Charles Darwin – the “Father of Evolution” NOTES – Evolution Charles Darwin – the “Father of Evolution”

The Diversity of Life Millions of different types of organisms live on the earth today They differ in structures, behaviors, and genes but are also alike in many ways Where did all of these organisms come from? How do scientists explain the differences and similarities in living things?

The Work of Darwin From 1831 to 1836, British scientist Charles Darwin sailed around the world as a ship’s naturalist He observed many living things and formed ideas about evolution In 1859, Darwin published On the Origin of Species, a book in which he explained his ideas about evolution and natural selection Darwin’s work formed the basis for the study of evolution and his ideas are still influential today

What is a species? Species – a group of organisms that are physically similar and can produce offspring that are then able to reproduce themselves EX. The Eastern Grey Squirrel (1 of about 280 squirrel species)

What is a species? The goal of a species is to survive long enough to reproduce a lot A species that does not reproduce enough is in danger of going extinct (disappearing from the Earth forever) The traits of a particular species are determined by the genes of that species

What is a species? Population – a group of organisms of the same species living in an area Gene Pool – the combination of all the versions (alleles) of all the genes in a population of any species Many versions of genes = larger gene pool = more difference between individuals Few versions of genes = smaller gene pool = less difference between individuals

A Population of Squirrels

Where did all the species on the Earth today come from? Remember 2 important statements from the cell theory: All living things are made of one or more cells All cells come from other cells This means that all cells must have come from some group of original cells in the distant past

How can different species come from the same cells? The simple answer: since the appearance of the first prokaryotic cells about 3.5 billion years ago, some of those cells have changed in enough different ways that they now form all the different living species The branch of biology known as evolution deals with this question

What is evolution? Evolution – Change in species over time (changes in the gene pool of a species lead to changes in the overall traits of the species) This sometimes leads to the formation of new species (speciation) Evolution says that species can change over many generations of reproduction Evolution happens to a species NOT to individual organisms

What is the main idea of evolution? The main idea of evolution is that all species are descended from the first living organisms, which were prokaryotic bacteria Species alive today share common ancestors some time in the past The more closely related 2 species are, the more recent their common ancestor existed Common ancestor – a species that existed in the past that split into 2 groups which eventually became 2 different species

What is the main idea of evolution?

What is the main idea of evolution?

What is the main idea of evolution?

What is the main idea of evolution?

What is the main idea of evolution?

What is the main idea of evolution?

What is the main idea of evolution?

A few steps in the history of species… mya = million years ago (1,000,000) 5 mya – common ancestor of humans and chimpanzees 70 mya – common ancestor of primates (humans, apes, monkeys) and grazing animals (horses, etc.) 250 mya – common ancestor of mammals and reptiles 450 mya – common ancestor of vertebrates (animals with a backbone) and invertebrates (animals without a backbone) 1,000 mya – common ancestor of animals and plants 3,500 mya – common ancestor of all life, the first prokaryotic cells

A few steps in the history of species… 4,500 mya – the formation of the Earth 13,000 mya – the formation of the Universe If you compare the history of life on Earth to one year, the first bacteria arrive at 12:00 AM on January 1st and the first humans appear at 11:59 PM on December 31st – 364 days, 23 hours and 59 minutes later – We haven’t been here very long!