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USC / Biology / BIOL 301 / What are the types of predators?

What are the types of predators?

What are the types of predators?


School: University of South Carolina
Department: Biology
Course: Ecology and Evolution
Professor: April south
Term: Summer 2015
Cost: 50
Name: Exam 3 Study Guide
Description: This is the study guide for Exam 3 on November 3. Hope this is helpful!
Uploaded: 11/02/2015
7 Pages 172 Views 4 Unlocks

Jeremiah bohon (Rating: )


What are the types of predators?

Chapter 13: Population Dynamics Over Space and Time

∙ Population fluctuations- happens with ALL populations

o Large organisms- fluctuate less due to large surface area to  volume ratio; allows for homeostasis in adverse conditions o Small organisms- reproduce faster and respond faster to  changing environmental conditions

o Age structure fluctuations- high numbers in any one age group  usually corresponds with high birth or death rates in that year o Overshoot- population exceeds carrying capacity (k), usually due  to a reduction in k because of decrease in resources

o Die-off- decrease in population density following an overshoot ∙ Cyclic behavior of populations- most populations have an inherent  pattern of regular oscillations over time

It lives on the outside of organisms and feeds on bodily fluids by puncturing the skin, what is it?

If you want to learn more check out What are the four lobes of the brain?

o Can occur over large geographic areas between related species o Reasons- may be due to storage of nutrients or delays in moving  from one life stage to the next

∙ Delayed density dependence- density dependence occurs based on  population density at some time in the past

dt=rN (1−Nt−τ 



o rτ < .37  no oscillations

o .37 < rτ < 1.57  damped oscillations (magnitude of oscillations  decreases over time)

o rτ > 1.57  stable limit cycle (large oscillations over time) ∙ Extinction- population ceases to exist

What is the difference between interspecific competition and intraspecific competition?

o Reasons- small populations are more susceptible; usually due to  lack of resources, natural disasters, or human activity

o Deterministic model- does not account for variation in population growth rates

o Stochastic model- accounts for variation in population growth  rates We also discuss several other topics like It is a type of memory that holds information for a brief period of time, what is it?

 Demographic stochasticity- due to random variations  among individuals Don't forget about the age old question of What are the sex-linked disorders?

 Environmental stochasticity- due to environmental  


∙ Habitat quality

o Habitat fragmentation- breaking up a habitat into smaller  habitats

o Basic metapopulation model- assumes that all patches of habitat  are of equal quality

 Each occupied patch has the same subpopulation size

 Each subpopulation supplies the same number of  

dispersers to other patches


o Rescue effect- dispersers supplement declining populations to  prevent extinction

Chapter 14: Predation and Herbivory

∙ Both can have dramatic effects on species abundance

o Invasive species- introduced species that grows rapidly and  negatively affects other species

o Types of predators

 Parasitoids- predators whose larvae eat prey from the  inside out

 Mesopredators- smaller carnivores that typically eat  


 Top predators- bigger carnivores that are at the top of the  food chain Don't forget about the age old question of Why did brits get concerned about the health of women in india in the 1860s and 1870s?

∙ Population cycles

o Stable cycles can occur when environment is complex so  predators cannot easily find prey

o Lotka-Volterra model- incorporates oscillations in abundance  of predator and prey populations

 Growth of Prey = dN


∙ rN = exponential growth rate of prey population

∙ cNP = loss of individuals due to predation

 Growth of predator population = drdt=acNP−mP

∙ acNP = birth rate

∙ mP = death rate

 Prey population is stable when dN/dt = 0

 Predator population is stable when dP/dt = 0 We also discuss several other topics like Why technological process is a source of sustained growth in gdp?

o Equilibrium isocline- population of one species causes the  population of another to be stable

 Prey at equilibrium when P = r/c

 Predators at equilibrium when N = m/ac

o Functional responses- relationship between prey density and  predator consumption Don't forget about the age old question of How does a nations economy grow?

 Type I- predator rate of consumption increases until  

satisfied (uncommon)

 Type II- predator rate of consumption decreases as prey  density decreases, then plateaus

∙ Any prey density increase causes consumption to  


 Type III- low, rapid, slowing prey consumption under low,  moderate and high prey density

∙ Most common in the wild

o Prey can find places to hide

o Predators have less practice finding prey but  

can develop search image (helps locate and  

capture food)

o Predators may exhibit prey switching

o Numerical response- change in number of predators due to  population growth or movement

∙ Evolution of defenses

o Behavioral- prey will use alarm calls, spatial avoidance and  activity reduction

o Chemical

 Warning coloration (aposematism)- distastefulness evolves  in association with conspicuous patters or colors

 Mimicry- selection favors palatable species that look like  unpalatable species

∙ Batesian mimicry- palatable species evolve similar  

coloration to unpalatable species

∙ Mullerian mimicry- several unpalatable species  

evolve similar warning colorations

 Plants- sticky compounds, resins, alkaloids

o Structural defenses- anything that reduces a predator’s ability to  capture, attack, or handle prey

 Crypsis- camouflage

o Costs- can reduce growth, reproduction, and development  Behavioral defenses have many trade-offs with food  

gathering, etc.

 Mechanical defenses are energetically costly

∙ Hunting strategies

o Active hunting- predator spends most of the time moving  around looking for prey

o Ambush (sit and wait) hunting- predator lies in wait for prey  to pass

Chapter 15: Parasitism and Infectious Diseases

∙ Types

o Ectoparasites- live on the outside of organisms and feed on  bodily fluids through puncturing the skin

 Little difficulty moving from host to host

 High exposure to external environment, low exposure to  immune system of host

 Organisms- arthropods (ticks, fleas, etc.), nematodes,  


o Endoparasites- live on the inside of organisms inside of cells  (intracellular) or in body cavities (intercellular)

 Difficult to move between hosts

 Low exposure to external environment, high exposure to  host immune system

 Organisms- bacteria, fungi, viruses, prions, helminths

∙ Infection ability

o Modes of transmission

 Horizontal transmission- passed between organisms that  are not parent/offspring

 Vertical transmission- passed from parent to offspring

 Vector- transmits a parasite between hosts

o Ability of parasite to jump between hosts

o Host immune response

o Existence of reservoir species

∙ Parasite/host dynamics- similar to predator/prey dynamics, except  parasites do not usually kill the host

o S-I-R Model- assumes no new births of susceptible individuals  and that once resistance is gained, it is retained

 S = number of individuals susceptible to a pathogen

 I = number of individuals infected

 R = number of individuals developing resistance  g = rate of transmission via contact between individuals ∙ GRAB

 b = rate of recovery and development of immunity ∙ B for b-cells of immune system!!

 Probability of contact between susceptible and infected  individuals = S(I)

 Rate of infection between susceptible and infected  individuals = S(I)(g)

 Rate of recovery of infected individuals = I(b)  Ratio of new infections to recoveries = reproductive  ratio of parasite


I(b)=rate of infection

rate of recovery

∙R0>1  infection will spread

∙R0<1  infection fails to spread

∙ Evolution of defenses- hosts can produce immune responses, develop  antibacterial or antifungal compounds or utilize biochemical responses ∙ Evolution of offenses- parasites can alter behavior of host to ensure  survival and increase probability of infection

Chapter 16: Competition

∙ Resource limitation

o Interspecific competition- between members of different species o Intraspecific competition- between members of the same species o Resources- things that organisms use/consume that cause  population increases when abundant

 Renewable- are constantly regenerated

 Nonrenewable- are not regenerated

o Leibig’s Law of the Minimum- the most limiting resource prevents the population from increasing further

 If 2 species compete for the same limiting resource, the  species that can drive abundance of the other species to  

the lowest level will survive

 Assumes that each resource has an independent effect on  population

o Competition exclusion principle- 2 species cannot coexist when  they are limited by the same resource

 One species will be superior in either gaining the resource  or surviving when it is scarce

o Competition by related species is intense because they have  similar uses for resources

 Selection will favor different habitat usage

o Competition between non-related species can be intense if  species are using a similar resource

∙ Models

o Competition coefficients- convert relative population numbers  from one species to another

o Competition based on single resource

d N1 

dt=r 1N1(1−N1−α N2 

d N2 


dt=r2 N2(1−N2−β N1 

K2 )

 Species 1 stable when N1=K1−α N2 OR when N1 is 0  Species 2 stable when N2=K2−β N1 OR when N2 is 0

o Isoclines- population size at which no growth is experienced  Species 1

∙ When N2=0, N1=K1 

∙ When N1=0, N2=K1 


 Species 2

∙ When N1=0, N2=K2 

∙ When N2=0, N1=K2 


o Competition based on multiple resources- 2 species can coexist  only when 1 is better at persisting at low levels of different  resources

∙ Factors that affect competition

o Disturbances- natural disasters

o Predation and herbivory

o Abiotic conditions

∙ Types of competition

o Exploitative competition- individuals consume a resource to  make it less abundant so others cannot use it

o Interference competition- competitors defend resources  Aggressive interactions

 Allelopathy- use of chemicals to harm competitors

o Apparent competition- 2 species have a negative effect on each  other through a enemy

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