Lecture 24 & 25: Life Tables & Population Dynamics Flashcards
What does an age structure pyramid look like when a population is growing, shrinking, and stable?
Growing: Wide base, pointy top
Shrinking: Narrow base, wide mid-top
Stable: relatively even from base to mid/top (though can taper at top)
Describe the survival of a Type I/K-selected species with regard to survivorship curves.
High survival until later in life.
Convex curve.
Ex. bear
Describe the survival of a Type II species with regard to survivorship curves.
Steady decline in survivorship throughout life.
Linear decrease.
Ex. squirrel
Describe the survival of a Type III/r-selected species with regard to survivorship curves.
Low survival when young, high survival later in life.
Concave curve.
Ex. dandelion
population projection tables – life tables
what do we need to predict population size?
1. how many age classes, ‘x’
2. # individuals in each age class, ‘n x ’
3. survival to next age/stage class, ‘sx ’
4. fecundity of each age/stage class, ‘bx ’
Life table stuff:
Fill out this life table
what is a cohort life table?
– follow a group of individuals from birth to death
1. good for sessile organisms
2. follow survival & reproduction of individuals as they age
what is a static life table?
– quantifies survival and fecundity of all individuals in a population during a single time interval
1. count all individuals in a population
2. must be able to age all individuals
Metapopulation Dynamics
population overshoots – time lags in response to competition
stochastic (random variation) vs. deterministic (no variation) models:
demographic stochasticity: random variation in birth & death rates among individuals
environmental stochasticity: random variation in birth & death rates due to fluctuating environmental conditions
