Chapter 10

Principles of Evolution

Evolution

Process of biological change by Process of biological change by which descendants come to which descendants come to differ from their ancestorsdiffer from their ancestors

A gradual change in species A gradual change in species over generations in over generations in

response to changes in the response to changes in the environmentenvironment

Naturalists who’s thinking set the stage for the development of Charles Darwin’s

theory

Darwin’s theory was a result of many years of study, and required the expertise of

many scientists to further explain observations

he made during his mid twenties

Erasmus Darwin

Charles grandfather, doctor and poet published in 1796

– all living things were descended from a common ancestor

– that complex life rose from simple life.

“A fool you know, is a man who never tried an experiment in his life”

Jean Baptiste Lamarck In 1809 he published

Philosophie Zoologique

A 'tendency to perfection', an innate quality of nature that organisms constantly 'improved' by successive generation

Inheritance of acquired traits, physical changes could be inherited and driven by environmental change

Theory of Inheritance of Acquired Traits

Modifications acquired during one’s lifetime are inherited by the next generation

implies that the organism itself can control the direction of change

Lamarck also believed species never went extinct, although they may change into newer forms

How Geology set the stageCatastrophismCatastrophism

Catastrophic events were

responsible for mass

extinctions

Gradualism

Change is a result of small steps over long periods of

time

Charles Lyell Principles of Geology

Uniformitarianism: processes that alter the Earth are uniform through long periods of time

The processes are still at work today

This theory expanded upon gradualism and eventually replaced catastrophism as the favored geological theory yell

Lyell met with Charles Darwin frequently to discuss Darwin’s theory “On the Origins of Species”

Alfred Wallace (1823-1913)

English Naturalist Studied the Amazon RainforestWrote several letters to Darwin Came about with the same theory at about the same time

Thomas MalthusBritish economist 1766-1834

Food, water, and shelter are natural limits to population growth.

population left unchecked will outstrip man's ability to live on this planet

The Theory of Evolution by means of Natural Selection

Charles Darwin (1809-1882)

English Naturalist

HMS Beagle age 22 ship's naturalist 5 year voyage 1831-1836

Published the book “Origin of Species” in 1859

The Voyage of the HMS Beagle

The Theory of Natural Selection

Variations are based on natural selection

Overproduction leads to competition

Adaptation- certain variations can allow an organism to survive better “Survival of the Fittest”

Natural selection acts on phenotype

“Nothing in biology makes sense, except in the light of

evolution”Theodosius Dobzhansky geneticist

Natural Selection in Action

The Peppered Moth

Evidence of Evolution

I. The fossil record- episodic speciation, mass extinction

II. Geographical distribution of species

III. Embryology- compare embryo development to determine lineage

IV. Anatomical Evidence

I. Homologous Structures-

II. Analogous Structures

III. Vestigial Organ- serves no useful purpose

How a How a fossil fossil formsforms

1

2

3

4

5

Mass extinction 25-70% of species wiped out

Generally followed by a period of adaptive radiation

BiogeographyThe geographical distribution of living things

Plant Biogeogra

phy

Animal Biogeogra

phy

Comparative Embryology

Homologous & Analogous Body structures

Similar in structure but appear different and have

different functionsShared common ancestor

Perform similar function but not

common ancestor

Vestigial Structuresremnant of early ancestorremnant of early ancestor

Comparative DNA analysis