Evolution of Populations Chapter 18

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Questions and Answers

What are the consequences of mutations on phenotypes?

Mutations can either be neutral, cause lethal diseases, or affect phenotypes differently. (correct)

Mutations always cause changes in phenotypes.

Mutations never affect the phenotypes.

Only lethal diseases can be caused by mutations.

How does genetic recombination occur during sexual reproduction in humans?

One member of each chromosome pair is shuffled randomly into each egg and sperm. (correct)

Genomes of both parents are mixed entirely at random without any specific mechanism.

Each chromosome in humans is copied twice before being passed to offspring.

All genes are recombined except for those on sex chromosomes.

What factor increases genetic variation by picking up a 'new' gene?

Lateral gene transfer (correct)

Natural selection

Genetic recombination

Mutations

What primarily determines the number of phenotypes for a given trait?

The number of genes controlling the trait Signup and view all the answers

How can natural selection affect single-gene traits?

By producing changes in phenotype frequencies through changes in allele frequencies Signup and view all the answers

Which is NOT a way that reproductive isolation can develop?

Habitat Isolation Signup and view all the answers

What is the primary result of reproductive isolation between two populations?

Complete cessation of gene flow between the populations Signup and view all the answers

Which isolation occurred due to differences in courtship rituals in Darwin’s finches?

Behavioral Isolation Signup and view all the answers

Which effect describes a change in allele frequencies due to the migration of a small subgroup?

Founder Effect Signup and view all the answers

What type of isolation occurs when species reproduce at different times?

Temporal Isolation Signup and view all the answers

Which event is considered the initial step leading to speciation in the Galapagos finches?

Founders Arrival Signup and view all the answers

What can result in a dramatic reduction in genetic diversity?

Genetic Bottlenecks Signup and view all the answers

In which scenario is genetic equilibrium achieved?

When allele frequencies are not changing Signup and view all the answers

Which of the following best describes polygenic traits?

Traits controlled by two or more genes Signup and view all the answers

Which phenomenon can occur in small populations leading to changes in allele frequency by chance?

Genetic Drift Signup and view all the answers

What does the gene pool of a population consist of?

All genes present in the population Signup and view all the answers

Which statement best describes how allele frequency changes in a population over time?

Evolution involves any change in allele frequency over time. Signup and view all the answers

What does natural selection act upon in an organism?

Its phenotype only Signup and view all the answers

Which of the following is NOT a source of genetic variation?

Inbreeding Signup and view all the answers

Which activities are directly responsible for generating variation in chromosomes?

Recombination during sexual reproduction Signup and view all the answers

What role do Hox genes play in the development of an embryo?

Determine which side of an embryo grows the different body parts Signup and view all the answers

How does genetic rearrangement influence eukaryotic cells?

It makes eukaryotic cells more complex Signup and view all the answers

What factor contributed to the adaptation and natural selection of birds in the Galapagos Islands?

A different environment on the islands Signup and view all the answers

Which factor influenced the mutation variations among birds from different islands in the Galapagos?

How plants produced their nuts Signup and view all the answers

What is the purpose of a molecular clock in genetic studies?

To estimate the time that two species have been evolving independently Signup and view all the answers

Why did birds from different islands in the Galapagos exhibit behavioral isolation?

They would not mate with each other due to beak size preferences Signup and view all the answers

What can small changes in Hox gene activity during the embryological stage cause?

Big changes in adult animals Signup and view all the answers

What is the significance of 'ticks' in the context of molecular clocks?

They help identify how many mutations happen in a human body Signup and view all the answers

How does the degree of specialization in birds impact competition for resources?

More specialized birds face less competition Signup and view all the answers

What is one way new genes can evolve according to molecular evolution?

Duplication and modification of existing genes Signup and view all the answers

Study Notes

Genes and Variations

Genetic information is stored in chromosomes, which generate variation
A gene pool consists of all genes present in a population
Allele frequency is the number of times an allele occurs in a gene pool as a percentage of the total alleles for that gene
Evolution involves any change in allele frequency in a population over time
Genotype refers to an organism's genetic makeup, while phenotype refers to its physical characteristics

Sources of Genetic Variation

Mutation: a heritable change in genetic information
Genetic recombination during sexual reproduction: shuffling of genes during meiosis
Lateral gene transfer: gene flow can increase genetic variation and introduce new genes

Single-Gene and Polygenic Traits

Single-gene traits: controlled by one gene
Polygenic traits: controlled by two or more genes
Natural selection on single-gene traits can produce changes in allele frequencies reflected in phenotype frequencies

Genetic Drift and Bottlenecks

Genetic drift: random change in allele frequency in small populations
Founder effect: allele frequencies change due to migration of a small subgroup
Genetic bottleneck: reduction in genetic diversity due to a dramatic decrease in population size

Speciation and Isolating Mechanisms

Reproductive isolation: when two populations stop interbreeding altogether
Behavioral isolation: differences in courtship rituals or behaviors
Geographic isolation: separation by geographic barriers
Temporal isolation: reproduction at different times
Speciation in Darwin's finches: geographic isolation, changes in gene pool, behavioral isolation, and ecological competition

Molecular Evolution

New genes can evolve through duplication and modification of existing genes
Gene duplication: copy of a gene can mutate and take on a new function
Genetic rearrangement: chromosomes can break and reconnect, acquiring new sequences of DNA

Developmental Genes and Body Plans

Hox genes determine the body plan of an embryo
Small changes in hox gene activity during embryological stage can produce big changes in adult animals

Molecular Clocks and Neutral Mutations

Molecular clock: uses mutation rates in DNA to estimate time of independent evolution
Ticks: measure the number of mutations that occur in a human body over time

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Description

This quiz covers the fundamentals of population evolution, including genes, variations, heritable traits, chromosomes, and allele frequency. Understand how genetic definitions shape species and populations.