Investigating Diversity

This lesson covers: 

1. Using observable characteristics to measure genetic diversity
2. Using comparative biochemistry to measure genetic diversity

Using observable characteristics to measure genetic diversity

Traditionally, genetic variation was assessed by examining observable phenotypic traits.

However, this method has its limitations:

• Traits are often polygenic - This means they are influenced by several genes, which makes it challenging to separate the influence of individual genes.
• Environmental factors can alter traits - This leads to variations that are not genetically based.
• Traits may change gradually across a range - Traits not falling into distinct categories makes them difficult to differentiate.

Height in humans is an example of continuous variation where multiple genes contribute to the trait, but environmental factors like nutrition also play a significant role.

Using comparative biochemistry to measure genetic diversity

Comparative biochemistry involves studying the molecular aspects of organisms to uncover genetic diversity, as well as evolutionary relationships.

For instance, DNA sequencing allows direct observation of DNA base sequences, providing a more accurate measure of genetic diversity.

Useful molecules to study evolutionary links:

• Cytochrome c - This is a highly conserved protein involved in cellular respiration, so slight changes can help identify evolutionary links.
• Ribosomal RNA - This integral molecule to protein synthesis changes slowly, making it useful for showing connections between species that diverged long ago.
• Nuclear, mitochondrial, or chloroplast DNA - Species that are more closely related will have more similar DNA sequences.
• Messenger RNA - Base sequences of mRNA are complementary to DNA so can assess DNA diversity.
• Amino acids - If they are closely related evolutionarily, two species have more similar amino acid sequences because they are determined by mRNA and DNA.