EE Lecture 25: Intro Population Ecology

Question 1

what is the fundamental eqt of population dynamics

Answer 1

Nt+1 = Nt + Bt - Dt + It - Et)

Question 2

what is eqt for exponential growth

Answer 2

dN/dt = rN

Question 3

what are the limitations for the exponential growth eqt

Answer 3

only occurs with no competition/predators and excess resources

Question 4

what does the r stand for in the exponential growth eqt

Answer 4

r = intrinsic rate of natural growth (b-d)

Question 5

define limiting factor

Answer 5

syop pops increasing exponentially by reducing growth rate

Question 6

define regulating factor

Answer 6

the subset of limiting factors that bring pops back to eqb,

Question 7

what are the two sides to regulating factors

Answer 7

doesnt only limit pops also makes them recover when rare

Question 8

how many types of survivorship curves are there

Answer 8

3
Type 1 - most individuals survive until old age
II-individuals have a constant chance of dying throughout their lives
III-most individuals die young

Question 9

give examples of density dependent processes

Answer 9

disease
predators
lack of space

Question 10

what is value of lamda for all pops under favourable condns

what does this lead to

Answer 10

lamda > 1

leads to exponential growth

Question 11

give examples of density independent processes

Answer 11

floods
hurricanes
temp
precipitation

Question 12

are floods density (in)dependent processes?

Answer 12

density INDEP

Question 13

is food a density (in)dependent process

Answer 13

density DEP

Question 14

what does a density independent factor mean

Answer 14

their effects on birth and death rates are independent of the number of individuals in the popn

Question 15

how do you know a factor is density INDEPENDENTq

Answer 15

because they dont tend to increase the pop size when small and dont decrease pop size when large

Question 16

what does density dependent mean

Answer 16

a factor that consistently leads to changes in popn growth as a function of density causing BR and DR and dispersal rates to change

Question 17

when is popn regulation said to occurq

Answer 17

when one or more density dep factors cause pop size to increase when numbers are low and decrease when numbers are high

Question 18

name some density dep factors

Answer 18

food
space
resources

Question 19

what effect do regulation factors have on lamda and r

Answer 19

tend to increase lamda and r when pop is small

decrease lamda/r when pop is big

Question 20

which factors can regulate pop size

Answer 20

only density dep factors

Question 21

name some pops where density dep has been bserved

Answer 21

song sparrow - the number of eggs laid per female decreased with density, as did the number of young that survived long enoughh to become indep of their parents

Question 22

give an example of density dependent mortality

Answer 22

highest initial planting densities of soya beans meant most of them died.
eggs of the flour beetle placed in glass tubes - death rate increased as density of eggs per tube increased

Question 23

what happens to a pop if lamda = 1

Answer 23

pop stops growing

Question 24

what type of density (in)dependence do flour beetles show

Answer 24

show density dependence

as egg density increases, death rate increases

Question 25

what is the logistic eqt of popn ecology

Answer 25

dN/dt = rN ( 1- [N/K])

Question 26

what does the term [1-(N/K)] in the logistic eqt represent

Answer 26

reresents the net effect of factors that reduce the pop growth rate from the constant (r) rate as seen in exponential growth

Question 27

compare logistic growth to exponential growth when densities are low

Answer 27

logistic growth is similar to, but slightly lower than exponential growth when densities are low

Question 28

when densities are low, why is logistic growth similar to, but slightly lower than exponential growth

Answer 28

because when N is small the term (1-N/K) is close to one, and hence a pop that grows logistically, grows at a rate close to r

Question 29

at what point does logistic growth level off

Answer 29

eventually a pop that grows logistically levels off at the carrying capacity = K