Unit 4 Flashcards
What was a key finding regarding the age at maturity of sunfish in Little Round and Warren Lakes?
They matured earlier and at smaller sizes
What environmental factor likely caused earlier maturation in sunfish from some lakes?
Higher predation pressure on adults
What does a constant proportion of individuals in each age class over time indicate?
Stable age distribution and constant population growth.
What is an endemic species?
A species found only in a specific, limited geographic area.
What is a metapopulation?
A set of connected subpopulations linked by gene flow (groups of subpopulations/dots)
What is local extinction in the context of metapopulations?
When a subpopulation disappears from a specific patch.
What is “population dynamics”?
changes in population size, composition, and distribution over time
What affects population dynamics?
birth, death, emigration, immigration
Age pyramid
show the number of individuals in a population within an age group
Useful for making predictions of populations and how they change over time
NARROWING = POPULATION DECLINE
Fish maturity
fastest and smallest: little round and warren
slowest and biggest: vance
GBM
measure of reproductive effort
Larger GBM means higher energy input for reproduction
A:J ratios
probability of survival
When A is larger, ratio is bigger
When J is larger, ratio is smaller
How does A:J ratio and GBM correlate?
Higher A:J ratio=less GBM
Type I curve
Convex curve
Late loss, high survivorship, majority reaches maturity
ex) humans
Type II curve
Diagonal curve
Constant loss, independent of age
ex) birds, rodents, prey
Type III curve
Concave curve
Early loss, low morality after maturity,
if they survive while theyre young, theyll survive for a long time
ex) plants
Mark recapture
capturing, marking, releasing
N= MC/R
N=total population size
M=#caught in 1st sampling
C=# caught in 2nd sampling
R=marked individuals recaptured in 2nd sampling
Subpopulation
population of individuals from one species connected to other populations of the same species (individual dots)
patch density
as patch density increases, so do subpopulations
Does the size of a population the previous year impact the probability of persistence?
Not really
population density
Species with larger average population densities tend to have lower extinction rates in subpopulations.
AS THE POPULATION GETS MORE DENSE, EXCTINCTION RATES GO DOWN
Small populations increase extinction rates
Brazilian water hyacinth metapopulation
the number of previous subpopulations present in the current year divided by the number of subpopulations examined that were present in the previous year.
Which of the following effects occurred after wolves were re-introduced into the Yellowstone ecological system?
The reintroduction of wolves decreased the population of elk (prey that the wolves fed on), which was a direct effect. The reintroduction also increased the aspen population, which was an indirect effect.
