The Nature of Science Case Study The evolution of penguins
Many species of bird can swim as well as fly but modern-day penguins are flightless. Scientists think that penguins are the descendants of early birds that roamed the earth over 60 million years ago. Over the course of time some of these birds moved to a new environment where they spent more time in the water than on land. These birds were able to fly but also needed to be able to swim well in order to survive. In this new environment natural selection favoured birds that could swim well over birds that could fly well. With each new generation penguins with smaller wings that were good for swimming became more common. After millions of years of evolution by natural selection none of the descendants of the birds could fly and their wings had become flippers. These descendants of flying birds had become a new species of flightless
Biodiversity The variety of animal and plant species.
The niche of a species consists of its habitat, the way it feeds and how it interacts with its environment and other living organisms in it.
penguins. Evolution by natural selection continued and there are now 18 different species of penguins. Many of these species live in cold climates and have also evolved to have thick layers of body fat to protect them from the cold.
Fig. 8 Penguins have evolved to be good swimmers, with wings becoming flippers over millions of years.
Biodiversity It is estimated that life on Earth began almost 4 billion years ago. According to Darwin’s theory the conditions for natural selection to occur have existed throughout that time. This has resulted in the evolution of millions of different species. Each species evolved unique characteristics that allowed it to survive in its own particular niche. The niche of a species consists of its habitat, the way it feeds and how it interacts with its environment, including the other living organisms in it. There are almost 90 different species of deer worldwide. Three of them live in Ireland. All
three species have slightly different diets and are all found in slightly different habitats. Each of these species is said to have its own niche.
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Fig. 9 Red deer, sika deer and fallow deer are three species of deer that live in Ireland.
