Charles Darwin Put forward a theory in 1856 He knew nothing about: Genes Chromosomes Mutations

He sailed around the world, on a ship called the Beagle. He was employed as a Naturalist. His job was to record new animals & plants. He was also interested in Geology.

His most famous observations were on Finches. As he sailed around the tip of South America he made drawings of these birds. Sailing up the W coast of South America he continued to observe these birds.

Darwin realised these Finches migrated from N to S America. Darwin travels took him up to Ecuador and on to the Galapagos Islands. Throughout this time he continued to observed these Finches.

These Finches were similar to those Darwin had observed in England. It was not until Darwin reached the Galapagos Islands that he noticed variation in these birds.

Darwin sailed round these islands. He noticed the Finches had different beak shapes.

SEED EATER BUD EATER LARGE INSECT EATER EATS BUGS FROM BARK INSECT EATER LEAF EATER

Finches were blown off course by the Humboldt Current. Populations of Finches landed on different islands, with different dominant food sources. Only those that were suited to life on that island survived.

On Darwin’s return to England he noted 4 key observations: All living organisms posses the ability to overproduce. 1 In spite of this overproduction, animal and plant numbers remain constant. 2 Members of the same species show variation. 3 Characteristics are passed on from generation to generation 4

Darwin deduced from his observations that…………… ‘ organisms are involved in a struggle for existence, so only those most adapted to their environment survive’ This hypothesis was coined EVOLUTION by NATURAL SELECTION

4 key points about Natural Selection Individuals within a species show variation Individuals within a species compete for resources Only the individuals best adapted to the environment will survive. Only the survivors will pass on their genes

2. Seed eating Finches migrate the length of the Americas. 1. Finches get blown off course by the Humboldt Current. 5. Populations of Finches colonise the various Galapagos islands. 6.Quickly large numbers of Finches die, due to starvation. 8. Only Finches that can access the dominant food survive. 9.The Finches that survive, do so because their beaks are well adapted to the dominant food source. 3. Only those that survive can go on to breed. 4. Over generations, beak shape will gradually change. 7. This is an example of Natural Selection

2. Seed eating Finches migrate the length of the Americas. 1. Finches get blown off course by the Humboldt Current. 5. Populations of Finches colonise the various Galapagos islands. 6.Quickly large numbers of Finches die, due to starvation. 8. Only Finches that can access the dominant food survive. 9.The Finches that survive, do so because their beaks are well adapted to the dominant food source. 3. Only those that survive can go on to breed. 4. Over generations, beak shape will gradually change. 7. This is an example of Natural Selection

SURVIVAL of the FITTEST Giraffes with short necks will not survive or reproduce as a result of an inability to feed on fresh tree growth, which is often high up. Over time only those Giraffes with long necks (the desired characteristic) will survive to reproduce. These are the desired parents, who will pass their long neck genes on to the next generation, who will in turn survive and reproduce. This is called survival of the fittest and is an example of natural selection.

EVOLUTION of COMPLEX ORGANS Complex organs arise by evolving very slowly, like breaking into a safe! Evolution solves complex problems one step at a time.

EVOLUTION of COMPLEX ORGANS Looking at different eyes in nature shows us how complex organs can develop. E.G. Molluscs

SEED EATER BUD EATER LARGE INSECT EATER EATS BUGS FROM BARK INSECT EATER LEAF EATER