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Chapter 26: Community Ecology (Beneficial Interactions Between Species…
Chapter 26: Community Ecology
Diversity
diversity and scale
larger ares are more diverse than smaller areas
species-area relationship
expressed by formula:
S=cA^z
species abundance distribution
diversity and latitude
high latitudes have low diversity
low latitudes have high diversity
Predator-Prey Interactions
predator selection among multiple prey
three important factors
predator's decision to attack
probability that something attacked will be successfully consumed
probability of prey encounters
optimal foraging theory
examines interactions between herbivores and plants
optimal diet model
#
makes four predictions
some prey items will always be eaten; others will never be eaten
predators prefer prey that yields high energy
plants will be eaten depending on their abundance
predators broaden their diet
competition between species
types
exploitation competition
interference competition
invasive species
resource
can lead to increased growth rates
examples
water
minerals
light
pollinators
one predator, one prey
functional response
feeding rate
faster with more prey individuals
handling time
prey dependent
paradox of enrichment
factor in the loss of species diversity
zero groth isocline
illustrates prey density effects
indicate prey population sizes
maximum sustained yield
alternatives
fixed effort harvesting
fixed quota harvesting
just enough species to keep population density at a stable point
Metapopulations in Patchy Environments
metapopulation
several interconnected local populations
common model makes four assumption
some patches are occupied by the species where as other suitable patches are not
empty patches will become colonized by migration from occupied patches
region of environment is composed of many discrete patches in which species can live
populations within individuals patches have a probability of going extinct within that patch
habitat types
source habitat
high quality patch
sink habitat
low quality patch
Interconnectedness of Species: Food Chains and Food Webs
ways to study species interactions
food web
energy flow web
food chain
keystone species
dramatically affects the structure of the community
Beneficial Interactions Between Species
facilitation
#
one organism helps another without receiving benefit
example
nurse plants
mutualism
examples
pollinators and their plants
both organisms benefit
primary succession
organisms become established
exmaple
volcanoes producing lava
fugitive species
survives by colonizing new patches
flourish temporarily
example
weeds
