3/20/2015

1

Chapter 16

Diversity: The differences and variety between living organisms

Evolution: A gradual change in phenotypes in a population that results in individuals with improved reproductive success. (changes arising through mutation)

Evolution is the scientific explanation (theory) to the vast diversity of life.

Theory: A well-supported, testable explanation of phenomena in the natural world.

Indiana Standards: B.1.31, B.1.32

3/20/2015

2

3/20/2015

3

3/20/2015

4

• Believe that the earth is only

5,700 to 10,000 years old.

• Intelligent designer (Creator

deity, God) created the earth in

six 24hr periods.

• Believe that all species alive

today survived a great flood.

• Belief that the earth is very old

(billions of years)

• Intelligent designer created the

earth and living things

3/20/2015

5

• A form of evolution in which an

intelligent designer uses

evolution to bring about the

universe according to his plan.

• This is the current view of the

Catholic Church.

• An intelligent designer created

the universe at the time of the

Big Bang and let the universe

evolve all by itself according to

natural laws.

3/20/2015

6

• Materialistic evolution is the

position of acceptance of

biological evolution, combined

with the position that the

supernatural does not exist

Diversity: The differences and variety between living organisms

Evolution: A gradual change in phenotypes in a population that results in individuals with improved reproductive success.

Evolution is the scientific explanation (theory) to the vast diversity of life.

Theory: A well-supported, testable explanation of phenomena in the natural world.

Indiana Standards: B.1.31, B.1.32

3/20/2015

7

Charles Darwin: Contributed to the theory of evolution more than anyone.

In 1831, Darwin set sail on a ship, the H.M.S. Beagle, from England on a voyage around the world.

On this trip he made many observations and collected data which helped him form his hypothesis on evolution.

3/20/2015

8

Darwin noticed three distinctive patterns of biological diversity as he traveled the world:

1. Species vary globally

2. Species vary locally

3. Species vary over time

Darwin was surprised by the amount of diversity he observed while on his voyage

He noticed that all the plants and animals he observed were well suited to their environment.

Some animals were only found on certain continents (No rabbits in Australia, no kangaroos in England).

Fossils he collected looked similar, but not identical to the animals alive today.

3/20/2015

9

3/20/2015

10

Glyptodont

Armadillo

This small group of islands located west of South America influenced Darwin more than any other stop on his voyage.

Each island in the group has its own unique characteristics (climate, vegetation).

He was intrigued by the diversity found among land tortoises on each island.

He noted that the shape of a tortoise’s shell could be used to identify which island it inhabited.

3/20/2015

11

3/20/2015

12

Charles Darwin accumulated a tremendous collection of facts to support the theory of evolution by natural selection.

One of his difficulties in demonstrating the theory, however, was the lack of an example of evolution over a short period of time, which could be observed as it was taking place in nature.

Although Darwin was unaware of it, remarkable examples of evolution, which might have helped to persuade people of his theory, were in the countryside of his native England.

One such example is the evolution of the peppered moth Biston betularia.

3/20/2015

13

Darwin named his mechanism for evolution “Natural Selection” because of its similarities to artificial selection.

Natural Selection is the process by which organisms most suited to their environment survive and leave more offspring.

Any heritable characteristic that increases an organisms ability to survive and reproduce in its environment is called an adaptation.

“Survival of the Fittest” Fitness describes how well an organism can survive and reproduce in its environment.

3/20/2015

14

Structures that are shared by related species that have been inherited from a common ancestor are called homologous structures.

Evolutionary theory explains the existence of homologous structures adapted to different purposes as the result of descent with modification from a common ancestor.

3/20/2015

15

Body parts that share common function, but not structure are called analogous structures.

The wing of a bee and the wing of a bird are analogous structures.

3/20/2015

16

Vestigial structures are inherited from ancestors but have lost much or all of their original function due to different selection pressures acting on the descendent.

3/20/2015

17

3/20/2015

18

Similar patterns of embryological development provide further evidence that organisms have descended from a common ancestor.

3/20/2015

19

http://www.google.com/url?sa=i&rct=j&q=embryo+similarities&source=images&cd=&cad=rja&docid=IjyplRXSpZY67M&tbnid=FBMRwd4njclXPM:&ved=0CAUQjRw&url=http://home.honolulu.hawaii.edu/~pine/book1qts/embryo-compare.html&ei=7Z-HUYrAJImOygGm1oGoBg&bvm=bv.45960087,d.aWc&psig=AFQjCNGMFvcO18gAH0CBIvaVQFwDaSuFEw&ust=1367929192412227http://www.google.com/url?sa=i&rct=j&q=embryo+similarities&source=images&cd=&cad=rja&docid=UgvvE7Aq1ijaGM&tbnid=eaCcVVFXMkGH4M:&ved=0CAUQjRw&url=http://scienceblogs.com/pharyngula/2007/05/08/basics-the-pharyngula-stage/&ei=06CHUfWXCIjkywGa64GgCQ&bvm=bv.45960087,d.aWc&psig=AFQjCNGMFvcO18gAH0CBIvaVQFwDaSuFEw&ust=1367929192412227

3/20/2015

20

Lamarck’s Evolution Hypothesis

Lamarck stated that by selective use or disuse of organs, organisms gained or lost certain traits during their lifetime.

These traits were then passed on to their

offspring (genetic inheritance).

(1744-1829)

3/20/2015

21

Lamarck’s Evolution Hypothesis

Tendency Toward Perfection: Constant change is needed to survive in the environment.

Organisms have a tendency toward complexity and perfection

Use and Disuse: Animals can change their organs based on using their bodies different ways. (wings in birds)

Inheritance of Acquired Traits: Lamarck thought that acquired traits could be inherited.

Lamarck, like Darwin, did not know how traits were inherited. Mendel’s work was around 30 years after Lamarck published his hypotheses

Lamarck’s Evolution Hypothesis

Today we know that Lamarck’s hypotheses were incorrect in several ways.

Evolution does not mean that a species becomes “better” over time.

Acquired traits by individuals during their lifetime cannot be passed on to offspring (strength).

Although his theories were wrong, his work paved the way for later biologists like Darwin.

3/20/2015

22

Population Growth

Thomas Malthus (1766-1834): Published a book noting how babies were being born faster than people were dying.

He stated that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone.

Population Growth

War, famine, and disease were the only forces working against this growth.

When Darwin read his work, he realized that this applied even more strongly to plant and animal populations because the reproduce even faster than people.

3/20/2015

23

3/20/2015

24

Evidence of Evolution

There are five key points to understand in the evidence of evolution:

Biogeography

The Age of Earth and Fossils

Comparing Anatomy and Embryology

Genetics and Molecular Biology

Testing Natural Selection

3/20/2015

25

Biogeography

Patterns in the distribution of living and fossil species tell us how modern organisms evolved from their ancestors.

Closely related by different.

Distantly related but similar.

The Age of Earth and Fossils

Evolution takes a long time.

If life has evolved, the Earth must be very old.

Radioactivity is used to establish the age of certain rocks and fossils.

The data suggests Earth is 4.5 Billion years old, supporting Darwin’s theory.

3/20/2015

26

The Age of Earth and Fossils

Many recently discovered fossils form a series that trace the evolution of modern species from extinct ancestors.

3/20/2015

27

Anatomy and Embryology

What do certain structures and similarities in embryonic development suggest about the process of evolutionary change?

Homologous Structures

Homologous structures are structures shared by related species that have been inherited from a common ancestor.

Same form, different function

3/20/2015

28

Analogous Structures

Body parts that share common function, but not structure, are called analogous structures.

Same function, different form

3/20/2015

29

Vestigial Structures

Vestigial structures are inherited from ancestors but have lost much or all of their original function due to different selection pressures acting on the descendants.

Loss of function

3/20/2015

30

3/20/2015

31

Genetic and Molecular Biology

At the molecular level, the universal genetic code and homologous molecules provide evidence of common descent.

The genetic code is nearly identical in almost all organisms, providing powerful evidence that all organisms evolved from common ancestors.

Testing Natural Selection

Peter and Rosemary Grant of Princeton University tested Darwin’s hypothesis of Natural Selection in Galapagos finches.

Beak size and shape evolves

Differences in beak size and shape must produce differences in fitness.

They documented that natural selection takes place in wild finch populations frequently, and sometimes rapidly.