population ecology (PP22) Flashcards
what are the levels of ecology
Organismal
How individual physiology & behaviour meet challenges
Population
Factors affecting population size & distribution
Community
Interactions between species
Ecosystem
Energy flow & chemical cycling between organisms & their environment
Global
Regional exchange of energy & materials, distribution of organisms around the planet
what is ecology
Field of science that studies interactions between organisms & their environment
what are biotic factors
Biotic interactions Between organisms (competition, predation, parasitism, mutualism)
what are abiotic factors
Temperature Water Sunlight Wind Rocks & soil (e.g. pH) Disturbances (e.g. fire, volcanic eruptions, hurricanes, etc.)
what is population ecology
Study of populations in relation to environment
Population ecology looks at the environmental influences on…
Population density & distribution
Age structure
Variations in population size
what is the difference between intraspecific and interspecific
intra: within species
inter: between species
explain population
- Group of individuals of the same species within a defined geographic region
- Rely on the same resources
- Influenced by similar environmental factors
- Likely to interact & breed with one-another
explain metapopulation
- Group of spatially separated populations of the same species which interact at some level
- GENE FLOW
- Fragmented subpopulations occupying spatially separate habitat patches in a fragmented landscape of unsuitable habitat
difference between immigration and emigration
Immigration: when organisms arrive at a new location & establish themselves at this location ‘permanently’ (inward bound)
Emigration: when organisms leave their original location (outward bound)
empty patches of land are susceptible to ?
colonization
what does persistence of local population depend on
Persistence of some local populations (sinks) depends on migration from nearby populations (sources)
what were the 4 conditions proposed before assuming that metapopulation dynamics explain species persistence:
- Patches should be discrete habitat areas of equal quality i.e. homogeneous
- No single population is large enough to ensure long-term survival
- Patches must be isolated but not to the extent of preventing re-colonization from adjacent patches
- Local population dynamics must be sufficiently asynchronous that simultaneous extinction of all local populations is unlikely
is each subpopulation stable or unstable
unstable (subject to random extinction / recolonization)
what does Dispersal among patches assure
long term viability
if an individual subpopulation goes extinct, can the overall population still persist?
yes
Some subpopulations do well while others do poorly
What are the 3 factors that must be taken into account when looking at populations
Size: number of individuals in the whole population
Density: number of individuals per unit area / volume
Dispersion: pattern of spacing among individuals within the boundaries of the population
what is the study of demography
Demography = study of the vital statistics of a population and how they change over time
What is population density and size the result of?
Result of a dynamic interplay between processes that add individuals to a population & those that remove them
what is the formula for population size?
Population size =
(Births + Immigration) – (Deaths + Emigration)
what is population regulation
tendency for population to be maintained around a characteristic abundance via action of density-dependent factors (both abiotic & biotic)
what is density affected by>
Density is affected by both intrinsic & extrinsic factors