Q34.3-3CC. - Campbell Biology

Question

Redraw Figure 34.2 to show four lineages: cyclostomes, lancelets, gnathostomes, and tunicates. Label the vertebrate common ancestor and circle the lineage that includes humans.

 

Step-by-Step Solution

Answer

Step 1: Phylogeny

The evolutionary history of a species is referred to as phylogeny. It's a hypothetical relationship that compares different species groups. It is generally represented as a phylogenetic tree.

Step 2: Phylogeny of living chordates

Chordates are a group of animals that includes vertebrates like humans. The vertebrates (fishes, amphibians, reptiles, and mammals), cephalochordates (known as amphioxus or lancelets), and tunicates (urochordates) are the three subgroups of living chordates.

Step 3: Phylogeny with four lineages

A phylogeny is made showing the four lineages cyclostomes, lancelets, gnathostomes, and tunicates. Humans belong to gnathostomes that evolved from a common vertebrate ancestor, as shown in the phylogeny.

Gnathosomes circled in the phylogeny are the only clade whose members have jaws.