Origins of LifeOrigins of LifePatterns of EvolutionPatterns of Evolution

- Classification -- Classification -

Phyletic GradualismPhyletic Gradualism (Uniformitarianism) (Uniformitarianism)

Sedimentation rates we commonly see today are Sedimentation rates we commonly see today are very very slowslow (centimeters/year) (centimeters/year)• Assuming those rates have been constant throughout Earth’s Assuming those rates have been constant throughout Earth’s

history, it would take millions of years for the sedimentary history, it would take millions of years for the sedimentary layers we see at locations such as the Grand Canyon to formlayers we see at locations such as the Grand Canyon to form

Phyletic Discontinuity Phyletic Discontinuity (Catastrophism)(Catastrophism)

Catastrophic events (volcanoes, floods, etc.) cause Catastrophic events (volcanoes, floods, etc.) cause rapid, widespread sedimentation and dramatic changes rapid, widespread sedimentation and dramatic changes to the geologic recordto the geologic record• Mt. St. Helens displaced huge amounts of dirt, rock and snow, Mt. St. Helens displaced huge amounts of dirt, rock and snow,

carving a mini grand canyon and leaving over 50 feet of carving a mini grand canyon and leaving over 50 feet of sediment deposited across the valleysediment deposited across the valley within a matter of within a matter of minutesminutes

Punctuated Punctuated EquilibriumEquilibrium

Slow sedimentation rates and Slow sedimentation rates and evolutionary changes evolutionary changes "punctuated" (interrupted) by "punctuated" (interrupted) by events that facilitate rapid events that facilitate rapid bursts of evolutionbursts of evolution• Mass extinctionsMass extinctions• Explains "Cambrian Explosion"Explains "Cambrian Explosion"

Sudden appearance of new Sudden appearance of new species (fossils)species (fossils)

• Explains lack of transitional fossilsExplains lack of transitional fossils

Fossil Dating MethodsFossil Dating Methods

Radioisotope DatingRadioisotope Dating• Decay of unstable elements used to measure Decay of unstable elements used to measure

elapsed time (assumes known original amount, elapsed time (assumes known original amount, constant rate of decay, and lack of contamination)constant rate of decay, and lack of contamination)

Molecular ClocksMolecular Clocks• Measurable rates of mutation used Measurable rates of mutation used

to compare DNA of organisms and to compare DNA of organisms and estimate time between evolved estimate time between evolved ancestors ancestors

StratigraphyStratigraphy• Age of rock layers and the fossils within are Age of rock layers and the fossils within are

interpreted with the belief that younger fossils are interpreted with the belief that younger fossils are deposited on top of older fossils (deposited on top of older fossils (superpositionsuperposition))

Classification & PhylogenyClassification & Phylogeny

ClassificationClassification• the process of describing, the process of describing,

naming, and grouping things naming, and grouping things based on their similaritiesbased on their similarities

• grouped organisms are easier grouped organisms are easier to studyto study

TaxonomyTaxonomy• scientific study of how living scientific study of how living

things are classifiedthings are classified PhylogenyPhylogeny

• the evolutionary history of a the evolutionary history of a organisms as depicted in a organisms as depicted in a "family tree""family tree"

Systems of ClassificationSystems of Classification Carolus Linnaeus (1750s)Carolus Linnaeus (1750s)

• grouped organisms based on observable features (long grouped organisms based on observable features (long before evolution was proposed)before evolution was proposed)

• system used for over 250 yearssystem used for over 250 years• devised naming system for organismsdevised naming system for organisms

Binomial NomenclatureBinomial Nomenclature 2 part naming system using Latin words2 part naming system using Latin words Genus speciesGenus species (i.e. (i.e. Felis concolorFelis concolor))

Phylogenetic ClassificationPhylogenetic Classification• Retains Linnaean system for the most partRetains Linnaean system for the most part• Species with similar Species with similar hypothesizedhypothesized evolutionary histories evolutionary histories

are grouped more closely togetherare grouped more closely together• Based on DNA similarities more than physical appearanceBased on DNA similarities more than physical appearance• Evolution of species is presupposedEvolution of species is presupposed

1707-1778

Levels of ClassificationLevels of Classification There are There are 77 levels of classification. levels of classification.

Remember: Remember: KKing ing PPhilip hilip CCame ame OOver ver FFor or GGood ood SSoupoup

KKingdom ingdom broadest levelbroadest level

PPhylumhylumCClasslassOOrderrderFFamilyamilyGGenus enus SSpeciespecies most specificmost specific

Binomial NomenclatureBinomial Nomenclature two-name system of namingtwo-name system of naming

• GenusGenus is 1 is 1stst name (upper case); name (upper case); speciesspecies is 2 is 2ndnd name (lower case name (lower case

Phylogenetic TreePhylogenetic Tree

Classification Classification based on :based on :• Morphology (similar Morphology (similar

physical structures)physical structures)• Fossil recordFossil record• Embryological Embryological

patterns of patterns of developmentdevelopment

• Genetic similarities Genetic similarities (DNA) (DNA)

CladogramsCladograms A phylogenetic tree is based on a grouping/sorting similar organisms A phylogenetic tree is based on a grouping/sorting similar organisms

into groups called clades. into groups called clades. This is a relatively new system of grouping incorporating the same This is a relatively new system of grouping incorporating the same

derivedderived characteristics to represent evolutionary relationships. characteristics to represent evolutionary relationships. • Organisms within Organisms within a group are a group are descended from a descended from a common ancestorcommon ancestor• There is a There is a branching pattern branching pattern (splits in two where(splits in two where changes occur)changes occur)• Change in Change in characteristics characteristics occur in lineagesoccur in lineages over timeover time

Homologous CharacteristicsHomologous Characteristics A structure found in different species, but derived from a A structure found in different species, but derived from a

common ancestral structure.common ancestral structure.• The structure may or may not be used for the same function in the The structure may or may not be used for the same function in the

species in which it occurs. species in which it occurs.

Examples:Examples:• skeletal skeletal

structure of structure of vertebrate vertebrate limbslimbs

• embryonic embryonic similaritiessimilarities

• similarities in similarities in DNA, RNA, & DNA, RNA, & their proteinstheir proteins

Embryonic Embryonic Homologues Homologues

Structures that have different Structures that have different mature forms but develop mature forms but develop from the same embryonic from the same embryonic tissuestissues

Limbs are structurally similar Limbs are structurally similar but have different functionsbut have different functions

Recent developments in Recent developments in biochemistry show "similarity biochemistry show "similarity does not imply a genetic does not imply a genetic relationship" relationship"

Alligator

Turtle

Primitive Fish

Mammal

Comparative EmbryologyComparative Embryology

Analogous StructuresAnalogous Structures

Similar in function, but NOT derived from a common ancestral Similar in function, but NOT derived from a common ancestral structure structure

Examples:Examples:• wings of birds wings of birds

& bats& bats• walking limbs walking limbs

of insects & of insects & vertebratesvertebrates

• eyes of a eyes of a horse and an horse and an octopusoctopus

• human skull human skull and beetle's and beetle's head shield head shield exoskeletonexoskeleton

Bones are homologous structures, but wings Bones are homologous structures, but wings are only analogous.are only analogous.

Inherited TraitsInherited Traits

Neo-Darwinism incorporates the Neo-Darwinism incorporates the similarities of genetics between similarities of genetics between species as evidence of evolutionspecies as evidence of evolution

Other scientists look at genetic Other scientists look at genetic code and see the complexity and code and see the complexity and efficiency of information transfer efficiency of information transfer as evidence for an intelligent as evidence for an intelligent “designer”“designer”

Six Six KingdoKingdo

msms ArchaebacteriaArchaebacteria EubacteriaEubacteria ProtistsProtists FungiFungi PlantsPlants AnimalsAnimals

First true cells are thought to have First true cells are thought to have arisen from aquatic, anaerobic, arisen from aquatic, anaerobic, "protocells""protocells"

6

EUBACTERIAARCHAEBACTERIA

Tree of Life VideoTree of Life Video

Domain (or Kingdom) ArchaeaDomain (or Kingdom) Archaea

Formerly part of the Formerly part of the Monera kingdomMonera kingdom

Bacteria that live in Bacteria that live in extreme conditions:extreme conditions:• hothot• acidicacidic• sulfuricsulfuric• deepdeep• coldcold

Domain (or Kingdom) Domain (or Kingdom) EubacteriaEubacteria

Formerly part of the Monera Formerly part of the Monera kingdomkingdom

"True Bacteria" "True Bacteria" • make us sickmake us sick• live in our intestineslive in our intestines• make cheesemake cheese

Different shapesDifferent shapes• Bacilli (rod-shape)Bacilli (rod-shape)• Strep/StaphyloStrep/Staphylococcuscoccus (round (round

chains/clusters)chains/clusters)• Spirilla (stringy spirals)Spirilla (stringy spirals)

Domain EukaryotaDomain Eukaryota

Includes all eukaryotic Includes all eukaryotic organismsorganisms

Includes 4 kingdoms:Includes 4 kingdoms:• ProtistaProtista• FungiFungi• PlantsPlants• AnimalsAnimals

Kingdom ProtistaKingdom Protista

Amoeba Paramecium Giardia

Water Mold Slime Mold

Euglena Dinoflagellates DiatomBrown AlgaeGreen Algae

Fungus-

Like

Plant-

Like

Eukaryotic (have Eukaryotic (have nucleus)nucleus)

Single-celledSingle-celled

Animal-Like

(protozoans)

Kingdom FungiKingdom Fungi

EukaryoticEukaryotic Multi-cellularMulti-cellular HeterotrophicHeterotrophic Sessile organismsSessile organisms Molds, mushrooms, Molds, mushrooms,

lichenslichens

Kingdom PlantaeKingdom Plantae

Bryophyte (Moss)

Pteridophytes (Ferns)

Conifers (cone-bearing plants)

Angiosperms (flowering plants)

EukaryoticEukaryotic Multi-cellularMulti-cellular Autotrophic (produce own Autotrophic (produce own

food)food) Sessile (don't move)Sessile (don't move)

Kingdom AnimaliaKingdom Animalia

Eukaryotic, multi-cellular, heterotrophic, motile Eukaryotic, multi-cellular, heterotrophic, motile Common Phyla:Common Phyla:

• Porifera (sponges, corral) Porifera (sponges, corral) • Cnidaria (jellyfish and similar animals)Cnidaria (jellyfish and similar animals)• Platyhelmenthes (flat worms, tapeworms) Platyhelmenthes (flat worms, tapeworms) • Nematoda (small unsegmented worms)Nematoda (small unsegmented worms)• Mollusca (inc. clams, oysters, etc..)Mollusca (inc. clams, oysters, etc..)• Annelida (segmented worms)Annelida (segmented worms)• Echinodermata (starfish and anemones)Echinodermata (starfish and anemones)• Arthropoda (crustaceans, insects, spiders)Arthropoda (crustaceans, insects, spiders)• Chordata (those with spinal chords: birds, mammals, Chordata (those with spinal chords: birds, mammals,

amphibians, bony fish, etc.)amphibians, bony fish, etc.)

Dichotomous KeysDichotomous Keys

1a. Organism has 4 legs Go to # 2

1b. Organism has more than 4 legs Go to # 20

2a. Organism has a tail Go to # 3

2b. Organism has no tail Go to # 35

3a. Organism has stripes Bengal Tiger

3b. Organism has no stripes African Lion