Chapter 15, Problem 37A

Summary Introduction

To explain:

The role of natural selection in producing a bird species with a woodpecker like beak

Introduction: Natural selection is the mechanism Darwin proposed to explain evolution. Through natural selection, traits that allow individuals to have most offspring in a given environment tend to increase in the population over time.

Answer to Problem 37A

Natural selection helped in producing a bird species with a woodpecker like beak. Birds with long beaks had a selective advantage over birds with short beaks as they could feed on insects living under the bark of trees. These birds survived and reproduced when other means of food was not available to ancient birds. Long beaked birds passed on their genes to their offspring and soon a population of birds with woodpecker like beaks evolved.

Explanation of Solution

Darwin proposed that there are some genetic variations in organisms and these variations are heritable.

Charles Darwin gave a theory of natural selection. He argued that if enough time is given, natural selection could modify a population to produce new species. Natural selection is based on ideas of excess reproduction, variation, inheritance, and advantages of certain traits in certain environments.

A woodpecker with its feet, tail, beak and tongue is well adapted to catch insects under the bark of trees. The mechanism that led to evolution of woodpecker is natural selection. Let us imagine a population of ancient birds that lived in a forest. These birds fed on seeds and plants. Due to some changes in the environment, the seeds became scarce and so less food was available to birds. The birds that were dependent on plants and seeds started to die out. Suppose the only available food was the insects that lived deep in tissues of the trees. The birds that had slightly longer beaks could find such insects under the bark of trees and fed on them. These long beaked birds were able to survive. Such birds got selected over time and gradually a new species of birds with woodpecker like beaks evolved.