Chapter 55 Community Ecology
Terms in this set (37)
all the interacting species within a defined area
coevolutionary arms race
cycle of reciprocal adaptation between interacting (-/- and +/-) species
four general fitness interactions
Consumption, commensalism, competition, mutualism
when one species benefits and the other is unaffected (+/0)
when organism eats or gains nutrients from another. Increases the consumer's fitness but weakens the victim's (+/-)
when both species use the same resources; resulting in low fitness for both (-/-)
competition that occurs between the same species...cause of density dependent species
when different species compete for the same limited resources
when both species interact in a way that benefits both of them (+/+)
a pattern of evolution where two species each others adaptation over time
range of resources that a species is able to use, or the range of condition that a species can handle
anti predator adaptation in which one prey species closely resembles another
competitive exclusion principle
two species that occupy the same niche cannot coexist (neanderthal disappearance)
total of theoretical environments a species can exist in
sketch and label a graph of the fundamental and realized niches of the barnacle species as a function of depth in the intertidal zone
an evolutionary change in resource use, caused by competition of generations
enables species to exploit different resources (makes niche differentation possible)
(in text) why is it important to carry out both treatments on the same rock?
If Connell had done the treatments on different rocks, a critic could argue that differences in survival were due to difference in the nature of the rocks-not differences in competition
standing/ constitutive defense
traits that allow individuals to not be eaten. Present in absence of predator
a harmless species has evolved to imitate the warning signals of a harmful species directed at a predator of them both.
two or more distasteful species, that may or may not be closely related and share one or more common predators, have come to mimic each other's warning signals
(in text) why did researchers feed crabs fish instead of mussels?
The hypothesis that mussels can sense the presence of crabs. If the crab had been fed mussels, a critic could argue that the mussels detect the presence of damaged mussels- not crabs.
(in text) Design an experiment to test the hypothesis that infected ants are more likely than uninfected ants to be eaten by birds
Put equal numbers of infected and uninfected ants in a pen that includes a bird predator. Count how many of each type are eaten over time.
(in text) The researchers assigned the treatments to different plants at random , and they did many replicates of each treatment. Why was this method important
These steps controlled for the alternative hypothesis that differences in tree-hopper survival were due to differences in the plants they occupied - not the presence or absence of ants.
(in text) Explain why niche differentiation (resource partitioning) does not involve a conscious choice by the individuals involved.
the individuals do not choose or try to have traits that reduce competition - they simply have those traits (or not). Resource partitioning just happens, because individuals with traits that allow them to exploit different resources produce more offspring, which also have those traits.
(in text) Explain what a coevolutionary arms race is, and give an example.
When species interact via consumption, a trait that gives one species an advantage will exert natural selection on individuals of the other species who have traits that reduce that advantage. This reciprocal adaptation will continue indefinitely. Example the interaction of Plasmodium with the human immune system.
At least 20 species are found in most or all of the ponds. Does this observation suggest that community composition is predictable or unpredictable?
Predictable, at least to a degree
Explain how early successional species alter the environment in ways that make growing conditions more difficult for themselves.
The shade provided by an early successional species increases humidity, and decomposition of their tissues adds nutrients and organic material to the soil. These conditions favor growth by later successional, which can outcompete the early successional species
explain how the presence or absence of a species like alder, where nitrogen fixation occurs, might alter the course of succession.
The presence or absence of a plant species where nitrogen fixation occurs would dramatically alter nutrient conditions, and thus the speed of succession and the types of species that could become established.
Suppose that the mainland habitats closest to an island were wiped out by surbanization. How would this affect the curves in part (c)
The effect would be to make the island more remote, which would lower the rate of immigration and move the whole immigration curve downward. The rate of extinction would increase, shifting the curve upward. The overall effect would be to decrease the number of species, because the island effectively would have become more remote.
True or False? Species act as agents of natural selection when they interact
What is niche differentiation?
The evolution of traits the reduce niche overlap and competition
The relationship between ants and treehoppers in the presence of spiders is an example
What is one advantage of inducible defenses?
They make efficient use of resources, because they are produced only when needed.
Pioneer species tend to have high____ and lower survivorship.
Which of these factors is not generally correlated with species diversity?