Bio 211

Quiz 2 KEY- Spring 04

 

1. What is the definition of a p-value? (I don't mean the decision you make, only what the p-value actually means in terms of the null hypothesis.) (4 pts)

A p-value is the probability that the null hypothesis is true. (Other versions of answers will be given due credit)

 

 

2. A threatened population of red-legged frogs has been censused for several years and has been found to be declining exponentially, as shown in the graph below. The rate of decline was estimated using regression on the natural log of the population sizes. What is the best estimate of realized population growth rate (r)? Again, please include the units. (5 pts)

 

3. Below is shown a life table for a population of Vancouver Island marmots.

 

x (yrs)
n(x)
m(x)
lx
lxmx
xlxmx
0
100
0
1.00
0
0
1
20
3
0.20
0.60
0.6
2
5
10
0.05
0.50
1.0
3
0
0
0.00
0
0

sums =
1.10
1.60

a) Calculate R0 for this population, including units. (3 pts)

R0 = sum(lxbx) = 1.10 individuals/individual-generation

 

b) What does this R0 indicate about the future size of the population? (2 pts)

This R0 indicates that the population is growing (by about 10% per generation)

 

c) Calculate the generation time, including units. (3 pts)

G = S(xlxmx)/S(lxmx) = 1.6/1.1 = 1.45 years, but of course this is per generation

(for units: yrs*ind/ind divided by ind/ind; cancelling ind/ind leaves only yrs)

d) Calculate r, including units. (3 pts)

r = ln(R0)/G = 0.0657 individuals/individual-year

(ind/ind-gen divided by yrs/generation leaving ind/ind-yr)