Chapter 14, Problem 13PS

Summary Introduction

To explain:

The reason that why the hybrid species Tragopogon mirus of Tragopogon dubius and Tragopogon porrifolius has never been found in Europe even when both these species are very common there.

Introduction:

The process of speciation may occur due to reproductive isolation by which the mating differences or geographical barriers lead to the formation of new species. Reproductive isolation is achieved through the reproductive barriers which are the evolutionary mechanism or behaviors that prevent organism of a different species from breeding.

There are two types of reproductive barriers: Prezygotic barrier prevents the fertilization between species and postzygotic barrier prevents the maturation of hybrid zygote formed by the mating of two different species. Prezygotic barrier involves habitat, mechanical, gametic, behavioral, and temporal isolation. Postzygotic barriers involve reduced viability of the hybrid formed, reduced fertility of the hybrid and the breakdown of the hybrid that result in the sterile generations.