8-Community Ecology 3

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Questions and Answers

Which hypothesis explains the increase in species richness observed when land at 30 degrees north was watered and fertilized for 50 years?

The area hypothesis

The ecological limits hypothesis (correct)

The evolutionary rates hypothesis

The history hypothesis

What does the Species-Area Curve illustrate regarding biodiversity?

More area is correlated with a higher number of species. (correct)

Area has no effect on species richness.

Smaller areas support more species due to limited resources.

Larger areas have lower species diversity.

Which factor is NOT mentioned as contributing to high mutation rates in the tropics?

Short generation times

Diverse ecological niches

Recent glaciation events (correct)

High rate of speciation

According to the history hypothesis, which factor contributes to lower species richness at higher latitudes?

Recent major disturbances affect species evolution. Signup and view all the answers

What is a common misconception about species richness in relation to the evolutionary rates hypothesis?

It suggests equal species richness in all latitudes. Signup and view all the answers

What are the two main factors that determine species richness on islands?

Immigration and extinction rates Signup and view all the answers

What happens to immigration rates as the number of species on an island increases?

Immigration rates decline Signup and view all the answers

At equilibrium, which statement is true regarding species turnover on an island?

Rates of species immigration and extinction are equal Signup and view all the answers

Which factor increases extinction rates on islands as species richness rises?

Increased interspecific competition Signup and view all the answers

How does the size of an island affect its immigration and extinction rates?

Larger islands can support more species, affecting immigration and extinction dynamics Signup and view all the answers

What is the effect of distance from the mainland on species immigration rates?

Closer islands have higher species immigration rates Signup and view all the answers

Which of the following would likely cause an increase in extinction rates on an island?

Reduction in average population sizes Signup and view all the answers

What is the predicted outcome for species richness on an island over time at equilibrium?

Species richness will stabilize at a dynamic equilibrium point Signup and view all the answers

What does the term 'latitudinal gradient' refer to in ecology?

The increase in species richness towards the equator. Signup and view all the answers

Which hypothesis suggests that species richness is limited by the availability of resources in an environment?

Ecological limits hypothesis. Signup and view all the answers

In the island biogeography theory, what effect does island size have on species richness?

Larger islands generally support more species due to increased resources. Signup and view all the answers

Which of the following is NOT a factor in the dynamics of species richness on islands?

Temperature gradients on the continent. Signup and view all the answers

What is a key characteristic of species found in tropical regions compared to those in higher latitudes?

They usually experience increased physiological adaptations. Signup and view all the answers

How do wildlife corridors contribute to species conservation?

They enhance connectivity between habitats. Signup and view all the answers

Which hypothesis relates to the concept of a 'carrying capacity' for species in a community?

Ecological limits hypothesis. Signup and view all the answers

What is the primary factor driving the increase in species richness towards the equator according to the provided hypotheses?

Increased solar energy input and water availability. Signup and view all the answers

In the context of island biogeography, what happens to species richness as distance from the mainland increases?

Species richness decreases due to lower immigration rates. Signup and view all the answers

What role does the rate of speciation play in maintaining species diversity?

It is inversely proportional to species extinction rates. Signup and view all the answers

Study Notes

Community Ecology 3: Species Diversity and Biogeography

Species richness generally increases towards the equator. A map shows the correlation between latitude and the number of species.
The latitudinal gradient is a pattern of species diversity. Several factors contribute to the gradient
The latitudinal gradient in species richness is influenced by:
Solar energy input and water availability: Graphs show a positive correlation between actual evapotranspiration and species richness for trees and vertebrates.
Rate of speciation: Higher temperatures correlate with higher physiological rates and mutations, supporting higher speciation rates in tropical regions.
Ecological limits: The total availability of resources limits the number of species that can be supported, with higher numbers in regions with vast resources, like the tropics.
Historical factors: The history of the region influences diversity patterns; recent glaciation periods limits the time for speciation, and thus affects the biodiversity patterns.

Island Biogeography

Species richness on islands is a dynamic balance between immigration and extinction rates.
Island size and distance from the mainland affect immigration and extinction rates.
Larger islands have a higher species richness due to lower extinction and higher immigration rates.
Islands closer to the mainland have a higher species richness due to higher immigration rates.
The Species-Area Curve demonstrates a positive relationship between island size and species richness.
The MacArthur-Wilson Island Equilibrium Model describes species richness on islands as a balance between these rates.
Island biogeography applies to habitat islands as well.
The immigration of new species decreases with an increased number of the species already present on the island.

Habitat Fragmentation

Habitat size affects rates of species loss.
Larger habitat fragments tend to lose species more slowly than smaller ones.

Wildlife Corridors

Wildlife corridors can connect fragmented landscapes and increase landscape connectivity.
Corridors increase the movement of wildlife between fragments, which can improve population viability.
Creating wildlife corridors is a more affordable approach for conservation compared to buying vast tracts of land.

Learning Catalytics Question

An experiment increasing species richness in a region at 30 degrees North is consistent with the ecological limits hypothesis.

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Description

Test your knowledge on biodiversity concepts and hypotheses related to species richness. This quiz covers topics such as the effects of watering and fertilization, the Species-Area Curve, and evolutionary rates. Assess your understanding of factors influencing species distribution across different latitudes.