Table of contents

1. Introduction to Biology2h 42m
2. Chemistry3h 37m
3. Water1h 26m
4. Biomolecules2h 23m
5. Cell Components2h 26m
6. The Membrane2h 31m
7. Energy and Metabolism2h 0m
8. Respiration2h 40m
9. Photosynthesis2h 49m
10. Cell Signaling59m
11. Cell Division2h 47m
12. Meiosis2h 0m
13. Mendelian Genetics4h 44m
14. DNA Synthesis2h 27m
15. Gene Expression3h 6m
16. Regulation of Expression3h 31m
17. Viruses37m
- Viruses
  37m
18. Biotechnology2h 58m
19. Genomics17m
- Genomes
  17m
20. Development1h 5m
21. Evolution3h 1m
22. Evolution of Populations3h 53m
23. Speciation1h 37m
24. History of Life on Earth2h 6m
25. Phylogeny2h 31m
26. Prokaryotes4h 59m
27. Protists1h 12m
28. Plants1h 22m
29. Fungi36m
- Fungi
  19m
- Fungi Reproduction
  17m
30. Overview of Animals34m
- Overview of Animals
  34m
31. Invertebrates1h 2m
32. Vertebrates50m
33. Plant Anatomy1h 3m
34. Vascular Plant Transport1h 2m
- Water Potential
  1h 2m
35. Soil37m
- Soil and Nutrients
  20m
- Nitrogen Fixation
  16m
36. Plant Reproduction47m
- Flowers
  33m
- Seeds
  14m
37. Plant Sensation and Response1h 9m
38. Animal Form and Function1h 19m
39. Digestive System1h 10m
- Digestion
  1h 3m
- Blood Sugar Homeostasis
  7m
40. Circulatory System1h 49m
41. Immune System1h 12m
42. Osmoregulation and Excretion50m
- Osmoregulation and Excretion
  50m
43. Endocrine System1h 4m
- Endocrine System
  1h 4m
44. Animal Reproduction1h 2m
- Animal Reproduction
  1h 2m
45. Nervous System1h 55m
- Neurons and Action Potentials
  1h 8m
- Central and Peripheral Nervous System
  46m
46. Sensory Systems46m
- Sensory System
  46m
47. Muscle Systems23m
- Musculoskeletal System
  23m
48. Ecology3h 11m
49. Animal Behavior28m
- Animal Behavior
  28m
50. Population Ecology3h 41m
51. Community Ecology2h 46m
52. Ecosystems2h 36m
53. Conservation Biology24m
- Conservation Biology
  24m

21. Evolution

Introduction to Evolution and Natural Selection

General Biology

21. Evolution

Introduction to Evolution and Natural Selection

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1:26 minutes

Problem 7

Textbook Question

Marsupial mammals give birth to young that complete their development in a pouch on the mother's abdomen. All the native mammals of Australia are marsupials, while these types of mammals are absent or uncommon on other continents. This observation is an example of
a. Developmental evidence for evolution
b. Biogeographic evidence for evolution
c. Genetic evidence for evolution
d. Fossil evidence for evolution
e. Not useful evidence for evolution

Verified step by step guidance

Step 1: Begin by understanding the concept of evolution and the types of evidence that support it. Evolution is the process by which species change over time through mechanisms like natural selection, genetic drift, and mutation. Evidence for evolution can come from various fields, including biogeography, genetics, fossils, and developmental biology.

Step 2: Analyze the problem statement. It mentions that marsupial mammals are native to Australia and are uncommon or absent on other continents. This distribution pattern of species is a key clue in determining the type of evidence being described.

Step 3: Recall the definition of biogeographic evidence for evolution. Biogeography is the study of the geographic distribution of species and ecosystems. It provides evidence for evolution by showing how species have adapted to different environments and how geographic isolation can lead to speciation.

Step 4: Compare the other options provided in the question. Developmental evidence refers to similarities in embryonic development across species. Genetic evidence involves DNA and molecular similarities. Fossil evidence involves remains or imprints of organisms from the past. None of these directly address the geographic distribution of species.

Step 5: Conclude that the observation of marsupials being native to Australia and uncommon elsewhere is an example of biogeographic evidence for evolution, as it highlights how geographic isolation has influenced the distribution and evolution of species.

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Key Concepts

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

Marsupial Reproduction

Marsupial mammals, such as kangaroos and koalas, give birth to relatively undeveloped young that continue their growth in a pouch. This unique reproductive strategy allows for a shorter gestation period and provides a safe environment for the young to develop while being nourished by the mother.

Biogeography

Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. It helps explain why certain species, like marsupials, are predominantly found in specific regions, such as Australia, and how geographical barriers influence evolutionary processes.

Evidence for Evolution

Evidence for evolution includes various types of data that support the theory of evolution, such as developmental, biogeographic, genetic, and fossil evidence. In this context, the unique presence of marsupials in Australia serves as biogeographic evidence, illustrating how species adapt and evolve in response to their environments.

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Related Practice

Textbook Question

An adaptation is a trait of an organism that increases:

a. Its fitness

b. Its ability to survive and replicate

c. In frequency in a population over many generations

d. A and B are correct

e. A, B, and C are correct

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Textbook Question

The DNA sequence for the same gene found in several species of mammals_________.

a. Is identical among all species.

b. Is equally different between all pairs of mammal species.

c. Is more similar between closely related species than between distantly related species.

d. Provides evidence for the hypothesis of common descent

e. More than one of the above is correct.

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Textbook Question

Some biologists summarize evolution by natural selection with the phrase "mutation proposes, selection disposes." Mutation is a process that creates heritable variation. Explain what the phrase means.

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Textbook Question

Although cellulose and starch are identical in terms of stored chemical energy, our ability to harvest the energy from these two polysaccharides differs considerably. What is responsible for this difference?

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Textbook Question

A swim bladder is a gas-filled sac that helps fish maintain buoyancy. The evolution of the swim bladder from the air-breathing organ (a simple lung) of an ancestral fish is an example of

a. Exaptation.

b. Changes in Hox gene expression.

c. Paedomorphosis.

d. Adaptive radiation.

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Textbook Question

A swim bladder is a gas-filled sac that helps fish maintain buoyancy. Evidence indicates that early fish gulped air into primitive lungs, helping them survive in stagnant waters. The evolution of the swim bladder from lungs of an ancestral fish is an example of

a. An evolutionary trend.

b. Paedomorphosis.

c. The gradual refinement of a structure with the same function.

d. Exaptation.

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Textbook Question

Why don't the biggest and strongest individuals in a population always produce the most offspring?

a. The biggest and strongest individuals always have higher fitness.

b. In some environments, being big and strong lowers fitness.

c. Sometimes the biggest and strongest individuals may choose to have fewer offspring.

d. Sometimes the number of offspring is not related to fitness.

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Textbook Question

If you were given a solution that has a pH of 8.5, what would be its concentration of protons? What is the difference in proton concentration between this solution and one that has a pH of 7?

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