Unit D: Changes in Living Systems

Lesson 2.4: Adaptations


The most endangered species in Banff National Park is the Banff Springs snail. These snails can live in only five thermal springs on Sulphur Mountain. But many other snail species have adapted to different habitats. In adapting to various habitats, over many generations, the shape and form of snail shells changed. Since snail shells do not decompose easily, the fossil record does an excellent job of preserving these changes.

In this lesson you will examine the process of adaptation by focusing on the fossil record of snails.

  • Read pages 488 and 489 of the textbook. Answer the questions as you encounter them. 

Science 20 Textbook.  Alberta Education


Essential Background Information

For a species to survive, organisms need to do two things;  survive in an environment and reproduce.  Organisms have adaptations which help them survive;  some  can be seen, like the long neck of a giraffe, but many cannot be seen, like the extremely slow energy use of a sloth.  Successful species pass adaptation to their offspring through genes.  Many offspring are exact duplicates of their parent, but especially among sexually reproducing species, offspring will vary.

Gene changes that occur between a parent and offspring are called mutations.   They produce different traits in offspring.  The puppies in Figure 1 are all different colours.  This is a trait we can see, and one that will likely not change their chances to survive or reproduce.  There are, however, traits that we cannot see, like better or worse immune systems, that might affect their survival.  If a mutation causes a trait that helps an organism survive or reproduce, it is called an adaptation. 
But environments change.  If the offspring of a species are all different, some of the offspring may be better suited to the new environment (and survive and pass on their genes), and the species will continue.

In the next investigation you will analyze and interpret the fossil record to trace the changes in snail shells over a period of thousands of years.

If you are working in a non-classroom environment, you may want to work with a friend or family member. Remember that there is more than one way to interpret evidence. When you compare the shells of different layers, you may want to use the partially completed chart as a guide.

Note: Fossils can be dated according to the rock layer they were found in. Fossils found in any given layer are younger than fossils found in a lower layer. This relative dating of fossils follows from the law of superposition, which is studied in Unit C. This law states that in a sequence of rock layers, the higher strata are younger than the lower strata.

  • Read the investigation on pages 490 and 491 of the textbook. Follow the steps of the procedure. (If you are working in a non-classroom environment, you may do just part of step 8 since you may be unable to look at and discuss the finished work of any other group.)

  • Answer the questions. Check your answers below.

    Science 20 Textbook.  Alberta Education



  • Read pages 492 to 495 of the textbook. Answer questions 29 - 32. Check your answers below.

    Science 20 Textbook.  Alberta Education


  • Read “2.4 Summary” on page 496 of the textbook. Then, complete “2.4 Questions”.

    Science 20 Textbook.  Alberta Education

     

Go to Assignment 2.4: Adaptations.