Biology Chapter 18: Evolution and Species Origin

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Questions and Answers

What is the primary mechanism of evolution proposed by Charles Darwin and Alfred Wallace?

Mutation

Gene flow

Genetic drift

Natural selection (correct)

Which of the following best defines a species?

A group of organisms that share a common habitat

A group of organisms that can interbreed and produce sterile offspring

A group of similar organisms that can interbreed to produce fertile offspring (correct)

A group of organisms with identical physical characteristics

What is one way that speciation can occur without geographic separation?

Extinction events

Genetic drift

Allopatric speciation

Sympatric speciation (correct)

Which of the following is NOT considered a type of evidence for evolution?

Meteorology Signup and view all the answers

How does natural selection primarily contribute to evolution?

By favoring traits that enhance survival and reproduction Signup and view all the answers

What do fossil records primarily provide evidence of?

The temporal succession of organisms over time Signup and view all the answers

What aspect of natural selection is driven by the environmental context?

Adaptation of populations Signup and view all the answers

What does the term 'descent with modification' refer to in the context of evolution?

Species change over time and give rise to new forms Signup and view all the answers

Which situation would most likely lead to allopatric speciation?

Flood causes the formation of a new lake. Signup and view all the answers

What is the primary cause of sympatric speciation?

Reproductive isolation between groups in the same area. Signup and view all the answers

Adaptive radiation occurs when members of a population:

Disperse and occupy different niches. Signup and view all the answers

Which process leads to the inability of two species to interbreed?

Reproductive isolation. Signup and view all the answers

Which of the following is a postzygotic barrier?

Production of non-viable offspring. Signup and view all the answers

Why are island chains considered ideal for adaptive radiation?

Species are isolated from mainland competitors. Signup and view all the answers

What does the term 'allopatric' imply in speciation?

Different geographic regions. Signup and view all the answers

What are homologous structures indicative of?

Shared ancestry among diverse organisms Signup and view all the answers

Which of the following accurately describes vestigial structures?

Remnants of functional structures from ancestors with no current function Signup and view all the answers

What characterizes convergent evolution?

Independently evolved similar traits in distantly related species due to similar environmental pressures Signup and view all the answers

What is the primary difference between homologous and analogous structures?

Homologous structures indicate shared ancestry, whereas analogous structures arise independently in similar environments Signup and view all the answers

In terms of evolution, what is a population?

A group of individuals from the same species sharing a specific gene pool Signup and view all the answers

How do Hox genes relate to molecular homology?

They are evolutionary conserved genes found in many organisms and indicate commonality Signup and view all the answers

Which misconception about evolution is incorrect?

Species can evolve only through natural selection Signup and view all the answers

What is an offspring produced from a cross between two species called?

A hybrid Signup and view all the answers

Study Notes

Chapter 18: Evolution and Origin of Species

Evolution is defined as "descent with modification"
Species change over time
A species is a group of similar organisms that can interbreed to produce fertile offspring
All species share a common ancestor ("Tree of Life")

Learning Objectives

Define evolution and natural selection
Describe various evidence for evolution
Define species, gene pool, and speciation
Describe how speciation can occur with or without geographic separation (allopatric vs. sympatric speciation)

What is Evolution?

Species change over time
Species are groups of similar organisms that can interbreed to produce fertile offspring

Natural Selection

Traits are inherited
Available resources are limited
Variation exists among individuals in a population
Offspring with traits best suited for competition survive and reproduce more
Heritable traits that enhance survival and reproduction become more common
Descent with modification

Adaptation

Natural selection leads to populations adapting to their environments over time
Populations become increasingly well-suited ("fit") to their environments

Key Points About Natural Selection

Natural selection is driven by the environment
Variation in traits results from random mutations
Individuals with favorable traits leave more offspring in the next generation
Natural selection acts on existing heritable variation
Over generations, populations adapt to their environments as favorable traits become more dominant

Evidence for Evolution

Fossils
Anatomy and embryology
Biogeography
Molecular biology
Direct observation of small-scale evolution

Fossils

Fossil records provide snapshots of the past and successions of organisms through time
Radiometric dating is used to estimate the age of fossils

Anatomy: Homology

Homologous structures are parallel structures in diverse organisms and indicate shared ancestry (a common ancestor)
Vestigial structures have no apparent function but appear to be remnants of functional structures in ancestors

Anatomy: Convergent Evolution

Analogous structures may evolve independently in species in similar environments by the process of convergent evolution

Divergent versus Convergent Evolution

Divergent evolution is a process where different species arise from a common ancestor
Convergent evolution is a process where distantly related species develop similar structures due to adaptations

Embryology

Embryonic structures are very similar across species

Biogeography

Each continent and geographically isolated places have their own distinctive collection of plants and animals
The geographic distribution of species supports the idea that species can evolve only in geographic areas previously colonized by their ancestors

Molecular Homology

Hox genes are a group of evolutionarily conserved genes found in many organisms
Hox genes have been duplicated and evolved

Evolution in Action

Examples of evolution in action include pesticide and antibiotic resistance, BT resistant moths, Methicillin-resistant Staphylococcus aureus, and COVID-19 evolution

Misconceptions About Evolution

Individuals do not evolve. Populations evolve.
Evolution does not explain the origin of life.
Organisms do not evolve on purpose

Checkpoint Questions

What is natural selection? (Use your own words.)
Can an individual organism evolve in its own lifetime? Why?
What is the difference between homologous and analogous structures? Give an example.

Speciation

Speciation is the formation of new species from an original species
Speciation can occur through geographic isolation (allopatric speciation) or without geographic isolation (sympatric speciation)

Allopatric Speciation

In allopatric speciation, isolated populations lead to speciation due to geographic separation (dispersal) or a natural event

Adaptive Radiation

Members of a population disperse and find different niches or habitats
Adaptations from this dispersal result in adaptive radiation (e.g., honeycreepers, fruit flies, snails in Hawaii)

Sympatric Speciation

Sympatric speciation occurs because two groups are no longer able to interbreed (reproductive isolation)
Examples include the anole lizard

Reproductive Isolation

Reproductive isolation is the inability of two populations to interbreed and produce viable, fertile offspring
Barriers can be prezygotic (preventing fertilization) or postzygotic (preventing viable/fertile offspring)

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Description

Explore the fundamental concepts of evolution and the origin of species in this quiz. Topics include natural selection, speciation, and the evidence supporting evolutionary theory. Test your knowledge on how species adapt and change over time, and the importance of genetic variation.