Mechanisms of Evolution and Adaptation

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Questions and Answers

Explain how heritable variation is essential for natural selection to occur. Why is acquired variation not relevant to natural selection?

Heritable variation provides the raw material upon which natural selection acts, favoring advantageous traits that are passed on. Acquired variation, resulting from environmental factors, isn't passed on to offspring, so it cannot be selected for or against.

Define continuous variation, and provide an example. Explain how both genetic and environmental factors can influence continuous variation.

Continuous variation shows a complete range of measurements from one extreme to the other. Height is an example. Genetic factors determine the potential range, while environmental factors, like nutrition, influence where an individual falls within that range.

What is discontinuous variation? Give one example from blood types or color blindness. Why are there no intermediate values?

Discontinuous variation shows defined categories with no intermediate values, like blood type (A, B, AB, O). There are no intermediate values because these traits are determined by single genes with distinct alleles, resulting in discrete phenotypes.

Describe TWO ways in which sexual reproduction generates variation in offspring. Explain briefly how each mechanism works.

Sexual reproduction generates variation through independent assortment and random mating. Independent assortment shuffles chromosomes during meiosis. Random mating combines different genetic combinations from two parents. Signup and view all the answers

Define mutation, and explain its significance as the primary source of new genetic variation in a population.

Mutation is a change in the nucleotide sequence of DNA. Mutations lead to new alleles, which are essential for evolutionary change. Without mutation there would be no new diversity upon which selection can act. Signup and view all the answers

Distinguish between point mutations and frameshift mutations. Briefly explain how each type of mutation affects the protein that is ultimately produced.

Point mutations involve changes at a single nucleotide base. Frameshift mutations involve insertions or deletions that alter the reading frame. Point mutations can change a single amino acid. Frameshift mutations can drastically alter the amino acid sequence and protein function. Signup and view all the answers

Explain the difference between somatic and germline mutations. Which type of mutation has the potential to drive evolutionary change in a population? Why?

Somatic mutations occur in body cells and aren't passed on. Germline mutations occur in reproductive cells and can be inherited. Germline mutations can drive evolutionary change because they are passed on to future generations Signup and view all the answers

Define natural selection. Explain how it leads to adaptation in populations over time, making them better suited to their environments.

Natural selection involves differential survival and reproduction based on heritable traits. Individuals with advantageous traits are more likely to survive and reproduce, passing on those traits to their offspring. Over many generations, this process leads to adaptation. Signup and view all the answers

Describe how high population density can affect selection pressure within a population. Give a specific example.

High population density can lead to increased competition for resources, such as food, water, and shelter. This creates stronger selection pressure. For example, in a dense population of plants, individuals that can grow taller and access more sunlight will have a selective advantage. Signup and view all the answers

Explain how limited resources and predation can act as selection pressures on a population, driving evolutionary change.

Limited resources and predation exert selection pressure by favoring individuals with traits that allow them to better acquire resources or avoid predators. Over time, these traits become more common in the population, leading to evolutionary change. For example, faster cheetahs will be more likely to eat, and slower gazelles will be less likely to be eaten. Signup and view all the answers

Flashcards

Heritable Variation

Changes in genetic material that can be passed to offspring, crucial for evolution.

Continuous Variation

Variation influenced by both genetic and environmental factors, showing a complete range of measurements.