Lecture 9- Can we predict population dynamics? Flashcards Preview

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What is this equation?

-finite rate of increase 

-if lamda =1-no change

larger than 1-increase in population

smaller than 1-decrease in population

-values can be 0 to 1 to infinity (theoretically)

-get it from two points on graph at different times


What is this equation?

-fundamental net reproductive rate

-if all the resources available and lamda constatnt over time we call it R

R= maximum rate at which the population will increase in that environment if resources unlimited 

-only when lambda constant it is R

-can get R from= sum of percentage surviving x fecundity /100



If we assume continuous growth what can we do with the growth graph?

-plot log of abundance aginst time

-becomes straight line

-the slope of the line= R


What is this equation?

-get it from differentiating the exponential growth equation

-use it for continuous growth

-when we know continuously what is happening 

-differential equation

r= intrinsic rate of natural increase in that habitat


What is this equation?

-rearranged version of dN/dt=rN

-per capita rate of increase while in exponential growth 


Which equation would we use for discrete growth ie. ehrn we know what is happening only at some times and not in between?


What is a famous saying by Thomas Robert Malthus about demand for resources?

-at some point demand for resources will exceed demand (e.g. food)

-populations cannot continue to grow exponentially 


What are the positive controls for population size?

-increase in death rate

-misery (war, disease, famine)


What are the preventative controls for population size?

-reuce birth rate

=moral restraint (celibacy, marry later)

=vice (birth control, abortion, infanticide, prostitution, homosexuality)


What is happening here in terms of population size and demand?

-the population and resource availability meet

-population size levels off (sigmoid curve) = reaches carrying capacity K


What is this equation?

-logistic equation

-r= rate of maximum population growth

-K= carrying capacity (the maximum sustainable population)


Why are there the exponential equation as well as the logistic equation?

-exponential= more of a model, says something about the way populations change but mostly theiretical

-logistic= takes into account that population can't grow forever, thus the carrying capacity is included and fits the experimental data better though the real world not so much (more factors at play there)


What are the r-selected species?

-those with:

-small body size

-short lifecycles

-short gestation period

-high fecundity (many offspring)

-resulting high rate of increase



What are K selected species?

-those with:

-larger body size

-longer lifecycles

-long gestation period

-low fecundity (not as many offspring)

-resulting in lower rate of increase


What does the logistic equation assume?

Was Malthus wrong?

-that everything else remains constant, when in fact it doesn't that is why in real life the mathematical models are not followed very closely

-sort of wrong, the world has much higher carrying capacity and it changes with incoming technologies etc.