An introduction to Ecology – Habitats, environment and survival

Unit 2, Area of Study 1 – organisms and their environments

What is Ecology?

• Ecology is the study of the relationships between organisms and their environments.

• The habitat (where the organism lives)• The other organisms it lives with• The non-living parts of the habitat

Habitat

• All organisms live in a particular area, called a habitat.

• Organisms are suited to their particular habitat.

• Organisms live in all types of habitats, even those that are considered “extreme” – very hot, acidic, cold, salty etc. Many of these “extremophiles” are bacteria

ANGLERFISH

Light-emitting bacteria

DEEP SEA

Types of habitat

• General descriptions:• Terrestrial (on land)• Aquatic (in water – may be freshwater or marine, or

estuarine [living in the river mouths that open to the ocean])

Microhabitats

• Within a larger habitat (for example, a forest habitat [called a biome in the following diagram]), there are a number of different areas that different organisms call home. These are microhabitats.

Resources

• Animals live in particular habitats for their resources. This usually includes water, shelter, food, nesting/breeding sites.

• Habitats are not uniform in the amount of resources. For example, a frog living in a pond may use the water for shelter and hydration, but breed on the edges of the pond, and need sunlight and air from the outside of the pond.

Range

• The area that encloses all the habitats the organism lives in is the range or distribution map of the species.

• Within the range, there may be areas of plentiful organisms, or areas where they are rare – a large range does not necessarily mean that a species is common

Range of Australian wombat species

Range changes

• Over time, the range of a species can change, usually due to change in habitat (eg. The clearing of forests)

• Many Australian native species have a shrinking range

The changing distribution of the introduced Cane Toad

Absence from a region

• There are a number of reasons an organism might NOT live in a particular habitat:– Unsuitable environment– Geographic barriers – Competition – another organism competing for

the same resources

Migration• Some mobile organisms travel long distances

between widely separated habitats• Annually

– Humpback whales spend summer feeding and mating in Antarctic water, but travel to Australia when it gets too cold, where the females give birth

– Bogong moths are caterpillars in QLD and NSW in winter. When they become moths, they hibernate in the Snowy Mountains, then fly to the north again in autumn to mate

• Once in their life cycle– Short-finned eels mature in freshwater lakes in southern and eastern

Australia, but when they are sexually mature, they swim across to their breeding areas in deep ocean near New Caledonia. Larvae hatch and are carried back to Australia, where they swim up freshwater rivers to lakes to mature.

Glossary words...

Ecology, habitat (or biome), microhabitat, terrestrial, aquatic, resources, range, migration, competition.

Page 263 – Quick Check questions

Homework: Read about Technology as a Tool in Biology (pp 263 – 266) and answer Quick Check questions pg 266

Niche

• In a habitat, many species live together.

• They all must somehow share the resources which are there, or must require different resources

Niche definitions

• “the way of life of a species”• “the role or profession of a species in a

community”• “the way of life of an organism”• “the status or role of an organism in its

community”

Niche continued

• Each species has its own niche, which may be described in terms of the resources it uses:– Where it lives– What it eats– When it feeds– The environmental conditions it tolerates (eg.

Temperature, amount of sunlight)

Describing niche

• Niche is usually described in words, for example, “its niche is that of a leaf-eating herbivore that feeds by day in the canopy of a tropical rainforest”.

• Have a go at writing niche description for the following organisms:

• Desert cactus• Giraffe

Niche overlap• When more than one species in a habitat

occupies the same niche, or part of the same niche (eg. It requires the same food or shelter source), there is niche overlap

• Niche overlap means that there will be competition between species for the same resources, with one species undoubtedly being the stronger species

Niche overlap continued• The result of niche overlap is that one of the

species will be either excluded from that habitat, or will have to adapt to fill a different niche.

• This, sadly, often happens when a species is introduced, and it pushes out a native species

– Eg. Rabbits have out-competed small herbivorous mammals in many areas of Australia

• Natural habitats have zero or very little niche overlap

Glossary etc

Niche, niche overlap

Pg 270, Quick Check questions