ecosystems and populations. terms ecology: study of how organisms interact with each other and...
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Terms Ecology: study of
how organisms interact with each other and their non-living environment (biotic-living and abiotic-non living factors)
Ecosystem: The biotic community and all abiotic factors.
Community: All the living organisms/populations in an area
Population: group of organisms of same species
Roles in Ecosystems Habitat: the area
where an organism lives; its address (eg. Tropical rainforest);
Niche: an organism’s profession; what it eats, what eats it, the habitat, time when active, etc.
Biodiversity
describes the number and variety of organisms in an ecosystem.
Greater biodiversity means more stability because if one species in a food web is lost, its predator can switch to another prey.
Indicator Species are species of organisms that provide an
early warning that an ecosystem is being affected by some factor.
Usually, these species are very sensitive to changes in an ecosystem, or to specific changes of ecosystem conditions.
Exotic Species Second only to
habitat loss as a cause of extinction
New species occupy niches of natural populations and out compete them
purple loosestrife
zebra mussels
starlings
Special concern – numbers are declining at the range / fringe of the area
Threatened – species may become endangered if threatening conditions are not reversed
Extirpated – a species no longer exists in one particular area, but is still found in other areas
Endangered – a species is close to extinction in all parts of their natural habitat
Extinct – a species no longer exists
Less severe risk
Most severe risk
Species At Risk
Genetically Modified Crops
Transfer of genes from one organism to another unrelated organism
Eg. Roundup resistance to canola
Biological Control
Using a natural predator to control an unwanted species.
Biotic Potential
the maximum number of offspring that the species could produce with unlimited resources
Environmental Resistance
Is the limiting factors on a population
Include food, shelter, water, predation, etc.
Puts brakes on biotic potential (B) – maximum reproductive rate
Exponential Growth
J shaped curve (initially) occurs with short-lived populations that rapidly deplete their environment
Limiting Factors to Populations
Shelford’s Law of Tolerance: an organism can survive within a certain range of any abiotic factor
Greater the range, the greater the ability for the species to survive
Limiting Factors on Populations
Law of the Minimum: if any one of many needed nutrients/limiting factors is reduced below the required levels, the population growth rate declines
Limiting Factors
Can be density independent – those that will affect a population regardless of its size Eg. Cold winter
Lack of water
Limiting Factors
Can be density dependant – those that increase when the population size increases Eg. Disease
Predation Food Supply
Taxonomy - naming
Naming system to identify different species
Used binomial nomenclature – two words
Species - Definition
A species is a group of organisms that can interbreed under natural conditions and produce fertile offspring
Levels of Classification
Kingdom AnimaliaPhylum ChordataClass MammaliaOrder PrimatesFamily HominidaeGenus HomoSpecies sapiens
(Kings play chess on fine grain sand)
Classification Giraffe Horse Pig
Kingdom Animalia Animalia Animalia
Phylum Chordata Chordata Chordata
Class Mammalia Mammalia Mammalia
Order Artiodactyla Perissodactyla Artiodactyla
Family Giraffidae Equidae Suidae
Genus Giraffa Equus Sus
Species camelopardalis caballus scrofa
The Kingdoms
5 of them:
1. Monera: Bacteria and blue-green algae
- sometimes subdivided into eubacteria and archaebacteria
- prokaryotic (very simple) cells