Chapter 53 and 54: Populations and Communities Flashcards
model of exponential population growth
unchecked growth; unrealistic in most circumstances, can lead to habitat destruction
carrying capacity
number of individuals that a habitat can sustain; limited by energy, shelter, nutrients, territories, water, etc.
logistic population growth model
incorporates carrying capacity; s-shaped curve
K-selection
for traits that are helpful at high densities; typical for populations that exist at the carrying capacity
r-selection
for traits that are helpful at low densities; maximizes population growth rate
density dependent
birth or death rates change with population size
density independent
birth and death remain constant regardless of density
equilibrium
births equal deaths in a population
causes of density-dependent regulation
competition, disease, predation, accumulation of wastes, and intrinsic factors
competition
finite resources shared among more individuals
disease
pathogens spread easier in crowded conditions
predation response to density
predator preferences may change at high prey numbers
accumulation of wastes
large population may produce waste faster than it degrades
intrinsic factors
physiological responses to crowding
population fluctuations
long term cycles associated with population size; dynamic
metapopulations
linked populations
sources
successful populations; lots of emigration to sinks
sinks
less successful populations; lots of immigration from sources
interspecific interactions
any interactions that occur between individuals of different species
broad categories of ecological interactions
competition (-/-), exploitation (+/+), and positive interactions (+/+ or +/0)
niche
sum of the biotic and abiotic needs of a species; place/role in a habitat
competition
(-/-) species compete for resources needed for growth, reproduction, etc. results from overlapping niches
principle of competitive exclusion
two species cannot coexist permanently in a community if their niches are identical
resource partitioning
differentiation of niches that enables similar species to coexist in a community
realized niche
the portion of a species fundamental niche that is used in actuality
exploitation
refers to any +/- interaction in which individuals of one species benefit by feeding on individuals of the other species (which are harmed); predation, herbivory, and parasitism
predation
(+/-) one animal eats another; predator adapted to locate and subdue, prey adapted to hide and escape
cryptic coloration
camoflague
aposematic coloration
bright coloration as a warning; generally poisonous, venomous
batesian mimicry
harmless resembling venomous
Mullerian mimicry
two or more venomous organisms resembling each other
herbivory
(+/-) special case of predation; animal eats a plant/algae
parasitism
parasite (+) lives off the hose (-); directly or indirectly affects host survival and reproduction
mutualism
(+/+) both species benefit
commensalism
(+/0) one species benefit and the other is not affected
trophic structure
feeding relationships among species; energy moves up from lower trophic levels
food chain
producers→primary consumers→secondary consumers
food web
better representation of feeding relationships; multiple connections among levels
energetic hypothesis
inefficiency of energy transfer between levels; about 10%
dynamic stability hypothesis
longer chains are less stable than shorter chains
dominant species
most abundant species or species with greatest biomass in a community
biomass
total mass of entire population
keystone species
key niches maintaining community structure; not necessarily dominant
facilitators
ecosystem engineers
nonequilibrium model
nature is not balanced or at equilibrium; community is a collection of things and disturbance keeps things in flux
intermediate disturbance hypothesis
some disturbance increases species diversity; allows for a mix and creates patches of different habitats
ecological succession
first colonizers replaced by other species, which are replaced by other species
primary succession
beginning without soil; eg. after volcanic eruption, glacier
secondary succession
succession with soil; takes less time than primary successions
species-area curve
curve that shows correlation between increase in area and increase in number of species
latitudinal gradient
more species closer to the equator; higher tropical diversity
island equilibrium model
island size and distance away from source determine number of species; large islands closer to the mainland have a greater number of species
