Metapopulations and corridors Flashcards
What is a population?
Discrete group of individuals that are relatively self-contained with little immigration and emigration - generally has the same gene pool
What is a metapopulation?
A population consisting of many local populations.
What is a source?
population in a good habitat that exports migrants
what is a sink?
population in poor quality habitat that receives migrants. There is low breeding success or high mortality in sink. Without immigrants population growth rate is <1.
What arte the implications of sources and sinks for conservation?
Numbers may be high in a sink habitat, if you did not recognise that a habitat is a sink you could make the wrong conclusions about habitat requirements i.e. thinking it is okay to lose a nearby patch and not knowing that it is the source.
What is Levin’s population model?
Considers patches as islands of suitable habitat set in an inhospitable matrix. All patches are of similar or equal quality - this is not always true. - patch area determines population size and extinction probability.
What is the background the protected areas?
human population is increasing, extinctions increasing, conservation is included in sustainable development goals, and CBD. There is a goal to conserve at least 17% of terrestrial are and 10% of marine area.
Are protected areas effective?
1) conflict with indigenous territories - increase poverty, exclusion
2) sustainable use zones - wildife still may be lost
3) global climate has warmed by 0.8oC and species distributions are changing - can static protected areas be useful? they help to retain species for longer and are the first spaces to be colonised by range expanding species.
How to make protected areas more effective?
Reccomendations include the creation of ecological networks to improve connectivity between habitat patches by: habitat expansion, establishing physical linkages such as corridors, habitat stepping stones, improving the permeability of the matrix to species movement.
What is the purpose of conservation corridors?
They are routes and habitats for organisms responsing to climate change.
They allow the movement of individuals, somems pecies move using major pathways.
They increase the movment of individuals along otherwise iolated populations. this can rescue these populations from stochastic local extinctions, and maintain genetic diversity.
What is connectivity?
A measure of how a landscape facilitates or impedes the movement of individuals between habitat patches.
What is structural connectivity?
The degree to which habitat patches are physically linked
What is functional connecivity?
Depenedet on species dispersal ability, the size and spatial arrangement of habitat ptches and the nature of the matrix. The same landscape can be functionally connecteed for one species but not another.
Give an example of the effect of corridors?
Corridors can influence pollen transfer. They can increase pollination. A study has found that the proportion of plants pollinated by butterflies, bees and wasps was greater in the connected sites. Pollinators moved from the central site to linked sites if they were connected by a corridor.
Is increasing connectivity an optimal use of resources?
Buffering core populations may be more efficient than increasing connectivity among numerous vulnerable fragments. Corrdiors are linear and so will suffer from edge effects which may be detremental as there ill be high edge-core area rations. For some species, corridors may work as sink populations, attracting organisms into patches which are edge dominated and the risk of mortalty is high. For edge adverse species, corrdior width needs to e such that some proportion of the corridor represents core habitat.
