Unit test 3 (Ch. 24-26) Flashcards
Why do species occur where they do?
organisms and their environment
1) ecological 2) evolutionary
interactions
what can organisms interact with in their environment?
abiotic and biotic factors
what’s an abiotic factor?
nonliving components (physical and chemical)
what is ecology?
scientific study of interactions
what are we studying in terms of interactions?
population interactions
community interactions
ecosystem interactions
what characteristics of a population are influenced by abiotic and biotic factors?
-distribution
-abundance
-demography
what does distribution mean in terms of characteristics in a population?
where an organism is found
what does abundance mean in terms of characteristics in population?
how dense its population is
what does demography mean in terms of characteristics in population?
its age structure
what is a population?
group of individuals of a signle species living in the same area at same time
in a population, what happens?
-individuals rely on the same resources
-likely to interact and breed with one another
how do we define a population?
**species concepts **help define individuals in a population
what is another process they use to define populations?
boundaries and range
what do we use first as ecologists? species concept or boundaries and range?
boundaries and range
how do we identify a populations range?
examining the extent of its habitat
what is the range of a species?
area where theyre found during its lifetime and includes areas where idviduals or communites may migrate or hibernate
what factors define the range of species?
-abiotic
-biotic
-positive and negative interactions
what are negative interactors?
-predators
-parasites
-disease
-competitors
what are positive interactors?
prey and food sources
what other factors determine range that aren’t listed in the previous question?
temp
water availability
salinity
sunlight
soil quality
how do we quantify populations in space?
once boundaries and range have been established, we can determine its size
what do we use to find the space in a population?
density and dispersion
what is the density of a population?
number of individuals in a population
what is the dispersion of a population?
pattern of spacing among individuals within the boundaries of a population
what causes a metapopulation in a heterogeneous landscape?
fluctuations in densities and influences migration patterns
what is a metapopulation?
group of spatially separated populations of the same species which interact at some level
what are the 3 dispersion types?
-clumped (starfish)
-uniform (penguins)
-random (dandilions)
what needs to be maintained between subpopulations for a metapopulation to exist?
gene flow
what may occur as gene flow between subpopulations?
allopatric and symmpatric speciation
what is demographics?
describes the vital statistics of a population over time
what is a life table?
age specific data of the survival and reproductive patterns of a population
what is a survivorship curve?
displays the proportion or numbers in an organism that’s still alive at each age
population dynamics is what?
population of all species have the potential to expand greatly when resources are abundant
does unlimited growth occur for long in nature?
no
what are the reasons unlimited growth does not occur for long in nature?
-resource availability
-access decreases as a population grows
how do we calculate change in a population size?
the change in (births and immigrants)-(deaths and emmigrants) over time
delta N/ delta t (t=time)
what happens when births exceed deaths and immigration exceeds emigration?
population growth!
what do you get when members who have access to abundant food and are free to reproduce at their physiological capacity?
exponential growth!
when exponential growth occurs what do we get from our formula delat N / delta t
rmax
what does the shape of the graph of exponential growth look like?
J shape
what does the J shape curve mean?
growth rate is constant but population is acumulating more new individuals over time
what are the factors that influence a population a sits density grows?
new types of interactions:
density dependent or denisty independent
what are density independent factors?
climate and human-related factors
how can populations stop growing if they have unlimited resources (rare in nature)?
if deaths and migration rates changes as density increases
how do density dependent processes affect death rates?
amount of resources available (food, water, nesting sites)
when resources run low in a population, what increases?
intraspecific competition
what is intraspecific competition?
type of interaction individuals in a population compete for limited resources
how do density dependent processes affect migration rates?
when density increases, the amount of resources decreases
since there isn’t enough resources in an area for the individuals and the competition is too intense, what does that lead to?
the individuals will risk leaving (emigrating) in order to find areas with more resources
so to sum up, what does density dependent factors have on migration rates?
high population density leads to a decrease in immigration and increase in emigration
how do density dependent processes affect death rates?
when density is increased, diseases can spread more too creating a threshold host density which can lead to a lot of deaths depending on the disease
what is logistical growth?
growth stops because resources arent unlimited and population reaches carrying capacity(K)
What is a community?
an association of populations of different species that live and interact in the same place at the same time
what is a metacommunity?
set of local communities that are linked by dispersal
how do we characterize community?
by examining the interactions between the organisms in it
what is interspecific competition? (-/-)
strong competition can lead to competitive exclusion due to competition for particular resources
what is gause’s law?
competitive exclusion principle means that 2 species cannot coexist in a community if their niches are identical
how can coexistence occur?
when the overlap between niches is reduced
what is a niche?
total of an organism’s use of the biotic and abiotic resources in it’s environment
what’s an example of ecological niche?
birch trees grow in cool, moist habitats and their seedlings are not tolerant to low light conditions
what is the range of conditions that allows a species to survive and reproduce?
fundamental niche
how does a fundamnetal niched occur?
in the absence of competition
what is the range of conditions under which a species actually occurs in natural communities?
a realized niche
what’s an example of a realized niche?
2 barnacle species: Chthamalus and Balanus compete in the intertidal zone
Chthamalus are found on the higher part of the tidal rocks and balanus on the bottom part so when the tide washes the balanus away, the Chthamalus can spread into the formely occupied region. this makes it a realized niche
how does a species survive competition?
resource partitioning
what is resource partitioning?
differentiation of niches via natural selection
what does resource partitioning enable?
species to coexist in a community
how does competition cause character displacement?
natural selection
since there is displacement in the characteristics in the species due to natural selection, what effect does it have on niches?
they occupy a different niche
which causes more character displacement?
sympatric over allopatric conditions
why does sympatric condition more often cause character displacement than allopatric?
allopatric conditions does no exhibit competition so no character displacement is necessary
What is predation? (+/-)
carnivorous interaction where the predator kills and eats the prey
what are feeding adaptations of predators?
claws
teeth
fangs
stingers and poison
defensive adaptations of prey?
hiding
running
comouflage
poison
what helps shape evolution via natural selection?
predator and prey interactions
what are predator strategies?
chasing
comouflage
mimicry
all to avoid notice by prey
what are prey strategies against predation?
fleeing
hiding
living in groups
mechanical defenses
special coloration
mimicry
what is mimicry for predation strategies?
coloration, chemical signlas or sounds
what is coloration in prey strategies?
aposematic coloration and cryptic coloration
what is aposematic coloration?
provides warning to predators who will avoid bright coloration because it signifies chemical defenses
what is cryptic coloration?
provides comouflage
what is the mimicry of prey’s strategies?
bestesian mimicry
mullerian mimcry
what is bastesian mimicry?
when a harmless species evolves to mimic an unpalatable or harmful species
what is mullerian mimicry?
2 or more unpalatable species evolve to resemble eachother which is not a result of common ancestry
if a species is not a result of common ancestor and shares common traits, what is that considered?
convergent evolution
what is another prey strategy?
deimatic behavior
what deimatic behavior?
occurs as prey make themsleves appear more dangerous via coloration, sound making itself larger or mimicry
Basically a form of bluffing
what is an example of a deimatic behavior?
butterfly resembling the face of a snake
what is herbivore (+/-)?
process whereby herbivore eats photosynthetic organisms, like plants or algae
what has herbivore led to through evolution?
the plants gaining chemical defenses and spines through leaves
what is symbiosis (+/-) (+/+) or (+/0)?
occur when 2 or more species live in direct and intimate contact with 1 another
what are the 3 types of symbioses?
parasitism
mutualism
commensalism
where is symbioses usually applied to?
on or in the largest of the organisms in the symbiosis
what is parasitism (+/-)?
parasite derives its nourishment from its host and harmed in the process
what is mutualism (+/+)?
interspecific interactions benefits both species
what is commensalism (+/0)?
one species benefits and the other is not affected
what characteristics of a community are commonly measured?
species composition
feeding relatioships
biodiversity
what is species composition?
describes all organisms in a given community
what are feeding relationships?
describe how energy is transferred in a community
what is biodiversity?
describes the number of species and their relative abundance
what is a trophic structure?
identifies the dynamics of a community based on the feeding relationships between organisms
what is a food chain?
indetifies the transfer of food energy up a community’s trophic levels
what does a food chain start with?
autotrophic organisms=primary producers
herbivores=primary consumer
carnivores=primary,secondary consumers
food webs are composed of…?
multiple food chains and give ecologists a much better understanding of how species interact with eachother
food webs describe the trophic interactions with arrows according to…?
who eats whom
when an arrow points to an organisms, it is the direction of?
comsumption
decomposers include?
bacteria and fungi which consume dead or dying organisms
what controls abundance or biomass of a species trophic level?
bottom-up
Carnivores
herbivores
autotrophs
nutrient level
This increases productivity at higher trophic levels like carnivores
if it’s top-bottom?
this model controls communit organization since predators limit prey populations
what is a trophic cascade?
an event where a species occupying a trophic level is decimated(killed) and the biomass at all other levels is impacted
like a domino effect
trophic cascade depends on whether its community organization is controlled bottom-up or top-bottom. what’s an example of this?
if it’s top-bottom food web, the predators on herbivores would increase the biomass of primary producers
cascades in a top-bottom food web is dependent on what to create a bigger impact?
the level of supression like more predators–>more impact
an example of the results of a density-mediated trophic cascade in top-bottom food web?
predators eat herbivores
herbivore population decreases
fewer herbivores eat primary producers
primary producers population increases
an example of a trait mediated trophic cascade food web?
predator gets induces; phenotypic, behavior, morphological or physiological change of the herbivore
so.. predators appear
herbivores hide
fewer herbivores eat primary producers
what is a dominant species?
the one with the most biomassor most abundant
hat is a keystone species?
not the most abundant but exerts strong control on community structure
what does biodiversity influence?
the nature of these interactions that help us identify the trophic ranks
how do we measure biodiversity?
measuring species richness and measuring relative abundance
what does measuring the richness provide?
the number of species present
what does measuring the relative abundance provide?
the proportion that each species represents of all individuals in the community
what is an example of biodiversity?
theres 2 forest communities…
both have the saem number of trees and contain 4 species (same species richness) but these species contain a difference in relative abundance
1 forest has 25% of each type of species
the other forest has 80% of 1 type of species and different percenatges for the rest
how do we calculate the diversity ?
H= -(pAlnpA + pBlnpB + pClnpC)
A,B,C = species
p=relative abundance (%)
what is productivity?
the rate of generation of biomass
when biodiversity increases, what happens?
productivity increases
what is the 1 mechanism that has been proposed to explain the positive biodiversity-productivity relationships?
niche partitioning
niche and resource partitioning have the goal of?
reducing competition within a community since natural selection gave these species their own niches
does stability increase with biodiversity?
yes
what does stability refer to in a community?
temporal constancy and resistance to environmental change
what are distrubances in a community?
storm
fire
flood
drought
human activity
all can change a community by removing organisms from it or altering resource availability
what is a nonequilibrium model?
describes communities as constantly changing after a disturbance
what are disturbances categorized by?
type
frequency and intensity
what effects does the different disturbances have on communities?
intermediate disturbances= foster greater species diversity than low or high
high disturbances= cause too much environmental stress so species leave
low disturbances= never disrupt competitively-dominant species
what is ecological succession?
transition in species composition in disturbed areas over ecological time
what is primary succession?
begins in a lifeless area where soil has not yet formed
what ecological processes will change over time and how will they change during primary succession?
-more niches will form
-more interspecific competition (interactions or competition for resources)
-migration of new species (more species diversity)
-increase biomass inneach trophic level
what is secondary succession?
an existing community has been removed by a disturbance **while the soil is left intact. **
