Chapter 14, Problem 1CC

Name the two types of speciation represented by this diagram. For each type, describe how reproductive barriers may develop between the new species.

Summary Introduction

To name: Two types of speciation represented in the diagram and also to describe for each type in what way the reproductive barriers might have developed between the new species.

Concept introduction:

The speciation is an evolutionary process by which new species are formed. It can occur due to geographic, behavioral, anatomical and physiological factors.

The new species formed differ from their ancestors and cannot interbreed with their ancestral species to produce viable offspring.

Explanation of Solution

The type of speciation represented in the diagram (a) is allopatric speciation and in (b) is sympatric speciation.

The allopatric speciation occurs when two populations of a species are separated by a physical barrier such as a mountain or a hill. The gene flow between the two populations is stopped and over the time they become reproductively isolated due to natural selection, mutation or genetic drift.

In sympatric speciation, a new species arise from an ancestral species, while occupying the same geographical region. The two populations become reproductively isolated due to polyploidy, habitat differentiation and sexual selection.

Pictorial representation: Fig. 1 shows two types of speciation: (a) Allopatric speciation (b) Sympatric speciation.

Fig.1: (a) Allopatric speciation (b) Sympatric speciation.