Topic 7 - Ecology Flashcards
Define population?
All members of a particular species w/in an ecosystem, found in the same time & place, & actually or potentially breeding
Define community?
All the interacting populations w/in an ecosystem
Define ecosystem?
All organisms & their nonliving environment w/in a defined area
Define Biosphere?
That part of the earth inhabited by living organisms; includes both living/nonliving components
Population dynamics is…? Contributing factors are…?
Changes in population size over time. 4 contributing factors: births deaths immigration (migration into an area) emigration (migration out of an area)
Population growth rate =? Results in?
Change in population size per individual per unit time (rate of natural increase)
r=birth rate - death rate
Population growth =r X N
Results in exponential growth (J shaped growth curve)
Exponential growth is?
Boom n bustttt (think awkward dance moves) growth curve
Often observed w/ invasive species invasions
Natural mortality is limited e.g. Cane toad
Logistic growth is?
Pop is maintained at steady level => CARRYING CAPACITY
Limits to growth ( e.g. lack of food) slowly decreases the pop. growth rate
Mortality Factors (2 kinds!)
Density-INdependant
Density-DEpendant
What are density INdependent factors? What do they do?
Are independent of pop. => physical conditions that affects all individuals regardless of pop. size e.g. natural disaster
What are density DEpendent factors? What do they do?
Limit pop. growth in proportion to size of pop. Increase in magnitude as pop. increases e.g. predation, competition
What is an ecological niche? Includes?
All aspects of an organism's way of life. Includes: -food source -nesting requirements -temp, pH, sunlight tolerances -water requirements etc
Note: Competition is fiercest b/w organisms w/ similar niche requirements
Define competition? What purpose does competition serve?
Interactions b/w organisms attempting to use the same limited resource e.g. food, hiding places, mates etc
Coz resources are finite, comp. serves to limit pop. growth
What is INTRAspecific competition?
competition b/w members of the SAME species
What is INTERspecific competition?
competition b/w members of DIFFERENT species
What is the competitive exclusion principle?
No two species can occupy the same ecological niche simultaneously.
If attempted => one will be forced out.
What is resource partitioning?
Evolutionary adaptation that reduces niche overlap
Niche breadth is narrowed compared to species that do not have to compete.
THINK BUG TREE EXAMPLE.
RP is an example of coevolution=> two interacting species acting as forces of natural selection on each other
State 2 types of species interactions & give example!
- Antagonistic e.g. predation, parasitism
2. Mutualistic e.g. mutualism (reallllllyyy?!)
In predation…?
predator is generally larger than prey. more than 1 prey is consumed during life of predator
In parasitism…?
Consumer is usually smaller than host. One host usually consumed during development
Death of host is typically gradual
In mutualism…?
both organisms benefit from the interaction
What is a trophic level?
Literally ‘feeding level’. categories of organisms in a community, & the position of an organism in a food chain, defined by the organism’s source of energy
(think energy pyramid example)
Energy flows….?
from one trophic level to the next, w/ maximum energy at base (primary consumers) & steadily diminishing at higher levels
producers=>primary consumers=>secondary consumers=>tertiary consumers
- energy pyramid
- but dont forget about the decomposers/detritus feeders!
Nutrient cycling is where…
nutrients pass from one trophic level to the next, as demonstrated in a food chain or food web
Detritus feeders & decomposers do what?
Detritus feed on debris
Decomposers feed on similar matter by secreting digestive enzymes externally
Both return nutrients to ecosystems in the form of simple molecules => make nutrients available to other individuals
Define biomass
Total weight of all living material w/in a defined area
Define biomagnification
Increasing accumulation of a toxic substance in progressively higher trophic levels
Description of food web
A representation of the complex feeding relationships w/in a community, incl. many organisms at various trophic levels, w/ many consumers occupying more than one level simultaneously
Description of food chain
A linear feeding relationship in a community, using a single representative from each trophic level
