3. Population Distribution Flashcards
species have limited geographic ranges depending on
both ecological and evolutionary factors
population
a group of individuals of the same species in the same area at the same time
rely on the same resources
interact with one another
interbreed
population ecology
the study of the factors which affect the population
factors that affect a population
1) abiotic factors - sunlight, temperature, rainfall, soil/nutrients
2) biotic factors - other living organisms - prey, competitors, predators, parasites, disease
3) intrinsic factors- adaptations- organisms in a population are adapted for a particular environment
meta populations
a population of populations
describes a group of populations connected only by dispersing individuals
dynamics are related to extinction and colonization rates
source population vs sink population
source population are usually where the members are dispersing from and they are looking for new habitat. not always going to land in spots favourable. sink populations are where population tend to decline and the only way that populations in sink populations persist is by immigration from the source population
dispersal and reproductive value
dispersal is risky
since risky, life history theory indicates that low reproductive value individuals should be the ones undertaking it
(eg- the old and one youngs -not re productively mature)
we see this pattern being repeated in nature
dispersal morphs
Dispersal morphs in ecology refer to different forms or types of a species that have adapted to spread or disperse their offspring to new locations. These morphs are typically a result of phenotypic plasticity, which is the ability of an organism to change its phenotype in response to changes in the environment.
eg- aphids can produce winged individuals. and then back to wingless when on plant to produce eggs
dispersal and sex bias with regards to dispersal
male lions in the pride commonly being the one to disperse from their parent pride
how are resources distributed in nature on a small scale?
are they distributed uniformly across the landscape or do they have a clumped distribution?
we typically find that resources are clumped in nature
eg- food court
dispersion
movements of organisms affect spatial distribution
spatial distribution of organism is termed dispersion
three main types of dispersion
random
regular (uniformed)
aggregated (clumped)
aggregated/clumped is the most predominant in nature
random dispersion
position of each individual is independent of others
can occur when you have a uniform environment - resources are equally available throughout the year
can occur where there are no interactions between individuals or interactions produce no patterns of avoidance or attraction
it occurs esenitally where there is a equal probability of an organism occupying any point in space and the indiivudlas in this type of dispersion pattern then to be unvelnly distirubted because of
no lcumping of reaources or competition for reasources
dosent matter where i go so whereever i land i have this random dispersal pattern
probability of me getting reaources in point a is th esame as point b
uniform/regular/ even/ overdispersed dispersion
individuals are more evenly spaced than would occur by chance
more common than random
occur as a result of intraspecific compeition
proceses that lead to this dispersion pattern are:
territoriality
competition for space or resources,
autotoxicity (when a plant releaes chemicals to prevent others from coming near it)
allelopathy ( produces chemicals to affect another plant species)
eg- of this pattern is nesting seasbirds
almost aequal number in all quadrants
how often do you think you see random dispersion in nature
eg- plants - spots randomyly
measure dispersion in a quadrant
