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What percentage of the Earth's species are found in tropical forests?
What percentage of the Earth's species are found in tropical forests?
The tropics support a lower rate of extinction compared to other regions.
The tropics support a lower rate of extinction compared to other regions.
True
What is the historical hypothesis about the tropics based on time?
What is the historical hypothesis about the tropics based on time?
The tropical climate has existed for a longer and more uninterrupted period of time.
The _________ hypothesis states that higher primary productivity in the tropics leads to greater species diversity.
The _________ hypothesis states that higher primary productivity in the tropics leads to greater species diversity.
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Match the following key terms with their descriptions:
Match the following key terms with their descriptions:
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Which statement best describes the altitudinal gradient in species diversity?
Which statement best describes the altitudinal gradient in species diversity?
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In tropical forests, only 5 million insects can be found.
In tropical forests, only 5 million insects can be found.
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What percentage of the global land surface is covered by tropical forests?
What percentage of the global land surface is covered by tropical forests?
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What is adaptive radiation known to result in?
What is adaptive radiation known to result in?
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Ring species occur when neighboring populations cannot interbreed.
Ring species occur when neighboring populations cannot interbreed.
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Define species richness.
Define species richness.
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The concept that defines species as those that can interbreed and produce viable offspring is called the ______.
The concept that defines species as those that can interbreed and produce viable offspring is called the ______.
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Match the following biodiversity terms with their definitions:
Match the following biodiversity terms with their definitions:
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Which of the following is a limitation of the biological species concept?
Which of the following is a limitation of the biological species concept?
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Morphological species concept can reliably categorize all organisms, including extinct species.
Morphological species concept can reliably categorize all organisms, including extinct species.
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What is one advantage of the morphological species concept?
What is one advantage of the morphological species concept?
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What can occur when a population experiences inbreeding depression?
What can occur when a population experiences inbreeding depression?
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Larger populations have a higher chance of survival compared to smaller populations.
Larger populations have a higher chance of survival compared to smaller populations.
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What might happen if a small population, such as the Florida panther, undergoes significant genetic drift?
What might happen if a small population, such as the Florida panther, undergoes significant genetic drift?
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The process that can convert an ecosystem into a dry environment is known as __________.
The process that can convert an ecosystem into a dry environment is known as __________.
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Match the following types of degradation with their examples:
Match the following types of degradation with their examples:
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What is a potential consequence of a population declining from 100 individuals to 50?
What is a potential consequence of a population declining from 100 individuals to 50?
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Negative population regulation can include factors that decrease population size.
Negative population regulation can include factors that decrease population size.
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How do positive and negative population regulations differ?
How do positive and negative population regulations differ?
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What percentage of the Earth's surface do coral reefs cover?
What percentage of the Earth's surface do coral reefs cover?
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Ecological extinction refers to a species that is extinct in one region but still exists in others.
Ecological extinction refers to a species that is extinct in one region but still exists in others.
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What human activity primarily threatens coral reefs through physical removal?
What human activity primarily threatens coral reefs through physical removal?
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________ factors are predictable, while stochastic factors are random.
________ factors are predictable, while stochastic factors are random.
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Match the following terms to their definitions:
Match the following terms to their definitions:
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How do stochastic events like disease outbreaks affect bird populations?
How do stochastic events like disease outbreaks affect bird populations?
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Demographic uncertainty means that every individual in a population will have the same number of offspring.
Demographic uncertainty means that every individual in a population will have the same number of offspring.
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What is the main effect of acidification on coral reefs?
What is the main effect of acidification on coral reefs?
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Which of the following best describes photochemical smog?
Which of the following best describes photochemical smog?
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The variation in traits within a population is always negative.
The variation in traits within a population is always negative.
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What is a selection coefficient?
What is a selection coefficient?
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_____ effect describes the impact of low population density on a species' mating opportunities.
_____ effect describes the impact of low population density on a species' mating opportunities.
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Match the environmental issue with its description:
Match the environmental issue with its description:
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How might natural selection lead to the spread of a beneficial trait in Darwin’s finches?
How might natural selection lead to the spread of a beneficial trait in Darwin’s finches?
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Genetic variation can only have a negative impact on a population's fitness.
Genetic variation can only have a negative impact on a population's fitness.
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In the context of endangered penguins, describe one consequence of genetic swamping.
In the context of endangered penguins, describe one consequence of genetic swamping.
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Study Notes
Adaptive Radiation
- Definition: Evolutionary process leading to rapid diversification of species from a single common ancestor.
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Key Characteristics:
- Results in species-rich environments.
- Example: Darwin's finches on Galapagos Islands.
- Difficult to trace the evolutionary path of diversification.
Ring Species
- Definition: A connected series of populations, each of which can interbreed with its neighboring populations, but where the two "end" populations are too distantly related to interbreed.
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Key Characteristics:
- Gradual genetic differences across the "ring."
- When the ring closes, the two end populations cannot interbreed.
Determining Biodiversity
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Species Richness: The number of species in a specific area.
- Alpha Diversity (Local Diversity): Species richness in a small, localized area.
- Gamma Diversity (Regional Diversity): Species richness over a large geographic region.
- Beta Diversity (Species Turnover): Rate of change in species composition between different areas.
Species Concepts
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Biological Species Concept (BSC): Defines species based on their ability to interbreed and produce fertile offspring.
- Pros: Accounts for reproductive isolation.
- Cons: Fails to account for asexual species and complications in identifying interbreeding potential in fossils.
- Example: Dogs, wolves, and coyotes can interbreed, yet are considered distinct species.
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Morphological Species Concept (MSC): Defines species based on physical characteristics.
- Pros: Easy to apply, especially for fossils.
- Cons: Can be subjective and may overlook cryptic species (different species with similar appearance).
Tropical Diversity: Historical vs. Ecological Hypothesis
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Historical Hypothesis: The tropics have remained relatively stable for a long time, allowing greater time for species diversification.
- Key Word: Time.
- Evidence: The tropical climate has existed for longer than other climates.
- Timeframe: Tropical climate likely existed for at least 100 million years, whereas tundra is likely 2 million years old.
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Ecological Hypothesis: The tropics have higher productivity and thus higher carrying capacity, supporting more species.
- Key Word: Rate.
- Evidence: Tropical forests cover 7% of global land surface and host over 50% of Earth's species.
- Mechanism: High primary productivity leads to more energy available for organisms.
Biodiversity & Extinction
- Zoozathalae support coral reefs by photosynthesizing and contributing to coral growth, which increases their capacity to support other organisms.
- Human activities like acidification from excess carbon dioxide and coral harvesting threaten coral reef ecosystems, impacting their biodiversity.
- Extirpation: Local extinction of a species.
- Regional Extinction: Extinction of a species within a specific geographic region but not globally.
- Ecological Extinction: A species’ population falls below a critical level where it can no longer fulfill its role in the ecosystem.
Population Dynamics
- Deterministic Factors: Predictable influences on population size, e.g., seasonal changes.
- Stochastic Processes: Random events that impact population size, e.g., disease outbreaks.
- Demographic Uncertainty: Random variation in birth rates, leading to unpredictable population fluctuations.
- Extinction Vortex: Negative feedback loop where small populations face increased extinction risk due to inbreeding depression and genetic drift.
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Population Viability: The likelihood that a population will persist over time.
- Large populations have higher viability due to greater genetic diversity and resilience to environmental changes.
- Small populations are more susceptible to extinction vortex effects.
Population Regulation
- Negative Population Regulation: Factors that decrease population growth rate as population density increases, e.g., competition for resources.
- Positive Population Regulation: Factors that increase population growth rate as population density increases, such as enhanced mating opportunities.
- Allee Effect: Positive feedback loop where low population density leads to decreased reproduction or survival, ultimately decreasing population size.
Natural Selection
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Natural Selection is a key evolutionary process driven by three main components:
- Variation: Individual organisms within a population show variation in their traits.
- Heritability: These variations are heritable, meaning they can be passed down to offspring.
- Differential Fitness: Some variations provide individuals with advantages or disadvantages in survival and reproduction, leading to differential fitness.
- Selection Coefficient: Measure of the relative fitness of a genotype compared to the most fit genotype in a population.
Genetic Drift
- Genetic Drift is the random change in allele frequencies within a population, most pronounced in small populations.
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Consequences of Genetic Drift:
- Loss of Genetic Diversity: Can lead to reduced genetic variation.
- Fixation of Alleles: Can lead to the loss of certain alleles and the fixation of others, potentially eliminating beneficial alleles.
Climate Forcing
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Climate Forcing: Any factor that can change the Earth's global energy balance.
- Orbital Forcing: Long-term variations in Earth's orbit around the sun, influencing solar radiation levels.
- Climate Blowback: Effects of climate change that exacerbate existing problems, creating a feedback loop.
Threats to Biodiversity
- Overexploitation: Harvesting resources from the environment at a rate exceeding sustainability.
- Genetic Swamping: Introduction of a large number of individuals from a different population into a small local population, which can overwhelm the local gene pool.
- Eutrophication: Enrichment of water bodies with nutrients, leading to excessive algal growth and oxygen depletion.
- Biomanipulation: Manipulation of food webs, often by removing top predators, to improve ecosystem health.
- Bottom-up Regulation: A food web is regulated by resource availability.
- Top-down Regulation: A food web is regulated by predation.
Environmental Degradation
- Dead Zone: Area of water with low oxygen levels, often caused by eutrophication.
- Acid Rain: Precipitation with high levels of sulfuric and nitric acids, mainly caused by sulfur dioxide and nitrogen oxides emissions.
- Photochemical Smog: Air pollution that forms when nitrogen oxides and volatile organic compounds react with sunlight.
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Description
Test your knowledge on adaptive radiation and ring species. Explore key concepts including species richness and biodiversity metrics. Understand the processes that lead to the diversification of species in different environments.
