Chapter 10 Principles of Evolution

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

A gradual change in species over generations in response to changes in the environment

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 stage Catastrophism 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 UUniformitarianism: processes that alter the Earth are uniform through long periods of time TThe processes are still at work today TThis theory expanded upon gradualism and eventually replaced catastrophism as the favored geological theory yell LLyell met with Charles Darwin frequently to discuss Darwin’s theory “On the Origins of Species”

Alfred Wallace ( ) English Naturalist Studied the Amazon Rainforest Wrote several letters to Darwin Came about with the same theory at about the same time

Thomas Malthus British economist  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 ( ) English Naturalist HMS Beagle age 22 ship's naturalist 5 year voyage Published the book “Origin of Species” in 1859

The Voyage of the HMS Beagle

The Theory of Natural Selection VVariations are based on natural selection OOverproduction leads to competition AAdaptation- certain variations can allow an organism to survive better “Survival of the Fittest” N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 fossil forms

Mass extinction 25-70% of species wiped out Generally followed by a period of adaptive radiation

Biogeography The geographical distribution of living things Plant Biogeography Animal Biogeography

Comparative Embryology

Homologous & Analogous Body structures Similar in structure but appear different and have different functions Shared common ancestor Perform similar function but not common ancestor

remnant of early ancestor Vestigial Structures remnant of early ancestor

Comparative DNA analysis