2.3 VARIATION

VARIATION

Variation is a topic that is very much related to the previous topics which are CELL DIVISION and MUTATION. Some previous concepts will be used again to explain VARIATION.

                           Concept map using cMap tools

       Actually, variation is an easy topic in the pre-university curriculum specification. Students are able to understand the concepts in the topic through reading, group discussion, making maps (mind map or concept map) and exectra.

     So to teach variation effectively to my students, I started to use flipped notes as the teaching tool. This is my first experience to use this tool. I just explained and shared a YouTube video by Cikgu Norhailmi bin Abdul Mutalib before students started to create their own flipped notes. Not just the content is important but the creativity of the students can also assist their learning.

    Here I would like to share the flipped notes by one of my tutorial classes which is (D1H2T5, 2018/2019) and the presentation activity. The photos uploaded are with permission from the students involved.

          I give credit to Cikgu Norhailmi bin Abdul Mutalib (jazakallahu khoiron kathiro) from SMK Jerlun, Kedah for the sharing of making the flipped notes.

 The concep map of the overall concepts in Selection

NATURAL SELECTION

 Graph of stabilizing selection for the Natural Selection

Selection acts to eliminate both extreme phenotypes but favours the intermediate phenotype. 
Example: 

Twin babies with medium weight (between 3kg to 4 kg) are selected to be born compared to heavier and lighter babies.

 Graph of directional selection for the Natural Selection

Selection acts to eliminate ONE extreme phenotype and intermediate phenotype but favours individuals at ONE extreme phenotype of the phenotypic range.

 
Example: 

During the industrial revolution in the United States which released a large quantity of smoke into the air, the black colour of the peppered moth or Biston betularia is chosen to survive after the white and the grey peppered moths were eaten by their predators which were birds. 

The white and black were extreme phenotypes while the grey was the intermediate phenotype.

Graph of disruptive selection for the Natural Selection

Selection acts to eliminate the intermediate phenotype but favours individuals at BOTH extreme phenotypes. 

Example: 

Types of the beak of finches at Galapagos Island. The finches with big and small beaks are selected to survive on the island.

The big and small beaks were extreme phenotypes.





SPECIATION
 
The concept map of overall concepts in Variation: Speciation

The Grand Canyon