Ecosystems and Population Change

Interactions Within Ecosystems

Ecology – is the study of interactions between organisms and their living and non-living environments.

SPCE – species population community

ecosystem

Ecological Niche – an organisms role in an ecosystem which includes its place in the food web, habitat, breeding area, etc.

Within ecosystems, each organism has its own specific role or place. No two species fulfill exactly the same role or ecological niche.

If a new species (exotic species) is introduced into an ecosystem, competition will result with any species that fulfills the same niche. Eventually, one of the two species will be out -competed and cannot survive in the ecosystem. During this process, the entire ecosystem will be disrupted.

Example: European rabbits were introduced to Australia to provide sport for game hunters. The rabbits had no natural predators, and became pests. The rabbit infestation resulted in the destruction of plant matter, crops and land. Agricultural grazing land became littered with rabbit holes that proved to be a hazard to grazing animals. Rabbits also dug under fences, allowing dingo’s (a native Australian wild dog) to sneak into paddocks and kill large numbers of sheep.

Population Terms for each environment

Biotic Potential: is the maximum reproductive capacity of a population if resources are unlimited

Carrying Capacity: is the maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment

Environmental resistance: Factors in an environment such as predators, competition, climate and food availability, that keep its various populations from reaching their maximum growth potential.

Limiting Factors

Are environmental conditions that may prevent populations from reaching their biotic potential.

Limiting factors may be biotic or abiotic

ABIOTIC FACTORS

too much / little light

temperature too cold / warm

harmful chemicals in the environment

BIOTIC FACTORS

insufficient food excessive

predators diseases or

parasites diminished ability

to compete

Terrestrial Ecosystems

Terrestrial ecosystems are limited by four major abiotic factors:

1. Soil: Provides nutrients for all plants that grow on land. Poor quality soil is an important limiting factor in many ecosystems

2. Available Water:

Precipitation that collects above ground is called surface water.

Ground water is found in the spaces between soil and porous rock that percolates (PERCOLATION)

The layer that is saturated with water is found within the water table

3. Temperature: Many plants and animals adapt to a specific range of seasonal temperatures.

4. Sunlight: has an effect on all terrestrial ecosystems. The amount of sunlight usually varies with the geographical location and with the canopy plants that are growing in a specific area.

Sustaining Ecosystems

Ecosystems are destined to change, gradually, over time. Sadly, human induced changes often leave ecosystems unable to replenish resources and the delicate balance of life is upset. Terrestrial and aquatic ecosystems each have a unique set of limiting factors and challenges that threaten their sustainability.

Our Field Study

Kaeli’s powerpoint

Grassland Biome

Riparian Forest Biome

Biodiversity and Classification Scientists estimate that there are between 2 and

4.5 million different types of organisms on the planet.

Likely there are / were many more.

To organize, name and group these organisms based on similar characteristics, scientists use a system called taxonomy.

Taxonomy – the science of classification according to presumed relationships among organisms.

Scientists use a hierarchical system, where organisms are classified in a series of smaller groups.

The 5 Kingdoms Prokaryotae – includes the bacteria (eubacteria

and archaebacteria (unicellular with no cell nucleus)

Protista – includes single celled plants and animals and algae (unicellular with a nucleus)

Fungi – includes the mushrooms, yeasts, moulds (multicellular, decomposers)

Plantae – includes the trees, flowers, mosses and ferns (multicellular, photosynthesizers)

Animalia – includes sponges, worms, crustaceans, insects, and mammals (multicellular and heterotrophic)

Hierarchical System Domain- Bacteria, Eukarya, Archea Kingdom – Monera, Protista, Plantae,

Fungi, Animalia Phylum – sub-groups of each kingdom Class Order Family Genus Species – organisms that are very similar

and can naturally interbreed to produce fertile offspring

Most General

Most Specific

Binomial Nomenclature When organisms are assigned a scientific name,

the name is given in two parts, Genus species, and the name is either written in italics or underlined. This system is called binomial nomenclature.

Genus name indicates organisms that are similar, and is always capitalized.

Species name indicates organisms that are different, and is written in lower case.

Ex. Canis lupis wolf Canis domesticus dog

Naming some 2 – 5 million organisms presents a challenge to scientists. To overcome this challenge, dichotomous keys are used to identify and classify organisms based on their characteristics.

Scientists today believe that organisms changed over time.