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30 Cards in this Set
- Front
- Back
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population |
group of individuals of same species in a given area |
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what are the population parameters of interest |
number of individuals present how they are dispersed rate of birth and death factors that influence dispersion, birth, death factors that regulate change in population numbers (size) |
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demography |
vital statistics quantitative description of a population |
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what is the most fundamental demographic measure of a population |
how many individuals are present in a population in a specific unit area |
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population density |
the expression of the number of individuals in a population per some unit area |
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what are the two approaches to measuring population density |
absolute density relative density |
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absolute density |
the measure of numbers per unit area |
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relative density |
number of individuals are proportionalized against some measure if cannot quantify area of unit area that is sampled leads to this approach EX: collect fish per hour |
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what are the methods of measuring absolute density |
total counts quadrat sampling transect counts mark-recapture methods |
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total counts |
count all the organisms present in a population this is hard to do, so take small sample from square measure and estimate population size |
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quadrat sampling |
enclosing a known unit area and counting the number of individuals present |
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transect counts |
along a known distance (line) or a known distance out from a line (belt transect) represents a subsample of the population |
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mark-recapture method (fish, birds) |
capture individuals, mark them, then later resample and examine the proportion of marked to unmarked individual estimates population size through relationship between number marked, number recaptured that are marked, and number recaptured that are not marked |
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total population size, N = |
number of marked individuals in first catch X total number of second catch / number of marked recaptures in second catch |
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what are examples of relative density methods |
mist nets pitfall traps baited live traps roadside counts |
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mist nets |
very fine mesh, entangle birds |
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pitfall traps |
set into the found catch wandering species such as beetles and spiders these have rain covers to prevent animals from drowning |
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baited live traps |
catch small mammals |
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roadside counts |
number of organisms observed while driving some stranded distance pheasants and birds of prey |
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dispersion |
spatial distribution of a population in a given area |
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what are the three types of dispersion |
clumped uniform random |
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random dispersion |
uncommon
there is no pattern individuals are randomly spaced from each other |
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clumped dispersion |
individuals are grouped together in very specific areas most common tied to key attributes of habitats |
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uniform dispersion |
spacing is equal between individuals in population |
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fragmented habitats |
some habitats are naturally patchy species have adapted to this condition and are typically corridors between patches human-caused patches result from fragmentation of larger habitats through habitat destruction |
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what are the three types of fragmented habitats |
fragmented perforated internally fragmented |
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fragmented habitats type |
isolated patches of forest separated by non forested areas |
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perforated fragmented habitats |
small clear cut areas within an intact forest small areas taken out of forest reduction of habitats |
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internally fragmented |
erection of power lines across a forest or the building of roads can isolate patches of first from one another barriers |
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metapopulation |
a series of small, separate population, in individual habitat patches that mutually affect one another fragmented populations may exchange individuals via migration, creating one linked population if individuals in one patch go extinct, other individuals in other patches survive and they supply individuals that disperse and recolonize the patches were extinction occurred |
