Ch. 54: Community Ecology Flashcards
How do two similar species co-exist in same niche without defying the competitive exclusion principle? (there is more than one possible answer here)
Resource partitioning: differentiation of ecological niches, enabling similar species to coexist in a community
Character displacement: a tendency for characteristics to be more divergent in sympatric population of two species than in allopatric populations of the same two species
How are species restricted to a realized niche versus their potential niche?
Realized niche: the niche actually occupied by that species during resource partitioning
Potential (fundamental) niche: the area a niche could potentially occupy with no competition
What is the advantage of Mullerian mimicry?
Mullerian mimicry: 2 or more unpalatable species resemble each other
- protection/safety
- reinforce a pattern for predators (so they have less to learn)
How can plants defend themselves against predation if they can’t run away or hide?
mechanical or chemical
- thorns vs toxin (bitter taste)
Is facilitation an example of symbiosis? Why or why not?
facilitation is an example of indirect symbiosis
Facilitation (+/+ or +/0): one species can have a positive effects on another species without direct and intimate contact
i. e. salt marsh with Juncus (foreground)
i. e. black rush makes the soil more hospitable for other plant species
Which community is more resistance to environmental stress? Why?
The more richly diverse a community is, the more resistance it has to environmental stresses.
Community interactions are classified by
whether they help, harm, or have no effect on the species involved
Diversity and trophic structures characterize
biological communities
Disturbance influences a species’
diversity and composition
Biogeographic factors affect
community diversity
Pathogens alter
community structure locally and globally
(biological) community
an assemblage of populations of various species living close enough for potential interaction
i.e. carrier crab and sea urchin
interspecific interactions
relationships between species in a community
- competition, predation, herbivory, symbiosis (parasitism, mutualism, commensalism) and facilitation
- can affect survival and reproduction of each species, and the effects can be summarized as positive (+), negative (-), or no change (0)
Interspecific competition
(-/- interaction)
species compete for a resource in short supply
Competitive exclusion
local elimination of a competing species
Principle: two species competing for the same limiting resources cannot coexist in the same place
Ecological niche
the total of a species’ use of biotic and abiotic resources
AKA organim’s ecological role
ecologically similar species can coexist in a community if there are one or more significant differences in their niches
Resource Partitioning
the differentiation of ecological niches, enabling similar species to coexist in a community
Species’ fundamental niche
niche potentially occupied by that species
Species’ realized niche
the niche actually occupied by that species
a species’ fundamental niche may differ from its realized niche
i.e. barnacles, spiny and golden mice
Character Displacement
a tendency for characteristics to be more divergent in sympatric populations of two species than in allopatric populations of the same two species
i.e. variation in beak size between Galapagos finches
Predation
(+/- interaction)
- interaction where one species, the predator, kills and eats the other, the prey
- some feeding adaptions of predators: claws, teeth, fangs, stingers, poison
- prey defensive adaptions:
= Behavioral: hiding, fleeing, forming herds or schools, self-defense, alarm calls
= Morphological and physiological defense adaptions
= cryptic coloration
Cryptic coloration
AKA camouflages
makes prey difficult to spot
Aposematic coloration
animals with effective chemical defense often exhibit bright warning coloration
Batesian mimicry
a palatable or harmless species mimics an unpalatable or harmful model
Mullerian mimicry
2 or more unpalatable species resemble each other
Herbivory
(+/- interaction)
- an interaction in which an herbivore eats parts of a plant or alga
- led to the evolution of plant mechanical and chemical defenses and adaptations by herbivores
Symbiosis
a relationship where two or more species live in direct and intimate contact with one another
Parasitism
(+/- interaction)
- one organism, the parasite, derives nourishments from another organism, the host, which is harmed in the process
- many parasites have a complex life cycle involving a number of hosts
- some parasites change the behavior of the host to increase their own fitness
Endoparasite
parasites that live within the body of their host
Ectoparasite
parasites that live on the external surface of a host
Mutualism
(+/+ interaction)
AKA mutualistic symbiosis
- an interspecific interaction that benefits both species
can be obligate or facultative
Obligate Mutualism
one species cannot survive without the other
Facultative Mutualism
both species can survive alone
Commensalism
(+/0 interaction)
- one species benefits and the other is neither harmed nor helped
- hard to document in nature because any close association likely affects both species
- i.e. cows and birds ?
Facilitation
(+/+ or +/0 interaction)
indirect symbiosis
- one species can have positive effects on another species without direct and intimate contact
i. e. black rush makes the soil more hospitable for other plant species
Species diversity
the variety of organisms that make up the community
- two components: species richness and relative abundance
Species Richness
the total number of different species in the community
Relative Abundance
the proportion each species represents of the total individuals in the community
