Interactions Flashcards
Predation
Consumption of one organism by another, in which the prey is alive when the consumer first attacks it
What type of interaction is predation?
+, -
What type of interaction is mutalism?
+, +
What type of interaction is parasitism?
+, -
What type of interaction is competition?
-, -
True Predators
Kill their prey immediately after attacking them, kill several over their lifetime, prey often consumed in whole
Parasites
Consume parts, attacks rarely lethal, concentration on few individuals.
Do not remove individuals from population
May increase probability of dying or reduce fecundity
Herbivores/Grazers
Attack large numbers during their lifetime
Remove only parts
Do not remove individuals from population
Detritivores
Consume dead organic matter
No direct effect on populations that produce detritus
Lotka Volterra Model
Link predator and prey populations together
Each population functions as a single density-dependent regulator on the other
What do Predators and Prey exert on each other?
Selective Pressures:
Producing more evasive prey and more skilled predators
Red Queen Hypothesis
Continuous Coevolution due to selective pressures of predator/prey interaction
Variables contributing to Predator Prey dynamics
Density Dependence in predator or prey Intraspecific competition among prey Interference competition among predators Heterogeneity in the environment Aggregative responses Refuges or hiding place Alternative prey
Exploitation by Humans
Form of highly selective and intensive predation
Objective of Explotation
Sustainable Yield
Maximum Sustainable Yield
Maximum rate at which predators can remove individuals without depressing the prey population
Functional Response
Relationship between predation rate to prey density (Change in the pre-capita rate of prey consumption)
Types of Functional Response
Type I, Type II, Type III
Type I Functional Response
Prey mortality rate is constant and is independent of prey density
Per-capita predation rate increases linearly with prey density
Characteristics of Type I Functional Response
Passive Predators (Spiders, filter feeders) May results when prey do not become sufficiently abundant to satiate the predators All of the time allocated to feeding is spent searching
Type II Functional Response
The number of prey captured during the total time period increases, and the handling time also increases, decreasing the time available for further searching
Most Common
Prey mortality rate decline with increasing prey density
Type III Functional Response
Predation rate is low at first, increasing in a sigmoidal fashion as the rate of predation reaches a maximum
Possible Explanations for Type III Functional Response
Availability of cover
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Prey Switching
Availability of Cover
The susceptibility of prey individuals will increase as the population grows and hiding place become filled
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The ability of a predator to recognize a prey species will increase as the prey population size increases
Prey Switching
The act of a predator turning to a more abundant alternate prey
Numerical Response to Prey Numbers
Occurs through reproduction of predators
Aggregative Response to Increase in Prey Numbers
Movement of predators into an area of high prey density
Optimal Foraging Theory
As a result of selection pressures, organisms will harvest their food efficiently
How do organisms harvest their food efficiently?
Maximize energetic gain
Minimize costs
Maximize fitness
Competition
Individuals use a common resource that is in short supply relative to the number seeking it
Intraspecific Competition
Competition between individuals of the same species
What does Intraspecific Competition lead to?
Density dependence of birth and death rates
Stable regulation of population size within limits imposed by the environment
Interspecific Competition
Competition between species
What does Interspecific Competition lead to?
Birth and death rates of one species vary with the population density of the other and vice versa
May cause exclusion/extinction of one species
Types of Competition
Exploitative
Interference
Exploitative
Competition between two or more individuals for a limited resource
Interference
Competition takes the form of direct conflict (terrirotiality)
May be dangerous
Require time and energy
How do populations respond when resources are limited?
Scramble Competition
Contest Competition
Scramble Competition
Occurs when growth and reproduction are depressed equally across individuals as competition intensity increases
Contest Competition
Takes place when some individuals claim enough resources while denying others a share.
Outcome of Scramble Competition
Local extinction if all individuals receive insufficient resources
Outcome of Contest Competition
Only a fraction of the population may suffer.
Those that access resources function to sustain the population
Competition Exclusion Principle
Complete competitors cannot exist
Fundamental Niche
Overall potential of a species
Realized Niche
Limited spectrum or conditions and resources which allows a species to maintain a viable population in the presence of competitors and predators
Area Actually occupied
Niche Overlap
Two or more organisms use a portion of the same resource simultaneously
Amount of niche overlap is proportional to the degree of competition for that resource
Competitive Release
Species expands its niche in response to the removal of a competitor, or when a species invades an island and expands into unoccupied habitats
Niche Differentiation
Process by which natural selection drives competing species into different patterns of resource use or different niches
Facilitation
Species interact where at least one individual benefits and no harm is caused to either (mutualism and commensalisms)
Mutualism
Close symbiotic relationship
What else is mutualsim described as?
Facultative
Obligate
Facultative
Can survive without mutualistic relationship
Obligate
Cannot survive without mutualistic relationship (pollination)
Self Pollination
Autogamy or Geitonogamy
Cross pollination
Xenogamy
Symbiosis
Two or more organisms of different species living together in close and prolonged association
Parasitism
Previously defined as a +, - interaction between two organisms
Traits of Parasitism
Parasites are smaller than hosts
Reproduce more quickly and in large numbers
Highly specialized for specific lifestyle
Definitive Host
Animal harbouring the adult or sexually mature stage of the parasite
Intermediate Host
Animal in which development occurs but in which adulthood is not reached
Parasitic Infection
Invasion by endoparasites (protozoa)
Parasitic Disease
invasion and pathology produced by endoparasites
Parasitic Infestation
External parasitism by ectoparasites
Reservoir Host
An animal that harbours a species of parasite that can be transmitted to another species
Vector
An arthropod or other living carrier that transports a pathogenic organism from an infected to a non-infected host
Carrier
A host that harbours a parasite but exhibits no signs or symptoms of infection or infestation
Zoonoses
A disease involving a parasite for which the normal host is an animal, but humans can also be infected
Microparasites
Multiply directly within their hosts
Viruses, bacteria and protozoans
Small with short generation time
Induce immunity to reinfection
Duration of infection short compared to life span of host
Direct Transmission, Sometimes vector/intermediate
Macroparasites
Grow in their host, multiply by producing infective stages which are released from the host to infect new hosts
Often inter-cellular or live in body cavities rather than within host cells
Larger than micro
Parasitic worms, lice, fleas, ticks, etc
Persistent with continual reinfection
Direct Transmission or indirect
Direct Transmission
Parasite need no other organism to move between hosts
Indirect Transmission
Parasite moves between hosts with the aid of another organism
