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Questions and Answers
What significant event led to the separation of marsupials from their ancestral groups?
What significant event led to the separation of marsupials from their ancestral groups?
Which of the following groups was NOT mentioned as successfully dispersing across the world's zoogeographical regions?
Which of the following groups was NOT mentioned as successfully dispersing across the world's zoogeographical regions?
Which factor primarily explains the lack of indigenous terrestrial mammals or birds in Antarctica?
Which factor primarily explains the lack of indigenous terrestrial mammals or birds in Antarctica?
According to the concept of dispersalism, how are related taxa found on either side of a barrier explained?
According to the concept of dispersalism, how are related taxa found on either side of a barrier explained?
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What is the primary characteristic of the fauna currently supported by Antarctica?
What is the primary characteristic of the fauna currently supported by Antarctica?
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What is a significant factor contributing to the distinct fauna of the Neotropical region compared to the Nearctic?
What is a significant factor contributing to the distinct fauna of the Neotropical region compared to the Nearctic?
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Which of the following animals is a Neotropical mammal that has also survived in the Nearctic region?
Which of the following animals is a Neotropical mammal that has also survived in the Nearctic region?
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Which family of mammals is considered endemic to the Neotropical region?
Which family of mammals is considered endemic to the Neotropical region?
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What aspect of bird diversity in South America is noted in the content?
What aspect of bird diversity in South America is noted in the content?
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Which of the following mammals is NOT mentioned as part of the Neotropical fauna?
Which of the following mammals is NOT mentioned as part of the Neotropical fauna?
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Which animal group is mentioned as having reached South America by rafting?
Which animal group is mentioned as having reached South America by rafting?
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What is one proposed hypothesis for the increased species richness in the tropics?
What is one proposed hypothesis for the increased species richness in the tropics?
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How does species richness vary with altitude according to the information provided?
How does species richness vary with altitude according to the information provided?
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What is a common characteristic of latitudinal gradients in species richness?
What is a common characteristic of latitudinal gradients in species richness?
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Which genera of skink are noted for having rafted from Africa?
Which genera of skink are noted for having rafted from Africa?
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What factor is not mentioned as influencing the distribution of animals across the earth?
What factor is not mentioned as influencing the distribution of animals across the earth?
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What occurs to mean annual temperatures as one moves away from the tropics?
What occurs to mean annual temperatures as one moves away from the tropics?
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Which of these statements is not true regarding the rafting of animals?
Which of these statements is not true regarding the rafting of animals?
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What was a significant indicator that the continents had drifted apart?
What was a significant indicator that the continents had drifted apart?
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Which geological evidence suggests the continents were once in different climatic zones?
Which geological evidence suggests the continents were once in different climatic zones?
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How can the age of volcanic rocks be determined?
How can the age of volcanic rocks be determined?
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What caused the dispersal of fauna between North America and Eurasia?
What caused the dispersal of fauna between North America and Eurasia?
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Which line of evidence connects the continental outlines with geological formations?
Which line of evidence connects the continental outlines with geological formations?
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What is the role of geomagnetism in understanding continental drift?
What is the role of geomagnetism in understanding continental drift?
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During which geological period was South Africa glaciated?
During which geological period was South Africa glaciated?
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Which of the following is NOT a piece of evidence for continental drift?
Which of the following is NOT a piece of evidence for continental drift?
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What phenomenon describes large mammals becoming smaller on islands over time?
What phenomenon describes large mammals becoming smaller on islands over time?
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Which animal groups are more likely to experience gigantism on islands?
Which animal groups are more likely to experience gigantism on islands?
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What is a common characteristic of island birds according to the information provided?
What is a common characteristic of island birds according to the information provided?
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What is a primary reason large mammals tend to become dwarfed on islands?
What is a primary reason large mammals tend to become dwarfed on islands?
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Why are large mammalian predators often absent from islands?
Why are large mammalian predators often absent from islands?
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What is one reason proposed for small species growing larger in island environments?
What is one reason proposed for small species growing larger in island environments?
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Which of the following is an example of island dwarfism?
Which of the following is an example of island dwarfism?
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What body weight does the dwarf elephant from Mediterranean islands approximately represent relative to its ancestor?
What body weight does the dwarf elephant from Mediterranean islands approximately represent relative to its ancestor?
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Study Notes
Neotropical Region
- Extends from southern Mexico to southern Brazil
- Includes the Amazon rainforest
- Fauna is diverse and distinct from the Nearctic region
- This difference is due to the continents' separation until 15 million years ago
- Armadillos, opossums, and porcupines are the only Neotropical mammals found in the Nearctic
- Neotropical region lacks the plains ungulates found in the Nearctic and Ethiopian regions
Bird Diversity
- South America is referred to as the "bird continent"
- Half of bird families and two orders are endemic (unique to the region)
- Toucans, trumpeters, hoatzins, and macaws are examples of endemic birds
- Hummingbirds are common but not endemic
Mammal Families
- Total number of families (excluding bats) is 32
- Cosmopolitan families (found worldwide) account for 10 of these
- Endemic families account for 16 of these
- Endemic families include:
- Caenolescidae (mouse-like opossums)
- Cebidae (New World monkeys)
- Callithricidae (Marmosets)
- Myrmecophagidae (South American anteaters)
Marsupial Distribution
- Recent genetic data suggests that marsupials originated in South America
- They spread across Antarctica to Australia
- The glaciation of Antarctica separated these groups
- Antarctica currently has no indigenous terrestrial mammals or birds
- It holds the highest diversity of seals
Successful Wanderers
- Several faunal families successfully dispersed globally
- These include shrews, squirrels, hamsters, lemmings, voles, field mice, hares, rabbits, deer, bears, dogs, cats, and weasels
- Bovids (cattle, sheep, plains game) dispersed globally except in the Neotropical and Australian regions
Continental Drift
- The theory of continental drift emerged from various pieces of evidence
- The coastlines of eastern South America and western Africa fit together
- The similarity of geological formations on these continents further supports the theory
- The presence of similar fossils on these continents also contributes to the evidence
- Geomagnetism also supports the theory:
- Rocks containing iron minerals become magnetised during their formation
- The magnetic field of the Earth changes periodically, allowing for dating of rocks
- This allows for the determination of the rock's location in relation to the Earth's magnetic poles
Rafting
- Rafting played a significant role in the colonization of islands and continents
- New World monkeys, caviomorph rodents, and certain skink genera likely reached South America by rafting from Africa
Latitudinal Gradients
- There are latitudinal gradients in species richness
- Species richness is higher in the tropics than at higher latitudes
- This pattern repeats across altitudinal gradients
- Several hypotheses explain these patterns:
- Geographical area hypothesis: The tropics cover a larger area, supporting more species and larger ranges
- Temperature hypothesis: Tropical regions have more uniform temperatures allowing for larger ranges and populations
Island Dwarfism and Gigantism
- Island dwarfism occurs when large mammals become smaller on islands due to limited resources
- Island gigantism occurs when small species grow larger on islands due to the absence of predators
- Examples of island dwarfism include:
- Dwarf elephants (extinct) on Mediterranean islands
- These elephants weighed about 200 kg, a fraction of their continental counterparts
Processes of Animal Distribution Across Continents
- Early biogeographers assumed species evolved in a specific area and dispersed from there
- This is known as dispersalism
- This concept is insufficient to explain all distribution patterns
- The history of the Southern Hemisphere is complex
- The major continents of the Northern Hemisphere were never far apart.
- The movement of continental seas and the rise or erosion of mountains influenced faunal dispersal.
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Description
Test your knowledge about the Neotropical region, which stretches from southern Mexico to southern Brazil and includes the Amazon rainforest. This quiz covers unique fauna, bird diversity, and the distinct mammal families found in this biodiverse area. Challenge yourself to learn more about this fascinating ecological zone.