Selection

Introduction

• Selection is a fundamental concept in biology that refers to the process by which certain traits or characteristics become more or less common in a population over time.
• It is a key mechanism in the theory of evolution proposed by Charles Darwin.

Example: Peppered Moths

• Peppered moths are a classic example of natural selection in action.
• These moths come in various colours, with light-coloured moths having DNA sequences that code for less melanin (pigment) and dark moths having DNA sequences that code for more melanin

Natural Selection in Peppered Moths

• During the 19th century, industrial pollution killed lichens on trees, and soot deposits darkened the tree bark.
• Light-coloured moths, which previously camouflaged against light lichens, became more visible to predators (birds) on the darkened bark.
• As a result, light moths were selectively preyed upon, reducing their chances of survival and reproduction.

Selective Advantage

• Dark moths, with better camouflage on the darkened bark, had a higher chance of surviving and reproducing.
• Dark moths passed on the DNA sequences that coded for more melanin to their offspring.
• Over time, the frequency of these DNA sequences increased in the population, leading to a higher proportion of dark moths.

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Selection

Summary

• Selection is a fundamental biological process that drives evolutionary changes in populations.
• The example of peppered moths illustrates how environmental changes can lead to the selection of specific traits, resulting in observable shifts in a population's characteristics over time.