Selective Pressure and Survival of the Fittest

Question: Describe the specific adaptations and how they affect the organisms? Answer: Selective pressures and survival of the fittest Adapting to life in the desert where temperatures are high and availability of water is low, the camel has evolved over millennia into an animal with several morphological and physiological adaptations that help the species to survive in the extreme arid climate. The camels ears are protected with a soft fur in order to keep out dust. The eyes are lined with long eyelashes that help to keep the sand out. The leathery pads on two toes of each foot spread out and prevent the feet from sinking into the sand. The physiological adaptations include the hump that has fat reserves and can allow the camel to go without food or fodder for several days. The fat contained in the hump is metabolized to provide energy. Unlike mammals the body temperature can fluctuate by 60C to avoid water loss through perspiration. The oval-shaped erythrocytes can flow even when loss of water makes the blood viscous. Water can be conserved through excretion of concentrated urine and dry fecal pellets (Roberts Ingram, 2001). The polar bear has to live in another kind of extreme climate and so has small extremities that reduce the bodys surface area and allow minimum heat loss. A thick layer of blubber keeps the body insulated from cold and acts as an energy reserve during periods of starvation. The body fat gets oxidized to release carbon dioxide and water. The water is useful when fresh water becomes scarce during harsh winters. The large paws help to distribute the weight and prevent the feet from sinking into the snow. A coating of fur on the paws and blubber under the skin helps insulate the paws from the snow (Starr, 2007). References: Roberts, M. and Ingram,N., 2001, Biology, 2nd Edition NelsonScience. Starr, C. 2007, Biology: Concepts and Applications without Physiology, 7th Edition, Cengage Learning Inc.