Sources and sinks (Lecture 9) Flashcards
demography
the science of births and deaths used to project population growth
the foundation of population biology which is the fundamental basis for understanding ecology
Two examples of demographic statistics…
- age specific survivorship
2. Age specific fecundity
Conservation biology
application of basic ecology (including demography) to threatened and endangered species and communities
A negative abiotic effects is an example of an…
Edge Effect
Five edge effects are:
- Negative abiotic effects
- Increased predator, competitor or parasite activity
- Alter food supply (up or down)
- Invasive species
- increased input of pollutants (noise to chemicals)
When there is _________ specialist species found in these areas are typically the first to be lost
Loss of unique habitat
Life tables helps us evaluate ___________ for a species
value of a habitat
Source
a compartment that over a large period of time shows no net change in population size but is a net exporter of individuals
B>D and E>I
B+I-D-E>0
B-D>E-I
B-D>E-I happens in….
Source
B+I-D-E>0
Happens in….
source
when, B>D and E>I the population is believed to be
a source
sink
a compartment that is a net importer of individuals
BE
B-D < and = E-I
When B<I the population is believed to be
Sink
lambda is > 1 in a _____ population
a. source
b. sink
a. Source
lambda is < 1 in a _____ population
a. source
b. sink
sink `
how to calculate lamda in source/sink populations
lamda=SA+(F/2)*SJ
SA= adult survival F= Fecundity JS= juvenile survival
Habitat Specific vital rates (3)
adult survival rates
seasonal productivity
dispersal
If their is a high mortality _____ in population need to be avoided
sinks
psuedosink
attracts immigrants while it creates negative density dependence and creates a lambda of less then one.
Examples of Ecological islands
Mountain tops bogs ponds specialized habitats (soils) forest fragments urban parks
Severe traps
active choice to occupy
Equal preference
settlement w/o regard to suitability
Three mechanisms that could lead to the existence of severe traps:
- Settlement cues change so that habitat becomes more attractive but suitability does not change
- a habitat’s attractiveness is unchanged but suitability decreases
- habitat attractiveness increases and suitability decreases
When habitat attractiveness increases and suitability decreases this leads to…
existence of severe trap
When settlement cues change so that habitat becomes more attractive but suitability does not change this leads to…
existence of severe trap
Define ecological trap
a habitat that seemingly provides necessary and sufficient conditions for an organism to survive and reproduce, and therefore attracts individuals to it but is inadequate as a habitat.
Or… a “sink” but one that is overly attractive
How do growth rate and survival work together interms of source sink, dispearsal, self sustaining. NO ANSWER
??? There is a slide on this…
Meta-population biology
the biology of small isolated populations
Four conditions that must exist for “true” Metapopulation to exist….
- population exist in discrete patches
- All populations stand a risk of extinction
- Non synchronized dynamics of each local population
- dispersal sufficient to allow “rescue”
Loss of genetic variability is harmful to small populations because…
they are prone to extinction
Metapopulation classification scheme is based on_______ and ___________
patch size and isolation (or connectivity of patches)
What would adding more patches to the landscape do?
increases the the probability of regional persistence
but increases the risk of extinction
Calculation of Metapoputions
df/dt= I-E
or
simple model of metapopulation dynamics
df/dt=[pi(1-f)]-[pe*f]
f= fraction of sites occupied (0-1) I= immigration rate E= extinction rate
Calculation of Immigration rate
I = pi(1-f)
f= fraction of sites occupied p = probability of immigration
Extinction Rate calculation
E= pe*f
f= fraction of sites occupied
pe=probability of extinction
When few sites are occupied in a metapopulation what is happening to the …
A. Immigration rate?
B. Extinction rate?
A. Immigration rate is high
B. Extinction rate is low
extinction rate is high when _______ sites are occupied
many
Six assumptions for the simple model of metapopulations
- Homogeneous patches
- Large number of patches
- No spacial structure ( no neighborhood effect)
- No time lags
- constant probability of of extinction and probability of immigration
- Regional occurrence f (fraction of sites occupied) affects local colonization (pi) and extinction (pe)
Can you have external sources of colonization in a classic metapopulation?
No!
Only internal
Is the main land part of metapopulation dynamics?
No!
Assume constant probability of extinction in all small patches and a constant “rain” of dispersers from “mainland”
What affects extinction probability?
Population size (and freedom of organismto move around)
Species area relationship on islands
there is a relationship between island size and number of species present (species richness)
Factors that influence species richness? (5)
- Area size
- Island isolation
- Habitat diversity
- Plant diversity ( influences the animals that can occupy the island)
- Topographic diversity
MacArthur and Wilson’s Equilibrium Theory of Island biogeography. Draw and explain graph
ENTER GRAPH
“I” declines as S increase because few of the new arrivals will be new species ( organisms all ready occupying the island)
As size of potential pool of immigrant species increases, _______________ increases
Equilibrium number of species always increases
What is the MacArthur and Wilson’s equation for equilibrium number of species?
S=I*P/(I+E)
S= equilibrium number of species T= turnover rate at equilibrium P=Size of source pool of species I = immigration E= Extinction
What is the MacArthur and Wilson’s equation for turnover rate at equilibrium?
T= I*E/(I+E)
S= equilibrium number of species T= turnover rate at equilibrium P=Size of source pool of species I = immigration E= Extinction
Small or Large populations deal with stochastic event better?
Large - less likely to go extinct
target effect is…
When an island is larger in size it is easier to be colonized.
island size effects extinction and immigration rate
turnover rates are expected to be higher on larger islands
Draw the immigration rate in the MacArthur Wilson Model
GRAPH
Draw the extinction rate in the macArthur wilson model
Graph
What does the intersection of the immigration and ixtinction curve determine in the MacArthur-Wilson model? (2)
- equlibrium number of species
2. turnover rate at equilibrium
Describe the area effect in the MacArthur -Wilson model
Smaller islands have smaller populations sizes , which increases the extinction rate and leads to a lower species equilibrium
Smaller islands have smaller populations sizes , which increases the extinction rate and leads to a lower species equilibrium is __________________________
the area effect in the MacArthur Wilson Model
_______ and _______________ affect extinction and immigration in the Mac Arthur wilson model
Area and Distance
Area and distance affect ________ and________ in the Mac Arthur wilson model
extinction
immigration
MacArthur Wilson model predicts less_____ on more isolated islands because they ______________.
turnover
they received fewer immigrants
__________ may generate greater turnover on more isolated islands because of the increase in the extinction rate.
The rescue effect.
Rescue effect
genetic and demographic contribution of immigrant to increase persistence of isolated populations
_______ when assuming that the immigration rate is higher on large islands than small ones.
Target effect
