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What are the three main components of natural selection?
What are the three main components of natural selection?
What was Hopi's hypothesis regarding coat color in mice?
What was Hopi's hypothesis regarding coat color in mice?
Which of the following represents a method used to test the predictions of Hopi's hypothesis?
Which of the following represents a method used to test the predictions of Hopi's hypothesis?
What is meant by 'differential reproductive success' in the context of natural selection?
What is meant by 'differential reproductive success' in the context of natural selection?
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What outcome supported Hopi's hypothesis about mouse coat color after testing the predictions?
What outcome supported Hopi's hypothesis about mouse coat color after testing the predictions?
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What is a life history trait?
What is a life history trait?
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What is a trade-off in the context of energy allocation?
What is a trade-off in the context of energy allocation?
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In a life table, what does the term R0 represent?
In a life table, what does the term R0 represent?
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What does the intrinsic rate of increase (r) indicate?
What does the intrinsic rate of increase (r) indicate?
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Why might older organisms have increased fecundity?
Why might older organisms have increased fecundity?
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What might be a reason for organisms to delay reproduction?
What might be a reason for organisms to delay reproduction?
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What does lx represent in a life table?
What does lx represent in a life table?
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What does a high mortality rate for young organisms imply for their life history strategy?
What does a high mortality rate for young organisms imply for their life history strategy?
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Which hypothesis suggests that chameleons from the Seychelles and Africa share a common ancestor?
Which hypothesis suggests that chameleons from the Seychelles and Africa share a common ancestor?
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How is coalescence time affected by population size?
How is coalescence time affected by population size?
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What does the term 'coalescence' refer to in evolutionary biology?
What does the term 'coalescence' refer to in evolutionary biology?
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Which scenario leads to coalescence happening quickly in the recent past?
Which scenario leads to coalescence happening quickly in the recent past?
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What does inference in the context of evolutionary biology involve?
What does inference in the context of evolutionary biology involve?
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According to the hypotheses, what is one way chameleons may have colonized the Seychelles?
According to the hypotheses, what is one way chameleons may have colonized the Seychelles?
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What effect does random reproductive success have on coalescence times?
What effect does random reproductive success have on coalescence times?
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What does prediction involve in the context of population dynamics?
What does prediction involve in the context of population dynamics?
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What does a phylogeny represent in the study of organisms?
What does a phylogeny represent in the study of organisms?
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What is the purpose of using a molecular clock in phylogenetic studies?
What is the purpose of using a molecular clock in phylogenetic studies?
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How can phylogenies determine the geographic history of a group of organisms?
How can phylogenies determine the geographic history of a group of organisms?
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Which of the following is indicated by a phylogenetic tree regarding lice evolution?
Which of the following is indicated by a phylogenetic tree regarding lice evolution?
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Why is the date of a most recent common ancestor important in phylogenetic studies?
Why is the date of a most recent common ancestor important in phylogenetic studies?
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What does the concept of a common ancestral lineage explain in the context of geography?
What does the concept of a common ancestral lineage explain in the context of geography?
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What does the statement 'humans would not have had body lice until they started wearing clothes' imply?
What does the statement 'humans would not have had body lice until they started wearing clothes' imply?
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What is a critical method for understanding the timing of evolutionary events among organisms?
What is a critical method for understanding the timing of evolutionary events among organisms?
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Study Notes
Natural Selection
- Natural selection has three components: variation, inheritance, and differential reproductive success.
- Hopi's hypothesis was that coat color in mice matches the local environment.
- Alternative explanations include environmental factors like sun exposure or diet affecting coat color.
- Predictions of the hypothesis include variation (variation in coat color within populations), inheritance (genetic variation associated with coat color variation), and differential reproductive success (mice with mismatched coats are more susceptible to predators).
- The predictions were verified, which supported the hypothesis.
Organism Fitness
- Life history traits affect survival and reproduction.
- Energy is limited and must be allocated to different functions.
- Reproduction often comes at the cost of survival or maintenance.
Role of Chance in Evolution
- The law of large numbers states that random events tend toward an average outcome with many repetitions.
- Locus is a physical location of DNA on a chromosome.
- Gene is a locus that codes for a protein.
- Allele is a single variant of a gene.
- Frequency is the proportion of individuals in a population with a certain trait.
- Diploid is a state of having two sets of chromosomes.
- Genotype is a set of alleles in an individual's genome.
- Heterozygote is an individual with two different alleles at a given gene.
- Heterozygosity is the frequency of heterozygotes in a population.
- Genetic drift changes allele frequencies over time due to random sampling, especially in small populations.
- Allele frequencies fluctuate over time in finite populations, even without natural selection, some alleles fix or are lost, and heterozygotes become less common.
- Separate populations diverge in allele frequencies due to this random process.
Phylogenies
- A phylogeny is a diagram showing the pattern of shared ancestral relationships among organisms.
- Shared ancestry leads to similarities in phenotypes (observable traits).
- Phylogenies resemble family trees.
- Phylogeny shows how closely related organisms are.
- Branching on a phylogeny represents a single lineage splitting and evolving in different directions.
- Each line on a phylogeny represents a lineage.
- Ancestral lineages are found along the branches.
- Common ancestors are identified on the phylogeny.
- The age of the most recent common ancestor is a way of quantifying how related organisms are.
- Phylogenies are based on the assumption that all life forms share a common origin.
How Traits Evolve
- Species trees and gene trees show genealogical information.
- Coalescence occurs when gene lineages trace back in time to their most recent common ancestor; this time varies depending on population size. Random sampling during reproduction leads to changes in allele frequencies.
- There are two measures of variation over time: (1) The time taken for lineages to converge, (2) population size. As time stretches out the smaller the populations the quicker convergence occurs.
New Species Formation (Speciation)
- Biological species are interbreeding natural populations, reproductively isolated from other groups.
- Cryptic species are species that look the same but are distinct genetically.
- Species boundaries aren't fixed; they can change over time.
- Reproductive barriers are required for speciation.
- Geographic barriers, behavioral barriers, and timing barriers can isolate populations.
- Genetic incompatibilities might also form.
- Genetic drift causes differences between populations.
- Natural selection can favor different traits in isolated populations, leading to divergence.
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Description
Explore the key principles of natural selection, including variation, inheritance, and reproductive success. This quiz examines hypotheses about organism fitness and the impact of chance on evolutionary outcomes. Test your understanding of these fundamental biological concepts.
