Lecture 26: Community Ecology

What is a community?

a group of populations of different species living close enough to interact in a specific area

What is community ecology?

examines the interactions between populations of different species

What is interspecific interactions?

interactions between individuals of different species and they could either help, harm, or have no effect on species involved. They include interspecific competition, predation, herbivory, and symbiosis.

What is interspecific competition (-/-)

when individuals of different species compete for a resource that limits their growth and survival. Examples: when non-native grasses competing with native plants for nutrients and water, mountain lions and bobcats in gold creek compete for prey such as mule deer or rabbits

What is the principle of competitive exclusion?

Two species cannot coexist permanently in a community if their niches are identical

What is a habitat?

where an organisms lives

What is a niche?

an organism’s use of the biotic and abiotic resources in it environment

What is resource partitioning?

It is a type of interspecific competition and it is the division of environmental resources by existing species such that the niche of each species differs from the niches of all coexisting species.

How does resource partitioning enable similar species to coexist in a community?

Each species are found in different niches and the community so they are dividing the resources by living in different areas of the same communtiy

What is a fundamental niche?

the niches potentially occupied by a species

What is a realized niches?

the portion of fundamental niche that is actually occupied

What is the impact of interspecific competition of the fundamental niche of an organisms?

interspecific competition often gives rise to difference between a species fundamental nice and its realized niche

What is predation (+/-)?

interaction in which one species (the predator) kills and eats the other species (the prey)

What is mechanical defeneses?

discourage animal predation by causing physical discomfort with pain. Examples: porcupine quills and hard shell of tortoises physically preventing the consumption of eating the tortise

What is chemical defense?

species can secrete a specific chemical to discourage animal predation. Examples: skunk releasing its gas and millipede having toxic skin

What is aposematic coloration?

warning coloration. Examples: llama sea slug that have a green dot skin and poison dart frog that turns red and if eaten can lead to physical discomfort due to poison gland

What is cryptic coloration?

camouflage. Examples pygmy seahorse as it camouflage into coral

What is batesian mimcry?

a harmless species that mimics a harmful one. Example nonvenomous green parrot snake and venomous green parrot snake

What is Mullerian mimicry?

two or more unpalatable species mimic one another and have a defense mechanisms. Example cuckoo bee and yellow jacket

What is symbiosis?

interaction when individuals of two or more species live in direct and intimate contact with one another. Has three types Parasitism (+/-), mutualism (+/+), and commensalism (+/0)

What is parasitism (-/-)

are organisms that get their nourishment from their host in which their host are harmed in the process. Can be endoparasites or ectoparasites.

What is endoparasite?

they live within the body of their host. Examples: tapeworm

What is ectoparasites?

parasites that feel on external surfaces of a host. Examples: adult tick

What is mutualism (+/+)?

where both members benefit from their close interactions. They can be either obligate or facultative

What is obligate mutualism (+/+)?

the survival of one or both organisms involved is dependent upon the relationship. Examples: termites digest food and termite symbionts gains food and helps digestive cellulose for termites

What is facultative mutualism (+/+)?

both organisms benefit from but are not dependent upon their relationship for survival. Example: clownfish uses it as a home and food and sea anemones is protected by the clownfish

What is commensalism (+/0)?

where one organisms will benefit while the other is not benefitted from this relationship. Examples: lemon shark are not affected and remora are attached to sharks to gain meals by eating left over of host meals

What is a trophic structure?

feeding relationships of a community

What is a food chain?

a linear sequence of organisms through which nutrients and energy pass as one organisms eats another

What is a food web?

it consist of many interconnected food chains and are more realistic representation of consumption relationships in ecosystem

How do food webs differ from food chains?

A food chain is simple and a linear path that shows how energy moves from one organisms to another while food webs are more complex and show many connected food chains from the same ecosystem