community ecology - exam 4 Flashcards
community
all populations of organisms living close enough together for potential interaction
INTERspecific interacions
interactions w/ individuals of DIFFERENT species in the community
coevolution
reciprocal evolutionary change in interacting species
predation
+/- interaction
good for predator
bad for prey
forms of predation
herbivory
carnivory
parasitism
defenses agaisnt predators
escape
be hard to eat
annoy
be hard to see
mimicry
tell the truth (poison)
herd
be vigilant
mob predator
leave & regrow limbs
batesian mimicry
a harmless species mimics a harmful species
aposematic coloration
warning coloration
bright colors warns predators that they are poison
mullerian mimicry
2 or more harmful species resemble each other
predators don’t have to learn multiple colorations
predator adaptations
coevolution
acute senses
speed, agility, jaws, teeth, poison
ambush
attraction
symbiosis
interaction between organisms of 2 different species that involves direct physical contact
mutualism
+/+
both species benefit
obligate symbiosis
when at least 1 of the partners cannot complete its life cycle on its own
facultative symbiosis
partners do not necessarily require one another to survive &/or reproduce
endosymbiotic
one organisms lives inside another
often obligatory
commensalism
+/0
one benefits
the other is neither harmed nor benefits
usually not obligatory
parasitism
+/-
one benefits
other suffers but doesn’t usually die
parasites adapt to very specific hosts
competition
-/-
can occur when resources are scarce
niche
the match of a species to a specific environmental condition
when does interspecific competition happen
when niches overlap
competitive exclusion principle
2 species that share the same limiting resource cannot coexist indefinitely
1 species will win @ the expense of another
fundamental niche
if no other species existed, where would you live
bigger
realized nich
where you’re actually found
smaller
how can competitive exclusion be avoided
if 1 or both of the species evolve:
to use a diff resource
occupy a diff area of the habitat
feed during diff time of day
resource partitioning
division of limited resources by species to help avoid competition
character displacement
greater difference in a trait when 2 species co-occur than when 1 is present by itself
phenotypic differences
ex - same beak = more competition for food
species richness
total # of species in a community
relative abundance
proportion that each species represents
Shannon Diversity Index
takes both species richness & relative abundance into account
higher = greater diversity
Shannon Equitability Index
metric used to assess how evenly the individuals are distributed among the different organisms present
benefits of diversity
increased productivity
better able to withstand & recover from disturbance
biomass
total mass of all organisms in a habitat
trophic level
organisms that share the same function in the food chain
primary producer
photosynthesizer
creates all energy that’s passed up the food chain
primary consumer
grazers
herbivores
secondary consumer
predators
tertiary consumers
top predators
food webs
more realistic model
accounts for omnivores / animals that fulfill more than 1 role
ecosystem engineer
changes species richness & diversity by changing physical environment
dominant species
species in a community that are most abundant
2 dominant species hypotheses
most competitive in exploiting limited resources
most successful @ avoiding disease or predation
keystone species
big imapct on community structure
not necessarily abundant
ex - sea otter, sea urchin, kelp
top down control
populations of lower trophic levels are controlled by the organisms at the top
bottom up control
driven by presence or absence of the producers
trophic cascade
predators alter behavior of their prey thereby releasing next lower trophic level from predation
trophic cascade example
increase big fish = decrease little fish
decrease little fish = increase zooplankton
increase zooplankton = decrease algae
