Podcast
Questions and Answers
What is the process that gives rise to most allopolyploids?
What is the process that gives rise to most allopolyploids?
- Uniparental disomy
- Clonal reproduction
- Hybridization followed by chromosome doubling (correct)
- Chromosome fragmentation
What role does polyploidy play in the colonization of new environments?
What role does polyploidy play in the colonization of new environments?
- It solely increases plant size.
- It restricts populations to specific climates.
- It reduces genetic variation in populations.
- It enhances adaptability to diverse habitats. (correct)
In the common garden experiment with Achillea borealis, which plants were monitored for survival?
In the common garden experiment with Achillea borealis, which plants were monitored for survival?
- Diploid and hexaploid plants
- Tetraploid and neo-hexaploid plants (correct)
- Allopolyploid and diploid plants
- Only hexaploid plants
Which environment is associated with tetraploid populations of Achillea borealis?
Which environment is associated with tetraploid populations of Achillea borealis?
How does genome duplication generally affect plant adaptation?
How does genome duplication generally affect plant adaptation?
What is the effect of natural selection on body size in fly populations according to the findings?
What is the effect of natural selection on body size in fly populations according to the findings?
How does polyploidy affect genetic variation in organisms?
How does polyploidy affect genetic variation in organisms?
What is a consequence of failed segregation during meiosis that can result in polyploidy?
What is a consequence of failed segregation during meiosis that can result in polyploidy?
Which of the following is NOT a way polyploidy is important in evolution?
Which of the following is NOT a way polyploidy is important in evolution?
What is one way that inversions in Drosophila are related to adaptation?
What is one way that inversions in Drosophila are related to adaptation?
Which of these statements about clines and body size in fly populations is accurate?
Which of these statements about clines and body size in fly populations is accurate?
What does polyploidy alter in organisms that can contribute to evolution?
What does polyploidy alter in organisms that can contribute to evolution?
What role do the inversions in Drosophila play in relation to climate adaptation?
What role do the inversions in Drosophila play in relation to climate adaptation?
What is a nonsynonymous (or replacement) substitution mutation?
What is a nonsynonymous (or replacement) substitution mutation?
How do new genes, such as those associated with chondrodysplasia, typically arise in organisms?
How do new genes, such as those associated with chondrodysplasia, typically arise in organisms?
What distinguishes paralogous genes from orthologous genes?
What distinguishes paralogous genes from orthologous genes?
Which process can lead to the creation of new alleles in a population?
Which process can lead to the creation of new alleles in a population?
What is a synonymous (or silent) substitution mutation?
What is a synonymous (or silent) substitution mutation?
What is the result of mutations that are not repaired and become premutations?
What is the result of mutations that are not repaired and become premutations?
Which mechanism is most associated with the generation of genes from scratch?
Which mechanism is most associated with the generation of genes from scratch?
How does genome duplication influence phenotypic adaptation?
How does genome duplication influence phenotypic adaptation?
Study Notes
Cline Evidence for Natural Selection
- Cline patterns in Drosophila body size are consistent across North America, South America, and Europe.
- These parallel clines demonstrate that the body size variation is not a result of historical accident but is driven by natural selection.
- Larger flies are favored in cold, wet climates, while smaller flies are favored in hot, dry areas.
- Genes located in inversions play a role in influencing body size.
Genome Duplication and Polyploidy
- Polyploidy, the condition of having more than two sets of chromosomes, can arise due to errors in meiosis (meiosis I or II).
- Polyploidy can lead to the formation of new species by altering cell size, geometry, and gene dosage, resulting in novel phenotypes.
Polyploidy and Speciation
- Most allopolyploids result from hybridization between two species followed by chromosome doubling.
- Polyploidy facilitates adaptation to new environments.
- A common garden experiment with Achillea borealis showed that tetraploid populations thrive in coastal grasslands, conifer forests, and mountain meadows, while hexaploid populations are found in sand dunes and oak woodlands.
New Alleles and Gene Formation
- Mutations are changes in the DNA sequence.
- Spontaneous deamination is a common type of mutation that can lead to new alleles.
- Premutations are DNA alterations that are susceptible to repair.
Mutation Effects on Protein Function
- Mutations can lead to changes in the encoded protein, impacting its structure and function.
- Synonymous (silent) substitutions are mutations that do not change the encoded amino acid.
- Nonsynonymous (replacement) substitutions alter the amino acid specified by a codon, potentially affecting protein function.
Mechanisms of Gene Duplication
- Gene duplication is a major source of new genes.
- Unequal crossing over: During meiosis, misalignment of homologous chromosomes can result in one chromosome gaining DNA and the other losing it, creating a duplicate copy of a gene.
- Retroposition: A copy of an mRNA molecule is reverse transcribed into DNA and inserted into the genome, creating a new gene.
Example of Gene Duplication:
- A duplicate copy of the gene for fibroblast growth factor 4 (fgf4) is found in some dog breeds, contributing to chondrodysplasia, a condition characterized by short legs.
New Genes from Scratch
- C22orf45 is a gene with an unknown function that is unique to humans.
- The appearance of entirely new genes is rare but a significant evolutionary process.
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Description
This quiz explores the evidence for natural selection through cline patterns in Drosophila body size across different climates. It also delves into the concepts of genome duplication and polyploidy, discussing their roles in speciation and adaptation. Test your understanding of these evolutionary processes!
