Ecology - Community Structure Final

Question 1

How might interspecific competition play a role in shaping communities in nature?

Answer 1

determines how many and which species coexist in a community

Question 2

Give two predictions about the interactions of potential competitors within a community

Answer 2

Potential competitors that coexist in a community should, at the very least, exhibit some form of niche differentiation
Potential competitors with little niche differentiation should be unlikely to coexist

Question 3

Which of these predictions was supported by Pyke’s work with alpine bumblebees in Colorado?

Answer 3

Potential competitors that coexist in a community should, at the very least, exhibit some form of niche differentiation

Question 4

What is a feeding guild

Answer 4

a group of species that exploits the same type of resource in a similar way

Question 5

What is niche complementarity?

Answer 5

species that occupy a similar position along one dimension of the niche will tend to differ along another!

Question 6

How might predators enhance community diversity?

Answer 6

prey on competitively dominant species and thereby prevent competitive exclusion

Question 7

what happened when Paine removed the starfish predator

Answer 7

barnacles took over

Question 8

what could be used to characterize/classify a “keystone predator”

Answer 8

seeing a community seeming to be organized around it

Question 9

How might a predator serve as a vehicle for transmission of a parasite?

Answer 9

Parasite can live in or on the side of them while they live and can influence host behavior to increase their own transmission (allowing paratsite with complex living cycle can move from one place to another)

Question 10

In what ways might a parasite alter the behaviour of its host?

Answer 10

Cause them to engage in certain prey to eat or go to certain places like water
also make them become more available to prey so that they are killed by a predator and then they die

Question 11

What is parasite-mediated competition?

Answer 11

Paratistes influence biodiversity when they alter the outcome of competitive interactions between host species

Question 12

How might a tolerant host species cause an indirect negative effect on a second, less tolerant host species?

Answer 12

occurs when a tolerant host species amplifies a parasite’s abundance, causing an indirect negative effect on a second, less tolerant host species

Question 13

How might a microparasite facilitate a biological invasion?

Answer 13

reducing local biodiversity by eliminating populations of one host species

Question 14

How might a parasite contribute to biodiversity?

Answer 14

by allowing a competitively inferior species to coexist with a dominant species

Question 15

How might a parasite lead to a reduction in biodiversity?

Answer 15

mass population declines or even extinctions

Question 16

Under what conditions might the effects of parasitism on ecological communities be most pronounced?

Answer 16

when the hosts are keystone or dominant species with important functions in an ecosystem`

Question 17

Give an example of how the introduction of a parasite caused a dramatic change in ecosystem structure.

Answer 17

sea urchins in the Caribbean experienced a massive die-off associated with microbial pathogens, eliminating the keystone roles of urchins as grazers on coral reefs

Question 18

How do grasslands and some conifers depend on fire for their survival?

Answer 18

To prevent the establishment of trees and shrubs and the fire allows them to open their cones to disperse their seeds

Question 19

What types of biomes have evolved under regular fires

Answer 19

Mediterranean-type shrublands of the southwest (chaparral)
African savannas and southern pinelands

Question 20

How can fires set succession back?

Answer 20

Favor fire resistnact species , eliminate competing for soil moisture and nutrients from fire sensitive and shade tolerant trees

Question 21

How do fires act as “sanitizers”?

Answer 21

terminating outbreaks of insects and parasites

Question 22

What kinds of things make trees more susceptible to wind throw?

Answer 22

Trees whos trunk lack the suppleness of youth are especially vulnerable of wind throw
Trees growing on shallow drained shoils who roots are not well anchored and threatened by diseases, lightening strikes, hurricanes, tornadoes, and heavy rain, land slides and mudslides

Question 23

What are some environmental problems associated with over grazing by animals?

Answer 23

If overdone, it can lead to denudation, soil erosion or invasion by less desirable species

Question 24

How might beavers be considered ecosystem engineers?

Answer 24

Beavers (system engineers) alter the landscape by creating ponds from flowing streams

Question 25

What are some of the ways in which moving water might act as a disturbance that affects ecosystems?

Answer 25

Storm floods scour stream bottoms, cut away banks, change the course of streams and rivers, move and deposit sediments and carry away aquatic organisms

Question 26

Explain how the creation of gaps by disturbance can enhance species diversity of a community.

Answer 26

Rocky shores or coral reefs, the arsive action of waves and storm tossed logs open up gaps

Grasslands: badgers and groundhogs expose patches of mineral soul that are colonized by herbaceous plants