Chapter 17, Problem 12A

Solution

To analyze:

The representation given in the figure.

Introduction:

Different models were proposed to compare the similarities and differences and to ease the understanding of evolutionary relations and comparisons and also to understand the relations between generations such as molecular clocks, pedigree, phylogenetic tree and cladogram. These all are similar but are slightly different from each other.

The diagram in the given figure represents molecular clock.

A molecular clock is a model that is used to compare DNA sequences from two difference species to estimate how long species have been evolving since they diverged from common ancestor.Molecular clocks are used to compare the DNA sequences or amino-acid sequences of genes that are shared by different species. The differences between the genes indicates the presence of mutations, the more mutations that have accumulated, the more time have been passed since divergence.

A cladogram is a branching diagram that represents a proposed phylogeny or evolutionary history of a species or group. A cladogram can be simple, relating only two or three groups of organisms, or it can be massively complex and comprise all the known forms of life.

A pedigree is a diagram that represents the biological relationships between an organism and its ancestors. It shows the genotypes and phenotypes of an organism and its ancestors.

A phylogenetic tree is a figure that signifies evolutionary relationships among organisms. Phylogenetic trees are suppositions, not conclusive facts. The pattern of branching in a phylogenetic tree reflects how species or other groups evolved from a sequence of common ancestors.