Population Ecology Flashcards
Explain the differences between the exponential and logistic models of population growth
Exponential model : the whole population multiplies by a constant factor in each generation
Logistic model: initial exponential growth curtailed by one or more limiting factors
Describe briefly some of the major applications of population ecology:
Biological control: predicting the fall in a population resultant from the introduction of disease or pest.
Sustainable harvesting: predicting the population nu,bets that result from different intensity of harvesting cohorts of different ages
Recovery of endangered species: in situ or in translocated populations
What are the common characteristics of all communities?
Interactions between different species of organisms
Level of species richness and diversity
Presence of dominant/keystone species
Trophic relationships (feeding relationships)
Energy flow
Difference between species richness and species diversity:
Species richness: the number of different species in a community
Species diversity: the number of different species and their relative abundance
List the 6 main types of interactions between organisms in a community and their effects:
Neutralism: neither species affected
Commensalism: one species benefits, no affect on the other
Amensalism: one species harmed, no affect on the other
Mutualism: both species benefit
Predation: one species benefits, the other harmed
Competition: both species disadvantaged
Explain the differences between primary and secondary succession:
Primary succession is a sequence of communities that replace one another until a climax community is reached
Secondary succession occurs when a climax community is altered by a disturbance and the community changes to re-establish the climax community or an alternative stable state.
How do feeding relationships regulate energy flow and nutrient cycling within communities?
Energy is initially fixed by green plants then different organisms feeding on one another pass the energy from one level to the next with approx 10% of the energy being passed from one level to the next. Nutrients from the soil are also absorbed by plants and cycled through different organisms, eventually being returned to the soil through detritivors (organism that feeds on and breaks down dead plant or animal matter).
Give examples of how mean disturbances alter natural communities:
Introduction of disease pest plants and animals Changes of fire frequency or hydrology Selective grazing by stock Clearing Climate change
