4.7 INVESTIGATING DIVERSITY

HOW CAN GENETIC DIVERSITY WITHIN OR BETWEEN A SPECIES BE MEASURED?

COMPARING:

1. Frequency of measurable/observable characteristics.

2. DNA base sequence.

3. mRNA base sequence.

4. Amino acid sequence of a specific protein..

5. Immunological techniques.

ISSUES WITH “Comparing frequency of measurable or observable characteristics”?

• Often coded for by multiple genes.

• Environment can also influence characteristics, but doesn’t directly show differences in an organisms DNA.

IMMUNOLOGICAL TECHNIQUES:

Comparing amount of antibody bound to antigen/protein (in different species)

_{[Antibodies that are specific to antigens from a particular species can be mixed with antigens from a different species to see if they are also complementary. If the antigens of the two species are similar, many antigen-antibody complexes will be formed.]}

EXPLAIN THE CHANGE IN METHODS OF INVESTIGTING GENETIC DIVERSITY OVER TIME

• Used to be from measurable/observable characteristics.

• Now, gene technologies allow DNA sequence investigations.

EXPLAIN THE KEY CONSIDERATIONS IN QUANTITATIVE INVESTIGATIONS OF VARIATION WITHIN A SPECIES.

1. Large, random ethical (release unharmed) sample.

2. Calculate mean and SD.

3. Use statistical test to see if there is a significant difference between populations.

PROBLEMS IN CLASSIFYING ORGNAISMS AS DISTINCT SPECIES.

• Extinct species greatly outnumber the living ones.

  • Most species did not leave fossils, if they have, they are incomplete.

  • Fossil records do not allow breeding tests.

• There is considerable variation within any one species.

• Groups of organisms that are isolated from each other may be classified separately.

• Breeding tests canned be used on organisms who asexually reproduce.

BIODIVERSITY:

Variety of living organisms in a community/habitat.