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31 Cards in this Set
- Front
- Back
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What is a metapopulation?
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A population consisting of many local populations. A situation where habitat patches are large enough to support locally breeding populations so that the population actually exists as a group of spatially discrete subpopulations.
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Who coinded the concept of meta-population?
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Richard Lewis
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The ponds in in SIberia represent what kind of suitable habitat?
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They represent a sutibale habitat for aquatic meta-populations.
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What kind of butterfly did Paul Ehrlich and collegues at Standford University study?
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The bay checkerspot butterfly ( Euphydryas editha).
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What books did Paul and Anne Ehrlich write?
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The Population Bomb
Extinction etc. |
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Where do the bay checkerspot butteries live?
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Only in grassland growing on serpentine soils. there are four study sites in and around the Standford campus:
1. Edgewood Park 2. Jasper Ridge Biol. Preserve --> studied since 1960 and had three localized populations 3. Coyote Reserivor 4. Morgan Hill |
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Discuss the dynamics between each of the three local populations of checkspot butterflies on Jasper Ridge.
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One subpopulation (G) went locally extinct in 1964 but then was reestablished through emigration from the other populations in 1066 and then went extinct again in 1974. ALl three different.The collective dyanamics is not a fai representation of each subpopulation but combines to give an over all higher population number.
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What are the 4 conditions that need to be met to define a metapopulation? WHo defined this?
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Defined by Ikkia Hanski:
1) Subtiable habitat occurs in discrete patches that may be occupied by local breeding populations 2) Even the largest populations have substantial risk of extinction 3)Habitat patches must not be too isolated to prevent recolonization after local extinction 4)The dynamics of the local populations are not synchronized |
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In many situations, what are the general characteristics in refernce to metatpopulations?
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core population which is the main source of emigrants and which is unlikely to go extinct
Satellite populations which are re-stocked by emigrants from the core population and which are more likely to go extinct. |
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What are the two sets or processes acting at two distinctive spatial scales?
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1) local or with-in patch scale= indiviuduals interact routinely with each other. Populations growth and regulation by demographics such as birth and death
2) metapopulation or regional scale= local populations (patches) interact through dispersal and colonization |
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What does the long term-persistence of the metatpopulation depend on?
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The process of re-colonization because all local populations have a probability of extinction
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Dispersal is key? WHy?
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1) No dispersal = populations are independent ( no metatpopulations)
2) extensive dispersal= populations are not at all independent (one big single populations) 3) intermediate levels= balance of local extinction and recolonization which ultimately leads to a metapopulation |
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What ultimately leads to a metapopulation?
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1) intermediate levels of dispersal with balance of local extinction and recolonization
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Explain the Model by Levin of the balance of extinction and colonization for metapopulations.
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As the number of patches occupied increases:
than the higher the rate of extinction the higher the rate of colonization, BUT it will start to decrease when the all the patches become occupied. |
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Name two factors that influence metapopulation dynamics
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1) Patch Area
2) Isolation |
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Where does the bush cricket live?
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This flightless katydid bush cricket lives in VOmb Valley in Sweeden. It inhabits grass and heath in ladscape dominated by pine forest. Three surveys were done (85, 89, 90) that showed ares of grassland that had crickets. The avaible patches were 72 % to 79% occupied. SIZE AND LOCATION OF EACH PATCH WAS IMPORTANT.
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How is the size and location of each patch important to the population dynamics?
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The closer a patch was to another (occupied) patch, the more likely that it will be re-colonized.
T Smaller patchs are more likely to go extinct because thy had smaller populations to begin with. (This is well known from studies of island populations) |
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Overall, the study on busch crickets showed what?
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The relationship between local population size and patch area in the metatpoulation shows that more crickets live in larger areas.
*** ALSO WHY SMALLER AREAS HAVE HIGHER RATES OF EXTINTION. |
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The skipper butterfly in souther Britain demonstated the relations of ______ and _____.
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The relation of patch area and isolation and affects on population dynamics. The more isolated the patch area is from another populated patch, the less of a change it of occupacny. Most isolated had 10% of occupancy.
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Can habitat heterogeneity influence local population persitence?
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Yes.
1) the size and distance from nearest patch (occupied) influences the dynamics 2) Large habitats are also more likely to have heterogeneity I different spatial heterogeneity of cover types; dense low grassland; tall grassland, sparse grassland) Dry years- densely covered grassland Wet years- sparse grassland on sandy soil |
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Some habitat patches may function as the major source of emigrants. Define the Rescue Effect coined by james brown and Astrid Kodric-Brown
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The Rescue Effect: the closer a patch is to a large patch, the more likely that it will remain occupied.---> result of high immigration rates.
Common Example: Mainland-island population structure is common.(Morgan Hill and checkerspot Butterfly, which is a poor disperser, thus extinction and recolonization is the rule in the smaller patchers near the larger Morgan Hill patch. |
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What is a source population?
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Source populations exist in high-quality habitat and permit sink populations in lower quality habitats.
i. Lead to terms "source habitats" and "sink habitats" Example: checkered white butterfly with source population along streams (riparian) in dredge tailings creating by mining in early 1900's in Central Valley CAli. Only place where butterfly can over winter |
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What happened to the skipper butterfly on chalk grasslands in Southern England
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Major decrease in population (enviormental stochasticity operating at regional scale affecting many populations at same time)
due to loss of grassland resulted first from loss of grazing and then due to loss of rabbits (myxomatosis virus introduced in 1950's) |
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What is a key characteristic of species adapted to ephemeral or disturbance prone habitats?
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dispersal ability (vagility)
r species vs K-species ruderal vs. stress or competitive species in plants |
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What makes plant (seeds) effective at dispersal?
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high fertility and wind dispersal
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Small species can have more individuals per unit area and thus requiring a smaller area. Ddisadvantage?
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small endothermic organisms (shrews) smallest speices had higest rate of extinction probaly due to greater sensitivity to enviormental stochasticity and variation in food supply.
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List the hierarchial framework for the concept of population.
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1. local population
2. metapopulation 3sub species 4. species |
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Local Population
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estimations of birth, death, emigration, and immigration; individuals distributed within patch of suitable habitat
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Metapopulation
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collection of local populations close enough so that dispersing individuals can readialy colonize empty patches. rates of dispersal maintain gene flow among populations
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sub species
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collection of metatpopulations in geographic region that are separated from other collections of metapopulations to the extent that there is substantial demographic independence
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species
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all the sub species, encompassing the entire distribution and geographic range of the species
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