Exam 3 Flashcards
which type of animal likely spends the least amount of time in the handling phase of the predation process
herbivores
Handling involves dispatching the prey and accessing the edible portions, which will likely be more difficult for animal prey compared to plant prey
Prairie dogs live in colonies where some members are always on the lookout for predators. If they see a predator, they will call out a waring for other colony members to flee. This would be classified as a … defense.
behavioral
A prey species with great cryptic defenses will likely elicit which type of functional response from a predator?
type III
A Type III response indicates difficulty for predators in finding their prey until the density increases to a certain point.
If at a certain point in time, you find that both the predator and the prey populations are more abundant than their respective isocline value, you would expect predator populations to … and prey populations to ….
increase; decrease
This scenario would occur in quadrant 3; you would expect predators to increase and prey to decrease.
variation in population size over time and space
population dynamics
- populations that grow beyond their carrying capacity
- can occur when the carrying capacity of a habitat decreases from one year to the next
overshoot
a substantial decline in population density that typically goes well below the carrying capacity
die-off
regular oscillation of population size over a long period of time
population cycles
populations are stable at
carrying capacity
when a population experiences a large reduction in size during a die-off, it can
undershoot its carrying capacity
Whenever the size of the population decreases due to predation, disease, or a density-independent event, the population responds by
growing
when the abundances of trophic groups in a community are determined by the amount of energy available from producers in that community
bottom-up control
when the abundance of trophic groups is determined by the existence of predators at the top of the food web
top-down control
because most communities contain an abundance of vegetation, trophic groups must be controlled from the
top of the food web
- indirect effects that are caused by the changes in the traits of an intermediate species
- commonly happens when a predator causes its prey to change its feeding behavior, which in turn alters the amount of food consumed by the prey
trait-mediated indirect effects
indirect effects that are caused by the density of an intermediate species
density-mediated indirect effects
- occurs when two species interact without involving other species
- often set off a chain of events that affects stlll other species in the community
direct effect
when two species interact in a way that involves one or more intermediate species
indirect effect
- when indirect effects are initiated by a predator
- can also be initiated when one species causes changes in the traits of another species
trophic cascade
group species that feed on similar items but need not be closely related
guilds
the levels in a food chain or food web of an ecosystem
trophic levels
first trophic level of a food web
producers
those that eat producers
primary consumers
those that eat primary consumers
secondary consumers
eat secondary consumers
tertiary consumers
consumers of dead organic matter
scavengers, detritivores, and decomposers
- linear representations of how species in a community consume each other and therefore how they transfer energy and nutrients from one group to another in an ecosystem
- greatly simplify species interactions in a community
food chain
- complex and realistic representations of how species feed on each other in a community and include links among many species of producers, consumers, detritivores, scavengers, and decomposers
- Describe the feeding relationships of ecological communities
food webs
why is analyzing the feeding relationships of ecological communities so important
feeding relationships help determine whether a species can exist in a community and whether it will be rare or abundant
frequently disturbed habitats typically support
species that are adapted to disturbances
tells us that more species are present in a community that experiences occasional disturbances than in a community that experiences frequent or rare disturbances
intermediate disturbance hypothesis
When the product is a high value (rτ > 1.57)
the population continues to exhibit large oscillations over time, a pattern known as a stable limit cycle
a population that continues to exhibit large oscillations
stable limit cycle
If this product is an intermediate value (0.37 < rτ < 1.57)
the population initially oscillates, but the magnitude of the oscillations declines over time (damped oscillations)
the population initially oscillates, but the magnitude of the oscillations declines over time
damped oscillations
When this product is a low value (rτ < 0.37)
the population approaches the carrying capacity without any oscillations
The smallest populations experienced the … probability of extinction and the largest populations experienced the … probability of extinction
highest; lowest
When a model is designed to predict a result without accounting for random variation in the population growth rate
deterministic model
When random variation in birth rates and death rates is due to differences among individuals and not due to changes in the environment
demographic stochiasticity
when random variation in birth rates and death rates is due to changes in the environmental conditions
environmental stochiasticity
When disturbances in a community are of low frequency or intensity species richness is
is relatively low
when disturbances are moderate in frequency or intensity, species richness
is relatively high
when disturbances are high in frequency or intensity, species richness
declines
- substantially affect the structure of communities even when the individuals of that species may not be particularly numerous
- can cause a community to collapse
- influence the structure of a habitat
- sometimes called ecosystem engineers
keystone species
species diversity is affected by
- resource availability
- habitat diversity and connectivity
- keystone species
- disturbances
a larger population is broken up into smaller groups of conspecifics that live in isolated patches
subpopulations
The collection of subpopulations that live in isolated patches are linked by dispersal
metapopulation
- show the relative abundance of each species in a community in rank order from the most abundant to the least abundant
- are particularly good for illustrating how communities differ in species richness and species evenness
rank-abundance curves
a comparison of the relative abundance of each species in a community
species evenness
in a rank-abundance curve, the most abundant species receives a rank of
1
The greatest evenness occurs when
all species in a community have equal abundances
the least evenness occurs when
one species is abundant and the remaining species are rare
measures of species diversity
- Shannon-Wiener Index
- Simpson’s Index
patterns of abundance
absolute and relative
a normal, or bell-shaped distribution that uses a logarithmic scale of the y axis
log-normal distribution
the number of individuals of each species that are counted
absolute abundance
the proportion of individuals in a community represented by each species
relative abundance
refers to the number of species in a community
species richness
When individuals frequently disperse among subpopulations, the whole population functions as a
single structure and they all increase and decrease in abundance synchronously
live on the outside of organisms
ectoparasites
- live inside organisms
- typically cause fatal diseases
endoparasites
When dispersal is infrequent, however, the abundance of individuals in each subpopulation
can fluctuate independently of one another
a process by which small habitats represent only fragments of the original habitat
habitat fragmentation
we characterize communities by
either by their dominant organisms or by the physical conditions that affect the distribution of species
when do metapopulations typically occur
- when a habitat is naturally patchy
- result of human activities
models of spatial structure of subpopulations
- basic metapopulation model
- source-sink metapopulation model
- landscape metapopulation model
- those in which the species do not depend on each other to exist
- composed of species that live in the same place because they have similar adaptations and habitat requirements
independent communities
- those in which species depend on each other to exist
- act as superorganisms
interdependent communities
- describes a scenario in which there are patches of suitable habitat embedded within a matrix of unsuitable habitat’
- emphasize how colonization and extinction events can affect the proportion of total suitable habitats that are occupied
- indicates that a metapopulation persists because of a balance between extinction of the subpopulation in some habitat patches and the colonization of others
basic metapopulation model
- builds on the basic metapopulation model and adds the reality that different patches of suitable habitat are not of equal quality
source-sink metapopulation model
- occupants of high-quality habitats are a source of dispersers
source subpopulation
- low-quality habitats that rarely produce enough offspring to produce any dispersers
- These habitats depend on outside dispersers to maintain the subpopulation
sink subpopulations
- incorporates differences in the quality of the suitable patches and the quality of the surrounding matrix
- most realistic, yet the most complex, spatial structure of the populations
- Fluctuations in abundance in one subpopulation can influence the abundance of other subpopulations
landscape metapopulation model
how we determine whether a community is made up of an interdependent or an independent group of species
- line transect studies
- removing one or more species from the community
- boundary created by sharp changes in environmental conditions over a relatively short distance, accompanied by a major change in the composition of species
- typically support a large number of species
- typically documented by a line-transect survey to determine the abundances of different species along an environmental gradient
ecotone
- When two species have a negative effect on each other through an enemy–including a predator, parasite, or herbivore
- causes an outcome that looks like competition, but the underlying mechanism is not competition
apparent competition
- individuals consume and drive down the abundance of a resource to the point that other individuals cannot persist
exploitative competition
types of competition
- apparent
- exploitative
- interference
- when competitors do not immediately consume resources but defend the resources
- antagonistic interactions that result in resource exclusion for the subordinate competitor; energy is spent interfering w/ competitor
interference competition
interference competition involves a … interaction
direct
exploitative competition is considered an … interaction
indirect
operates through a shared resource
types of interference competition
- aggressive interactions
- allelopathy
- occurs when organisms use chemicals to interfere with their competitors
- can be a phenotypically plastic trait
allelopathy
the most competitive animals are typically
the most susceptible to predators
the outcome of competition can be altered by
- abiotic conditions
- disturbances
- interactions w/ other species (predation and herbivory)
If the subpopulations rarely exchange individuals, the fluctuations in abundance will be
independent among subpopulations
if subpopulations are highly connected by individuals frequently moving among habitat patches, the subpopulation will
act as one large population, with all experiencing the same fluctuations
ways to increase the total number of individuals in a metapopulation
- provide corridors between neighboring populations, thereby increasing the rate of colonization
- decrease the rates of extinction reducing the major causes of population decline in subpopulations
habitat patches are … equal in quality
rarely
which patches are less likely to be occupied
- small
- distant
- the phenomenon of dispersers supplementing a declining subpopulation that is headed toward extinction
- should result in a higher probability that less isolate patches will be occupied
rescue effect
When any species is introduced to a region of the world where it has not historically existed
introduced / exotic / non-native species
an introduced species that spreads rapidly and has negative effects on other species and human economies
invasive species
- live within and consume the tissues of a living host, eventually killing it
- limit the abundance of their prey
parasitoids
introductions of one species to help control the abundance of another species
biological control
predators that exist in ecological communities
- mesopredators
- top predators
competition is most intense between what relation of species
closely related species
- one species persist, the other dies out
- two species cannot coexist indefinitely when they are both limited by the same resource
- when two species are limited by the same resource, one species either is better at obtaining the resource or is better able to survive when the resource is scarce
competitive exclusion principle
- states that a population increases until the supply of the most limiting resource prevents it from increasing further
- assumes that if a given resource limits the growth of individuals and populations, increasing the availability of other resources will not improve such growth
- whichever resource reaches its limiting value first will be the resource that regulates the growth of the diatom population
- When two species compete for a single limiting resource, the species that wins in competition is the one that can persist at lower level of the resource
Liebig’s law of the minimum
- constantly regenerated
- can originate from either inside or outside the ecosystem in which the competitors live
renewable resources
anything an organism consumes or uses that causes an increase in the growth rate of a population when it becomes more avialable
resource
true or false:
ecological factors can be considered resources
false
- can cause the population of either species to decline and eventually die out
- competition among individuals of different species
interspecific competition
competition among individuals of the same species
intraspecific competition
when two or more species continue to evolve in response to each other’s evolution
coevolution
when all species involved in an interaction coevolve together, which species is likely to get an upper hand
none
host adaptations to parasites
- avoiding areas that have been contaminated w/ feces that contain parasites
- removing ectoparasites from around their body
- producing antibacterial and antifungal chemicals
parasite adaptations against host
- leaving the body of the first host and then searching for the second host
- manipulating behavior of the first host to ensure that the second host consumes it
hosts experience higher fitness if
they avoid being parasitized
close synchrony of population cycles between predators and the prey they consume suggests
oscillations are the result of interactions between them
incorporates oscillations in the abundances of predator and prey populations and shows predator numbers lagging behind those of their prey
Lotka-Volterra
assumptions of the SIR model
- no births of new susceptible individuals and that individuals retain any resistance they develop
- if a pathogen can kill the host, the pathogen should increase in abundance until the hosts begin to die
- as the host population declines, the pathogen population will subsequently decline, and as the pathogen population declines, the host population should subsequently recover
if R0 > 1
infection will continue to spread through the population and an epidemic will occur
when R0 < 1,
infection fails to take hold in the host population
the probability that a host will become infected by a parasite depends on
- parasite’s mechanism of transmission
- mode of entry into host’s body
- ability to jump between species
- existence of reservoir species
- response of host immune system
when a new disease is discovered, or a formerly common disease that declined in the past suddenly becomes common again
emerging infectious disease
- occurs when a parasite moves between individuals other than parents to their offspring
- risk of transmission is essentially zero
horizontal transmission
- occurs when a parasite is transmitted from a parent to its offspring
- parasite must evolve in such a way that it does not cause the death of its host until after the host has reproduced and passed the parasite to its offspring
vertical transmission
carry a parasite but do not succumb to the disease that the parasite causes in other species; serve as a continuous source of parasites as other susceptible host species become rare
reservoir species
several groups of roundworms and flat worms that can cause serious diseases
helminths
- begin as a beneficial protein in the brain of an animal, but occasionally a proteinf olds into an incorrect shape and becomes pathogenic
- do not contain RNA or DNA, replicate by coming into contact with normal proteins and causing the normal proteins to fold incorrectly
prions
disadvantage of ectoparasitism
- exposed to the variable conditions of the external environment
- must find a way to pierce the flesh of their host to feed
advantage of endoparasitism vs ectoparasitism
- endoparasites have the advantage of being protected form the external environment and are therefore not exposed to most of their enemies
- living inside the host gives easy asccess to the host’s body fluids on which they feed
disadvantage of endoparasitism
- must contend with host immune system
- may have a difficult time getting in/out of the host body
relationship between the density of the prey population and an individual predator’s rate of food consumption
functional response of the predator
- occurs when a predator’s rate of prey consumption increases linearly with an increase in prey density until the predator is satiated
- functional response used by Lotka-Volterra
type I functional response
- occurs when the number of prey consumed solows as prey population density increases and then plateaus
- the number of prey consumed slows because as predators consume more prey, they must spend more time handling the prey
- slowing rate of prey consumption causes a decline in the proportion of prey consumed by each predator
type II functional response
costs of defenses against predators
- reduced feeding or increased crowding as prey move to locations away form predators
- cost of reduced growth and development
- energetically expensive to produce
when a palatable species evolves to closely resemble an aposematic species
Batesian mimicry
occurs when several unpalatable species evolve a similar pattern of warning coloration
Mullerian mimicry
the advertising by an animal to potential predators that it is not worth attacking or eating
aposematism
predator hunting strategies
active hunting or ambush hunting
most ommon behavioral defenses agaisnt predators
alarm calling, spatial avoidance, reduced activity
avoiding being detected by a predator through camouflage that either matches the environment or breaks up the outline of an individual to blend in better with the background environment
crypsis
a change in the number of predators through population growth or population movement due to immigration or emigration
numerical responses
- prey consumption increases very slowly when prey population density increases from very low numbers
- consumption is rapid when prey population density is moderate
- prey consumption slows when prey population density is high
- as predators spend more time handling prey and eventually become satiated, this proportion subsequently declines
type III functional response
- number of predators associated w/ a stable prey population
- P = r/c
predator zero growth isocline
in the region above the predator isocline line, the prey population
decreases because predators remove them faster than they can reproduce
- number of prey that causes the predator population to become stable
- any combination of predator and prey numbers that lie to the right of the line allows predator population to increase (increased abundance of prey
- in region to left, predator population decreases due to lack of prey
zero growth prey isocline
change in abundance by considering trajectory of both populations simultaneously
joint population trajectory
three factors that impact the slowly increasing consumption at low prey population
- prey can hide in refuges where they are safe from predators
- predators have less practice locating and catching prey and therefore are relatively poor at doing it
- prey switching
occurs when one prey species is rare and a predator changes its preference to another prey species that is more abundant
prey switching
a learned mental image that helps the predator locate and capture food
search image
simplest model of infectious disease transmission that incorporates immunity
susceptible-infected-resistant (SIR) model
differences between the parasite-host and predator-prey model
- parasites, unlike predators, do not always remove host individuals from a population
- hosts, unlike prey, may develop immune responses that make some individuals resistant to the pathogen
the first individual to be infected by a pathogen
primary case of disease
variables that convert between the number of individuals of one species and the number of individuals of the other species
competition coefficients
line that represents all population sizes at which a population experiences zero growth
zero population growth isocline
in stressful environments, how likely is it to see competitive interacts
unlkely
what specific characteristic is not a trait ticks use to detect, pursue, catch, and handle “prey”?
barbed tongue
true or false:
Liebig’s law of the minimum: the species that’s better at surviving with smaller amounts of resource is a better competitor
false
true or false:
carnivores typically have longer digestive tracts than herbivores
false
which statement is consistent with the competitive exclusion principle?
2 species with identical niches cannot coexist indefinitely
group of species interacting in the same place at the same time
community
factors that determine communities
water, soil, topography
the theory of how communities assemble that emphasizes immigration, extinction, and speciation, and the randomness of those processes; more ecological drift
neutral theory
the theory of how communities assemble that focuses on species traits and adaptations; more stable communities
niche theory
can occur by resource partitioning (at different times or different locations)
competitive coexistence
competition alters a species … niche and requires a … resource
realized; limiting
