Please enable JavaScript.
Coggle requires JavaScript to display documents.
Community Ecology (Predator-Prey Interactions (One predator, one prey…
Community Ecology
Predator-Prey Interactions
One predator, one prey
helps to understand how humans should harvest our pray
predator prey populations cycle up and down
prey dependent
#
predators functional response is dependent on prey density
predator cannot over consume the prey
if predator eliminates the prey both go down
if predator could keep population at inflection point
species would be stable
maximum substantial point
inflection point
point where growth rate changes + to -
fixed effort harvesting
pop health determined by amount of fish, deer, etc
healthy pop, harvest is good
hunting or fishing only allowed for length of time
Predator selection among multiple prey
insects often consume one species
most animals eat a variety of plants and animals
three factors apply
probability predator encounters prey
optimal forage theory
decision by the predator to attack an individual
probability that an attacked prey is always eaten
optimal diet model
predators will prefer prey that yields most energy
when prey is scarce predators will go after other prey
some prey will always be consumed
less profitable prey < more probable prey
Competition between species
species compete for the same resources
exploitation competition
organisms consume a shared resource
interference competition
organism restricts anothers access to resource without using it
competing species can coexist if they interfere with themselves most
Apparent Competition
plants cannot compete for and use a resource
prey species often are all ate by the same predators
Interconnectedness of Species: Food Chains and Food Webs
food web
numerous network of food interrelationships
energy food webs
trace how energy flows through a system
difficult to construct
major studies of food web is incomplete
keystone species
affect the structure of community
has an impact out of proportion of its size
"foundation of the community"
food chain
direct line of consumption
Diversity
Diversity and scale
Scale matters
Larger areas more diverse
Larger areas have more diverse habitats
more variations in
soil
geology
topography
relationship between area and species
species area relationship
S=cA^z
S = Number of species
A = Area
c and z are constants in communities
no community will have equal numbers
individuals
species
Determining size of areas is problematic
preliminary studies done to see if long term studies not a waste
Diversity and Latitude
diversity changes with lattitude
Northern/southern habitats
less species
receive little sunlight and warmth
temperatures are bitterly cold
high altitudes
little to no ice free land
Equatorial habitats
more diverse
latitudinal diversity
insight into complexity and processes of community
earths climate was much warmer 50 mya
began to cool 50 mya
ferns and conifers were diverse
angiosperms had originated
40 mya antartica began to form
Beneficial Interactions Between Species
mutualism
both species benefit
pollinators and flowers
relationships have costs
facilitation
one organism benefits the other is unharmed
one organism facilitates the presence of another
Nurse plants
alter a small area of a habitat immediately below themselves
creates a more favorable environment for seeds
#
Metapopulations in Patchy Environments
metapopulations
several local pops connected by migration and gene flow
four assumptions
region of the environment is composed of many discrete patches
some patches occupied by species where others are not
empty patches will become colonized by migration from other patches
Populations within patches have a probability of going extinct
habitat
high quality
source habitat
low quality
sink habitat
migration from patches
flying, walking, swimming
plants: dispersal of seeds and spores
may be blown by wind
dispersed by birds
generally becoming warmer
global warming
habitats near equator become too warm for species
