7. Community Ecology (Predation, Biocontrol, Disease, and Dominant and Keystone Species)

Facilitation (interaction)

• ( + / + ) or ( + / 0 )

• one species benefits from the presence of another, which positively impacts its growth, survival, or reproduction

Lotka-Volterra Predator Prey Equations

(pic)

prey distribution =>

search behavior, interference among predaotrs, aggregation of prey

3 types of functional response

• Type I function response: linear: predator consumption rate is is constant; a constant proportion of the prey population is removed per unit time

• TypeII function response: capture rates rise at a continually decreasing rate until an asymptote is reached

  • predator hadling time is incorporates into the functional response

• type III functional response: the attack rates lag initially at low prey densities and then increase with increase in prey densities and eventually decrease similar to the Type II response. the sresponse is sigmodi (s-shaped)

  • predator learning, predator switching behaviors or fixed and variable costs associated with foraging are being modeled

aposematic coloration

animals with effective h=chemical defense often exhibit bright warning colors

batesian mimicry

a palatble or harmless species mimics an unpalatable or harmful model

Müllerian mimicry

two or more unpalatable species resemble each other

herbivory

an interaction in which herbivores eats parts of a plant or alga

• does not necessarily kill the victim

problems with chemical control:

• some insecticides also reduce the pop of predators

• biomagnification

• insecticide resistance

• cost

biological control

use predators or parasites to reduce pest population below some threshold level

pathogens

disease-causing microorganisms

dominant species

those that are most abundant or have the highest biomass

keystone species

exert strong control on a community by their ecological roles, or niches

• ex. filed studies of sea stars exhibit their role as a keystone species in intertidal communities