Ecology Notes
Species and Ecosystems:
Species = is a group of organisms that produce fertile, viable offspring.
- hybrids = two different species produce offspring by cross-breeding which are reproductively
sterile (e.g. liger, mule)
Population = is a group of organisms of the same species that are living in the same area at the same
time
Community = group of populations living and interacting in the same area
Habitat = the environment in which a species normally lives
Ecosystems = interactions between the community (biotic factors) and the habitat (abiotic
environment)
Biomass = the total mass of a group of organisms, consisting of the carbon compounds contained
within the cells
Types of Nutrition:
- Autotrophs = synthesize their own organic molecules from simple inorganic substances (e.g.
CO2 / O2) – process is driven by energy from photosynthesis (sunlight) or chemosynthesis
(oxidation of inorganic molecules) (Producers)
o Nutrients = carbon/nitrogen/oxygen/hydrogen/phosphorus from air/water/soil
- Heterotrophs = gets their organic molecules from other organisms (eating), they cannot
produce their own organic molecules
o Consumers ingest organic molecules from living or recently killed organisms
o Detritivores ingest organic molecules found in the non-living remnants of organisms
(e.g. detritus, humus)
o Saprotrophs release digestive enzymes and then absorb the external products of
digestion (decomposers)
- Mixotrophs = can both synthesize and absorb organic molecules, depending on the resources
available. (e.g. Euglena Gracillis – photosynthesize or feed on detritus)
Consumers = feed on living organisms by ingestion
- Herbivores on plant matter (e.g. cows/sheep)
- Carnivores on animal matter (e.g. tigers/wolves/sharks)
- Omnivores on both (e.g. pandas/humans)
Scavengers = feed on dead/decaying matter by ingestion (e.g. hyenas/vultures)
Detritivores = obtain nutrients from non-living organic substances (detritus – dead, particulate
organic matter/humus – decaying leaves mixed with soil) (e.g. earthworms/woodlice/snails)
Saprotrophs = live on/in non-living organic matter, secrete enzymes onto it so they can digest and
absorb it, facilitating external digestion. (decomposers – e.g. bacteria/mushroom/mold)
, Sophie Jones 12.5
Nutrient Cycle:
There are many components that effect the sustainability of an ecosystem (to survive without
external factors) these include: energy availability (sunlight) / nutrient availability (recycling of
nutrients by decomposers/saprotrophs) / recycling of wastes (bacteria detoxify wastes)
Mesocosms are small/enclosed environments of a larger environment that are observed under
controlled conditions (e.g. fish tank). Built as so:
Verdant foundation: pebbles/sand for drainage
Activated charcoal to prevent mold
Moss to create a barrio
Select the right plants: slow growing/thrive in humidity
With no sign of infection
Maintain conditions: continuous source of light
Avoid fluctuations of temp.
No overwatering/allow right humidity
Positive associations = when two species interact and exist together within an environment
- E.g. predator-prey symbiotic associations
Negative associations = species that tend not to occur within the same environment, this is because
of competition for resources. (competitive exclusion – one species is more efficient than the other
in using the resources, so the other dies out) (resource partitioning – both species alter their use of
the environment to allow both to survive)