4.6.5 Investigating Diversity

Genetic Diversity

• Genetic diversity is the variety of alleles within or between species. It can be determined by:
  1. Comparing the frequency of measurable or observable characteristics.
  2. Analysing the base sequence of DNA.
  3. Analysing the base sequence of mRNA.
  4. Comparing the amino acid sequences of proteins encoded by DNA and mRNA.

Methods of Investigation

1. Observable Characteristics

• Characteristics such as size, shape, or colour were traditionally used to investigate diversity. Limitations:

• Polygenic Inheritance: Many characteristics are controlled by more than one gene, making comparisons complex.

• Convergent Evolution: Similar characteristics may evolve independently in unrelated species, leading to false classifications.

• Environmental Influence: Characteristics influenced by environmental factors may not accurately reflect genetic differences.

2. Molecular Comparisons

• DNA Base Sequences: Comparing DNA sequences provides direct insight into genetic differences. Modern techniques, such as DNA sequencing, allow for precise comparison.
• mRNA Base Sequences: Reflect the genes that are actively transcribed, offering another layer of genetic information.
• Amino Acid Sequences: Proteins encoded by genes can be compared to reveal evolutionary relationships.

Advantages of Molecular Techniques

• Accuracy: Molecular methods are more reliable than observable characteristics as they directly reflect genetic information.
• Quantitative Data: Base and amino acid sequences allow for numerical comparison, improving objectivity.
• Evolutionary Insights: Helps construct phylogenetic trees to show evolutionary relationships.