BIOL 243 Study Guide - Final Guide: Compartmental Models In Epidemiology, Flow Diagram, Macroecology
17 Sep 2019
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Lecture 18
Define flow diagram, mass action, state variable, parameter, epidemiology, and SIR model.
Flow diagram: illustration of interconnections between state variables that provide visualization
of how each state variable influences each other.
Mass action terms are the rate at which predator attac
ks prey or prey kills
predator and are common in predator prey models. PARAMETER
Epidemiology is the study of patterns and processes controlling the rates of spread of disease.
SIR stands for susceptible, infected, and recovered and these models are used to measure
epidemiology.
What is the value of models? Why are they useful? What are their limitations?
They are useful because they are a visual representation of complex math problems and useful if
no data is available.
They might be too simple though.
Lecture 19
Define competition?
Competition is an interaction between individuals for limited resources that
reduce survival, growth, and fertility.
●There is a negative effect for both sides.
● It’s a consequence of increasing population size and limited
resources.
What are the types of competition?
1. Intraspecific competition: Competition between individuals of the same
species.
○E.g.- Eg/ damselfish guarding territory in coral reef
2. Interspecific competition: Competition between individuals of different
species.
○E.g.- two plant species competing for pollinators.
Which form or type is more common?
Intraspecific competition is more common because of:
1. reproduction (requires interaction) and
2. similar physical requirements (e.g.-food, shelter) between organisms
of the same species.
What is interspecific competition important for?
1. Natural selection (so it might be reduced over time)
2. Fixation of adaptive (divergent) traits within species
3. Phenotypic divergence between species
4. Abundance and distribution of species
Evolutionary avoidance of competition?
●Interspecific competition can be reduced or eliminated over time because:
1. Trait(s) of one (or both) species evolve→ character
displacement.
2. Effectively reducing two species from competing for limited
common resources→ So, specialize for different resources.
●Hard for intraspecific competition to avoid competition because:
1. Reproduction/mating
Describe the difference between interference and
exploitative competition
Interference competition
●Direct interaction between individuals
●Both always have negative effects (E.g.- Species A has a negative effect on
species B and B has a negative effect on A).
●It can be inter or intra specific.
●E.g.- Defending for territory
○Fighting for food
Exploitative competition
●Indirect interaction between individuals.
●Individuals harm each other by taking up resources before others are able to.
●Both individuals draw resources from a shared and limited resource pool.
●The more the resources an individual has, the higher is its fitness (more
resources=higher fitness).
●If one individual is better at acquiring resources, it’s negative to the other.
●Can be inter or intra specific.
●E.g.- the competition for light between tall trees and smaller plants in the same
ecological area in the forest.
○ Mangrove roots competing for nutrients.
List six different biological mechanisms by which
interspecific competition can occur
1. Consumption: One species inhibits another by consuming a shared
resource.
○More common in plants.
○Animals=food
○Plants= light, water, resource
2. Pre-emption: Sessile organism occupies a physical resource, making it less
available to others.
○E.g.-The space preempted by the barnacles is unavailable to other
competitors.
3. Over-growth: When one organism grows over another without direct
contact.
