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Chapter 22: Problem 24

What genetic changes take place during speciation?

Short Answer

Expert verified
Short Answer: Speciation occurs due to genetic changes within populations, primarily driven by genetic variation, reproductive isolation, and natural selection. Genetic variation arises from mutations, genetic recombination, and gene flow. Reproductive isolation prevents gene flow between diverging populations, allowing genetic differences to accumulate. Natural selection acts on genetic variation, favoring certain traits in different environments and leading to adaptive evolution, eventually resulting in the formation of distinct species.

Step by step solution

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1. Understanding the process of Speciation

Speciation is a process in which a single species evolves into one or more distinct species due to genetic changes. This can occur through several mechanisms, such as allopatric speciation (geographical isolation), sympatric speciation (reproductive isolation within the same geographical area), or hybrid speciation (the formation of a new species through hybridization of two closely related species). It is essential to understand the concept of speciation to analyze the genetic changes that occur during this process.
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2. Identifying sources of Genetic Variation

Genetic variation is essential for speciation as it provides the raw material for natural selection to act upon. The sources of genetic variation include mutations, genetic recombination during sexual reproduction (crossing-over and independent assortment), and gene flow (movement of genes between populations). Understanding these sources of genetic change is critical for analyzing the process of speciation.
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3. Explaining the role of Reproductive Isolation

Reproductive isolation is a key factor in the speciation process, as it prevents gene flow between diverging populations and allows genetic differences to accumulate. Reproductive isolation can occur due to prezygotic barriers (e.g., mating preferences, differences in timing or habitat preferences) or postzygotic barriers (e.g., hybrid inviability or sterility). Recognizing the importance of reproductive isolation in speciation helps to explain the genetic changes that take place during this process.
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4. Describing the role of Natural Selection in Speciation

Natural selection acts on the genetic variation within populations and drives the evolution of new species. It is essential to understand how natural selection can lead to genetic changes during speciation. In different environments or under different selection pressures, certain traits may be favored over others, leading to an increase in the frequency of those traits in the population. This process, called adaptive evolution, can ultimately result in the formation of new species.
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5. Summing up the Genetic Changes during Speciation

During speciation, genetic changes occur within populations due to genetic variation, reproductive isolation, and natural selection. These changes can accumulate over time, leading to the formation of new and distinct species. By understanding the steps and factors involved in speciation, we can appreciate the intricate process that drives the diversification of life on Earth.

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Most popular questions from this chapter

Population geneticists study changes in the nature and amount of genetic variation in populations, the distribution of different genotypes, and how forces such as selection and drift act on genetic variation to bring about evolutionary change in populations and the formation of new species. From the explanation given in the chapter, what answers would you propose to the following fundamental questions? (a) How do we know how much genetic variation is in a population? (b) How do geneticists detect the presence of genetic variation as different alleles in a population? (c) How do we know whether the genetic structure of a population is static or dynamic? (d) How do we know when populations have diverged to the point that they form two different species? (e) How do we know the age of the last common ancestor shared by two species?

Are there nucleotide substitutions that will not be detected by electrophoretic studies of a gene's protein product?

A certain form of albinism in humans is recessive and autosomal. Assume that \(1 \%\) of the individuals in a given population are albino. Assuming that the population is in Hardy-Weinberg equilibrium, what percentage of the individuals in this population is expected to be heterozygous?

The genetic difference between two Drosophila species, \(D\). heteroneura and \(D .\) sylvestris, as measured by nucleotide diversity, is about 1.8 percent. The difference between chimpanzees (P. troglodytes) and humans (H. sapiens) is about the same, yet the latter species are classified in different genera. In your opinion, is this valid? Explain why.

In a population of cattle, the following color distribution was noted: \(36 \%\) red \((R R), 48 \%\) roan \((R r),\) and \(16 \%\) white \((r r) .\) Is this population in a Hardy-Weinberg equilibrium? What will be the distribution of genotypes in the next generation if the HardyWeinberg assumptions are met?
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