains genetic variation through the reintroduction of less fit types?

Natural selection

Mutation-selection balance (correct)

Heterozygote advantage

Genetic drift

Which of the following has the potential to both increase and decrease genetic diversity?

Natural selection Signup and view all the answers

What term describes the proportion of gene loci with two or more alleles in a population?

Polymorphism Signup and view all the answers

Which school of thought emphasizes the importance of balancing selection in maintaining genetic variation?

Balance school Signup and view all the answers

Which process is NOT directly mentioned as increasing genetic diversity?

Genetic drift Signup and view all the answers

The principle behind the heterozygote advantage suggests that which individuals have higher fitness?

Heterozygous individuals Signup and view all the answers

What does the selection response indicate about polygenic quantitative traits?

They exhibit abundant genetic variation. Signup and view all the answers

Why is it challenging to conduct comparative studies on traits?

Traits studied are often group specific. Signup and view all the answers

What fundamental question do Lewontin's allozyme studies aim to address?

What proportion of genes are variable? Signup and view all the answers

What advantage do enzyme polymorphism studies provide?

They allow identification of heterozygotes. Signup and view all the answers

What type of genes can be identified through protein electrophoresis?

Both monomorphic and polymorphic genes. Signup and view all the answers

What was a significant outcome of the first allozyme studies?

Genetic variation is very high. Signup and view all the answers

What do allozymes represent?

Different allelic forms of the same protein. Signup and view all the answers

What does the presence of high genetic variation suggest for natural populations?

They have the potential for evolutionary change. Signup and view all the answers

What is the primary focus of early quantitative genetic evidence?

Continuous polygenic traits Signup and view all the answers

What method is commonly used to study genetic variation in populations?

Controlled breeding of selected individuals Signup and view all the answers

What does the selection response for bristle number in fruit flies demonstrate?

Heritable variation in a fitness-related phenotype Signup and view all the answers

What happens when selection is relaxed in maize populations?

The mean trait value can shift significantly Signup and view all the answers

What potential explanation exists for evolutionary responses in continuous traits?

Many alleles at intermediate frequency changing in frequency Signup and view all the answers

What is a common outcome of artificial selection based on controlled breeding?

Reduced genetic variation in the population Signup and view all the answers

Which of the following describes the relationship between many underlying genes and phenotypes?

Continuous traits are influenced by multiple genes Signup and view all the answers

What is the likely effect of initially rare and deleterious alleles when selection resumes?

They increase in frequency despite their effects Signup and view all the answers

Which factor contributes to the maintenance of genetic variation in natural populations?

Heterozygote advantage prevents extinction. Signup and view all the answers

What is a consequence of negative selection in the context of genetic variations?

It eliminates detrimental mutations quickly. Signup and view all the answers

Which statement accurately describes selectively neutral variation?

It does not affect fitness relative to other mutations. Signup and view all the answers

What is the role of balancing selection in maintaining genetic diversity?

Favors variations that confer fitness advantages. Signup and view all the answers

Which of the following describes the mutation-selection balance concept?

Less fit types persist due to ongoing mutation inputs. Signup and view all the answers

In the context of genetic variation, what does the term 'frequency-dependent selection' imply?

The fitness of a phenotype depends on its frequency in the population. Signup and view all the answers

What is a significant consequence of the population bottleneck during the domestication of maize?

Reduced genetic diversity in maize compared to teosinte. Signup and view all the answers

What does the Neutral Theory suggest about molecular variation?

Neutral mutations provide a base for evolutionary changes. Signup and view all the answers

What is the primary factor that distinguishes changes in the genetic code that affect protein from those that do not?

Direct inference of genetic differences. Signup and view all the answers

Which of the following describes mutation-selection balance in a population?

Neutral and detrimental mutations persist due to constant mutation inputs. Signup and view all the answers

How does the DNA sequence variation in natural populations generally manifest?

1 in 50 bases are polymorphic. Signup and view all the answers

What effect did selection on certain genes have on maize's DNA diversity compared to teosinte?

It reduced maize DNA diversity beyond expectations from genetic drift. Signup and view all the answers

What is the DNA diversity comparison between maize and its wild ancestor, teosinte?

Maize has reduced DNA diversity compared to teosinte. Signup and view all the answers

What is a major difference between maize and teosinte at the genetic level?

Maize has undergone significant genetic selection reducing its diversity. Signup and view all the answers

What does DNA sequence diversity indicate concerning bases in natural populations?

There is approximately 1 base polymorphic per 1200 bases. Signup and view all the answers

Which statement best describes the genetic makeup of maize as a result of domestication?

It represents a reduced genetic variability due to founder effects. Signup and view all the answers

Study Notes

Forces Influencing Genetic Diversity and Evolution

Mutation, recombination, and migration tend to increase genetic diversity.
Genetic drift tends to decrease genetic diversity.
Natural selection can increase or decrease genetic diversity.

Measuring Genetic Variation

Heterozygosity (H): The fraction of heterozygous individuals across gene loci.
Polymorphism (P): The proportion of gene loci with two or more alleles. A locus can be polymorphic without being heterozygous.

Maintaining Genetic Variation

Mutation-selection balance: Less-fit types are reintroduced by mutation and subsequently removed by selection.
Balancing selection: Includes heterozygote advantage, frequency-dependent selection, and fitness varying across space or time.

Early Evidence for Genetic Variation

Early quantitative genetic studies focused on continuous polygenic traits, using artificial selection experiments across multiple generations.
These experiments demonstrated heritable variation in fitness-related phenotypes, influenced by many underlying genes. However, information on P and H was often lacking.

Allozyme Electrophoresis and Genetic Variation

Allozyme gel electrophoresis allowed for measuring the proportion of variable genes (P and H).
Studies revealed high levels of genetic variation in diverse organisms. Higher than predicted by the classical school of thought.

Interpreting High Genetic Variation

High genetic variation can be explained by mutation-selection balance, balancing selection, and selectively neutral variation.

Neutral Theory

The neutral theory suggests that most molecular variation is selectively neutral. Negative selection eliminates detrimental mutations, positive selection fixes beneficial ones, leaving only neutral mutations to contribute to variation.

DNA-Level Genetic Variation Studies

Direct DNA sequencing provides more precise measurements of genetic differences, distinguishing changes affecting protein function from neutral ones.

DNA Variation Across Organisms

Significant variation exists in DNA sequences across different organisms, with some having higher levels of polymorphism than others.

DNA Variation in Maize vs. Teosinte

Domesticated maize exhibits reduced genetic diversity compared to its wild ancestor, teosinte. This is attributed to population bottlenecks during domestication, further compounded by selection on specific genes.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the fundamental concepts of genetic diversity and the forces that influence evolution, including mutation, recombination, and natural selection. Assess your understanding of genetic variation and the mechanisms that maintain it through various selections. This quiz covers key principles from genetics and evolutionary biology.