EVOLUTION

ZOOLOGYZOOLOGY

Chapter 4Chapter 4

Charles Darwin 1809-1882

Question for Thought

Earth has millions of other kinds Earth has millions of other kinds of organisms of everyof organisms of every

imaginable shape, size, and habitat. imaginable shape, size, and habitat. This variety of living things is This variety of living things is

called called biological biological diversitydiversity. How did all these . How did all these

different organisms arise?different organisms arise? How are they relatedHow are they related??

In your own words, describe what YOU think the theory of evolution means…

Darwin’s Theory of Evolution

Evolution refers to a change over time. refers to a change over time. Organic Evolution is the process by Organic Evolution is the process by which modern organisms have which modern organisms have descended from ancient organisms. descended from ancient organisms.

A scientific A scientific theory is a well-supported is a well-supported testable explanation of phenomena that testable explanation of phenomena that have occurred in the natural world.have occurred in the natural world.

What is a species?Populations in which genes

are exchanged through interbreeding

What is speciation?What is speciation?

The process of developing The process of developing new species.new species.

How do you think Darwin came up with his theory?(He did not “Google” it!)

Ideas from other scientists that shaped Darwin’s Thinking

James Hutton:James Hutton:

1795 Theory of 1795 Theory of Geological changeGeological change

Charles Lyell:Charles Lyell:Book: Book: Principles of Principles of GeographyGeography

Jean Baptist Jean Baptist LamarckLamarck: Tendency : Tendency toward Perfection toward Perfection (Giraffe necks)(Giraffe necks)

Voyage of the Beagle

Voyage of Beagle Dates: Dates: February 12th, 1831February 12th, 1831 Captain:Captain: Charles Darwin Charles Darwin ShipShip: H.M.S. Beagle: H.M.S. Beagle Destination:Destination: Voyage around the world. Voyage around the world. Findings:Findings: evidence to propose a evidence to propose a

revolutionary hypothesis about how life revolutionary hypothesis about how life changes over timechanges over time

Patterns of Diversity

Darwin visited Argentina and Australia Darwin visited Argentina and Australia which had similar grassland ecosystems. which had similar grassland ecosystems.

those grasslands were inhabited by very those grasslands were inhabited by very different animals. different animals.

neither Argentina nor Australia was neither Argentina nor Australia was home to the sorts of animals that lived in home to the sorts of animals that lived in European grasslands.European grasslands.

Patterns of Diversity

Darwin posed challenging questions. Darwin posed challenging questions. Why were there no rabbits in Australia, Why were there no rabbits in Australia,

despite the presence of habitats that despite the presence of habitats that seemed perfect for them?seemed perfect for them?

Why were there no kangaroos in Why were there no kangaroos in England?England?

Living Organisms and Fossils

Darwin collected the preserved Darwin collected the preserved remains of ancient organisms, called remains of ancient organisms, called fossils. .

Some of those fossils resembled Some of those fossils resembled organisms that were still alive today.organisms that were still alive today.

Living Organisms and Fossils  

Others looked completely unlike any Others looked completely unlike any creature he had ever seen. creature he had ever seen.

As Darwin studied fossils, new questions As Darwin studied fossils, new questions arose. arose. Why had so many of these species Why had so many of these species

disappeared? disappeared?

How were they related to living species?How were they related to living species?

Fossils

True FossilsTThe remains of the dead animal or plant or the imprint he remains of the dead animal or plant or the imprint

left from the remains. Such as…left from the remains. Such as… bonesbones teethteeth skin impressionsskin impressions hairhair the hardened shell of an ancient invertebratethe hardened shell of an ancient invertebrate impression of an animal or plantimpression of an animal or plant, even if the actual , even if the actual

parts are missing.parts are missing.

Trace Fossils…

Something that was made Something that was made by the animal while it by the animal while it was living that has was living that has hardened into stone. hardened into stone. Such as…Such as…

footprintsfootprints burrowsburrows coprolitecoprolite (animal poop) (animal poop)

Other places to find ancient animal remains: Frozen glaciersFrozen glaciers AmberAmber Tar pitsTar pits

The Galapagos Island The smallest, lowest islands were hot, The smallest, lowest islands were hot,

dry, and nearly barren-Hood Island-sparse dry, and nearly barren-Hood Island-sparse vegetationvegetation

The higher islands had greater rainfall and The higher islands had greater rainfall and a different assortment of plants and a different assortment of plants and animals-Isabela- Island had rich animals-Isabela- Island had rich vegetationvegetation..

Animals found in the Galapagos

Land TortoisesLand Tortoises

Darwin FinchesDarwin Finches

Blue-Footed BoobyBlue-Footed Booby

Marine IguanasMarine Iguanas

Animals

The Galapagos Island

Darwin was fascinated in particular by the Darwin was fascinated in particular by the land tortoises and marine iguanas in the land tortoises and marine iguanas in the Galápagos. Galápagos.

Giant tortoises varied in predictable ways Giant tortoises varied in predictable ways from one island to another.from one island to another.

The shape of a tortoise's shell could be The shape of a tortoise's shell could be used to identify which island a particular used to identify which island a particular tortoise inhabited. tortoise inhabited.

Galapagos Islands

Darwin’s Finches

The Journey Home

Darwin Observed that characteristics Darwin Observed that characteristics of many plants and animals vary of many plants and animals vary greatly among the islandsgreatly among the islands

Hypothesis:Hypothesis: Separate species may Separate species may have arose from an original ancestorhave arose from an original ancestor

The Origin of Species

Darwin publish his Darwin publish his findings in 1859.findings in 1859.

Natural & Artificial Selection

Natural variationNatural variation--differences --differences among individuals of a speciesamong individuals of a species

Artificial selectionArtificial selection- nature provides - nature provides the variation among different the variation among different organisms, and humans select those organisms, and humans select those variations they find useful.variations they find useful.

Evolution by Natural Selection

The Struggle for ExistenceThe Struggle for Existence--members of each species have to members of each species have to compete for food, shelter, other compete for food, shelter, other life necessitieslife necessities

Survival of the FittestSurvival of the Fittest-Some -Some individuals better suited for the individuals better suited for the environmentenvironment

Struggle For Existence & Survival of The Fittest

Natural Selection

Over time, natural Over time, natural selection results in selection results in changes in inherited changes in inherited characteristics of a characteristics of a population. These population. These changes increase a changes increase a species fitness in its species fitness in its environment.environment.

Descent Descent with ModificationDescent with Modification-Each living organism has -Each living organism has

descended, with changes from other species over timedescended, with changes from other species over time Common DescentCommon Descent- organisms today were derived - organisms today were derived

from common ancestorsfrom common ancestors

Evidence of Evolution

The Fossil RecordThe Fossil Record

Geographic Distribution of Living ThingsGeographic Distribution of Living Things

Homologous Body StructuresHomologous Body Structures

Similarities in Early DevelopmentSimilarities in Early Development

Evidence for Evolution

The Fossil RecordThe Fossil Record--Layers show changeLayers show change

Geographic Geographic Distribution of Living Distribution of Living ThingsThings

Homologous Body Homologous Body StructuresStructures

Similarities in Early Similarities in Early DevelopmentDevelopment

Evidence of Evolution The Fossil RecordThe Fossil Record Geographic Geographic

Distribution of Distribution of Living Things-Living Things-similar similar environments have environments have similar types of similar types of organismsorganisms

Homologous Body Homologous Body StructuresStructures

Similarities in Early Similarities in Early DevelopmentDevelopment

Homologous Structures

Homologous StructuresHomologous Structures-structures that -structures that have different mature forms in different have different mature forms in different organisms, but develop from the same organisms, but develop from the same embryonic tissueembryonic tissue

Evidence for Evolution

Vestigial organs Vestigial organs - organs that serve - organs that serve no useful function in an organismno useful function in an organism

i.e.) appendix, miniature legs, armsi.e.) appendix, miniature legs, arms

Similarities in Early Development

Molecular Biology Recent science has Recent science has

been able to study been able to study the genetic blueprint the genetic blueprint of organisms. of organisms. Similarities in DNA Similarities in DNA may show may show relationships to relationships to common ancestors.common ancestors.

Summary of Darwin’s Theory…

Individuals in nature differ from Individuals in nature differ from one another.one another.

Organisms in nature produce more Organisms in nature produce more offspring than can survive, and offspring than can survive, and many of those who do not survive many of those who do not survive do not reproduce.do not reproduce.

Summary of Darwin’s Theory

Because more organisms are produced Because more organisms are produced than can survive, each species must than can survive, each species must struggle for resources.struggle for resources.

Each organism is unique, each has Each organism is unique, each has advantages and disadvantages in the advantages and disadvantages in the struggle for existence.struggle for existence.

Summary (cont.)

Individuals best suited for the Individuals best suited for the environment survive and reproduce environment survive and reproduce most successfully.most successfully.

Species change over long periods Species change over long periods of time.of time.

Summary (cont.)

Species alive today descended with Species alive today descended with modification from species that modification from species that lived in the past.lived in the past.

All organisms on earth are united All organisms on earth are united into a single family tree of life by into a single family tree of life by common descent.common descent.

Phylogeny

The evolutionary relationship The evolutionary relationship among species. among species.

Utilizes tree-like diagrams to Utilizes tree-like diagrams to show evolutionary lines of show evolutionary lines of descent.descent.

Darwin’s diagram to illustrate common descent.