Adaptations

Adaptations

An adaptation is a characteristic that enables an organism to survive in an environment.

Adaptations contribute to the fitness and survival of individuals

Adaptations result from natural selection- there is variation within a population- organisms with the characteristics that

enable their survival will survive- those organims that survive, reproduce

to pass on these characteristics.

Remember Charles Darwin

Three types of adaptations

• Structural – physical characteristics eg thick fur coats

• Physiological –the processes occuring in an organism eg Hibernation

• Behavioural – actions of an organism eg basking in sun

Frill necked lizards (Chlamydosaurus kingii) bask in the sun until they reach an adequate core body temp, then they will retreat into the shade.

The cladodes of the she-oak (casuarinas) have tiny little leaves that can only be seen with a lens. This reduces surface area for water retention.

The Australian alpine grasshopper (Koscioscula tristis) has a blue colouring at higher temperatures and an almost black colour at low temperatures.

The leaves of the Eucalypt hang vertically to reduce the area that is exposed to the sun in the hottest part of the day.

Penguins use countercurrent exchange to prevent heat loss. The warm blood in arteries heats the cool blood returning to the body.

Problems

The environment is not static - an organisms current characteristic may have been inherited thousands of years ago when they existed in a different habitat.

Vestigal Organs Vestigal organs are the remnants of fully functional structures in their ancestors

Dolphins and whales have lungs which are of no use for living in water

Therefore:

• An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation

Looking at FossilsFossils can tell us a lot about the history of life on earth

But interpreting the characteristics of fossils is even

more difficult

Are the bony plates of the stegosaurus for defence, temperature regulation or to attract a mate?

Many adaptations are not obvious

Missconceptions

“An adaptation is a change in an organism that helps it survive and reproduce in its environment”

Misconception

“An adaptation is a change in an organism produced as a response to a change in the environment e.g phototropism”