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Chapter 1 – Exploring Chapter 1 – Exploring LifeLife

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Why Study Biology?Why Study Biology? ScienceScience

Systematic method of inquirySystematic method of inquiry BiologyBiology

Scientific study of lifeScientific study of life Important to study and understand Important to study and understand

sciencescience Awareness and appreciation of lifeAwareness and appreciation of life Important in decisions of lifeImportant in decisions of life

o Issues dealing with biology arise dailyIssues dealing with biology arise daily

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Science, Technology, and Science, Technology, and SocietySociety

The goal of science -- understanding natural The goal of science -- understanding natural phenomenaphenomena

The goal of The goal of technology – technology – applying scientific applying scientific knowledge for some specific purposeknowledge for some specific purpose

Science and technology -- interdependentScience and technology -- interdependent Science -- marked by “discoveries” Science -- marked by “discoveries” Technology -- marked by “inventionsTechnology -- marked by “inventions””

Science + Technology?Science + Technology? DNADNA

Ethical issues?Ethical issues?

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Building on the Work of Building on the Work of OthersOthers

CooperationCooperation Professionals, graduate students, undergraduate studentsProfessionals, graduate students, undergraduate students

CommunicationCommunication RepeatabilityRepeatability

Different groups often work on same researchDifferent groups often work on same research Model Organisms (e.g., Model Organisms (e.g., Drosophila melanogaster Drosophila melanogaster or or

Arabidopsis thalianaArabidopsis thaliana)) Diverse viewpoints -> SerendipityDiverse viewpoints -> Serendipity

Printing press -- China (paper and ink) and Europe Printing press -- China (paper and ink) and Europe (mass production in mills)(mass production in mills)

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Logical ThoughtLogical Thought Induction (Inductive Reasoning) – deriving Induction (Inductive Reasoning) – deriving

general principles from particular facts or general principles from particular facts or occurrences (esp. when repeated)occurrences (esp. when repeated) The sun always rises in the east!The sun always rises in the east!

Deduction (Deductive Reasoning) – Deduction (Deductive Reasoning) – deriving a conclusion from the stated deriving a conclusion from the stated premises by reasoning from the general to premises by reasoning from the general to the specificthe specific IfIf organisms are made of cells (premise 1), organisms are made of cells (premise 1),

and and if if humans are organisms (premise 2), humans are organisms (premise 2), thenthen humans are composed of cells (deductive humans are composed of cells (deductive prediction)prediction)

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Inquiry -- search for information Inquiry -- search for information and explanationand explanation

The process of science:The process of science: Discovery science: describing natureDiscovery science: describing nature

o _________ Reasoning ?_________ Reasoning ? Hypothesis-based science: explaining Hypothesis-based science: explaining

naturenatureo _________ Reasoning ?_________ Reasoning ?

Scientific InquiryScientific Inquiry

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Discovery ScienceDiscovery Science

Describes nature Describes nature Examples of discovery science:Examples of discovery science:

understanding cell structureunderstanding cell structure expanding databases of genomesexpanding databases of genomes

Induction in Discovery ScienceInduction in Discovery Science Generalizations based on specific Generalizations based on specific

observationsobservations

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Types of DataTypes of Data Data are Data are

recorded recorded observationsobservations

Two types of Two types of data:data: Quantitative Quantitative

data: data: numerical numerical measurementsmeasurements

Qualitative Qualitative data: recorded data: recorded descriptionsdescriptions

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Hypothesis-Based Hypothesis-Based ScienceScience

Proposing and testing hypothesesProposing and testing hypotheses Hypotheses -- hypothetical explanationsHypotheses -- hypothetical explanations

deductive reasoningdeductive reasoning tentative answer to a well-framed questiontentative answer to a well-framed question an explanation on trial -- making a an explanation on trial -- making a

prediction that can be tested prediction that can be tested and falsifiedand falsified can can NOTNOT prove ….. prove …..

The Scientific MethodThe Scientific Method ObservationObservation

Many ways to make Many ways to make observationsobservations

Leads to (a) Leads to (a) questionquestiono Why?Why?o How?How?

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Hypothesis #1:Dead batteries

Hypothesis #2:Burnt-out bulb

Observations

Question

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Hypothesis #1:Dead batteries

Hypothesis #2:Burnt-out bulb

Test prediction

Test falsifies hypothesis

Prediction:Replacing batterieswill fix problem

Prediction:Replacing bulbwill fix problem

Test prediction

Test does not falsify hypothesis

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Deduction: The “If…then” Logic of Deduction: The “If…then” Logic of Hypothesis-Based ScienceHypothesis-Based Science

Flow of logic from the general to Flow of logic from the general to the specificthe specific If a hypothesis is correct, then we If a hypothesis is correct, then we

can expect a particular outcomecan expect a particular outcome

EXPLORATIONAND

DISCOVERY

FORMINGAND

TESTINGHYPOTHESES

SOCIETALBENEFITS

ANDOUTCOMES

COMMUNITYANALYSIS

ANDFEEDBACK

The The Process Process

of of ScienceScience

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Mimicry and CamouflageMimicry and Camouflage One species resembling something else One species resembling something else

for “personal gain!”for “personal gain!” Cryptic coloration – camouflageCryptic coloration – camouflage Aposematic coloration – warning colorationAposematic coloration – warning coloration Batesian mimicry – harmless species Batesian mimicry – harmless species

resembling a harmful oneresembling a harmful one Müllerian mimicry – two or more species Müllerian mimicry – two or more species

resembling each otherresembling each other Also seen in reproductive strategies Also seen in reproductive strategies

(wasps/orchids) and predation (angler (wasps/orchids) and predation (angler fish)fish)

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A Case Study: A Case Study: Investigating Coat Investigating Coat

Coloration in Mouse Coloration in Mouse PopulationsPopulations

Color patterns vary widely -- Color patterns vary widely -- sometimes between members of the sometimes between members of the same speciessame species

Peromyscus polionotus Peromyscus polionotus with different with different color patterns -- different environmentscolor patterns -- different environments The beach mouse lives on white sand The beach mouse lives on white sand

dunes dunes The inland mouse lives on darker soilThe inland mouse lives on darker soil

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Florida

Inland population

Beachpopulation

Beach population

GULF OF MEXICO

Inland population

Camouflage Coloration in Camouflage Coloration in MiceMice

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Overarching Hypothesis – camouflage Overarching Hypothesis – camouflage coloration benefits by protecting from coloration benefits by protecting from predationpredation Specific Hypothesis – mice with coloration Specific Hypothesis – mice with coloration

that didn’t match the habitat would be preyed that didn’t match the habitat would be preyed on more heavily than the native well-matched on more heavily than the native well-matched mice.mice.

Camouflage Coloration in Camouflage Coloration in MiceMice

Light models Dark models Light models Dark models

Camouflaged Non-camouflaged Non-camouflaged Camouflaged(control) (experimental) (experimental) (control)

Beach habitat Inland habitat

Pe

rce

nta

ge

of

att

ac

ke

d m

od

els 100

50

0

Results

Camouflage Coloration in Camouflage Coloration in MiceMice

““hundreds” of plastic micehundreds” of plastic mice Repeatability!Repeatability!

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The Myth of The Myth of thethe Scientific Scientific MethodMethod

Idealized process of inquiryIdealized process of inquiry Rarely true textbookRarely true textbook RepeatabilityRepeatability

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VariablesVariables

Only test one thing at a time!Only test one thing at a time! IIndependent – the thing ndependent – the thing II

manipulatemanipulate E.g., fertilizerE.g., fertilizer

Dependent variable – the thing that Dependent variable – the thing that you’re investigatingyou’re investigating How much to the plants actually grow?How much to the plants actually grow?

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The idea of The idea of CONTROLCONTROL What makes the difference?

Random chance Experimental design

Experimental group vs control group Variable of interest changes Control variability

Control groups Positive control Negative control

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Theories in ScienceTheories in Science

Theory -- broader than a hypothesisTheory -- broader than a hypothesis A scientific theory:A scientific theory:

Must explain a body of factsMust explain a body of facts Be able to predict future similar occurrences Be able to predict future similar occurrences Be falsifiable and survive empirical experimentationBe falsifiable and survive empirical experimentation supported by a large body of evidencesupported by a large body of evidence

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Characteristics of Living Characteristics of Living OrganismsOrganisms

OrderOrder Evolutionary adaptationEvolutionary adaptation Responses to the environmentResponses to the environment RegulationRegulation Energy processingEnergy processing Growth and developmentGrowth and development ReproductionReproduction

Order

Energy processing

Growth anddevelopment

Regulation

Reproduction

Responseto the

environment

Evolutionaryadaptation

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Viruses: A Nasty PuzzleViruses: A Nasty Puzzle

Like living organisms:Like living organisms: Contain DNAContain DNA ReproduceReproduce EvolveEvolve

Lack characteristics of life:Lack characteristics of life: Not made of cells:Not made of cells:

o Just genetic material and proteinJust genetic material and protein Lack homeostasis, reproduction, and energy collectionLack homeostasis, reproduction, and energy collection

o Depend on cells to do these functionsDepend on cells to do these functions

Giant viruses …..Giant viruses …..

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OrderOrder Part 1 Part 1

http://www.youtube.com/watch?v=ahXIMUkSXX0

Part 2 Part 2 http://www.youtube.com/watch?v=lOIP_Z_-0Hs

Part 3Part 3

http://www.youtube.com/watch?v=14-NdQwKz9w

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A Hierarchy of Biological A Hierarchy of Biological Organization -- Organization --

EcologicalEcological

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A Hierarchy of Biological A Hierarchy of Biological Organization -- Organization --

OrganismalOrganismal

New Properties Emerge at New Properties Emerge at Each Level in the Each Level in the

Biological HierarchyBiological Hierarchy Life can be studied at different levels -- molecular to planetaryLife can be studied at different levels -- molecular to planetary Study can be divided into different Study can be divided into different kindskinds of organization of organization

BiologicalBiological Taxonomic Taxonomic

Study can be divided into different levels of biological Study can be divided into different levels of biological organizationorganization

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Looking at BiologyLooking at Biology Emergent propertiesEmergent properties – – arrangement and arrangement and

interactions as complexity increasesinteractions as complexity increases Can characterize nonbiological entities as wellCan characterize nonbiological entities as well

o For example, a functioning bicycle …..For example, a functioning bicycle …..

ReductionismReductionism -- reduction of complex systems to -- reduction of complex systems to more manageable simpler componentsmore manageable simpler components For example, studying the molecular structure of DNA For example, studying the molecular structure of DNA

helps us to understand the chemical basis of inheritancehelps us to understand the chemical basis of inheritance

UnderstandingUnderstanding -- balances reductionism with -- balances reductionism with emergent propertiesemergent properties Studying the interactions of DNA with other moleculesStudying the interactions of DNA with other molecules

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Structure and FunctionStructure and Function

Often relatedOften related Leaves for photosynthesisLeaves for photosynthesis Hummingbird wingsHummingbird wings

Basic unit? The cellBasic unit? The cell

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Two Main Forms of CellsTwo Main Forms of Cells Characteristics shared by all cells: Characteristics shared by all cells:

Plasma membranePlasma membrane CytosolCytosol RibosomesRibosomes DNA -- genetic informationDNA -- genetic information

EukaryoticEukaryotic divided into membrane-bound organellesdivided into membrane-bound organelles DNA – linear strands in nucleusDNA – linear strands in nucleus

ProkaryoticProkaryotic lack organelleslack organelles DNA -- single, circular strandDNA -- single, circular strand

Membrane

Cytoplasm

EUKARYOTIC CELL PROKARYOTIC CELL

DNA(no nucleus)

Membrane

1 µm

Organelles

Nucleus (contains DNA)

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Eukaryotic cell

Membrane

Cytoplasm

Membrane-enclosed organelles

Nucleus(membrane-enclosed)

DNA (throughoutnucleus) 1 µm

Prokaryotic cell

Membrane

DNA(no nucleus)

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Plant vs AnimalPlant vs Animal

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OrganellesOrganelles Major OrganellesMajor Organelles

Mitochondria – sites of cellular Mitochondria – sites of cellular respirationrespiration

Chloroplasts – sites of photosynthesisChloroplasts – sites of photosynthesis Peroxisomes – sites of HPeroxisomes – sites of H22OO22 production production Central VacuoleCentral Vacuole

Minor OrganellesMinor Organelles Smooth Endoplasmic ReticulumSmooth Endoplasmic Reticulum LysosomesLysosomes

Site of Aerobic Site of Aerobic RespirationRespiration

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Inner membrane

Cristae

Matrix

100 nmMitochondrialDNA

Freeribosomes in themitochondrialmatrix

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Chloroplast

ChloroplastDNA

RibosomesStroma

Inner and outermembranes

Granum

Thylakoid1 µm

Site of PhotosynthesisSite of Photosynthesis

Reproduction drives Reproduction drives ContinuityContinuity

Genes -- Genes -- units of inheritanceunits of inheritance Genes -> chromosomesGenes -> chromosomes DNA -> genesDNA -> genes

Cell Division – basis for growth, repair and Cell Division – basis for growth, repair and reproductionreproduction

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DNA, the Genetic DNA, the Genetic MaterialMaterial

Eukaryotic chromosomes -- one Eukaryotic chromosomes -- one long DNA molecule with hundreds or long DNA molecule with hundreds or thousands of genesthousands of genes

GenesGenes -- units of inheritanceunits of inheritance DNA -- controls growth, DNA -- controls growth,

development and maintenancedevelopment and maintenance

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Nucleus

DNA

(a) DNA double helix (b) Single strand of DNA

A

T

G

G

T

A

T

A

C

A

C

T

A

C

Nucleotide

Cell

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Lenscell

(a) Lens cells aretightly packed

with transparentproteins called

crystallin.

(b) How do lens cells make crystallin proteins?Crystallin gene

DNA

mRNA

Chain of aminoacids

Protein

Crystallin protein

TRANSCRIPTION

TRANSLATION

A C C A A A C C G A G T

T G G T T T G G C T C A

U G G U U U G G C U C A

PROTEIN FOLDING

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Genomics: Large-Scale Genomics: Large-Scale Analysis of DNA Analysis of DNA

SequencesSequences GGenome enome – entirety of genetic instructionsgenetic instructions GenomicsGenomics – study within and between – study within and between

speciesspecies Depends onDepends on

““High-throughput” technologyHigh-throughput” technology BioinformaticsBioinformatics Interdisciplinary research teamsInterdisciplinary research teams

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EcologyEcology ImportanceImportance

Interactions of environment and organismsInteractions of environment and organisms Necessary to study impact of interactionsNecessary to study impact of interactions ExamplesExamples

o Introduced species: zebra musselsIntroduced species: zebra mussels Economic costEconomic cost

o Habitat restorationHabitat restoration Long-leaf pine forest & red-cockaded woodpeckerLong-leaf pine forest & red-cockaded woodpecker

o Damage to biosphere: chlorofluorocarbonsDamage to biosphere: chlorofluorocarbons Health and organism damageHealth and organism damage

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A Closer Look at A Closer Look at EcosystemsEcosystems

Organisms interact Organisms interact environmentenvironment other organismsother organisms

Organisms and environment affect Organisms and environment affect each othereach other

Ecosystem dynamics:Ecosystem dynamics: Cycling of nutrientsCycling of nutrients Food WebsFood Webs Energy flowEnergy flow

Energy FlowEnergy Flow Energy/Nutrients flows through Energy/Nutrients flows through

biological systemsbiological systems Sun Sun Producers Producers Consumers Consumers

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Producers and Producers and ConsumersConsumers

Plants are producersPlants are producers Convert sunlight energy to chemical Convert sunlight energy to chemical

energyenergy ConsumersConsumers

Harvest energy developed by producersHarvest energy developed by producers Often several levels of consumersOften several levels of consumers

o 1°, 2°, 3°1°, 2°, 3°

DetrivoresDetrivores

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Trophic Trophic StructureStructure

Feeding Feeding relationships relationships between between organismsorganisms

FoodFood chainschains link link trophic levelstrophic levels

Food webs – link Food webs – link food chainsfood chains

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Grouping Species: The Grouping Species: The Basic IdeaBasic Idea

Taxonomy -- names and classifies Taxonomy -- names and classifies species species

Kingdoms and domains -- broadest Kingdoms and domains -- broadest units of classificationunits of classification

King Philip Cleverly Ordered Fried King Philip Cleverly Ordered Fried Green squidGreen squid … …

Ursidae

Ursus

Carnivora

Mammalia

Chordata

Animalia

Eukarya

Species Genus Family Order Class Phylum Kingdom DomainUrsusamericanus(Americanblack bear)

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Families, Genera & Families, Genera & SpeciesSpecies Family – Ursidae Family – Ursidae

GeneraGenera AiluropodaAiluropoda HelarctosHelarctos MelursusMelursus TremarctosTremarctos UrsusUrsus

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Families, Genera & Families, Genera & SpeciesSpecies Family Ursidae – species Family Ursidae – species Ursus Ursus

americanusamericanus Species in different generaSpecies in different genera

Ailuropoda melanoleucaAiluropoda melanoleuca – Giant Panda – Giant Panda Helarctos malayanus – Helarctos malayanus – Sun BearSun Bear Melursus ursinus – Melursus ursinus – Sloth BearSloth Bear Tremarctos ornatus – Tremarctos ornatus – Spectacled BearSpectacled Bear

Species in the same genusSpecies in the same genus Ursus arctos – Ursus arctos – Brown BearBrown Bear Ursus arctos horribilis – Ursus arctos horribilis – Grizzly BearGrizzly Bear

Ursus arctos Ursus arctos ssp. ssp. horribilishorribilis Ursus maritimus – Ursus maritimus – Polar BearPolar Bear

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Binomial Scientific Binomial Scientific NamesNames The The scientific namescientific name of an organism is formed of an organism is formed

from the genus name and specific epithetfrom the genus name and specific epithet Each two-part scientific name is unique and Each two-part scientific name is unique and

recognized worldwiderecognized worldwide Names are treated as Latin and always Names are treated as Latin and always

underlinedunderlined or or italicizeditalicized The first letter of the genus name is The first letter of the genus name is alwaysalways

capitalizedcapitalized The first letter of the species name is The first letter of the species name is alwaysalways lower lower

casecase Authorities, “variety,” etc. unitalicized.Authorities, “variety,” etc. unitalicized.

Species name is Species name is alwaysalways paired with its genus paired with its genus namename Homo sapiensHomo sapiens

Specie == MoneySpecie == Money57

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Biological DiversityBiological Diversity

Biologists have named about 2 million speciesBiologists have named about 2 million species

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Biological DiversityBiological Diversity

ATBI in Great Smoky Mountains National Park

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Biological DiversityBiological Diversity

Estimates of total species range from 10 million to over 200 millionEstimates of total species range from 10 million to over 200 million

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History of Classification History of Classification SchemesSchemes

Until 1969 – 2 Kingdoms (Plant & Until 1969 – 2 Kingdoms (Plant & Animal)Animal)

1969 – Robert Whittaker: 5 1969 – Robert Whittaker: 5 KingdomsKingdoms all bacteria in Kingdom Moneraall bacteria in Kingdom Monera

1990 – Carl Woese: 3 Domains1990 – Carl Woese: 3 Domains

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The Five Kingdoms of The Five Kingdoms of LifeLife

ProkaryotesProkaryotes ArchaeaArchaea BacteriaBacteria CyanobacteriaCyanobacteria

AnimalsAnimalsPlantsPlantsFungiFungiProtistsProtists

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Kingdoms and DomainsKingdoms and Domains

ProkaryotesProkaryotes Archaea – Archaea – Domain ArchaeaDomain Archaea Bacteria Bacteria – – Domain BacteriaDomain Bacteria Cyanobacteria Cyanobacteria – – Domain BacteriaDomain Bacteria

Animals – Animals – Domain EukaryaDomain EukaryaPlants Plants – – Domain EukaryaDomain EukaryaFungi Fungi – – Domain EukaryaDomain EukaryaProtists Protists – – Domain EukaryaDomain Eukarya

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Biological DiversityBiological Diversity

Bacteria 4 µm 100 µm

0.5 µm

Kingdom PlantaeProtists

Kingdom AnimaliaKingdom FungiArchaea

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Classification & BiologyClassification & Biology TaxonomyTaxonomy – study of how things are – study of how things are

classified classified Phylogenetics -- Phylogenetics -- Reconstructing Reconstructing

evolutionary historyevolutionary history

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Systematics:Systematics:Links Taxonomy and Links Taxonomy and

PhylogenyPhylogeny Systematists Systematists

depict depict evolutionary evolutionary relationships in relationships in branching branching phylogenetic phylogenetic treestrees

Carnivora

Pantherapardus

(leopard)

Mephitismephitis

(striped skunk)

Lutra lutra(European

otter)

Canisfamiliaris

(domestic dog)

Canislupus(wolf)S

pec

ies

Gen

us

Fam

ilyO

rder

Felidae Mustelidae Canidae

Panthera Mephitis Lutra Canis

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Cladistics / PhylogeneticsCladistics / Phylogenetics Clades can be Clades can be

nested in nested in larger clades, larger clades, but not all but not all groupings or groupings or organisms organisms qualify as qualify as cladesclades

Carnivora

Pantherapardus

(leopard)

Mephitismephitis

(striped skunk)

Lutra lutra(European

otter)

Canisfamiliaris

(domestic dog)

Canislupus(wolf)S

pec

ies

Gen

us

Fam

ilyO

rder

Felidae Mustelidae Canidae

Panthera Mephitis Lutra Canis

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The Tree of LifeThe Tree of Life

Related organisms -- similar adaptationsRelated organisms -- similar adaptations Such kinships connect life’s unity and Such kinships connect life’s unity and

diversity to descent with modificationdiversity to descent with modification Natural selection eventually produces Natural selection eventually produces

new species from ancestral speciesnew species from ancestral species

Homologies and “Tree Thinking”

HomologyHomology – similarity from common ancestry – similarity from common ancestry Evolutionary/ Phylogenetic treesEvolutionary/ Phylogenetic trees -- --

hypotheses about relationships between hypotheses about relationships between organismsorganisms Often nested patterns Often nested patterns

Different types of data …Different types of data … anatomical anatomical DNA sequence dataDNA sequence data Morphology Morphology EnvironmentEnvironment

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LE 25-11bLE 25-11b

Turtle Leopard

Hair

Amniotic egg

Four walking legs

Hinged jaws

Vertebral column

Salamander

Tuna

Lamprey

Lancelet (outgroup)

Cladogram

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Phylogenetic GroupingsPhylogenetic Groupings Monophyletic -- ancestral species Monophyletic -- ancestral species

and all its descendantsand all its descendants Paraphyletic -- ancestral species and Paraphyletic -- ancestral species and

some, but not all, of the descendantssome, but not all, of the descendants Polyphyletic -- various species that Polyphyletic -- various species that

lack a common ancestorlack a common ancestor

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LE 25-10aLE 25-10a

Grouping 1

Monophyletic

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LE 25-10bLE 25-10b

Paraphyletic

Grouping 2

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LE 25-10cLE 25-10c

Polyphyletic

Grouping 3

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TaxonomyTaxonomyA Constant State of FluxA Constant State of Flux

Classifications Change ……Classifications Change …… Systematists regularly propose changes Systematists regularly propose changes

in classificationin classification Classifications Change When New Classifications Change When New

Information Is DiscoveredInformation Is Discovered

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Early Biological Early Biological ThoughtThought

Expressed by ancient Expressed by ancient Greek philosophersGreek philosophers Plato (427-347 B.C.)Plato (427-347 B.C.) Aristotle (384-322 B.C.) Aristotle (384-322 B.C.)

arranged all organisms arranged all organisms on a linear scale of on a linear scale of increasing complexity increasing complexity (“ladder of Nature”)(“ladder of Nature”)

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The Three Domains of LifeThe Three Domains of Life

Source: Wikipedia

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See also: See also: http://comenius.susqu.edu/biol/202/taxa.htm

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Unity in the Diversity of Unity in the Diversity of LifeLife

Underlying diversity – unityUnderlying diversity – unity Evident in details of cell structureEvident in details of cell structure

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DNA -- made up of two long chains DNA -- made up of two long chains in a double helixin a double helix Four “letters”Four “letters” Twenty “words”Twenty “words”

Unity of pathwaysUnity of pathwaysUnity of structuresUnity of structures

Unity in the Diversity of Unity in the Diversity of LifeLife

LE 1-16aLE 1-16a

Cilia of windpipe cellsCilia of Paramecium

15 µm 5 µm

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LE 1-16bLE 1-16b

Cilia of windpipe cellsCilia of Paramecium

Cross section of cilium,as viewed with anelectron microscope

0.1 µm

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Living Organisms EvolveLiving Organisms Evolve Individual organisms change rapidlyIndividual organisms change rapidly

Growth of individualGrowth of individual A seed becomes a treeA seed becomes a tree

Groups of organisms change slowlyGroups of organisms change slowly SpeciesSpecies

o Group of interbreeding organismsGroup of interbreeding organismso Produce fertile offspringProduce fertile offspring

EvolutionEvolutiono Characteristics of a species changing over timeCharacteristics of a species changing over time

Individuals change – populations evolveIndividuals change – populations evolve

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Adaptation: Adjusting to Adaptation: Adjusting to Environmental Environmental

ChallengesChallenges Change/ MutationChange/ Mutation Acted on by natural selectionActed on by natural selection Over time -- adaptive evolutionOver time -- adaptive evolution

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Natural versus Natural versus Artificial Artificial SelectionSelection

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