Conservation Biology Flashcards
How is diversity related to latitude?
Diversity decreases as latitude increases. So generally at more tropical latitudes, there is greater species diversity.
What are the two key factors in equatorial-polar gradients of species richness?
- Evolutionary history
- Climate
How does evolutionary history contribute to equatorial-polar gradients of species richness?
Tropical environments tend to be older.
The growing season is longer in the tropics (equal amounts of day and night), which means that biological time is faster.
How does climate contribute to equatorial-polar gradients of species richness?
Two climatic factors (sunlight and precipitation, both high in tropical environments) are positively correlated with species richness.
How is species richness correlated with the amount of sunlight and water?
Species richness is positively correlated with amount of sunlight and water.
What is evapotranspiration?
The evaporation of water from soil and plants.
What is the relationship between species diversity and area?
The larger the area, the more species are found in that area.
What equation relates area to species?
S = cA^z where S = number of species in the habitat, c = constant, A = area of the habitat, and z = how many species should be found in a habitat as its area increases.
In a log-log plot of S vs A, what is the slope of the line through the data points?
z (how many species should be found in a habitat as its area increases) is the slope of the line through the data points.
In the 1960s, what did the ecologists MacArthur and Wilson study?
They tested the predictions of the species-area relationship on different island chains.
What did MacArthur and Wilson’s study find?
On different island chains, the number of species differed. The closer the islands were to the mainland, the more likely there were to be species present on those islands. They also showed that z is usually between 0.2 and 0.4.
What does the basic model of island biogeography say?
The model says that area and distance to a migrant pool, by influencing immigration and extinction rates, determines the number of species on the island.
Describe the equilibrium established in the theory of island biogeography.
The number of species on an island should be at equilibrium (roughly constant over time). This equilibrium is dynamic (i.e. the result of continual turnover of species; some become extinct, and new ones arrive).
At equal distances from the mainland, how is the number of species an island can support related to its size?
Large islands should support more species relative to smaller islands at equal distances.
At equal size, how is the distance an island is from the mainland related to the number of species it can support?
Distant islands should have fewer species relative to close islands of equal size.
