Concept explainers
- a. In this hypothetical phylogenetic tree, which number represents the common ancestor of all the taxa?
- b. Which letter represents the basal taxon?
- c. Which of the terminal taxa (A-F) are sister taxa?
a.
To identify: The number that represents the common ancestor of all taxa in the hypothetical phylogenetic tree.
Introduction: The phylogenetic tree is a branching diagram that shows the pattern of evolutionary descent. It paves the way to know the evolutionary relationship between different species or groups of organisms based on their genetical and physical characteristics.
Explanation of Solution
The phylogenetic tree is a branching diagram that shows the pattern of evolutionary descent. In a rooted phylogenetic tree, branching represents the evolutionary relationships. The branch point is the point where a single lineage is evolved into a distinct one. The lowest or the common ancestor is the one that serves as a root for all taxa in the phylogenetic tree. Number “1” serves as a common ancestor for all taxa in the given hypothetical phylogenetic tree.
b.
To determine: The letter that represents the basal taxon.
Introduction: The phylogenetic tree shows the evolutionary pathways and connections among different organisms.
Explanation of Solution
The phylogenetic tree is used to show the pattern of evolutionary descent of different organisms. The dichotomous branch point in the phylogenetic tree represents the divergence of two taxa from a common ancestor. A basal taxon is the one that is diverged early from its ancestor in the evolutionary history of a group. In the given phylogenetic tree, letter “A” represents the basal taxon because it has diverged early from its ancestor.
c.
To determine: The sister taxa of the terminal taxa (A-F).
Introduction: The phylogenetic tree depicts the lines of evolutionary descent of different organisms from a common ancestor. It helps in the study of evolutionary history of different organisms.
Explanation of Solution
A phylogenetic tree depicts the branching history of common ancestry. In the phylogenetic tree, branch point represents the divergence of two taxa from a common ancestor. These two diverging taxa are the closest relatives of each other and known as a sister taxa. In the given phylogenetic tree, letters B and C and letters D and E represent the sister taxa of the terminal taxa (A-F), as they are diverge from a common ancestor.
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