Lecture 7: Community Ecology Flashcards
How does size affect the reproductive output?
Larger sizes of salmon produced larger eggs
X- axis has length of salmon
Y -axis had egg weight
How do bamboo reproduce?
Synchronized semelparity: all produced seeds at once, hence some seeds escape to germinate.
What is masting?
Iteroparity synchrony of Acron production, in order for the plants to have some of its seeds escape predators and grow.
What is a fast life style called?
R-strategy
What are the characteristics of r-strategy?
- faster growth rate
-shorter generation time
-smaller body size
-More investment in reproductive tissues
-Poor competitors
-Good at dispersal
-Produce more but lighter seeds
-Semelparity more likely
-Shade intolerant, seed domancy
-Born to run
What is a slow life style?
K -strategy
What are characteristics of K-strategy
-Slower growth rate
-longer generation time
-larger body size
-more internal care
-lower reproductive rate
-More competative ability
-Poor at dispersal
-More investment in individual offspring
-Iteroparity more likely
Shade tolerant
What does selection generally prefer?
Faster reproduction, because it can get more gene copies in
What is Ex?
Expected years left for an individual
What Vx:
Reproductive value: number of future daughters a individual can have of age x
What shape does the graph have for reproductive value in human?
hump shape. (age at x, Vx at y)
What is conspecific?
Competition between same species (intraspecific competition)
What is heterospecific?
Interspecific competition: Competition between different species.
What is scramble or exploitative competition?
One individual uses a resource hence depleting the resource for other species.
Like squirrels and birds
What is contest/ Interference competition?
Individuals interacting for something like land.
like argintine ants and Invasive ant species
the superior one kills the other one, binging down the population.
What is Lotka-Voltera model?
Model for interspecific competition, models two species
dN1/dt = rN(1- N1/K1 - ALPHA12*N2/K1)
What is alpha and why is it important?
It is the competition co-effieciet,
determines percapita effect.
What are the four possible outcomes in Lotka_Volterra model?
- Two species can coexist
- Specie 1 always wins, N1=K1, N2 = 0
- Specie 2 may always win (N2 = K2, N1 = 0)
- Winner may depend on starting N’s
What determines which species win?
K and alpha.
When is coexistance possible?
Intraspecific competition is stronger than intra specific competition. Both species must inhabit their own populations.
What is equilibrium for species?
Number of population has stopped changing
What is stability?
The ability to come back to the initial population after a disturbance, ie forest fire etc.
What is coexistance?
Two or more species, having positive dN/dT at equilibrium
What are the principles of Lotka-Volterra?
- In order for species to co-exist, the competition within a species must be weaker than competition in the same species
2.If two species compete too much, one will outcompete the other.
- Gauge in 1934 said, In response to competition two species never have similar niches
- Hardin in 1960 said complete competitors cannot co-exist
What is character development and why does it occur?
Occurs if two species having similar niches are living together, then they have drastic changes in their characteristics in order to reduce negative effects.
Coexisting similar species evolve differences
What is the paradox of plankton?
Principle of exclusion seems false, Hutchinson said this, different species of plankton live together an share similar resources.
How was the paradox of plankton resolved?
Lotka-voltera model was too simple, and real communities are not at competitive equilibrium, infact there can exsist below K because of they can be limited by climate or other factors.
