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Ch. 24 - Speciation
Freeman - Biological Science 8th Edition
Freeman8th EditionBiological ScienceISBN: 9780138276263Not the one you use?Change textbook
Chapter 24, Problem 13

A revolution in the study of human evolution is under way thanks to the invention of techniques that enable DNA sequencing of not only modern humans, but also ancient humans. Modern humans (Homo sapiens) and archaic humans called Neanderthals (H. neanderthalensis) shared a common ancestor in Africa but diverged in different geographic areas. When modern humans migrated out of Africa and dispersed around the world starting about 100,000 years ago, they overlapped with Neanderthals in Europe. This scenario is best described as
a. Species living in sympatry following allopatric speciation
b. Species living in sympatry following sympatric speciation
c. Species living in allopatry following allopatric speciation
d. Species living in allopatry following sympatric speciation

Verified step by step guidance
1
Understand the definitions of sympatry and allopatry: Sympatry refers to species living in the same geographic area, while allopatry refers to species living in separate geographic areas.
Understand the definitions of allopatric and sympatric speciation: Allopatric speciation occurs when a species is divided by a geographic barrier, leading to speciation due to physical separation. Sympatric speciation occurs without geographic separation, often through ecological or behavioral differences.
Analyze the scenario: Modern humans and Neanderthals shared a common ancestor in Africa but diverged in different geographic areas, indicating initial allopatric speciation.
Consider the migration and overlap: When modern humans migrated out of Africa, they overlapped with Neanderthals in Europe, indicating that they were living in sympatry at that point.
Combine the concepts: The scenario describes species that initially underwent allopatric speciation and later lived in sympatry, which aligns with option a: species living in sympatry following allopatric speciation.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Allopatric Speciation

Allopatric speciation occurs when a population is geographically separated, leading to the evolution of distinct species due to isolation. This separation prevents gene flow between groups, allowing them to evolve independently. Over time, genetic differences accumulate, resulting in the emergence of new species adapted to their specific environments.
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Allopatric Speciation

Sympatry

Sympatry refers to the condition where two or more species live in the same geographic area and regularly encounter one another. Despite sharing the same environment, these species maintain distinct identities and do not interbreed, often due to behavioral, ecological, or temporal barriers that prevent gene flow between them.
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Human Migration and Interaction

Human migration out of Africa involved Homo sapiens dispersing globally, encountering and interacting with other hominins like Neanderthals. This overlap in Europe led to gene flow between the species, evidenced by genetic traces of Neanderthals in modern humans. Understanding these interactions is crucial for studying human evolution and speciation.
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Related Practice
Textbook Question

All over the world, natural habitats are being fragmented into tiny islands by suburbs, ranches, farms, and roads. If asked to join a science panel to speak to Congress, could you explain how this fragmentation process could lead to extinction? How it could lead to speciation?

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Textbook Question

A revolution in the study of human evolution is under way thanks to the invention of techniques that enable DNA sequencing of not only modern humans, but also ancient humans. Human populations today are not considered separate species under the biological species, morphospecies, and phylogenetic concepts. Explain what kind of evidence supports this statement.

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Textbook Question

A revolution in the study of human evolution is under way thanks to the invention of techniques that enable DNA sequencing of not only modern humans, but also ancient humans. Before the application of DNA sequencing to fossils, which species concept was most useful for distinguishing human fossils? What is one disadvantage of this approach?

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Textbook Question

Svante Pääbo and colleagues were the first to sequence the Neanderthal genome from fossils and compare the sequences to modern humans. According to the data shown here, did the two species interbreed when they overlapped in Europe? Explain.

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Textbook Question

In a follow-up study in 2020, Joshua Akey and colleagues discovered that the genomes of modern Africans contain a small amount of Neanderthal DNA due to migration of some Europeans back to Africa after interbreeding with Neanderthals. Given the large amount of variation within human populations, how would you know whether there is a significant difference in percentage of Neanderthal DNA between modern Europeans and modern Africans?

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