Question

An area (A) occupied by a species splits into two areas (B and C). One of these areas (B) then splits into two areas (D and E). The other of the areas (C) splits into two areas (F and G); area F then splits into two areas (H and I), and area G then splits into two areas (J and K). Draw a series of maps that describe vicariance through time, labeling each of the areas by letter. Then draw the phylogeny expected if each vicariance event results in speciation, and appropriately apply the area letters to the nodes and terminal taxa of the phylogeny

Answer 1

A process vicariance through which the geographical range of a single taxon, or a complete biota, is divided into discontinuous populations by the production of an extrinsic barrier to the gene exchange: i.e., a barrier rising externally to a species.

Different orientation of tree diagrams can show the same information. In Figure 1,the three trees, have similar geography and hence the similar evolutionary assosciations. In every case, the first event of divergence separated the species that arise from species A which arise to tips B and C. Then the species B divide into two species D and E, another species C into F and G, again species G arise to tips J and K and species F into H and I. This means that H,I and J, K have more common ancestor with each other which either common with A or B. Tips C or D are hence more commonly related to each other than either is to tip D or tip E.