The D.cat is the most closely related organism to the common ancestor. Therefore , D.cat is correct .
The placement of organisms in a phylogenetic tree is determined by analyzing the differences in their DNA sequences, reflecting evolutionary relationships.
In this scenario, the cat is considered more basal because it has the fewest differences (2) from the common ancestor's DNA sequence.
The number of differences indicates the extent of genetic divergence from the common ancestor.
In comparison, the goldfish and rhinoceros each have 3 differences, implying a slightly more distant relationship, while the pigeon shares 2 differences with the cat.
The concept of basality in this context refers to the relative closeness to the root of the phylogenetic tree, suggesting that the cat and pigeon diverged from the common ancestor earlier than the goldfish and rhinoceros.
The phylogenetic tree serves as a visual representation of evolutionary history, where branching points indicate divergence events.
The molecular clock hypothesis is crucial; it posits that the rate of genetic mutations is relatively constant over time.
Consequently, more genetic differences signify a longer period since divergence.
This information aids in constructing a timeline of evolutionary events and contributes to our understanding of the relationships among different species.