topic 8 Flashcards
(32 cards)
what is population ecology
how a population changes over time as a results of birth, death, immigration and emmigration
what are the three general principles that explain population patterns
distribution and abundance - where and when, how many, patterns
structure- age and sex
dynamics - change over time
what is a population
a group of potentially interbreeding indiv found in a specific area
what does evolution affect
populations
what is absolute density
the number of indivs of a pop per unit area
and is ecological density
the number of indiv per unit of suitable habitat
what are distribution limits
the geographical limits of a species due to its physical environment
accounts for environ cond (temp, humidity..)
prey/ food distribution
spatial pattern tendancies
what is dispersal
the permanated movement of orgs in and out of a pop (from thier borth place to somewhere new)
in= immigration
out= immigration
what is migration
the seasonal movement of indive from one lotion to another
what is migration
the permenat relocation of an org from one pop to another
why do orgs disperse
to avoid competition/ ensure resource avaibility (avoid unfavourable cond)
prevent inbreeding
increase personal fitness
what are the risks with dispersal
there are increased energetic and time costs
more suseptable to predation
reduced opportunities to enhance fitness/ mating as they much estbilsh a territory and learn there new enriron
what is sex biased disperal
the enhanced movement of one sex when compared to another
commonly males will move/ disperse more as they are the one looking to increase thier fitness and please females
what is a common method for aquatic dispersal?
movement downstream as it requires less energy than moving upstream.
of they choose to move up stream they are likey to stick to edges, avoid high current areas, and possibly have a terrestrial adult stage.
what is metapopulation
a group of spatially separated populations of the same species which still interact to a certain degree.
commonly pops will be separated by geographical barriers
what are the characters of metapop
populations of sub pop
they are connected bu movement of indivs from one sub to another
and sub can go extinct or be recolonized
risk of extinction is greatest for smaller for sub pop commonly on smaller landscape patches
how does is the distirbution pattern influenced by the scale of the study
larger plot of land will allow for populations to look aggregated
smaller plots may provide the opportunity for populations to look uniform, random or aggregated
what are the interactions between randomly dispersed species?
neutral interaction. resources are evenly distributed
what are the interactions between uniform dispersion
antagonistic. commonly related to a depletion of resources or competition/ claim habitat
may interact only for mating purposes
what are the interactions between aggregated disperion
attraction/ mutal interaction of indivs, possibly due to localization of resources/ limited habitat or benefits from group living
may result due to the failure for offspring to disperse from parents
what is the relationship between org size and density
decline density with inc org size on avg
apparent in animals and in plants
ex. treese will preform self thinking as seedling age and require more resources
what is species abundance
the number of invids from one species found within environmental boundaries (their range)
what are the three factors that assist in the classification of commonness and rarity
the geographic range of species (broad or restricted)
habitat tolerance (urytopic or stenotopic)
local population size (large vs small)
what does 1 factor of rarity correlate to
a moderate risk of extinction
