Gene trees are evolutionary trees that show the evolutionary lineages of specific genes separate from organisms. Below is a gene tree for the genes that code for opsins in humans. Opsins are the light sensitive proteins in the eyes. Humans have four opsins that are active in visual perception: long-wavelength sensitive (LWS or red-sensitive), medium-wavelength sensitive (MWS or green sensitive), short-wavelength sensitive (SWS or blue sensitive), and rhodopsin (RH, not color sensitive). Which mutational process would be most likely to create a gene tree like this?

• A. Point mutations.
• B. Deletion events.
• C. Horizontal gene transfer.
• D. Gene duplication events.

Answer: (D)

Verified step by step guidance

1. Begin by understanding the concept of a gene tree. A gene tree represents the evolutionary relationships between different genes, showing how they have diverged from common ancestral genes over time.
2. Examine the gene tree provided. It shows the evolutionary relationships between four opsins in humans: LWS (red-sensitive), MWS (green-sensitive), SWS (blue-sensitive), and RH (not color-sensitive). Notice how these genes are branched, indicating divergence from a common ancestor.
3. Consider the mutational processes listed: point mutations, deletion events, horizontal gene transfer, and gene duplication events. Point mutations and deletion events typically alter existing genes but do not create new gene copies. Horizontal gene transfer involves the transfer of genes between organisms, not within a single organism's lineage.
4. Focus on gene duplication events. Gene duplication is a process where a gene is copied in the genome, resulting in multiple copies of the same gene. These copies can then evolve independently, leading to the diversification of gene functions, as seen in the opsins.
5. Conclude that gene duplication events are the most likely process to create a gene tree like the one shown. This process allows for the creation of multiple opsins from a single ancestral gene, each evolving to detect different wavelengths of light.