Dominant and Recessive Traits by act50979

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									                           Dominant and Recessive Traits
Today, we are going to look at four characteristics or traits that we think influence the
distribution of these two species of mussels. These four traits affect the internal and external
conditions in which the mussels live. Listed below are the traits

Byssal thread production – This trait controls the amount of byssal threads produced by a
mussel. Byssal threads are the tiny fibers that attach a mussel to the rock or other mussels in the
area it lives.

Byssal thread thickness – This trait controls the thickness of the byssal fibers the mussel
produces.

Length of the foot – This trait decides if the foot (the muscle that the bivalve uses to move) is
long or short

Heat stress resistance – Many intertidal organisms produce hormones that regulate their internal
system against the heat of the sun when they are exposed.


       For this activity you will need a penny to help you decide which organisms will have
which traits. You will use generate 5 Mytilus galloprovincialis.samples and 5 M. trossulus
samples. Use the Chart 1 to decide the characteristics of M. galloprovincialis. And Chart 2 for
M. trossulus. Complete the 10 samples and then combine them with your classmates’ to create a
graph of the population’s traits.
Chart 1 (M. galloprovincialis)
                      Heads/Head               Head/Tails             Tails/Tails
Byssal thread     Lots of byssal          Lots of byssal          Few byssal threads
production        threads                 threads

Byssal thread     Byssal threads are      Byssal threads are      Byssal threads are
thickness         thick                   medium                  thin

Length of foot    Foot 5-6cm (long)       Foot 4-5cm              Foot 3-4cm (Short)
                                          (medium)

Heat stress       Heat Stress resistant   Heat stress resistant   Not resistant to heat
resistance                                                        stress



Chart 2 (M. trossolus)
                      Heads/Head               Head/Tails             Tails/Tails
Byssal thread     Lots of byssal          Lots of byssal          Few byssal threads
production        threads                 threads

Byssal thread     Byssal threads are      Byssal threads are      Byssal threads are
thickness         thick                   medium                  thin

Length of foot    Foot 5-6cm (long)       Foot 4-5cm              Foot 3-4cm (Short)
                                          (medium)

Heat stress       Not resistant to heat   Not resistant to heat   Heat stress resistant
resistance        stress                  stress
M. galloprovincialis Samples
                                Coin toss results        Trait expressed
Byssal thread production   1.                       1.
                           2.                       2.
                           3.                       3.
                           4.                       4.
                           5.                       5.
Byssal thread thickness    1.                       1.
                           2.                       2.
                           3.                       3.
                           4.                       4.
                           5.                       5.
Length of foot             1.                       1.
                           2.                       2.
                           3.                       3.
                           4.                       4.
                           5.                       5.
Heat stress resistance     1.                       1.
                           2.                       2.
                           3.                       3.
                           4.                       4.
                           5.                       5.

M. trossulis Samples
                                Coin toss results        Trait expressed
Byssal thread production   1.                       1.
                           2.                       2.
                           3.                       3.
                           4.                       4.
                           5.                       5.
Byssal thread thickness    1.                       1.
                           2.                       2.
                           3.                       3.
                           4.                       4.
                           5.                       5.
Length of foot             1.                       1.
                           2.                       2.
                           3.                       3.
                           4.                       4.
                           5.                       5.
Heat stress resistance     1.                       1.
                           2.                       2.
                           3.                       3.
                           4.                       4.
                           5.                       5.

								
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