CHAPTER 4

EVOLUTION :HISTORY AND

EVIDENCE

Organic evolution- “ descent with modification “

Population- consist of individuals of the same species

that occupy a given area at the same time.

- share a unique set of genes

PRE- DARWINIAN THEORIES OF CHANGE

EMPEDOCLES ( 495 – 435 B.C. )

- described concepts of change in living organisms over time.

ARISTOTLE ( 384 – 322 B.C. )

- Discovered the principle of nature by analyzing accidental changes or motion.

GEORGES LOUIS LECLERC COMTE BUFFON ( 1707 – 1788)

- Spent many years studying comparative anatomy.

- Believe in a special creation of species and

ERASMUS DARWIN ( 1731 – 1802 )

- Grandfather of Charles Darwin

- Interested in question of origin and change

- Believed in the common ancestry of all organism

JEAN BAPTISTE LAMARCK ( 1744 – 1829 )

- His theory was based on a widely accepted theory of inheritance

- Believed that need was dictated by environmental change and that change involved movement toward perfection

DARWIN’S EARLY YEARS AND HIS JOURNEY

CHARLES ROBERT DARWIN (1809 – 1882 )

- Born on February 12, 1809

- His interest centered around dogs, collecting, and hunting birds

- He entered medical school in Edinburgh, Scotland

- He trained for clergy in the Church of England

VOYAGE OF THE HMS BEAGLE

EARLY DEVELOPMENT OF DARWIN’S IDEAS OF EVOLUTION

Geology Charles Lyell James Hutton

- theory of uniformitarianism- based on the idea that the forces of wind, rain,

rivers, volcanoes and geological uplift shape the earth today.

This book planted two important ideas in Darwin’s mind:

1. The earth could be much older than 6,000 years

2. If the face of the earth changed gradually over long periods, could not living forms also change during that time?

FOSSIL EVIDENCETOXODON THOANTHERIUM

GIANT ARMADILLOSGIANT SLOTH

GALAPAGOS ISLAND

ADAPTIVE RADIATION

- THE FORMATION OF NEW FORMS FROM AN ANCESTRAL SPECIES

THE THEORY OF EVOLUTION BY NATURAL SELECTION

Thomas Malthus- Essay on the Principle of Population

- believed that the human population has the potential to increase geometrically.

Natural Selection1. All organism have a far greater reproductive potential than is ever

realized.

2. Inherited variations exist.

3. Because resources are limited, existence is a constant struggle.

4. Adaptive traits are perpetuated in subsequent generations.

ADAPTATION- occurs when a change in a phenotype increases a

animal’s chance of successful reproduction.

Alfred Russel Wallace- led zoological expediton to the Malay Achipelago

- synthesized a theory of evolution similar to Darwin’s theory of natural selection

MICROEVOLUTION -a change in the frequency of alleles in population over time.

MACROEVOLUTION-large scale changes that result in extinction and the

formation of new species.

EVIDENCE OF MACROEVOLUTIONARY CHANGE1. Patterns of plant and animal distribution

2. Fossils

3. Biochemical molecules

3. Anatomical structures

5. Developmental patterns

BIOGEOGRAPHY-study of the geographic distribution of plants and

animals.

BIOGEOGRAPHERS TRY TO EXPLAIN:

1. How similar group of organisms have dispersed to places separated by seemingly impenetrable barriers.

2. Why plants and animals, separated by geographical barriers are often very different inspite of similar environments.

3. Why oceanic islands often have relatively few, but unique, resident species.

PALEONTOLOGY-study of the fossil record, which provides some of

the most direct evidence for evolution.

FOSSILS- evidence of plants and animals that existed in the past and have become incorporated into the earth’s crust.

Homology- the two different organisms are similar

in structure and function because they share a common ancestry

COMPARATIVE ANATOMY

- the comparative study of the body structures of different species of animals

- the study of the structure of living and fossilize animals and the homologies that indicate evolutionary close relationship

MOLECULAR BIOLOGY- branch of biology that deals with

the molecular basis of biological activity- chiefly concerns with

understanding the interactions between : *the various systems of the cell *DNA, RNA and protein

biosynthesis

DEVELOPMENTAL PATTERNS• Developmental stages of related animals

often retain common features.• Early embryonic stages of vertebrates are

remarkably similar.- many organ system of the vertebrates

also show similar developmental patterns• Differences in adult stages arise as a result of

evolutionary genes that control the onset of developmental stages and the rate at which development occurs.

INTERPRETING THE EVIDENCE: PHYLOGENY AND COMMON DESCENTPhylogeny

- refers to the evolutionary relationships among species

- the depiction of ancestral species and the relationships of modern descendants of a common ancestor