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EvolutionChange Over Time

Evolution Definition: A change in a population of a

species over timeOrganisms evolve to adapt better to their

environmentAccording to Evolution, all living things

(organisms) on the planet are related andhave a common ancestor

A unicellular prokaryote (bacteria) thatlived near hydrothermal vents where thetemperature is near 200 degrees Fahrenheitamidst poisonous hydrogen sulfide anddeadly sulfuric acid

Formation of EARTH

First need to talkabout formation ofearth: 4.6 billionyears ago!

• How do we know this stuff:RADIOACTIVE DATING-

• Not relative dating-

•Solar system in beginning (~5 billion yrs ago)was a swirling mass of gas and dust thatcollapsed inward leaving some debris outside(planets)

First Prokaryotes(the early cells that are still around today

aka bacteria) Since no oxygen on earth before 1.7

bya, first cells must have beenanaerobic--

Most likely heterotrophs thatdepended on organic molecules.After consuming all organicmolecules, there was a need for someorganisms to evolve into autotrophs

These first autotrophs resembledarchaebacteria (aka extremophiles)

These early archaebacteria obtainedtheir energy by chemosynthesis,which produced atmospheric O2.

First cells by endosymbiosis

• After almost 1 billion years of O2 production, life exists onlyin the ocean.

Then many of these cells began sticking together, first incolonies, then permanently attached; first multicellularorganisms: early invertebrates

Then after more oxygen was released by early plant formsand algae, multicellular organisms diversified rapidly(Cambrian explosion)

The Scientists

LamarckDarwin

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Jean Baptiste LamarckEvolution occurs as structures develop

through use, or disappear because ofdisuse, and these“acquiredcharacteristics” are passed to offspring

EXAMPLE: Over aGiraffe’s lifetime it canstretch its neck and itsoffspring will be bornwith long necks….

Valid? Not valid?

Who was Charles Darwin

Studied Medicine Hated the sight of

blood Received a BA in

Theology Had 10 children

Theory of Evolution At the age of 22,

Darwin was an unpaidnaturalist on a navalvoyage on the HMSBeagle

On the trip, Darwinsaw things that hethought could only beattributed to aprocess of gradualchange

Theory of EvolutionIn The Galapagos Islands,

Darwin collected morethan a dozen species offinches (13)Each had a specialized

diet and way of obtainingfood.These finches resembled

a finch species from SouthAmerica.

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Darwin’s Finches Theory of Evolution “descent with modification

evolution aka: change over time

Returned from trip at age 27. Still leftwith the question:“How does evolution occur?”

Darwin made following principles:1. There is variation within populations2. Overproduction: Not all young in each

generation can survive, results incompetition

3. Adaptations leads to some variationsbeing favorable

4. Descent with modification: Individualsthat survive and reproduce are those withfavorable variations Therefore, those traits will increase in a

population and the nature of the populationwill gradually change

Natural SelectionPopulations change in response totheir environment so they are more

likely to reproduce.

Selection acts on populations,species evolve

Survival of the Fittest

Fitness refers to the better trait in apopulation.

Look at the next slide and try to figureout which trait is the fittest in thebeetle population.

Evolution happens becauseof natural selection

Eventually what will happen to the beetlepopulation?

The population will change so muchevolution will occur.

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AdaptationAdaptations are inherited traits that

increase a group’s chance ofsurvival & reproduction

This type of finch has a thickbeak adaptation for

cracking open seeds

Variation & Species

1. Variation = differences betweenmembers of a population

Example from class:2. Species = group that can breed &

produce healthy & fertile offspring

What is a species?

LIGER = male lion + female tiger

Are tigers &lions in the

same species?

Why or whynot?

Artificial Selection Selective breeding, humans selectively

breed species for specific traits.

How do new species form?Geographic Isolation When members of a population are

separated Ex: polar, grizzly, & black bears

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Reproductive IsolationWhen members of a population can’t

breed even though they live nearbyEx: different mating seasons or different

mating calls

Different Types of Evolution1. Divergent evolution2. Convergent evolution3. Coevolution

Divergent EvolutionIsolated populationsevolve independently

Ex: polar & grizzly bearschanged independentlydue to different habitats

Convergent EvolutionUnrelated species become morealike because they live in similar

environments

Ex: shark & dolphin

CoevolutionSpecies that interact closely adapt to one

another

Ex: flowers & hummingbirds

Adaptive RadiationEvolution of many diverse species from

one common ancestor

Ex: Galapagos finches discovered byDarwin

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Fossils gave the idea of speciesbecoming extinct.After this mass extinction there was asharp increase in the number ofspecies. This is called EpisodicSpeciation

Biodiversity: amount of varietyof living things in an area.

Between the coralreef and Antarctica,which place hashigher biodiversity?

Evidence for Evolution

5 Lines of Evidence for Evolution

Adaptations – Camouflage, Mimicry

Fossils Anatomy Embryology Biochemistry – DNA Evidence

Example: Camouflage adaptations ofmantids that live in different environments…

Structural adaptations have beenobserved in populations of birds,insects, and many other organisms.

Adaptations: Camouflage

Scorpion fish

Hi!

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Adaptations: Mimicry

katydidmoth caterpillar

Adaptations: Mimicry

monarch butterflyviceroy butterfly

Pair Share

In your own words, explain how mimicryis different from camouflage.

Analyzing Fossil Evidence

Fossil: a trace of a long-dead organism Biological diversity: many different fossils

found showing different species orsubspecies.

Episodic speciation: time when a largenumber of species appear

Mass extinction: brief periods in timewhere large numbers of speciesdisappeared (Ex: dinosaurs)

Fossils

Elephant evolutionbased on fossils

The fossil record provides evidencefor the theory of evolution.

Transitional forms link fossils tomodern species.

Ichthyostega(transitional fossil from fish to land

animals)2 min. video clip – http://animal.discovery.com/videos/animal-

armageddon-ichthyostega.html

Archaeopteryx(transitional fossil from reptiles to

birds)Watch first 1 min. 30 sec. video clip –

http://www.youtube.com/watch?v=p7EHJoy8TCw&feature=related

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Trilobite The records for marine fossils,such as this 400 million year oldtrilobite, are the best tool forstudying biodiversity throughhistory because they’re longerand better preserved than therecords for land fossils. (imagefrom Oxford University)

Sedimentary Fossil Formation

Anatomy:Forearm bones in mammals

Homologousstructures:similar infunction andorganisms dosharecommonorigin.

“Look the same”

Homologous structures

Anatomy:• Analogous structures: similar infunction, but organisms do not share acommon origin. “work the same”

Example: Insect wings and bird wings.

Anatomy:

Vestigial structures: body parts thathave lost their function over time andare now useless.

Examples: human appendix

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Embryology: Vertebrate embryos aresimilar, pointing to common origin.

Developmental homology

Embryology Biochemistrya.k.a. Molecular evidence Biochemistry: Similarities in DNA

sequence point to a common origin. The fewer the differences, the more closely

related two organisms are. Cladogram: Visual way to show how

closely related species are.

Pair Share

Refer to theillustration. Thebones labeled Aare known as

a) vestigial structures.b) sequential

structures.c) homologous

structures.d) fossil structures.