BIO252 Exam 4 Questions with Verified Solutions Latest Version 2025 Graded A+
What are the different type of species interactions we discussed? - Answers biological community: set of
species that share a time and a place, e.g. food web (food chains up and down, guild across)
competing for same resources
Which species interact and how?
Direct & indirect
ON AXIS:
amensalism: one species is negatively affected, the other is not affected
commensalism: one species benefits and the other is not affected
neutralism: interact but neither species affected
IN BOXES:
one species enemy/victim depending on negative or positive impact of each
mutualism: both species benefit
competition: both species are negatively affected by interaction, same resource
How is population density affected by competition with other species? - Answers Mutualist: pop density
increases slightly with interaction (more of other species around)
Neutral: No change based on other species
COMPETITIVE: population density decreases with competition/population decreases with increased
population density of other species
NEUTRAL: Continue on their own path. K graph looks independent. Intraspecific competition (not inter)
What is a zero-growth isocline? What does this look like for two species that do NOT compete (i.e. have
a neutral interaction)? What does it look like when one competitor is stronger than the other? - Answers
intraspecific: perpendicular, k value is equilibrium for each
, interspecific zero growth, EQUAL RESPONSE: parallel
zero-growth isocline: carrying capacity is dependent on the population size of the other species. (K1-
(N2+N1)/K2)
NO GROWTH-- populations held constant, one species has a higher carrying capacity than the other
dN/dt = rmax N([K-N]/K)
interspecific different response: can meet at an equilibrium where one is not depleted, where lines
intersect
isocline - Answers Shows the densities of a species and its competitor that saturate that species'
resources and stops its population growth. For each species, there are regions of positive, negative, and
zero growth.
HIGHER K WINS
rmax - Answers max population growth rate
competitive exclusion - Answers equal competitive response
if two species totally share a niche, the superior drives the other one extinct
stable coexistence - Answers each species less abundant than if it were alone
Under what conditions might we expect two competing species to coexist? - Answers niche overlap but
not totally shared, different competitive response
prey refuges
character displacement - Answers Evolutionary niche (and structure-function) shifts where competitions
co-occur
The tendency for characteristics to be more divergent in sympatric populations of two species than in
allopatric populations of the same two species.
What are the different type of species interactions we discussed? - Answers biological community: set of
species that share a time and a place, e.g. food web (food chains up and down, guild across)
competing for same resources
Which species interact and how?
Direct & indirect
ON AXIS:
amensalism: one species is negatively affected, the other is not affected
commensalism: one species benefits and the other is not affected
neutralism: interact but neither species affected
IN BOXES:
one species enemy/victim depending on negative or positive impact of each
mutualism: both species benefit
competition: both species are negatively affected by interaction, same resource
How is population density affected by competition with other species? - Answers Mutualist: pop density
increases slightly with interaction (more of other species around)
Neutral: No change based on other species
COMPETITIVE: population density decreases with competition/population decreases with increased
population density of other species
NEUTRAL: Continue on their own path. K graph looks independent. Intraspecific competition (not inter)
What is a zero-growth isocline? What does this look like for two species that do NOT compete (i.e. have
a neutral interaction)? What does it look like when one competitor is stronger than the other? - Answers
intraspecific: perpendicular, k value is equilibrium for each
, interspecific zero growth, EQUAL RESPONSE: parallel
zero-growth isocline: carrying capacity is dependent on the population size of the other species. (K1-
(N2+N1)/K2)
NO GROWTH-- populations held constant, one species has a higher carrying capacity than the other
dN/dt = rmax N([K-N]/K)
interspecific different response: can meet at an equilibrium where one is not depleted, where lines
intersect
isocline - Answers Shows the densities of a species and its competitor that saturate that species'
resources and stops its population growth. For each species, there are regions of positive, negative, and
zero growth.
HIGHER K WINS
rmax - Answers max population growth rate
competitive exclusion - Answers equal competitive response
if two species totally share a niche, the superior drives the other one extinct
stable coexistence - Answers each species less abundant than if it were alone
Under what conditions might we expect two competing species to coexist? - Answers niche overlap but
not totally shared, different competitive response
prey refuges
character displacement - Answers Evolutionary niche (and structure-function) shifts where competitions
co-occur
The tendency for characteristics to be more divergent in sympatric populations of two species than in
allopatric populations of the same two species.
