GB 24- Community Ecology

community

association of populations of different species that live and interact in same place at same time

Community Ecology:

• study of interactions that determine distribution and abundance of individuals and populations

resources

• anything from environment that meets needs of a species

ecological niche

• role of a species within structure and function of community

competition

two or more individuals attempt to use the same resource

1. Use by one decreases availability for others

2. Lose-lose (-/-) interaction; both participants hurt

intraspecific competition

Competition between members of same species/population

interspecific competition

Competition between members of different species

importance of competition

Considered most important determinant of:

1) # species in community

2) Size of each population

competitive exclusion

selection in one competitor due to competition to use different set of resources

• One species excludes other from part of fundamental niche

• -> Realized niche

• Can happen within species

-> Sympatric speciation

resource partitioning

Differentiation of niches that allows similar species to coexist

character displacement

• With competing species have different traits where they overlap

• But similar traits in non-overlapping populations

predation

• Consumption of 1 species by another, predator eats prey

• +/- interaction; predator benefits, prey adversely affected

• Often leads to coevolution

i. Each exerts a strong selective force on the other -> evolution due to interaction

ii. Species A evolves an adaptation in response to species B <-> Species B

• evolves in response to the adaptation of species A i

• Predator gets better at catching prey

• Prey gets better at avoiding predator

Adaptation in Predators

1. Acute senses

2. Claws, fangs, poison/venom

3. Fast, agile

4. Camouflage it ambushes prey

Adaptation in Prey

• Mechanical defense

• Chemical defense

• aposematic coloration

• cryptic coloration

• mimicry

• Fleeing - run and hide, sometimes distract

• Ink, autonomy

• Living in groups

• More likely to notice predator, less likely to be eaten

Aposematic coloration

• Warming coloration - advertises bad taste or toxicity

• Example: monarch butterflies

• Eat milkweeds -> toxins accumulate

cryptic coloration

camglouge, blend into environment

mimicry

The visual similarity of one species to another which protects one or both

Batesian mimicry

Defenseless species looks like dangerous species

Müllerian Mimicry

• Different species resemble each other, all with real
  defenses

• Advantageous to all - predator only has to learn 1 coloration

Plants

• Herbivory - organism eats part of plant or alga;

• +/- interaction

• Can't escape, but often have defenses

• Physical - spines, thorns, thick waxy leaves

• Chemical - bad taste or toxicity

symbiosis

• Intimate, long-term relationship between 2 or more species

• Usually involves 1 species living on or in the other

• 3 forms of symbiosis: parasitism, mutualism, commensalism

parasitism

1. +/- interaction - parasite benefits, host is harmed (rarely killed)

2. Examples: heartworms, tapeworms, ectoparasites

3. parasite gets nutrients from host

mutualism

1. +/+ interaction - both benefit, often depend on each other

2. Example: mycorrhizae, termites, ants & acacia

commensalism

1. +/0 interaction - one benefits, neutral of the other

2. Example: tree and epiphyte, egrets and African buffalo