Exam 2 (BIOL211)

What are the two models that model population growth?

logistic growth rate model
exponential growth rate model

What is the equation symbol that resembles growth rate?

dN/dt

What does dN/dt represent?

growth rate

How do you represent per capita pop. growth rate?

dN/dt / indiv

What are the assumptions of an exponential growth rate model?

ideal conditions
overlapping generations
unlimited resources

What is the equation for the exponential growth model.

rmax *N

What is r max?

intrinsic rate of increase

When do you expect to see a exponential growth rate model?

when predation pressures are lost
during colonization

What are the assumptions of a logistic growth rate model?

limited resources
has intraspecific competition

What does the logistic growth rate model use instead of r max?

uses the realized r

What is carrying capacity?

max pop size an environment can sustain

What does the relationship between growth rate and carrying capacity (K) look like in real life?

real pop would probs overhsoot and dip down and continue to oscillate around K

What is the logistic growth rate model equation?

rmax*N*(1-N/K)

What does the 1- N/K represent in the logistic growth model?

environmental/resource limitations

What happens when N<K?

r is positive
population continues to grow but at slower speed

What happens when N=K?

we hit carrying capacity
r is 0
population not growing

What happens when N>K?

resources are depleted
r is negative
pop declines

What is the purpose of a life table?

book keeping device to add age structure into predictions of pop change

What are the 2 types of life tables?

chort
static

What does lx represent?

proportion of OG indiv surviving to start of age class x

What does Nx represent?

pop size

What does dx represent?

proportion of OG indiv that die during age class x

What does Mx represent?

average number of offspring produced by indiv at age class x

What is a chort life table?

includes indiv born at same time and track pop until last one dies

What are some disadvantages when using a chort life table?

some animals have too long of a life span

What is a static life table?

recoding number of indiv in each age class at one moment in time

What are the cons of a static life table?

not feasible if age of species is hard to determine
does not follow indiv through whole life

What are pros of the static life table?

allows you to calculate pop growth with just one moment in time

What are the pros of a chort life table?

gives data for entire life span

What are the 2 variables in a life table that can be used to create survivorship curves?

X
Nx

What are the three types of theoretical survivorship curves?

type 1
type 2
type 3

What is the type 1 survivorship curve and give example of species that models this?

chance to die increases in old age
elephants, humans

What is the type 2 survivorship curve and give example of species that models this?

when mortality rates are equal across all ages
birds

What is the type 3 survivorship curve and give example of species that models this?

higher chance of dying in young ages
turtles

What kind of survivorship curves do real life populations most commonly represent?

a mix of type 1 and type 3

What is Ro?

average number of offspring produced by indiv in its lifetime

Does the Ro calculation include indiv that die before producing offspring?

yes

What does it mean for a population size if Ro=1?

pop size is stable

What does it mean for a population size if Ro>1?

pop size is increasing

What does it mean for a population size if Ro<1?

pop size decreasing

How do you calculate Ro

multiply lx and mx for each age class
then sum up all values

how do you calculate r using life tables?

ln(Ro)/T

What is T in equation to get r?

generation time

How do you calculate T?

multiply x, lx and mx for each age class
then you sum up all values
divide this by Ro

What kind of scale are survivor ship curves always on?

a log scale