Competition

simple

Hair and eye color may be such neutral variations in human beings

variations a

antelope’s speed m

water retention in a desert plant

survive to maturity

favorable variations

passed from generation to generation natural selection.

relationship

simply by looking at it.

“survival of the fittest.”

“Fittest” means that organisms must not only survive to adulthood, they must actually reproduce.

advantageous genetic variations are passed along and become represented with increasing frequency in succeeding generations.

breeding programs.

Canis familiaris

several discipline

The Chihuahua

Saint Bernard

breeding programs.

Artificial selection

the same gene pool

the ability to interbreed and produce fertile offspring.

“man’s best friend.”

20 years

natural selection.

Organisms produce more offspring than the environment can support

Africa a

ow, researchers Dr Stephen Lycett and Alastair Key have shown that the hands of our ancestors may have been subject to natural selection as a result of using simple cutting tools

apes,

2.6 million years ago,

show that 'biometric' variation

Darwin proposed that the use of stone tools may have influenced the evolution of human hands.

Assume that there were salamanders living in some grasslands. Suppose, Lamarck argued, that these salamanders had a hard time walking because their short legs couldn't trample the tall grasses or reach the ground. Suppose that these salamanders began to slither on their bellies to move from place to place. Because they didn't use their legs, the leg muscles wasted away from disuse and the legs thus became small.

passed this acquired trait

legless salamanders evolved

no legs.

by inheriting the acquired characteristic of

Darwin's Background

o have extraordinary talents.

genius, did not at first appear

Darwin disliked school

d observing birds and collecting insects to study.

sent to medical school in Scotland

"intolerably dull

interested in attending natural history lectures.

university at Cambridge, England, in 1827.

Darwin be chosen for the position of naturalist on the ship the HMS Beagle.

to collect specimens, make observations, and keep careful records of anything he observed that he thought significant.

Principles of Geology by Charles Lyell,

In the Andes he observed fossil shells of marine organisms in rock beds at about 4,300 m.

One reason that Darwin was so eager to study life on land was that he suffered from terrible seasickness and couldn't wait to get off the Beagle.

thousands

trekked hundreds of miles through unmapped region.

catalog his specimens and write his notes.

praised by the scientific community.

experts for study.

bird specialist

Darwin's bird collections from the Galapagos Islands, located about 1,000 km west of South America.

13 similar

Other experts

believe that species change over time.

evidence f

In 1837 Darwin began his first notebook on evolution. For several years Darwin filled his notebooks with facts that could be used to support the theory of evolution.

fossils of similar relative ages are more closely related than those of widely different relative ages.

He ran his own breeding experiments and also did experiments on seed dispersal.