Classification of Living Things Chapter 20. Classification of Living Things 2OutlineTaxonomy ...
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Transcript of Classification of Living Things Chapter 20. Classification of Living Things 2OutlineTaxonomy ...
2Classification ofClassification of Living Things Living Things
OutlineOutline
TaxonomyTaxonomy Binomial SystemBinomial System Species IdentificationSpecies Identification Classification CategoriesClassification Categories
Phylogenetic TreesPhylogenetic Trees SystematicsSystematics Taxonomy (naming of organisms)Taxonomy (naming of organisms) Classification (placing species in the proper categories)Classification (placing species in the proper categories)
Systematics TodaySystematics Today Cladistic SystematicsCladistic Systematics Phenetic SystematicsPhenetic Systematics
Classification SystemsClassification Systems The Five Kingdom SystemThe Five Kingdom System The Three Domain SsytemThe Three Domain Ssytem
3Classification ofClassification of Living Things Living Things
TaxonomyTaxonomy
Branch of biology concerned with identifying, Branch of biology concerned with identifying, naming, and classifying organismsnaming, and classifying organisms
Began with the ancient Greeks and RomansBegan with the ancient Greeks and RomansAristotle classified organisms into groups Aristotle classified organisms into groups such as horses, birds, and oakssuch as horses, birds, and oaks
John Ray (1627–1705)John Ray (1627–1705)Believed that each organism should have a Believed that each organism should have a set nameset name
Otherwise, “men…cannot see and record Otherwise, “men…cannot see and record accurately.”accurately.”
5Classification ofClassification of Living Things Living ThingsTaxonomy:Taxonomy:
Binomial SystemBinomial System
Mid-eighteenth century, Linnaeus developed Mid-eighteenth century, Linnaeus developed the binomial system of nomenclaturethe binomial system of nomenclature
First word is genus nameFirst word is genus name
Second word is specific epithetSecond word is specific epithet
Refers to one species (of potentially many) Refers to one species (of potentially many) within its genuswithin its genus
A species is referred to by the full binomial A species is referred to by the full binomial name (Genus species)name (Genus species)
Genus name can be used alone to refer to a Genus name can be used alone to refer to a group of related speciesgroup of related species
6Classification ofClassification of Living Things Living ThingsTaxonomy:Taxonomy:
Distinguishing SpeciesDistinguishing Species
Distinguishing species on the basis of Distinguishing species on the basis of structure can be difficultstructure can be difficultMembers of the same species can vary in Members of the same species can vary in structurestructure
Attempts to demonstrate reproductive Attempts to demonstrate reproductive isolation is problematic because:isolation is problematic because:
Some species hybridize, andSome species hybridize, and
Reproductive isolation is difficult to observeReproductive isolation is difficult to observe
8Classification ofClassification of Living Things Living Things
Classification CategoriesClassification Categories
Modern taxonomists use the following Modern taxonomists use the following classification:classification:SpeciesSpeciesGenus – one or more speciesGenus – one or more speciesFamily – one or more generaFamily – one or more generaOrder – one or more familiesOrder – one or more familiesClass – one or more ordersClass – one or more ordersPhylum – one or more classesPhylum – one or more classesKingdom – one or more phylaKingdom – one or more phylaDomain – one or more kingdomsDomain – one or more kingdoms
9Classification ofClassification of Living Things Living Things
Eukarya- membrane-bounded nucleusEukarya- membrane-bounded nucleus
Animalia- motile, multicellular, internal cavity for Animalia- motile, multicellular, internal cavity for digestion of nutrientsdigestion of nutrients
Chordata- organisms that at one time have a dorsal Chordata- organisms that at one time have a dorsal hollow nerve cord, a notochord, pharyngeal hollow nerve cord, a notochord, pharyngeal pouches, and a postanal tailpouches, and a postanal tail
Mammalia- warm-blooded vertebrates with Mammalia- warm-blooded vertebrates with mammary glands; body with hair; mammary glands; body with hair;
Primates- well-developed brain opposable thumb Primates- well-developed brain opposable thumb
Hominidae- upright stance and bipedal locomotionHominidae- upright stance and bipedal locomotion
Homo- Full brain development, hand anatomy for Homo- Full brain development, hand anatomy for making toolsmaking tools
Species- sapiens modern humans; speech centersSpecies- sapiens modern humans; speech centers
10Classification ofClassification of Living Things Living Things
Classification CategoriesClassification Categories
The higher the category, the The higher the category, the more inclusivemore inclusive
Organisms in the same domain have general Organisms in the same domain have general characteristics in commoncharacteristics in common
In most cases, classification categories can In most cases, classification categories can be subdivided into additional categoriesbe subdivided into additional categories
SuperorderSuperorder
OrderOrder
SuborderSuborder
InfraorderInfraorder
11Classification ofClassification of Living Things Living Things
Phylogenetic TreesPhylogenetic Trees
Systematics - the diversity of organisms at all Systematics - the diversity of organisms at all levelslevels
One goal of systematics is to determine One goal of systematics is to determine phylogeny (phylogeny (evolutionary historyevolutionary history) of a group) of a group
Phylogeny often represented as a Phylogeny often represented as a phylogenetic treephylogenetic treeA diagram indicating lines of descentA diagram indicating lines of descentEach branching point:Each branching point: Is a divergence from a common ancestorIs a divergence from a common ancestor
Represents an organism that gives rise to two Represents an organism that gives rise to two new groupsnew groups
12Classification ofClassification of Living Things Living Things
Phylogenetic TreesPhylogenetic Trees
Classification lists the unique characters of Classification lists the unique characters of each taxon and is intended to reflect each taxon and is intended to reflect phylogenyphylogeny
Primitive characters:Primitive characters:
Present in all members of a group, andPresent in all members of a group, and
Present in the common ancestorPresent in the common ancestor
Derived characters:Derived characters:
Present in some members of a group, butPresent in some members of a group, but
Absent in the common ancestorAbsent in the common ancestor
13Classification ofClassification of Living Things Living ThingsTracing PhylogenyTracing Phylogeny
Fossil RecordFossil Record Fossil record is incompleteFossil record is incomplete
It is often difficult to determine the phylogeny of a It is often difficult to determine the phylogeny of a fossilfossil
HomologyHomology Refers to features that stem from a common ancestorRefers to features that stem from a common ancestor
Homologous structures are related to each other Homologous structures are related to each other through common descentthrough common descent
Analogy-wings of an insect and the wings of a bat Analogy-wings of an insect and the wings of a bat are analogousare analogous Similarity due to convergence-similar characters in Similarity due to convergence-similar characters in
distantly related lines of descent.distantly related lines of descent.
15Classification ofClassification of Living Things Living Things
Tracing PhylogenyTracing Phylogeny
Convergent EvolutionConvergent Evolution
The acquisition of a feature in distantly related The acquisition of a feature in distantly related lines of descentlines of descent
The feature is not present in a common The feature is not present in a common ancestorancestor
Parallel EvolutionParallel Evolution
The acquisition of a feature in two or more The acquisition of a feature in two or more related lineagesrelated lineages
The feature is not present in a common The feature is not present in a common ancestorancestor
16Convergent Evolution-both like dry, hot environments & succulent with spiny
leavesbut not closely related.
17Classification ofClassification of Living Things Living Things
Molecular DataMolecular Data
Protein ComparisonsProtein Comparisons Immunological techniquesImmunological techniques Degree of cross reaction used to judge relationshipDegree of cross reaction used to judge relationship
Amino acid sequencingAmino acid sequencing Similar sequence in same protein indicates close Similar sequence in same protein indicates close
relationshiprelationshipRNA and DNA ComparisonsRNA and DNA Comparisons
Systematics assumes:Systematics assumes: Two species with similar base-pair sequences are Two species with similar base-pair sequences are
assumed to be closely relatedassumed to be closely related Two species with differing base-pair sequences are Two species with differing base-pair sequences are
assumed to be only distantly relatedassumed to be only distantly relatedMolecular ClocksMolecular Clocks
Use non adaptive nucleotide sequencesUse non adaptive nucleotide sequences Assumed constant rate of mutation over timeAssumed constant rate of mutation over time
19Classification ofClassification of Living Things Living Things
Cladistic SystematicsCladistic Systematics
Traces evolutionary history of the group Traces evolutionary history of the group under studyunder study
Uses shared derived characters to:Uses shared derived characters to:
Classify organisms, andClassify organisms, and
Arrange taxa into a cladogramArrange taxa into a cladogram
A cladogram is a special type of phylogenetic A cladogram is a special type of phylogenetic treetree
A clade is an evolutionary branch that includes:A clade is an evolutionary branch that includes: A common ancestor, together withA common ancestor, together with
All its descendent speciesAll its descendent species
21Classification ofClassification of Living Things Living Things
ParsimonyParsimony
Cladists are always guided by the principle of Cladists are always guided by the principle of parsimonyparsimony
The arrangement requiring the fewest The arrangement requiring the fewest assumptions is preferredassumptions is preferred
This would:This would:
Leave the fewest number of shared derived Leave the fewest number of shared derived characters unexplainedcharacters unexplained
Minimize the number of assumed evolutionary Minimize the number of assumed evolutionary changeschanges
The reliability of a cladogram is dependent on The reliability of a cladogram is dependent on the knowledge and skill of the investigatorthe knowledge and skill of the investigator
23Classification ofClassification of Living Things Living Things
Phenetic SystematicsPhenetic Systematics
Assumes it will never be possible to construct Assumes it will never be possible to construct a truly phylogenetic classification systema truly phylogenetic classification system
Species are classified according to the total Species are classified according to the total number of shared similaritiesnumber of shared similarities
Disregards assumed phylogenetic Disregards assumed phylogenetic considerationsconsiderations
Ignores issues of convergent or parallel Ignores issues of convergent or parallel evolutionevolution
24Classification ofClassification of Living Things Living Things
Traditional SystematicsTraditional Systematics
Mainly uses anatomical dataMainly uses anatomical data
Classify organisms using assumed phylogeny Classify organisms using assumed phylogeny with emphasis on phenotypewith emphasis on phenotype
Stress both common ancestry and degree of Stress both common ancestry and degree of structural difference among divergent groupsstructural difference among divergent groups
Construct phylogenetic trees by applying Construct phylogenetic trees by applying evolutionary principles to categoriesevolutionary principles to categories
Not strict in making sure all taxa are Not strict in making sure all taxa are monophyleticmonophyletic
25Classification ofClassification of Living Things Living Things
Classification SystemsClassification Systems
Until the middle of the twentieth century, Until the middle of the twentieth century, biologists recognized only two kingdomsbiologists recognized only two kingdoms
Plantae (plants)Plantae (plants)
Animalia (animals)Animalia (animals)
Protista (protists) were added as third Protista (protists) were added as third kingdom in the 1880skingdom in the 1880s
Whittaker expanded to five kingdoms in 1969 Whittaker expanded to five kingdoms in 1969 by adding Fungi and Moneraby adding Fungi and Monera
26Classification ofClassification of Living Things Living ThingsThree-Domain System-compare table Three-Domain System-compare table
20.320.3
The Bacteria and Archaea are so different The Bacteria and Archaea are so different they have been assigned to separate they have been assigned to separate domains domains
Similar in that both are asexually reproducing Similar in that both are asexually reproducing unicellular prokaryotesunicellular prokaryotes
Distinguishable by:Distinguishable by:
Difference in rRNA base sequencesDifference in rRNA base sequences
Plasma membrane chemistryPlasma membrane chemistry
Cell wall chemistryCell wall chemistry
27Classification ofClassification of Living Things Living Things
Three-Domain SystemThree-Domain System
Domain EukaryaDomain Eukarya
Unicellular and multicellular organisms Unicellular and multicellular organisms
Cells with a membrane-bounded nucleusCells with a membrane-bounded nucleus
Sexual reproduction commonSexual reproduction common
Contains four kingdomsContains four kingdoms
Kingdom Protista
Kingdom Fungi
Kingdom Plantae
Kingdom Animalia
30Classification ofClassification of Living Things Living Things
ReviewReview
TaxonomyTaxonomy Binomial SystemBinomial System Species IdentificationSpecies Identification Classification CategoriesClassification Categories
Phylogenetic TreesPhylogenetic Trees SystematicsSystematics Taxonomy (naming of organisms)Taxonomy (naming of organisms) Classification (placing species in the proper categories)Classification (placing species in the proper categories)
Systematics TodaySystematics Today Cladistic SystematicsCladistic Systematics Phenetic SystematicsPhenetic Systematics
Classification SystemsClassification Systems The Five Kingdom SystemThe Five Kingdom System The Three Domain SystemThe Three Domain System