BSC 385 exam 4 questions n answers
rated A+
evolution of mutualism - correct answer ✔✔- mutualism will arise only if:
- the benefit outweighs the cost
- it is an ESS for both species; so only if
pwsm +qwum > wnm
wnm - the fitness of individuals in a non-mutualistic population
p - proportion of successful mutualists
q - the proportion of unsuccessful mutualists
FOR BOTH SPECIES
ecological community - correct answer ✔✔- a group of interacting species that co-occur in a
particular place
- two parameters describe communities:
-- composition: what species are present?
-- structure: how do those species interact with each other
environmental filtering - correct answer ✔✔abiotic factors have primacy over whether a species
is going to be able to maintain a population in any one place
direct filtering - correct answer ✔✔- determined by environmental tolerances of the species
- fundamental niche
,indirect filtering - correct answer ✔✔- mediated by interactions with other species that are
subject to filtering
- realized niche
evening primrose and its herbivores - correct answer ✔✔- evening primrose has local ecotypes
that depend on abiotic conditions
- its herbivore community changes depending on ecotype
- an indirect filtering effect mediated by the host plant's variable rains
- effects of filtering on one species can ripple through the community
the local ecotypes of the evening primrose - correct answer ✔✔filter their local herbivore
community
neutral models - correct answer ✔✔assume that:
- communities are random combinations of species physiologically able to live in the same place
- two mechanisms determine species membership in communities - dispersal in ecological time
and speciation in evolutionary time
- if communities are altered, they do not necessarily recover the same community structure (i.e.
the dice get thrown again)
niche-based models - correct answer ✔✔- biological interactions (e.g. competition) shape (and
are shaping) the niches of coexisting species and so determine community composition
- NOTE the "ghost of competition past" may give the appearance of competition not being
important in the current community (i.e. that niches are already well separated or even
randomly distributed) via competitive exclusion and character displacement some time in the
past
, under a neutral model of community structure... - correct answer ✔✔species associate at
random
testing community structure models - correct answer ✔✔null hypothesis - the neutral model
neutral model - the niches are arranged at random so that some niches are very similar, others
very different
niche-based model - the niches are over or hyper-dispersed in niche space
can be tested by comparing real niche distributions with those generated randomly
if competition is important and likely to be more so between similar species, would you expect
similar-size rodents to co-ccur more or less frequently? - correct answer ✔✔less frequently
What would you expect to matter more to coexistence? - correct answer ✔✔Niche overlap
the role of competition in niche separation - correct answer ✔✔- is separation of the body sizes
of granivorous rodents due to competition?
- prediction 1: rodents of similar size in the same guild should coexist less frequently than
expected by chance
- Prediction 2: This pattern should hold more strongly for species of very similar body size than
for species of more different size
- Prediction 3: If species from other guilds (not expected to compete directly) are included in the
analysis, their co-occurrence should be random
competitive hierarchy - correct answer ✔✔an extension of competitive dominance in two-
species pairs
competitive networks - correct answer ✔✔more likely, especially given trade-offs in
performance among species
rated A+
evolution of mutualism - correct answer ✔✔- mutualism will arise only if:
- the benefit outweighs the cost
- it is an ESS for both species; so only if
pwsm +qwum > wnm
wnm - the fitness of individuals in a non-mutualistic population
p - proportion of successful mutualists
q - the proportion of unsuccessful mutualists
FOR BOTH SPECIES
ecological community - correct answer ✔✔- a group of interacting species that co-occur in a
particular place
- two parameters describe communities:
-- composition: what species are present?
-- structure: how do those species interact with each other
environmental filtering - correct answer ✔✔abiotic factors have primacy over whether a species
is going to be able to maintain a population in any one place
direct filtering - correct answer ✔✔- determined by environmental tolerances of the species
- fundamental niche
,indirect filtering - correct answer ✔✔- mediated by interactions with other species that are
subject to filtering
- realized niche
evening primrose and its herbivores - correct answer ✔✔- evening primrose has local ecotypes
that depend on abiotic conditions
- its herbivore community changes depending on ecotype
- an indirect filtering effect mediated by the host plant's variable rains
- effects of filtering on one species can ripple through the community
the local ecotypes of the evening primrose - correct answer ✔✔filter their local herbivore
community
neutral models - correct answer ✔✔assume that:
- communities are random combinations of species physiologically able to live in the same place
- two mechanisms determine species membership in communities - dispersal in ecological time
and speciation in evolutionary time
- if communities are altered, they do not necessarily recover the same community structure (i.e.
the dice get thrown again)
niche-based models - correct answer ✔✔- biological interactions (e.g. competition) shape (and
are shaping) the niches of coexisting species and so determine community composition
- NOTE the "ghost of competition past" may give the appearance of competition not being
important in the current community (i.e. that niches are already well separated or even
randomly distributed) via competitive exclusion and character displacement some time in the
past
, under a neutral model of community structure... - correct answer ✔✔species associate at
random
testing community structure models - correct answer ✔✔null hypothesis - the neutral model
neutral model - the niches are arranged at random so that some niches are very similar, others
very different
niche-based model - the niches are over or hyper-dispersed in niche space
can be tested by comparing real niche distributions with those generated randomly
if competition is important and likely to be more so between similar species, would you expect
similar-size rodents to co-ccur more or less frequently? - correct answer ✔✔less frequently
What would you expect to matter more to coexistence? - correct answer ✔✔Niche overlap
the role of competition in niche separation - correct answer ✔✔- is separation of the body sizes
of granivorous rodents due to competition?
- prediction 1: rodents of similar size in the same guild should coexist less frequently than
expected by chance
- Prediction 2: This pattern should hold more strongly for species of very similar body size than
for species of more different size
- Prediction 3: If species from other guilds (not expected to compete directly) are included in the
analysis, their co-occurrence should be random
competitive hierarchy - correct answer ✔✔an extension of competitive dominance in two-
species pairs
competitive networks - correct answer ✔✔more likely, especially given trade-offs in
performance among species
