EVOLUTIONNatural Selection

Review

Spontaneous Generation Living things come from nonliving things

Vital Force The air contains something that produces microorganisms

Review

When was the Earth formed? 4.6 billion years ago

What were the first life forms? Prokaryotic cells

Define Evolution. Describes how things change over time

Thoughts in 18th Century

Scientists believed species were permanent and unchanging

Earth was only thousands of years old

Scientists began to present evidence that species change over time and that the Earth is much older.

Scientists are influenced by other scientists

James Hutton: a geologist in 1785 Realized that certain kinds of rocks are

formed from molten lava Some other rocks form very slowly, as

sediments build up and are squeezed into layers

Froces beneath Earth’s surface push rock layers upward and build mountain ranges

Mountains can be warn down by rain, wind, heat and cold

Scientists are influenced by other scientists

Charles Lyell-1830-1833 Laws of nature are constant over time and

that scientists must explain past events in term of processes they can observe in the present

Hutton and Lyell

Laws of nature concluded that Earth is extremely old and that the processes that changed Earth in the past are the same processes that operate in the present

Jean-Baptiste Lamarck

French Naturalist1. Suggested that organisms could change

during their lifetimes by selectively using or not using various parts

2. Suggested that individuals could pass these acquired traits on to their offspring, causing change over time

Jean Baptiste Lamarck

1809 Inheritance of Acquired Characteristics

Individuals acquired traits during lifetime as a result of experience then can pass those traits onto their offspring. Larger muscles from work, children would have

larger muscles

Thomas Malthus

English Economist 1798- notes humans were being born

faster that dying causing over crowding Forces working against population

growth, include war, famine, and disease Applied to other organisms as well

Alfred Russel Wallace

English naturalist working in Malaysia 1850’s

Thoughts were almost identical to Darwin’s which caused Darwin to publish book

Charles Darwin

1809-1882 Traveled on the Beagle

Noticed similar organisms around the world Did a lot of work on Galapagos Islands off of

South America Wrote book On the Origin of Species by

Means of Natural Selection Used the phrase Descent with modification

Beaks of finches on Galapagos Islands

Natural Selection

Four main parts of Darwin’s reasoning Overproduction: more offspring can be

produced than can survive to maturity Genetic Variation: individuals within a

population have different traits Struggle to Survive: individuals must

compete with each other for limited resources

Differential Reproduction: individuals that have certain traits are more likely to survive and reproduce

Speciation

Speciation: the formation of new species Convergent Evolution: different species evolve

similar traits because of environment they live in These species are not related

Divergent Evolution: organisms begin to look different because of the environment they live in Adaptive Radiation: a new species in a new

environment will undergo divergent evolution until population fills many part of the environment

Speciation

Geographic Isolation: a population is split due to the habitat becoming divided Ex: canyons, mountain ranges, bodies of water,

deserts, accidentally transported to new area Reproductive Isolation: there are barriers to

successful breeding between population groups in same area1. Prezygotic: before fertilization

1. Ex. Mating calls, time of mating

2. Postzygotic: after fertilization1. Ex: offspring cannot reproduce

Rates of Speciation

Gradualism: changes occur at a regular, gradual rate

Punctuated Equilibrium: Many years of no change, then all of the sudden have a significant change

Evidence of Evolution

Fossil: remains or traces of an organism from long ago.

Biogeography: study of the location of organisms1. Animals that seemed closely related yet

are adapted to different environments in nearby regions.

2. Animals that seemed unrelated but have similar adaptations to similar environments

Evidence of Evolution

Anatomy and Embryology Anatomy: the study of body structure Embryology: the study of how organisms

develop

Homologous Structures: anatomical structures that occur in different species and that originates by common ancestor Ex: human, penguin, alligator, bat all have a

humerus, radius, and ulna

Evidence of Evolution

Analogous Structure: structures that have similar functions but different structures Ex: wings of birds and insects

Vestigial Structure: structure that have no known function Ex: tailbone, appendix

Biological Molecule DNA and RNA

The greater number of similarities between any given species the more closely related