Introduction to Ecology Flashcards
what is ecology
relationship of an organism to its environment
External relations of plants and animals to each other and to past and present conditions of their existence
More modern definition of ecology
scientific study of interactions that determine distribution and abundance of organisms
Interactions may be between
organism and abiotic environment
Organism and biotic environment
Organisms of same or different species
algal bloom
growth of algal population out of control- produce toxins and start killing fish
Most important elements for any organism
Phosphorous
Carbon
Nitrogen
Which element is the cause of algal blooms
phosphorous
Ecology essential for
- monitoring long term changes in environment eg GW
- Assessing and understanding impact of humans on their environment
- Underpinning conservation eg preserving biodiverisity
4 levels ecology can be studied at
organism, population, community and ecosystem
organism level
how individuals are affected by the environment
1 species/population
Related to evolution
Population level
What explains presence of particular species and abundance
Community level
How they emerge, structure of communities and pathways followed by energy
ecosystem level
looks at combination of communities of organisms and physical and climatic properties
Population ecology
growth of populations and variation in size
population
group of organisms of the same species that occupy particular space
Rely on same resources, influenced by similar environmental factors, similar gene pool and can potentially interbreed
Population structure
encompasses density and spacing of individuals within suitable habitat and proportion of individuals of each sex and age class
Spatial structure
part of pop structure that encompasses density and spacing of individuals
3 ways to describe a population
size area and density
Area
use GIS- maps species
Larger area for population- can handle variety of environ factors
Smaller- more specialised, maybe endemic
Having this data is helpful for identify how healthy populations are
Some populations have clear boundaries, others don’t
Size
Number of individuals of all ages alive at a particular time in a particular population
Varies over time
Need multiple measurements
Use sampling and marking to determine pop size because not easy to count individuals eg if move around
Mostly working with estimates
How to measure size
collect x individuals say x=100
mark them
resample y individuals, say y=100
Proportion of these individuals will be marked
N= (originally marked x resampled)/ recaptured
Size assumptions
Marked and unmarked equally likely to live/die, and are equally distributed through the pop
Marks stay on
Sampling is the same ie not a lot of births and deaths
Not a lot of migration
Density
Combo of size and area
Helps estimate pop size in v large areas
density=
pop size/area
relationship between body size and density
usually strong negative correlation
Larger body sizes better fitness, so fewer individuals
Dispersion
pattern of spacing among individuals
Types of dispersion
Clump (fishes). uniform (penguin), Random (seed dispersal)
dispersal limitation
absence of a pop from a habitat because of barriers to dispersal
more suitable conditions for a species=
higher density
areas with narrowest range of conditions tend to support
highest pop densities
