PCE - 3

Question 1

what are the 3 elements of the leslie matrix?

Answer 1

1) Sx - age specific survival
2) Mx - Age specific fecundity - number of offspring produced
3) Fx (Fertilities) - combine reproduction with survival - age specific fecundity x age specific survival - Fx = Sx Mx

Question 2

what can a leslie matrix be used for?

Answer 2

• used to take information in life table and turn into something else
• population projection via matrix multiplication

Question 3

what does lamda mean?

Answer 3

population growth rate

Question 4

what happens to the population when lamda is bigger, smaller and equal to 1?

Answer 4

lamda < 1 = population declines
lamda > 1 = population grows
lamda = 1 = stable population - births = deaths

Question 5

what can the exponential model of population growth be used for?

Answer 5

can be used to make predictions based on assumptions and test hypotheses

Question 6

what is exponential and does it happen?

Answer 6

describes and idealised population in an unlimited environment - never happens

Question 7

what are the conditions for exponential population growth to occur?

Answer 7

• no limiting factors - no restriction on available energy - no restriction on growth or reproduction - this population will increase in proportion to the birth and death rates - rare that this would occur

Question 8

what is K?

Answer 8

carrying capacity - energy/resource limitation

Question 9

what does negative feedback prevent?

Answer 9

unlimited population growth - resource limitation in crowded populations can stop population growth by reducing reproduction

Question 10

what can perturbation analyses be used for?

Answer 10

to measure importance of system components on productivity and identify the main age-specific vital rates that affect abundance and age structure

Question 11

what is the equation for working out the change in population size during time interval?

Answer 11

births during time interval - deaths during time interval

dN/dt = bN- dN

Question 12

in the equation for working out the change in population size during a time interval what do the letters: N, t, dN, dt, B and D mean>

Answer 12

N = population size 
t = time 
dN = change in population size 
dt = the change in time 
B = number of births 
D .= number of deaths

Question 13

whats the difference between count the babies and count the one year olds census?

Answer 13

count the babies census = you use the sx of the year before the age your looking at and times it by the mx of that age
count the one year old census = you always use the sx of age 0 and times that by the mx of the age you are finding the fx for

Question 14

if there are 34 births in one year of a population of 1000 what is the per capita birth rate?

Answer 14

0.034

Question 15

what happens as a density of a population increases?

Answer 15

as density increases, per capita resource declines

Question 16

what prevents unlimited population growth?

Answer 16

negative feedback - Resource limitation in crowded populations can stop population growth by reducing reproduction