Questions and Answers
What is species richness?
Species richness is the number of different species represented in an ecological community, landscape or region.
What is biological diversity?
Biodiversity; variety of life on earth.
What are the 3 levels of biodiversity?
Genetic diversity, species diversity, ecosystem diversity.
What 'human' things depend on biodiversity? (List 2)
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What is species abundance?
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What is the species-area relationship?
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What is the general trend found in species-area relationships?
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What counts as an island in the species-area relationship? (List 6)
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Why do larger areas contain more species?
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It is expected that biodiversity will be lost quicker on islands compared to in the same size habitat on land.
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What is the equilibrium theory of island biogeography?
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How would the immigration rate change over time on large and small islands (near or far from the mainland)?
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How would the extinction rate change over time on large and small islands (near or far from the mainland)?
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How does the equilibrium theory of island biogeography predict the number of species on an island?
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Why would the predicted rate of extinction rise with the presence of more species on the island? (List 3 reasons)
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What are the main predictions of the equilibrium theory of island biogeography? (List 4)
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What is habitat fragmentation?
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What do species-area curves show?
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Study Notes
Species Richness
- Refers to the number of different species present in a specific ecological community or region.
- It is purely a count and does not involve species abundance or distributions.
- Often conflated with species diversity; however, species diversity considers both richness and evenness.
Biological Diversity
- Known as biodiversity; encompasses the variety of life forms on Earth.
Levels of Biodiversity
- Includes genetic diversity, species diversity, and ecosystem diversity.
Human Dependence on Biodiversity
- Society and economy are both reliant on biodiversity for sustenance and resources.
Species Abundance
- Defines the number of individuals of a particular species in a specified area at a given time.
Species-Area Relationship
- Examines the correlation between the size of an island and its species diversity.
General Trend in Species-Area Relationships
- Shows a positive correlation where larger islands generally host more species.
Definition of "Islands" in Species-Area Relationship
- Encompasses various habitats surrounded by others, including real islands, mountain islands, lakes, caves, forests amid agriculture, and meadows in forests.
Larger Areas and Species Diversity
- Larger habitats support a wider variety of habitats, contributing to increased species numbers.
Hectare
- A metric unit of area measurement equivalent to 10,000 square meters (2.471 acres).
Biodiversity Loss on Islands
- It is expected that biodiversity diminishes faster on islands compared to similar-sized habitats on land due to isolation.
Equilibrium Theory of Island Biogeography
- Proposed by R.H. MacArthur and E.O. Wilson, this theory posits that species numbers on islands result from a balance between species colonization and extinction.
Immigration Rate Dynamics on Islands
- Initially high immigration rates decrease as more species establish.
- Closer and larger islands tend to receive more species compared to those that are farther and smaller.
Extinction Rate Dynamics on Islands
- The extinction rate tends to rise as species diversity increases, particularly more pronounced on smaller islands.
Predicting Species Numbers with Equilibrium Theory
- Combining the graphs of predicted immigration and extinction rates yields an optimal number of species the island can sustain.
Factors Leading to Increased Extinction Rates
- A greater number of species enlarges potential extinction pools.
- Increased species numbers often coincide with reduced population sizes.
- Rising competition among species enhances extinction potential.
Main Predictions of Equilibrium Theory
- Species numbers remain relatively constant, fluctuating through immigration and extinction.
- Larger islands harbor more species than smaller islands.
- Remoteness negatively impacts species richness.
Habitat Fragmentation
- Refers to breaking an ecosystem into smaller sections, significantly threatening biodiversity.
Species-Area Curves
- Illustrate the relationship between island size and species richness, calculable via the formula S = cAz, where:
- S = species richness
- A = area
- c and z are constants (typically z ~ 0.25-0.35), derived from data correlation.
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Description
Test your knowledge on species richness and its ecological significance. This quiz covers the definition, importance, and metrics related to species diversity in ecosystems. Ideal for students studying ecology and environmental science.
