EE Lecture 26: Density Dependence Flashcards
what four major types of population growth patterns exist
exponential
logistic
popn fluctuations
regual pop types
give eqtn for exponential growth, involving lamda
Nt+1 = lamda Nt
give two eqtn for exponential growth
Nt+1 = lamda * Nt dN/dt = rN
how do you know which exponential growth eqtn to use
depends on whether reproduction exists at discrete time periods (Nt+1 = lamda *Nt) or it is continuous dN/dt = rN
which exponential growth eqtn do you use for continuous reproduction
dN/dt = rN
which exponentia growth eqtn do you use for discrete reproduction
Nt+1 = lamda * Nt
when can periods of exponential growth occur
limited amounts of time when condns are favorable
within the established range of a species - when good weather occurs for several years running
when species reaches a new geographic area, either by dispersing on its own, or with human assistnce
what is the flaw in the logistic eqtn
for K to be constant, BR and DR would have to be too
K is a range of values - not a constant
K fluctuates around a mean
how can you find density dependence in long term pop studies
if Nt+1 = λ.Nt
Then ln Nt+1 = ln λ + ln Nt =(1.0). ln Nt + ln λ
what does a slope significantly
density dependence
what is flaw of ln(Nt+1) = ln(Nt)x + ln λ
y and x factirs arent fully independent of eachother
can popns persist without density dependence
no
do regulating factors have to be density dependen
yes
what growth do you have to investigate for exploring density dependence
investigate per capita growth
d4escribe graph for per capita growth rate on y, %K popn on x
linearly decreasing per capita growth rate with pop size (negative correlation straight line)
describe graph for %K on y, time on x
sigmoidal - logistic growth
describe graph for rN(1-N/K) with whol pop growth rate y, %K on x
parabolic change in number of individuals, n shape
what are moths a keystone species for
blue and great tits
what is K
an additive transformation of mortality
K = -log(survival)
what does -log(survival) equal
K
how do you do K factor analysis
linear regression of K on log density
where do most outbreaks of winter moth popns occur
regularly at higher latitudes and on heather moorland
what are the major contributers to biological control of winter moth
indirect effects on pupal predation
whyat regulates moth popn in S.UK
pupal predation
when is key factor analysis more robust
when supported by simulation modelling
what does constant recruitment imply about the popn
v strong regulation
limited spawning @ high density and massive recruitment @ low density
discuss Icelanding cod fisheries
recruitment seems to be more or less constant - use stock recruitment curves along with K factor analysis
