Ecology (BIO 47)
Review for Exam 2
Population Dynamics
Abiotic vs. Biotic factors
Exponential growth
Unlimited resources
J-shaped curve
Steeper J means faster growth
Logistic growth
Resources are rarely limited for long
Carrying Capacity = K
S-shaped curve
Factors affecting population growth
Density dependent (disease, parasites, food, etc)
Density Independent (storms, fire, other natural disasters)
Dispersal and Metapopulations
Growth rate = birth rate + immigration – death rate – emigration
Salamander example – small pops of salamanders may require immigrants to
maintain a viable population
Source – Sink Populations
Dispersal
Metapopulations
Environmental stochasticity (randomness)
Demographic stochasticity
Life Histories
Life history definition
Trade-offs in life history strategies
Examples
Successful life history strategy means the population is stable or growing r>0
Age structure graphs – stable vs. growing
Life table – what kind of info is found there? Use info to build Survivorship curves
Survivorship curves – identify & give examples for types I, II, & III
SimSturgeon example of tradeoffs
Reproductive effort
Classifying life histories
**r-selected species – characteristics & examples
**K-selected species – characteristics & examples
Ruderals/stress tolerant/competitive life histories in plants
Opportunistic/equilibrium/periodic
Competition
Limited resources result in competition
Cost for both -/Land iguana simutext example
Examples of resources
Direct vs. indirect competition
Niche
Fundamental vs. realized niche
**Niche overlap & competition in barnacles
Example of fundamental vs realized niche
Environmental tolerance
Mosquito example
Principle of competitive exclusion
Resource competition – Exploitative competition
Indirect
Results in self-thinning in plants
Interference competition
Direct
Allelopathy (toxins secreted by plants – affect growth of other species)
Territoriality in animals
Preemption
Intraspecific Competition vs. Interspecific competition
**Lotka-Volterra Competition equations
Four possible outcomes:
Species 2 eliminated.
Species 1 eliminated.
Either species 1 or species 2 eliminated, depending on starting
conditions.
Both species coexist.
Flour beetle example
Common garden experiments
Definition & examples
Spatial and temporal variability
Character displacement (example)
Coexistence
Mosquito example
Exploitative Interactions – Predation herbivory & parasitism
Beneficial for one, cost for the other species +/Who benefits?
Other types of species interactions:
Competition -/Amensalism -/0
Commensalism +/0
Mutualism +/+
Parasitism
Parasite (+) Host (-)
Usually not fatal
Complex life cycles – often multiple hosts for different life stages
Endoparasites vs. ectoparasites
Parasitoids & hyperparasites
Examples
Effects of parasites on hosts – examples
Herbivores
Grazers vs. browsers
Frugivores, granivores
Plant defenses
Mechanical
Chemical
Nutritional
Tolerance
Predation
Stalk
Pursuit
Ambush
Random encounter
Prey defenses
Physical
Chemical
Behavioral
Aposematism
Crypsis
Mimicry
Predator-Prey Dynamics
Lynx/Hare example
Often other factors affect predator & prey populations
Deterministic vs. stochastic models
Assumptions of Lotka Volterra predator prey equations
Density dependence reduces cycling
Refuges for prey
Functional response
Orange mite example
Evolutionary arms race
Coevolution
Predator prey coevolution example – newt/garter snake
Trade-offs involved in coevolution
Red Queen hypothesis