ADAPTATIONS

 A.  An adaptation is an INHERITED characteristic or set of characteristics which  improves the chances of survival of an organism.  A complex adaptation evolves over a long period of time.  Some inherited characteristics have no apparent adaptive value.
Examples of adaptations: 
           desert animals
           desert plants
           arctic animals
           arctic plants
           bird beaks
           land plants vs aquatic plants
           prairie plants
           epiphytes

B. Types of adaptations:
        1. Morphological- those which involve the structures of organisms,
                            or their anatomy.  (Most obvious form). (examples: structures
                            of human foot, beaks of birds or hooves of horses).
                            Morphological  adaptations are important in food-getting.         

        2. Physiological- those which involve the various physical and
                             chemical needs of organisms, including biochemical characteristics.
                            (examples: various enzymes needed for digestion, clotting of
                            blood or muscular contraction).

        3. Behavioral- those which involve reactions to the environment.
                            (example: migration of birds, courtship behaviors, hiding and
                            storing nuts by squirrels, and tracking abilities of hunting dogs.)

C. Any one adaptation depends upon all other adaptations.  The behavioral adaptation of bird migration, for example, not only depends upon nervous coordination, but also upon morphological adaptations such as feathers, lightweight bones, and strong muscles.
 
D. Adaptations involving deception and camouflage are widespread in nature:

        1. Camouflage- a kind of "disguise" to blend with the environment.

                                   a. cryptic coloration- when the organism's color matches
                                       the color of his environment. This enables the organism to
                                       hide in his environment.  An example of this is the peppered
                                       moth, which can be either black or white.  The white moth
                                       matches the bark of the tree, whereas, the black moth
                                       matches the bark of the tree when it is covered with soot
                                       from industrial pollution.  Another example is the stripes on
                                       tigers which break up the general body outline of the animal
                                       when he is amongst the weeds so that another animal may not
                                       see the tiger approaching.  katydid

                                   b. shape- Some animals "hide" by means of their shape.  For
                                       example, many insects resemble the twigs of plants; pipefishes
                                       can resemble the algae among which they live by swimming in
                                       an upright position.    walking stick;   noctuid caterpillar; 

                                   c. mimicry- In nature, sometimes a tasty organism has a color
                                       pattern similar to that of a distasteful organism.  The origin of
                                       a mimic's coloration pattern is genetic.  By random chance,
                                       variations occur which cause one group of organisms (the
                                       mimics) to resemble another group (the models).  Those
                                       organisms which possess the variation are less likely to be
                                       eaten.  Therefore, they will survive to reproduce offspring
                                       with the same variation.  Eventually, through continued
                                       change and natural selection, the mimic gains a close
                                       resemblance to the model.
                                                       Furthermore, mimicry does not have to be total
                                      mimicry.  Any little change which improves the chances of
                                      survival and reproduction can be selected by natural selection.
                                      An example of this is the robber fly, who is the mimic of the
                                      bumblebee.  The two nsects are not closely related, but their
                                      similarity in coloration deceives possible predators.
                                      Consequently, predators gnore the mimic just as they do
                                      the model.

          Note: Below, the Monarch butterfly (model) is on the left, and the Viceroy (mimic) is on the right.

         

        2. Warning coloration-  This involves a display of bright colors and
                             patterns. These color patterns announce rather than conceal the
                             presence of animals.  For example, the yellow and black stripes
                            of a bumblebee are recognizable to possible predators.   See examples below:

                                    

E. Industrial Melanism, otherwise known as the Evolution of the Peppered Moth .
               Evolution and adaptation do not always require extremely long periods of
              time.  In England a rapid evolution of the peppered moth has been occurring
              for the last 100 years.  In the middle of the nineteenth century almost all of the
              peppered moths in England were light in color.  Black moths possessing a
              pigment called melanin were rare. Originally the tree trunks were very light in
              color. As a result, the moths blended with their environment.  Birds which fed
              upon peppered moths had difficulty locating light-colored moths. However,
              dark moths were easily seen.  As the industrialization in England increased,
              the tree trunks became covered with soot and smoke.  Eventually they
              turned black.  Then the mutant, black forms of the peppered moth, had a
              distinct advantage. When the black moths rested on the soot covered tree
              trunks they were invisible to the birds.  Light-colored moths, however,
              became easy prey.  During the last 100 years, the gene pool has evolved to
              such an extent that over 90% of the peppered moths are black.  This
              particular phenomenon is called industrial melanism.
 
             This story of industrial melanism is important for two reasons:
                         A. It shows that evolution is truly an interaction of organism and
                              environment.
                         B. It points out that evolution and natural selection operate on the
                              basis of genetic change within a population.

       

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