LO 3 Biological World strand LO 9 Nature of Science strand
Contents
14.1 The diversity of life . . . . . 148 14.2 Natural selection . . . . . . 150 14.3 Natural selection and evolution within a species . . . . . . 151
Why it matters
Evolution is responsible for the great range of living things on our planet. Understanding evolution helps us to understand the importance of biodiversity. In medicine, understanding evolution also helps us to understand the history of hereditary disease and the way disease-causing organisms are constantly changing. Evolution helps us to understand our place as humans among the wider world of living organisms.
14.1 The diversity of life
Species A group of
organisms which have similar characteristics and which can breed with each other.
Evolution The process of change in the general
characteristics of a species over a long period of time.
When living things reproduce, they create more of their own species. Offspring are similar but not identical to their parents. Over long periods of time the general characteristics of a species may change. For example, by looking at fossils of horses from different times in the past, scientists have concluded that some of the general characteristics of the horse species have changed. The way that species change over long periods of time is called evolution.
Fig. 1 Millions of different species live on Earth.
There are millions of different species living on our planet today. Nobody knows exactly how many different kinds of living things there are. Scientists have discovered nearly 200 different species of monkey and over 350,000 different species of beetle. In Ireland alone there are nearly 600 different species of seaweed.
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Fig. 2 Over 350,000 species of beetle have been discovered.
