A change in a kind of organism over timeCharles Darwin (1809-1882)

Wasn’t the first person to recognize that evolution has happened and is happening

Was the first to propose a feasible mechanism for evolution. It is called descent with modification .

Scientists have found large amounts of evidence to support Darwin’s views of evolution.

Theory:

Theory: well-tested explanation that unifies a broad range of observations

Remember: The word “theory” in everyday language and in scientific language means very different things.In everyday language, people use the word

theory to mean a hypothesis or an educated guess.

In science, people use the word theory to represent an idea that is strongly supported by evidence. It is accepted and used to explain many observations.

Cell theory: all living things are made up of one or more cells, etc.

Atomic theory: all matter is made up of one or more atom, etc.

Darwin published his book, On the Origin of Species by Means of Natural Selection, in 1859. In it, he outlines the major points of his theory.

Darwin published his book, On the Origin of Species by Means of Natural Selection, in 1859. In it, he outlines the major points of his theory.

Natural selection:

Darwin published his book, On the Origin of Species by Means of Natural Selection, in 1859. In it, he outlines the major points of his theory.

Natural selection: Process by which individuals that are better suited to their environment to survive and reproduce most successfully; also called survival of the fittest

Darwin published his book, On the Origin of Species by Means of Natural Selection, in 1859. In it, he outlines the major points of his theory.

Natural selection: Process by which individuals that are better suited to their environment to survive and reproduce most successfully; also called survival of the fittest

You can remember the main points behind natural selection as VISTA

Variation:

Variation: Members of the same population have different characteristics; no organism is exactly the same as another

Variation: Members of the same population have different characteristics; no organism is exactly the same as another

Inheritance:

Variation: Members of the same population have different characteristics; no organism is exactly the same as another

Inheritance: Certain traits can be passed down through generations

Variation: Members of the same population have different characteristics; no organism is exactly the same as another

Inheritance: Certain traits can be passed down through generations

We know that heritable variation is due to genes. Variation in genetic material is due to:

Variation: Members of the same population have different characteristics; no organism is exactly the same as another

Inheritance: Certain traits can be passed down through generationsWe know that heritable variation is due to genes.

Variation in genetic material is due to:Mutations: Sexual reproduction:

Variation: Members of the same population have different characteristics; no organism is exactly the same as another

Inheritance: Certain traits can be passed down through generationsWe know that heritable variation is due to genes.

Variation in genetic material is due to:Mutations: changes in a DNA sequence that affect

genetic informationSexual reproduction:

Variation: Members of the same population have different characteristics; no organism is exactly the same as another

Inheritance: Certain traits can be passed down through generationsWe know that heritable variation is due to genes.

Variation in genetic material is due to:Mutations: changes in a DNA sequence that

affect genetic informationSexual reproduction: process by which cells

from two different parents unite to produce the first cell of a new organism

Survival and reproduction:

Survival and reproduction: Organisms must survive in their environment and successfully mate and reproduce with another member of their species

Survival and reproduction: Organisms must survive in their environment and successfully mate and reproduce with another member of their speciesNatural selection is often referred

to as “survival of the fittest.” What is “fitness?”

Survival and reproduction: Organisms must survive in their environment and successfully mate and reproduce with another member of their speciesNatural selection is often referred to as

“survival of the fittest.” What is “fitness?” Certain characteristics and behaviors

make an organism more likely to survive in a given environment when competing with other members of the population

Time:

Time: Generation after generation, individuals continue to compete to survive and produce offspring, and not all are successful

Time: Generation after generation, individuals continue to compete to survive and produce offspring, and not all are successful

Adaptation:

Time: Generation after generation, individuals continue to compete to survive and produce offspring, and not all are successful

Adaptation: any inherited characteristic that increases an organism’s chance of survival

Time: Generation after generation, individuals continue to compete to survive and produce offspring, and not all are successful

Adaptation: any inherited characteristic that increases an organism’s chance of survivalDarwin referred to this accumulation of

adaptations over time as

Time: Generation after generation, individuals continue to compete to survive and produce offspring, and not all are successful

Adaptation: any inherited characteristic that increases an organism’s chance of survivalDarwin referred to this accumulation of

adaptations over time as natural selection

Time: Generation after generation, individuals continue to compete to survive and produce offspring, and not all are successful

Adaptation: any inherited characteristic that increases an organism’s chance of survivalDarwin referred to this accumulation of

adaptations over time as natural selectionHe believed that descent with modification

had created the great diversity of life

V: Giraffes had different neck lengthsI: The lengths of the necks could be passed on from

one generation to the nextS: Giraffes with longer necks were able to get more

food and so they could survive to reproduce

T: Gradually, each succeeding generation of giraffes had longer necks because the longer necked giraffes were surviving more often than the short necked giraffes

A: Overall, the populations of giraffes all had long necks.

Voyage of the BeagleAfter graduating from college, Darwin

took a job as the naturalist on the H.M.S. Beagle, a boat that was traveling around the world with the purpose of creating better maps.

Darwin collected living organisms, fossils and other evidence of living things every time the ship landed in a new area.

What did Darwin observe on his travels?

What did Darwin observe on his travels?Fossils:

What did Darwin observe on his travels?Fossils: preserved remains or evidence

of an ancient organism

What did Darwin observe on his travels?Fossils: preserved remains or evidence

of an ancient organism

Darwin wondered Why had so many of these species disappeared? How were they related to living species?

What did Darwin observe on his travels?Fossils: preserved remains or evidence

of an ancient organism

Darwin wondered Why had so many of these species disappeared? How were they related to living species?

What did Darwin observe on his travels?

What did Darwin observe on his travels?Organisms on Islands

What did Darwin observe on his travels?Organisms on Islands

Studied the finches and giant tortoises of the Galapagos Islands

What did Darwin observe on his travels?Organisms on Islands

Studied the finches and giant tortoises of the Galapagos Islands

Found that organisms on the islands were similar to those on the mainland, but had slightly different characteristics that allowed them to survive in their new habitats

What did Darwin observe on his travels?Organisms on Islands

Studied the finches and giant tortoises of the Galapagos Islands

Found that organisms on the islands were similar to those on the mainland, but had slightly different characteristics that allowed them to survive in their new habitats

Darwin wondered Why was there so much diversity? Is there a way that leads to such a variety of ways of reproducing?

What did Darwin observe on his travels?

What did Darwin observe on his travels?

Lamarck’s Theory of Evolution Through the Inheritance of Acquired CharacteristicsUse and disuse:

Organisms can alter the size or shape of their body by using their bodies in new ways

Parts of their body would decrease in size if they weren’t used, and over the course of generations, completely disappear

Lamarck’s Theory of Evolution Through the Inheritance of Acquired CharacteristicsInheritance of acquired characteristics

Acquired characteristics are passed down to future generations

If you spent a lot of time lifting weights and building muscles, your children will be born with big muscles

Lamarck’s Theory of Evolution Through the Inheritance of Acquired CharacteristicsExample: Giraffe’s long neck

Giraffe’s necks got longer because they would stretch to reach the highest leaves

Their offspring were born with these stretched necks, and continued to stretch them even longer, giving birth to offspring with even longer necks

Does Lamarck’s theory of evolution work?

Lamarck was wrong, but we can learn from his mistakes.

Acquired traits aren’t inherited.Only traits determined by our genes

are inherited.During Darwin’s time people did not

know how traits were inherited. They had no knowledge of genes and DNA.

Darwin wanted to ensure that he had as much research as possible to support his ideas.1. Studied the diversity of barnacles: collected

specimens from all he could find to study their differences amongst the populations

2. Bred Fancy Pigeons: bred pigeons for a period of time to examine their different beaks and how they were inherited

Artificial Selection: selection by humans for breeding of useful traits from the natural variation among different organisms

Fossil RecordDifferent layers of rock are formed at different times during Earth’s history

The deeper the rock, the older it isFossils found in deeper layers are older

Can be used to see how organisms have changed over time

BiogeographyDifferent animals found on different continents but in similar climates and environments demonstrated similar behaviors or had similar anatomy

Comparative AnatomyHomologous Structures: structures that have different mature forms but develop from the same embryonic tissues

Examples: Human arm, cat leg, whale fin, bat wing

Vestigial Organs: Organs that are reduced in size and serve little or no function

Examples: Traces of leg bones in snakes, human appendix

Comparative EmbryologyThe early stages of many animals with backbones are very similar (be careful Not identical!)

Molecular BiologyAll living organisms are made of the same basic materials

Proteins, nucleic acids, carbohydrates, lipids

It is incorrect to think of evolution by natural selection as a process that takes a long time to see occurring. We can see changes in groups of organisms from generation to generation. Here are some examples of evolution that is occurring around us.

Antibiotics: drugs intended to kill or interfere with the growth of bacteria

Used to be known as “magic bullets” or “wonder drugs” because they were so effective

Mutations have resulted in antibiotic resistant bacteria that can survive the medication

If they survive, they reproduce more antibiotic resistant bacteria

Bacteria reproduce really quickly so once powerful antibiotics are now sometimes useless.

We use pesticides to keep insects from destroying crops

Mutations result in insects that are resistant or immune to certain pesticides

Pesticide resistant insects then survive and reproduce, resulting in more pesticide resistant insects.