Chapter 13Chapter 13

The Theory of EvolutionThe Theory of Evolution

Charles DarwinCharles Darwin

Charles DarwinCharles Darwin – visited the – visited the Galapagos Galapagos IslandsIslands and noted that groups of animals and noted that groups of animals varied from island to island but yet were varied from island to island but yet were similar.similar.

He observed 13 species of finches. Each had a He observed 13 species of finches. Each had a type of beak and coloring adapted to it’s type of beak and coloring adapted to it’s environment/ island. Upon closer and internal environment/ island. Upon closer and internal observation, Darwin concluded that they observation, Darwin concluded that they must’ve come from a common ancestor.must’ve come from a common ancestor.

EvolutionEvolution – the development of new types of – the development of new types of organisms from preexisting types of organisms organisms from preexisting types of organisms over time. (an inheritable change in over time. (an inheritable change in characteristics)characteristics)

Charles LyellCharles Lyell

(1797-1875) believed in (1797-1875) believed in Uniformitarianism – which states that Uniformitarianism – which states that the geologic processes shaped Earth in the geologic processes shaped Earth in the past continue to operate in the the past continue to operate in the same way today.same way today.

Another belief by Georges Cuvier Another belief by Georges Cuvier believed in Catastrophism – which believed in Catastrophism – which states that sudden geologic states that sudden geologic catastrophes caused the extinction of catastrophes caused the extinction of large groups of organisms at certain large groups of organisms at certain points in the pastpoints in the past

Natural SelectionNatural Selection

Natural SelectionNatural Selection – Process by – Process by which individuals that are better which individuals that are better adapted to their enviroment survive adapted to their enviroment survive and reproduce more successfully and reproduce more successfully than less well adapted individuals than less well adapted individuals do: this explains the mechanism of do: this explains the mechanism of evolutionevolution

AdaptationAdaptation – changes in population – changes in population over timeover time

Evidence of Evidence of EvolutionEvolution

• FossilFossil – remains or traces of an – remains or traces of an organism that died long ago.organism that died long ago.

• BiogeographyBiogeography – the study of – the study of the locations of organisms the locations of organisms around the world.around the world.

• Darwin observed animals that Darwin observed animals that seemed closely related but yet seemed closely related but yet were adapted to different were adapted to different environments.environments.

• On the flip side – he also saw On the flip side – he also saw animals that did not seem animals that did not seem related but had similar related but had similar adaptations to similar adaptations to similar environments that were far environments that were far apart. apart.

Divergent evolutionDivergent evolution – process in which – process in which the descendants of a single ancestor the descendants of a single ancestor diversify into species that each fit different diversify into species that each fit different parts of the environment parts of the environment (accumulation of (accumulation of differences b/t populations that once formed a single differences b/t populations that once formed a single population)population)

Convergent evolutionConvergent evolution – process by – process by which different species evolve similar traitswhich different species evolve similar traits

Anatomy & EmbryologyAnatomy & Embryology• AnatomyAnatomy – the study of body structure – the study of body structure

• EmbryologyEmbryology – the study of the development – the study of the development of organismsof organisms

• Homologous StructuresHomologous Structures – anatomical – anatomical structures that occur in different species, structures that occur in different species, that originated by heredity from a structure that originated by heredity from a structure in the most recently common ancestor of the in the most recently common ancestor of the species species

Anatomy & EmbryologyAnatomy & Embryology Analogous structuresAnalogous structures – closely related – closely related

functions but do not derive from the same functions but do not derive from the same ancestral structureancestral structure

Example: wingsExample: wingsButterfly wingsButterfly wingsare different fromare different frombat wings whichbat wings whichare different fromare different frombird wings but allbird wings but allare used to flyare used to fly

Anatomy & EmbryologyAnatomy & Embryology

Vestigial structuresVestigial structures – structures – structures that serve no function but that serve no function but resemble structures with resemble structures with functional roles in related functional roles in related organisms (tail bone)organisms (tail bone)

Embryonic development is also Embryonic development is also evidence of a common ancestor evidence of a common ancestor – if you look at the development – if you look at the development of vertebrates, they look very of vertebrates, they look very similar in the beginning of their similar in the beginning of their development.development.

Anatomy & EmbryologyAnatomy & Embryology

If a group of animals from similar If a group of animals from similar species have the same protein in species have the same protein in their blood – it can mean that they their blood – it can mean that they are related to a common ancestorare related to a common ancestor

Coevolution – when two or more species Coevolution – when two or more species evolved adaptations to each other’s influencesevolved adaptations to each other’s influences

Example: Plants have evolved so that the Example: Plants have evolved so that the animals that eat them also spread their pollen. animals that eat them also spread their pollen. As a result, plants and their pollinators As a result, plants and their pollinators coevolved. coevolved.

Artificial selectionArtificial selection – when humans chooses – when humans chooses an individual that will parent the next an individual that will parent the next generation, based on a certain characteristicgeneration, based on a certain characteristic

CHAPTER CHAPTER 1414

ClassificationClassification

Classifying OrganismsClassifying Organisms

BiodiversityBiodiversity – the variety of organisms – the variety of organisms considered at all levels from populations considered at all levels from populations to ecosystemsto ecosystems

TaxonomyTaxonomy – the science of describing, – the science of describing, naming, and classifying organismsnaming, and classifying organisms

TaxonTaxon – any particular group within a – any particular group within a taxonomic system.taxonomic system.

Dichotomous KeyDichotomous Key

dichotomous keydichotomous key, is a method of deducing , is a method of deducing the correct species assignment of a living the correct species assignment of a living thing. As the alternative name implies, it thing. As the alternative name implies, it works by offering two (or sometimes more) works by offering two (or sometimes more) alternatives at each juncture, and the choice alternatives at each juncture, and the choice of one of those alternatives determines the of one of those alternatives determines the next step. For each level of distinction, there next step. For each level of distinction, there is normally a further indent. Some keys use is normally a further indent. Some keys use different numbering systems. different numbering systems.

Dichotomous KeyDichotomous Key Are you above or below 5’4.Are you above or below 5’4. Do you have hair below or above your Do you have hair below or above your

shoulders?shoulders? Are you right or left handed?Are you right or left handed? Do you wear glasses?Do you wear glasses? Do you have a job?Do you have a job? Do you play a sport for the school?Do you play a sport for the school? Then questions get specific with your name.Then questions get specific with your name.

Levels of ClassificationLevels of Classification

• KINGDOM

• PHYLUM

• CLASS

• ORDER

• FAMILY

• GENUS

• SPECIES

REMEMBER IT BY• KING• PETER• CAME• OVER• FOR• GRAPE• SODA

As you move through the hierarchy from kingdom to species, animals become more similar in appearance.

Levels of OrganizationLevels of Organization

• Binomial Nomenclature: the scientific name with two parts given to an organism: the genus name followed by species identifier.

• Example: Human: Homo sapien

Domestic Dog: Canis familiaris

PHYLOGENETICSPHYLOGENETICS

PhylogeneticsPhylogenetics – the analysis of the – the analysis of the evolutionary or ancestral evolutionary or ancestral relationships among taxarelationships among taxa

Phylogenetic diagramPhylogenetic diagram or or phylogenetic treephylogenetic tree – looks like a family – looks like a family tree and has a branching pattern that tree and has a branching pattern that indicates how closely related, by indicates how closely related, by their evolutionary relationships, a their evolutionary relationships, a subset of taxa are thought to be. (can subset of taxa are thought to be. (can change upon new discoveries)change upon new discoveries)

CladisticsCladistics CladisticsCladistics – a system of phylogenic analysis – a system of phylogenic analysis

that uses shared and derived characteristics as that uses shared and derived characteristics as the only criteria for grouping taxathe only criteria for grouping taxa

Shared characterShared character – feature that all members of – feature that all members of a group have in common – such as scales for a group have in common – such as scales for reptiles or hair in mammalsreptiles or hair in mammals

Derived characterDerived character – a feature that evolved only – a feature that evolved only within the group under consideration. Only birds within the group under consideration. Only birds have feathers, among living and extinct animals have feathers, among living and extinct animals – birds are the only animals to have feathers so – birds are the only animals to have feathers so you can hypothesize that feathers evolved you can hypothesize that feathers evolved strictly within the bird lineagestrictly within the bird lineage

CladogramsCladograms

Clade – organisms that share one or more Clade – organisms that share one or more derived characters probably inherited from derived characters probably inherited from a common ancestor.a common ancestor.

Cladograms – a phylogenetic diagram Cladograms – a phylogenetic diagram representing common ancestorsrepresenting common ancestors

Starts with out-group – an organism that is Starts with out-group – an organism that is distantly related to the other organismsdistantly related to the other organisms

Exploring Further pg. 308Exploring Further pg. 308

CladogramCladogram

The horseThe horse ChordataChordata MammaliaMammalia PerissodactylaPerissodactyla EquidaeEquidae Equus Equus CaballusCaballus

DonkeyDonkey ChordataChordata MammaliaMammalia PerissodactylaPerissodactyla EquidaeEquidae EquusEquus AsinusAsinus

Crossing Crossing SpeciesSpecies

Although donkeys and horses Although donkeys and horses are similar they are not of the are similar they are not of the same species.same species.

They can produce offspring but They can produce offspring but their offspring is sterile.their offspring is sterile.

The same is true for lions and The same is true for lions and tigers which produce sterile tigers which produce sterile ligers ligers