Adaptations An adaptation is a characteristic that enables an organism to survive in an environment. Adaptations contribute to the fitness and survival of individuals
Remember Charles Darwin 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.
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 (Chlamydosauruskingii) 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 (Kosciosculatristis) 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 Fossils Fossils 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?
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”