Chapter 12: Metapopulations Flashcards
Models of population before this chapter assume ___ population
closed
Metapopulations?
- collections of local populations interacting within a larger area
What are the four conditions for a metapopulation ?
- suitable habitat in discrete patches
- Substantial risk of extinction of all populations
- Recolonization possible after extinction (patches not too isolated)
- Dynamics of local populations not synchronized ( within each of the smaller local populations the trends are different between them aka diff things are happening in them )
Metapopulation example : Bay checkerspot butterfly?
a number of small local populations
dark areas = where they live
graph: studied three local populations that make up one metapopulation…plotted what is happening within each local population….we know it is a meta: different trends…….area G went extinct in 64…but came back in 66 (immigration)….extinct in 74 and didn’t come back…why? (area may have been developed….no habitat available anymore??many things could have happened)
- core population?
- satellite populations?
- larger core population (low risk of extinction bc things that happen in the environment are less likely than it will take out every individual out of a larger vs small population ) –> largest sub population in meta ..
- smaller satellite population - considered a metapopulation
In all metapopulations:
- within patch?
- regional scale?
- population growth governed by birth and death rates ( within sub pop…)
- dynamics governed by interactions of populations (dispersal and colonization)
L> also if a population went extinct what is the probability of it bouncing back via immigration. Many factors: whether the habitat was actually suitable or not….if not very high quality,,
Metapopulation dynamics:
- what is a key feature?
dispersal of individuals between habitat patches
Metapopulation dynamics:
- Persistence a dynamic balance between what tow things?
- extinction and recolonization of habitat patches
Metapopulation dynamics:
-___ and ___ of patches affects metapopulation dynamics
size
location
Metapopulation dynamics:
- ___ patches may have more habitat types. This ___ is hypothesized to reduce risk of extinction.
- larger
- heterogeneity
- more variability within that site..areas of high and low quality habitat basically bc you do not have everything the same..if something were to happen to one of those area its not likely to happen all the time.
Metapopulation dynamics:
- grasshopper example
dominated by pine forests
dark areas = where the grasshopper could live
looked at where they were and why
first graph: inter patch distance..how far apart each local pop are form each other…and number of patches in that area ..you find that all the ones with a 40-260 = where colonization occurs..above 280 there is no colonization occurring…therefore there is a limit for dispersal from the source population. What does it have to do with how big the area is?
second graph: all the patches in 0.25-1 is where all the extinctions occurred…as your habitat patch gets larger your extinction probability gets smaller
Some patches may be major source of emigrants:
- rescue effect?
- reduced risk of extinction by immigration
- increasing rate of immigration increases population size and decreases risk of extinction
Some patches may be major source of emigrants:
- rescue effect
L> how do species on a network of islands not go extinct?
- if there is some dispersal from the mainland
- *population size increases
- *increases heterogeneity
- *metapopulation have a mainland- island effect…core population (largest) = mainland…an island is any kind of habitat patch that is habitual and surrounded by uninhabited areas.
Source and Sink populations:
- differences in habitat quality among patches may also produce?
rescue effect
Source and Sink populations:
- dispersal from source populations is when r? In huh quality habitat might permit sink populations to persist when r?
r>0
r<0
Source and Sink populations:
- Why don’t persistence and size of a population give a good idea of quality of patch?
- if you are rescuing a population..pumping individuals into the sink pop just bc there are individuals there doesn’t mean the area is good quality but they could thriving just because of immigration from a source population it just means that there is an overall larger dynamic going on in the source population..maybe moving to that environment bc they ave where else to go
Source and Sink populations:
- source pop?
= r that is greater than zero… r is essentially the net rate of population growth. If greater than zero= population is growing so it is increasing in size and providing immigration to other populations
Source and Sink populations:
- sink pop?
- decreasing population…r is less than zero..usually areas that are not ideal for spices, causing it to decline a source of population keep them sink populations present by adding immigrants to them
Source and Sink populations:
- issues?
- conservation programs…we can try to make an area good for a species thats actually not good for them…not always a good thing bc you are potentially decreasing a population over time.
Source and Sink populations:
- sink populations could be decreasing bc?
- of uneven sex ratio for a good level of reproduction so you need that immigration to balance the sex ratio allowing birth rates to go up…
Source and Sink populations:
-Liberian lynx
- most endangered female in the world
- 1000 individual’s in 1000 events
- 9 spatially genetically isolated populations. These 9 metapopulations
- *genetic dispersal between them..
Source and Sink populations:
- Liberian lynx:
- habitat fragmented by human activities such as?
- agriculture, tourism, urban areas and roads and resistance
Source and Sink populations:
- Liberian lynx
- persistence of species depends on?
exchange among
Source and Sink populations:
- Liberian lynx
- characteristics of population?
- no immigration or emigration
- little populations are easily lost unless immigration occurs
Source and Sink populations:
- Liberian lynx
- Habitat corridors?
- where they can move between the local populations
- keeps them connected and lowering extinction
- *havent translocated anything trying to find increase to increase movements so they can be maintained
Synchronization fo dynamics of local populations:
- Asynchrony?
of local populations is key to persistent
Synchronization fo dynamics of local populations:
- If extinction?
- probabilities of local populations correlated, greater risk of metapopulation going extinct
Synchronization of dynamics of local population
if all decreasing at the same time you will have lower levels of immigration and a higher probability of every one of those populations going extinct at the same time !
Species differences:
- colonization rate?
rate differs among species due to differences in dispersal rate
Synchronization of dynamics of local population
-dispersal affected by?
-dispersal affect by life history of
Synchronization of dynamics of local population
- large organisms have lower density (larger home range) and larger
- larger organisms have tower density (in there ante )
-affected by dispersal affected area!, fecundity rte, mode of reproduction
Species Difference:
- Species Difference?
-large organisms have lower density (later)…and arguer minim
Species Difference:
- Species Difference?
- small homoetherms lower sometimes had the book bag caught ..more vulnerable to storage
classic definition of a population?
- group of organism of the sam species occupying a particular area at a give time.
Most useful framework?
1.local population
2.metapopulation
3. subspecies
4.species
———————
- 1. the more smaller spatial scale what happens when
2. decreasing polypeptide formation
4 and 3.
l> increasing spatial and temporal distance of whole we …are a looking for a global population and what is happening.
