1
Q
Autotrophs require the ________ for energy intake
A
capture of sunlight
2
Q
For heterotrophs energy intake requires ____
A
the capture, consumption and assimilation of energy contained in another organism’s tissues
3
Q
What does this need for energy cause between organisms?
A
attack and defense interactions between the eaten and the eaters. called “red in tooth and claw”
4
Q
Exploitation definition
A
An interaction between individuals of two species in which the individuals of one species increase in fitness by consuming individuals (or parts of individuals) of another species. Individuals of the consumed species experience a decrease in abundance or fitness.
5
Q
The individual of one species who consumes the individual of another species experiences ____ fitness
A
increased
6
Q
The individual of one species who becomes consumed from the individual of another species experiences ____ fitness
A
decreased
7
Q
Shorthand of exploitation interactions
A
( + , — )
8
Q
The _____ and ____ dynamics of exploitation are central to our understanding of nature
A
ecological and evolutionary
9
Q
Most common form of exploitation
A
predation
10
Q
Predator definition
A
An organism that kills and consumes prey
11
Q
Prey definition
A
An organism that is killed and consumed by a predator
12
Q
Generally, a predator will consume many different types of ___ in their lifetime
A
prey
13
Q
Another common form of exploitation among two organisms
A
parasitism
14
Q
Parasite definition
A
An organism that obtains its energy from a host
15
Q
Host definition
A
An organism that harbours a parasite or pathogen
16
Q
Disease organisms are called
A
pathogens: an exploiter species that cause disease in its hosts
17
Q
Parasites can live either on the ___ or ____
A
inside (endoparasites) or outside (ectoparasites).
18
Q
Herbivory
A
When exploiters consume plants either in whole or select parts of them
19
Q
Herbivores definition
A
An organism that feeds on individuals, or parts of individuals, of a primary producer species.
20
Q
Can a prey be considered a shared resource in interspecific interaction?
A
Yes, ex: zebra for lion and hyena
21
Q
T/F: prey must be alive when predator catches them
A
True, as prey must experience a decrease in fitness, cannot happen if the prey is dead by the time predator consumes
22
Q
Detritivore definition
A
Any organism that feeds on dead plant and animal parts (detritus) as its primary source of energetic nutrition
23
Q
Saprophytic meaning
A
absorbing dead organic matter
24
Q
What assumption is made about the prey by ecologists when counting for exploitative interactions?
A
Prey must be alive, and not focusing on reproductive status, as most animals do not live past their reproductive stages anyway.
25
An expected outcome of exploitation
Exploiter populations would increase in abundance and exploited (prey) populations would decrease
26
First outcome of Gause's experiment with paramecia and the predators were ciliate
The predators quickly reduced prey numbers driving the prey population to extinction, and then being driven to extinction due to no food sources.
27
Error with Gause's first experimental design
Does not reflect conditions outside of the experiment (nature) as in real life prey are not always driven to extinction by exploitative interactions with predators indicating there is some mechanism at play.
28
Gause's second experimental design
Added bits of oats that served as places of refuge for paramecia from ciliate causing ciliate to go extinct as prey population density got low enough for predators to have trouble finding them
29
Gause's third design
Gause added new prey individuals (immigrants) every few days throughout the experiment. This caused a more stable predator and prey cycle in which when the numbers of one decreased the others increased and continued etc.
30
Exploiter-prey cycles
A complex cycle between predator (exploiter) and prey in which the density or abundance of each species alters the density or abundance of the other species; predator density increases as prey density increases, but prey density decreases as predator density increases. These reciprocal reactions lead to increasing and decreasing densities of each species with the prey species leading the cycle, and predators following 1/4 cycle behind.
31
Four outcomes of exploitation:
1. prey extinction that leads to exploiter extinction
2. exploiter extinction with surviving prey
3. exploiter-prey cycles
4. stable coexistence
32
Lotka Volterra Exploitation model
Used separate population growth equations for exploiters and prey assumed that the two species were interacting in a well resourced environment free from other species
- means that prey population experiences no density dependence or carrying capacity and that the only factor that keeps prey from growing to infinity is exploitation
33
Growth of the prey population depends on
intrinsic rate of increase (r) and the prey population density density (Np)
- term density is used instead of abundance for N values because these organisms are in a specific place with set area
34
Speed of a chemical reaction is dependent on
the concentration of the chemicals as a higher concentration means the chemical elements are more likely to bump into each other
also called mass action, law of mass action
35
Mass action offers a good
first estimate of exploiter-prey encounter rates
- seems reasonable that organisms “bump” into each other based on their density in a habitat
can multiply the densities of the exploiters (Ne) and the prey (Np) to get an estimate for the number of encounters
- not all encounters result in prey being caught
36
Capture rate (f)
A term in the lotka volterra predator-prey model
The capture rate (also called the attack rate) represents how efficiently predators encounter, attack, and successfully capture prey.
- actual number of prey captured will equal the capture rate multiplied by the number of encounters between exploiters and prey
If f is high, predators are very efficient hunters — they capture a lot of prey quickly.
If f is low, predators are inefficient — maybe the prey are fast, camouflaged, or live in refuges.
This means that predation pressure on the prey population increases when:
There are more predators
Predators are better hunters (higher f)
37
Exploiter conversion factor
A term in the lotka-volterra predator-prey model that translates consumed prey into an expected number of offspring for a focal species
- can determine births in the exploiter equation by multiplying the number of captured prey individuals from the prey equation by c
38
Mathematical expression of lotka volterra predator-prey model
dNp/dt = rNp - fNpNe
dNp/dt - instantaneous change in prey population density over continuous time
r - intrinsic rate of increase for prey population
Np - prey population density
Ne - exploiter population density
f - capture rate
Change in prey population density = exponential population growth of prey - number of prey lost to exploiters
39
birth rate for exploiters is
dependent on prey density (Np) and the exploiters ability to capture (f) and convert prey into offspring (c)
40
Mathematical expression for exploiters in the lotka volterra predator-prey model
dNe/dt = cfNpNe - dNe
- population will only grow if births are greater than deaths cfNp > d
Change in exploiter population density = births possible from prey consumption - natural deaths of exploiters
41
isoclines; lines of zero growth
pop density of the focal species neither grows nor declines along these lines
42
set prey equation =0 to find equilibrium
0 = rNp - fNpNe
0 = r - fNe
fNe = r
Ne = r/f
equilibrium for the prey is dependent on the density of the exploiter
If P increases → more prey consumed → prey population forced down until balance restored.
If P decreases → fewer prey consumed → prey population rises until balance restored.
- result comes from assuming that the exploiter eats prey purely based on prey density with each exploiter consuming a constant fraction of the prey it encounters (f)
43
set exploiter equation to 0
0 = cfNpNe - dNe
0 = cfNp -d
cfNp = d
Np = d/cf
exploiter density is solely dependent on prey density
44
Neutrally stable equilibirum point
if a disturbance knocks the prey and exploiter away from their equilibrium densities, they will neither return to the equilibrium nor move further from it
45
The pattern of each species responding to the density of the other leads to
repeating counterclockwise circuits around the quadrants of the phase plane
exploiter densities follow the prey densities about 1/4 cycle behind them because exploiters need time to respond to changes in prey populations
46
Neutral stability results in
exploiter prey cycles of constant amplitude
- emphasizes that the size of the disturbance away from the equilibrium point does not increase or decrease with each cycle but larger disturbances move densities further from the equilibrium point
- prey growth depends solely on predator density and predator density depends solely on prey density
47
Bigger assumptions of the lotka volterra exploiter-prey model
prey population experiences no density dependence from resource scarcity
48
Incorporate density dependence into lotka model
dNp/dt = rmaxNp [ K-Np/K] - fNpNe
when prey population is small, K - Np/K = rmax, if it approaches K, per capita growth rate with approach 0, if it goes above K population will decrease
49
Adding a carrying capacity (K) for the prey to the model leads to
density dependence or self regulation in the prey; prey limited by carrying capacity.
Combination of population growth arrows for prey and predator create a phase plane graph that spirals in toward a stable equilibrium
suggests that over time, population densities will cycle with smaller and smaller amplitude and eventually stabilize at constant densities of prey and exploiters
50
Damped oscillations
Population dynamics that cycle with decreasing amplitudes through time
51
Stabilizing factor
any factor that leads to exploiter and prey cycles reduced as each population arrives at its equilibrium
- prey carrying capacity most common
52
Second unrealistic assumption in lotka volterra model
exploiters will consume a constant fraction of the prey they encounter regardless of increases in prey density
- described through functional response
53
functional response
defined as the number of prey eaten per exploiter per unit of time
54
three common functional responses
Type 1
- FR of the lotka volterra; mathematically easy but organisms in the real world cannot increase their consumption endlessly (neutrally stable)
Straight line until it reaches a maximum feeding rate (where predator becomes full or time-limited).
Type 2
- exploiter consumption levels off at high densities of prey; plateau can come from gut constraints or handling time (unstable because increasing amplitudes)
- most common in real world, makes two species less likely to coexist
At low prey density → predator eats more as prey increase (search-limited).
At high prey density → feeding rate levels off (handling-time limited).
This is the most common in nature because all predators need time to handle prey.
Type 3
- consumption may be slow when prey population densities are very low (stable at low densities, unstable at higher densities)
- At low prey density → predators eat few prey because:
Prey are hard to find
Predators are inexperienced or ignore rare prey
Prey hide in refuges
As prey become more common → predators learn, switch diet, or prey lose refuges → consumption rises faster.
At high density → still plateaus due to handling-time limit.
Graph: S-shaped — slow start → steep middle → flat top.
55
If exploiter isocline intersects the prey isocline that has a positive slope we see
expanding spirals and increasing amplitude cycles producing instability and extinction of one or both species
predator is efficient
A positive slope suggests that more predators are required to either kill the prey as density increases
56
if exploiter prey isoclines meet where they are perpendicular we see
neutral stability and cycles
57
allee effect
A pattern observed in some species in which there is a fitness decline as density declines
One mechanism that produces this is avoidance of predation (higher survival rates in a group)
58
How do allee effects change the shape of prey isocline
it should always have a positive slope to show inverse density dependence (survival or reproduction increases with prey density) at low prey density, and then a negative slope as the Allee effect fades and density dependence takes over
positive slope suggests that more predators are required to either kill the prey as density increases or to balance increased reproduction as prey density increases
59
Herbivory is the
feeding of individuals of one species on individuals or parts of individuals of a primary producer species
60
generalist
A species or organism that is able to use an array of species, resources, or habitats to survive. In competition and exploitative or trophic interactions, a generalist is a species that rarely refuses available food items and whose diet tends to include a diverse array of food types. In mutualisms, a generalist is a species whose mutualistic partner can be a range of species.
61
Specialists
An organism that uses a single species, resource, or habitat to survive. In competition and exploitative or trophic interactions, a specialist is a species with a narrow diet that includes only a few food items. In mutualisms, a specialist is a species with a single mutualistic partner species
62
why is there more diet specialization in herbivores
evolutionary relationship
interaction between plant defenses
63
insect herbviore specialization is so common that many insect species show
lifetime fidelity not only to a single plant species but even to a single individual plant
leads to lifelong relationships with plant hosts
64
insect (invertebrate) specialist herbivores tend to be
small, have high metabolic rates and are often able to reach large population abundances
65
vertebrate generalists tend to have
a more direct negative impact on the plants they consume, owing it to their larger body size
- lower population densities than insects
66
recruitment
combination of factors that leads to new individuals entering the next age class, used most frequently to refer to plants entering a reproductive age class
67
Macroparasites
large enough to be seen with naked eye; mosquitoes
often reproduce with infective stages outside the host
68
microparasites
tiny and often occur intracellularly
reproduce directly within host where they achieve high densities
ex. viruses, bacteria
69
parasitoids
insect exploiters that attack other insects and lay eggs or larvae inside host
eggs eventually develop, consume and kill the host insect in the process
70
definitive host
a host that supports the adult form of a parasite
71
intermediate host
an organism that supports the non adult form of a parasite
72
coevolution
evolution by natural selection through reciprocal selective effects between two or more closely interacting species
73
BIO205
flashcards
Decks in class (10)
# Cards
-
Chapter 1: Ecology in the Anthropocene63
-
Chapter 5: Individuals: Physiology and Behaviour95
-
Chapter 6: Populations106
-
Chapter 7: Competition85
-
Chapter 8: Exploitation73
-
Chapter 10: Multispecies Interactions and Food Webs13
-
Chapter 11: Biodiversity17
-
Chapter 12: Spatial Dynamics7
-
Chapter 13: Communities through Time3
-
Chapter 15: Anthropocene Ecology6
