EVOLUTION

Evolution

• We are going to find out about;

– How life on Earth may have begun and is evolving

– How scientists developed an explanation for evolution

– How specific animals evolved

• „Analogie und Homologie“

The Variety of Life

• It is often easy to spot the differences between living things.

• But there are also lots of similaries; • Most living things use DAN to

pass on information. • Human skin cells and cells in a

butterfly use the same chemical reaction to make pigment.

Classifiaction

• Scientists use the similarities between living things to put them into groups.

What makes a species?

• Scientists define a species as a group of organisms so similar that: – They can breed together – Their off spring can also

breed (fertile)

• Example; • Horses and donkeys can

breed together to produce offspring – mules. But mules are infertile.

• So – horses and donkeys are different species.

Variation • Variation in a species is very important (we‘ll learn

more about this later). • There are genetic (male and female) and

environmental variations (short and long hair). • Some variations like skin colour can be both genetic

and environmental variations.

The evidence for evolution

• Most scientists agree that life on Earth started from a few simple organisms.

• This explains why there are so many smilarities amongst living things. • These simple organisms evolved over time to produce all the living things

we have on Earth today. • Complete the worksheet „Die Erdzeitalter “ – use page 18/19 as reference.

Evidence for evolution?

• Fossils are made from dead bodies of living things. Most fossils found are from extinct species.

• Conditions have to be just right for fossils to develop. There are gaps in the fossil record.

• Fossils help us to develop a picture of how evolution may have happened.

Brückenformen – Transitional Form

• Two years after Charles Darwin published his work on evolution the first fossil of an „Urvogel / Archaeopteryx“ was discovered.

• The Archaeopteryx lived in the late Jurrasic period, 150 million years ago. • It has features similar to both the modern bird and also the

reptile/dinosaur speices • This is why it was regarded as a transitional form • It is used as proof for evolution and Darwin‘s theory of evolution.

Complete worksheet „Kriechtier,

Archaeoperyx und Vogel in Vergleich“ Use page 112/113

Evidence for change now....

• Evolution didn‘t just happen during the prehistoric times. Evolution is ongoing. 2 different types.....

• Selective breeding: – Choosing organisms with certain characterists and

mating them to try to produce off spring that have the desired characteristics.

– E.g Labradoodle – Producing disease-resistant wheat by crossbreeding

wheat plants with disease resistance and wheat plants with a high yield.

• Natural Selection – When certain variants of a species are better suited to

their environment and are more likely to survive and breed.

– E.g. head lice in the UK. A variety were resistant to the poison and survived. UK now has a form of „super lice“

Natural Selection

• Read the articles of natural selection in giraffes and complete the worksheet.

– „Warum haben die Giraffen einen langen Hals“

– Use page 116 to help

Charles Darwin

• Most scientist now agree that evolution happens, but this wasn‘t always well accepted. Charles Darwin and his ideas were a break through in persuading people about evolution.

• Darwin explains how Evolution could happen through „natural selection“

• Darwin was always interested in plants and animals. At the age of 22 he set out on a 5 year journey aroung the World on the „Beagle“.

Charles Darwin – Journey of the Beagle

• The Beagle stopped at many places. At each stop Darwin looked at different species and made lots of observations.

• At the Galapagos islands he noticed variation in the wildlife.

• He noticed key differences in the finches in his observations.

• The finch varieties had different shaped beaks. The beaks were adapted to eat the food available of the different islands.

Complete worksheet on Charles Darwin. Use page 116