adaptations and evolution RW.pptx

ADAPTATIONS ⦿ Organisms that are native to a particular environment, have developed adaptations that enable them to survive and breed successfully. ⦿ These adaptations are inherited from parent to offspring and come about as a result of genetic mutations and natural selection. ⦿ All organisms includ...

ADAPTATIONS ⦿ Organisms that are native to a particular environment, have developed adaptations that enable them to survive and breed successfully. ⦿ These adaptations are inherited from parent to offspring and come about as a result of genetic mutations and natural selection. ⦿ All organisms including plants have adaptations. ⦿ There are three main types of adaptations; ◼Structural ◼Functional STRUCTURAL ADAPTATIONS These are physical features of an organism ⦿Examples include ◼Camouflage – to help organisms blend into their surroundings making them less visible to predators. Can you spot me? FUNCTIONAL ADAPTATIONS ⦿ Affect how the internal functions of an organism works. ⦿ Examples include: ◼Sweating - helps animals cool down so they don’t overheat. ◼Shivering when cold - helps to warm the body. ◼Animals can hibernate (reduction in metabolism) in winter when food is scarce. ◼Organisms such as the chameleon lizard can change colour to blend in with its environment. FAVOURABLE CHARACTERISTICS ⦿ These are characteristics that help organisms survive and successfully reproduce within their environment. ⦿ Through successful reproduction, these characteristics are passed on, becoming the most common. ⦿ Organisms with unfavorable characteristics are unsuited to their environment are more likely to die off, becoming less common. ⦿ This is known as natural selection DARWIN’S THEORY ⦿ Charles Darwin was a naturalist who traveled extensively, observing the geographical distribution of plants, animals, fossils and rocks in various parts of the world. ⦿ Believed in natural selection ◼Variations in characteristics appear within a species ◼nature picked the favourable characteristics over many generations. ◼Less favourable characteristics died out. ◼Survival of the fittest Charles Darwin (18091882) DARWIN’S GIRAFFES Ancestral giraffes had necks of different lengths By natural selection those with longer necks survived and produced long necked offspring Eventually all giraffes had long necks TYPES OF EVOLUTION Divergent evolution ⦿ new forms evolving from a single ancestor ⦿ Results in phenomena known as adaptive radiation HOMOLOGOUS STRUCTURES ⦿ In related species, characteristics have the same basic structure are called homologous characteristics. ⦿ This is because related organisms share some of their genes. ⦿ Studies of vertebrates show that they all have what is known as a pentadactyl limb (a limb with 5 digits) ⦿ Different animals have adapted these to perform different functions. CONVERGENT EVOLUTION ⦿ Organisms from quite different origins evolve similar adaptations. ⦿ They can have analogous structures- body parts that appear to be similar ⦿ E.g. sharks (cartilagenous fish) and dolphins (mammals) are different species however they have similar adaptations that enable them to move through water quickly. PARALLEL EVOLUTION ⦿ Organisms that look alike and have common ancestry, but are found in different locations