22
VCE BIOLOGY www.drlakshmisharma.com Dr Lakshmi Sharma NO LIMITS TO LEARNING! BELIEVE & YOU CAN ACHIEVE! POPULATION DYNAMICS

VCE Biology Population Dynamics

Embed Size (px)

Citation preview

VCE BIOLOGY

www.drlakshmisharma.comDr Lakshmi Sharma

NO LIMITS TO LEARNING! BELIEVE & YOU CAN ACHIEVE!

POPULATION DYNAMICS

POPULATION DYNAMICS

What do we mean by Population Dynamics?

Managing Populations

Abiotic & biotic factors

affect the abundance & distribution of organisms

Population explosion

a rapid increase in population size

Population decline

a decrease in population size

Is this Managing Populations ???

Is this Managing Populations ???

Sustainable use – to exist in the future

Harvesting of resources - drive species to extinction Some whale species have almost become extinct Sustainable use important - resources used in the future

Can you think of any sustainable resources & their practices ?

Definitions - Distribution & Abundance

Population – no. organisms of the same species

that live in a defined geographic area

Distribution – Geographic range and preferred habitat

Abundance – Size of a population

Knowing the distribution & abundance of species is important for sustainability & existence - Wombat

What are the factors which affect distribution & abundance?

Factors affecting distribution & abundance

Characteristics of the environment

light availability, temperature, tide

Characteristics of the organism

methods of eating, reproducing etc.

Interactions between organisms

distribution is limited by availability of prey/abundance of predators & competition for food and shelter.

Australian Grey Teal

Most widespread duck in Australia

Breeding-Murray Darling River

Very abundant

Reasons for Abundance

Nomadic – flies from pond to pond in search of places to feed and breed.

Lives in temporary, shallow waters which are often rich in food

They breed when flood waters rise and food/nest holes are abundant. (Courting and mating occurs quickly)

Reasons for Abundance cont’d

They eat a wide range of food (insects, molluscs, crustaceans, seeds, fruits)

Have no important predators

Is not in direct competition with other duck species

What determines size of population?

BirthDeath Immigration arriving from outside of a

populationEmigration out of a population

Populations

A rapid increase in population size –

EXPONENTIAL GROWTH

Population density limits pop growth - Intra

specific competition

The carrying capacity of an ecosystem death

= birth – constant

Population Explosions

Aquatic weeds – Salvina Fern – native to Brazil-2-5 days doubles pop.

Crown of thorns sea star – infestations damage coral reef – 14% of GBR infested

Population Explosions

Why?

Reproduction-ability to reproduce at greater rate

Favourable abiotic environment Lack of predators Dispersal factors carry to new area

Introduction of New Species

Boneseed from South Africa invaded coastal sand dunes in E. Australia

English broom weed threatens survival of native plants Camel survived in Australia now extinct in its native north

Africa & Arabia. Abundant pests include European Carp, mosquito fish,

water buffalo, the cane toad, the European rabbit, mice & red fox.

Introduction of New Species

Control of Pests

Prickly pear cactus -24m hectares- biological agent -moth ate plant

Rabbit-myxomatosis – resistance-rabbit calicivirus disease (1996)

Cane toads-control pest for cane beetles-did not control beetles and became pest

Any Questions ?