1. 10-1 CHAPTER 10 Taxonomy and Phylogeny of Animals Taxonomy and Phylogeny of Animals

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3. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-3 Linnaeus and Taxonomy More than 1.5 million species of animals are named More than 1.5 million species of animals are named Estimated that these account for Estimated that these account for Less than 20% of all extant animals Less than 20% of all extant animals Less than 1% of extinct animals Less than 1% of extinct animals Taxonomy Taxonomy Formal system for naming and classifying species Formal system for naming and classifying species Systematics Systematics Broader science of classifying organisms based on similarity, biogeography, etc. Broader science of classifying organisms based on similarity, biogeography, etc. Systematic zoologists have three goals Systematic zoologists have three goals To discover all species of animals To discover all species of animals To reconstruct their evolutionary relationships To reconstruct their evolutionary relationships To classify animals according to their evolutionary relationships To classify animals according to their evolutionary relationships

4. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-4 Linnaeus and Taxonomy Greek philosopher Aristotle first classified organisms Greek philosopher Aristotle first classified organisms Carolus Linnaeus designed the current system of classification Carolus Linnaeus designed the current system of classification Swedish botanist with extensive experience classifying objects, especially flowers Swedish botanist with extensive experience classifying objects, especially flowers Used morphology to develop a classification system of animals and plants Used morphology to develop a classification system of animals and plants Published in his work, Systema Naturae Published in his work, Systema Naturae Divided animal kingdom into species and gave each a distinctive name Divided animal kingdom into species and gave each a distinctive name Grouped species into genera, genera into orders, and orders into classes Grouped species into genera, genera into orders, and orders into classes His classification scheme has been drastically altered, but the basic principle is still followed His classification scheme has been drastically altered, but the basic principle is still followed

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6. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-6 Hierarchy of taxonomic ranks now includes 7 major groups Hierarchy of taxonomic ranks now includes 7 major groups Kingdom, phylum, class, order, family, genus, and species Kingdom, phylum, class, order, family, genus, and species All animals are placed in Kingdom Animalia All animals are placed in Kingdom Animalia Names of animal groups at each rank in the hierarchy are called taxa (taxon) Names of animal groups at each rank in the hierarchy are called taxa (taxon) Each rank can be subdivided into additional levels of taxa Each rank can be subdivided into additional levels of taxa Superclass, suborder, etc. Superclass, suborder, etc. Linnaeus and Taxonomy

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8. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-8 A scientific name of an animal consists of two words (binomial nomenclature) A scientific name of an animal consists of two words (binomial nomenclature) First word is the genus and is capitalized First word is the genus and is capitalized Second is the specific epithet written in lower case Second is the specific epithet written in lower case Scientific name should be printed in italics or underlined if handwritten Scientific name should be printed in italics or underlined if handwritten Homo sapiens Homo sapiens Genus name Genus name Always a noun Always a noun Names of genera must refer only to a single group of organisms Names of genera must refer only to a single group of organisms Linnaeus and Taxonomy

9. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-9 Species epithet Species epithet Usually an adjective that must agree in gender with the species Usually an adjective that must agree in gender with the species Never used alone Never used alone A specific epithet may be used in different genera A specific epithet may be used in different genera Sita carolinensis (white-breasted nuthatch) Sita carolinensis (white-breasted nuthatch) Poecile carolinensis (Carolina chickadee) Poecile carolinensis (Carolina chickadee) Ranks above species are single names written with a capital initial letter Ranks above species are single names written with a capital initial letter Reptilia and Cnidaria Reptilia and Cnidaria Linnaeus and Taxonomy

10. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-10 Geographic subspecies are trinomials Geographic subspecies are trinomials All three terms are in italics All three terms are in italics Subspecies is in lower case Subspecies is in lower case A polytypic species contains A polytypic species contains One subspecies whose subspecific name is a repetition of the species epithet One subspecies whose subspecific name is a repetition of the species epithet One or more additional subspecies whose names differ. One or more additional subspecies whose names differ. Linnaeus and Taxonomy

11. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-11 Introduction of evolutionary theory into animal taxonomy Introduction of evolutionary theory into animal taxonomy Changed taxonomist’s role from one of classification to systematization Changed taxonomist’s role from one of classification to systematization Classification Classification Denotes the construction of classes Denotes the construction of classes Grouping or organisms that possess a common feature called an essence Grouping or organisms that possess a common feature called an essence Used to define the class Used to define the class Linnaeus and Taxonomy

12. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-12 Systematization Systematization Places groups of species into units of common evolutionary descent Places groups of species into units of common evolutionary descent Character variation Character variation Used to diagnose systems of common descent Used to diagnose systems of common descent No requirement that an essential character be maintained throughout the system for its recognition as a taxon No requirement that an essential character be maintained throughout the system for its recognition as a taxon Linnaeus and Taxonomy

13. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-13 In classification In classification Taxonomist asks whether a species being classified contains the defining feature of a particular taxonomic class Taxonomist asks whether a species being classified contains the defining feature of a particular taxonomic class In systematization In systematization Taxonomist asks whether the characteristics of a species confirm or reject the hypothesis that it descends from the most recent common ancestor of a particular taxon Taxonomist asks whether the characteristics of a species confirm or reject the hypothesis that it descends from the most recent common ancestor of a particular taxon Linnaeus and Taxonomy

14. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-14 Species Biologists have repeatedly used certain criteria for identifying species Biologists have repeatedly used certain criteria for identifying species Common Descent Common Descent Central to nearly all modern concepts of species Central to nearly all modern concepts of species Smallest distinct groupings of organisms sharing patterns of ancestry and descent Smallest distinct groupings of organisms sharing patterns of ancestry and descent

15. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-15 Species Reproductive Community Reproductive Community Member of a species must form a reproductive community that excludes members of other species Member of a species must form a reproductive community that excludes members of other species Sexually reproducing populations Sexually reproducing populations Interbreeding is critical for maintaining a reproductive community Interbreeding is critical for maintaining a reproductive community Asexually reproducing populations Asexually reproducing populations Entails occupation of a particular ecological habitat in a particular place so that a reproducing population responds as a unit to evolutionary forces. Entails occupation of a particular ecological habitat in a particular place so that a reproducing population responds as a unit to evolutionary forces.

16. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-16 Species Any species has a distribution through space and distribution through time Any species has a distribution through space and distribution through time Geographic range Geographic range Species having very large geographic ranges or worldwide distributions Species having very large geographic ranges or worldwide distributions Cosmopolitan Cosmopolitan Species with very restricted geographic distributions Species with very restricted geographic distributions Endemic Endemic Evolutionary duration Evolutionary duration Distribution through time Distribution through time

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18. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-18 Species Typological Species Concept Typological Species Concept Before Darwin, a species was considered a distinct and immutable entity Before Darwin, a species was considered a distinct and immutable entity A type specimen was labeled and deposited in a museum A type specimen was labeled and deposited in a museum Represented the ideal form of a specimen Represented the ideal form of a specimen Small differences from the type Small differences from the type Considered accidental imperfections Considered accidental imperfections

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20. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-20 Species Today, organismal morphology still important in recognizing species Today, organismal morphology still important in recognizing species However, species no longer viewed as classes of organisms defined by possession of certain morphological features However, species no longer viewed as classes of organisms defined by possession of certain morphological features Type specimens serves only as a guide to general morphological features that one may expect to find in a particular species Type specimens serves only as a guide to general morphological features that one may expect to find in a particular species Variation is not viewed as an imperfect manifestation of an eternal “type” Variation is not viewed as an imperfect manifestation of an eternal “type”

21. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-21 Species Biological Species Concept Biological Species Concept Proposed by Theodosius Dobzhansky and Ernst Mayr Proposed by Theodosius Dobzhansky and Ernst Mayr Been refined and reworded several times Been refined and reworded several times A species is a reproductive community of populations (reproductively isolated from others) that occupies a specific niche in nature. A species is a reproductive community of populations (reproductively isolated from others) that occupies a specific niche in nature. Ability to successfully interbreed is central to the concept Ability to successfully interbreed is central to the concept Criteria of “niche” tie in ecological properties Criteria of “niche” tie in ecological properties

22. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-22 Species Sometimes species status can be evaluated directly by conducting breeding experiments Sometimes species status can be evaluated directly by conducting breeding experiments However, controlled breeding experiments can be difficult to conduct However, controlled breeding experiments can be difficult to conduct Molecular and other studies may detect sibling species Molecular and other studies may detect sibling species Species too similar in morphology to be diagnosed as separate species by morphological characters alone Species too similar in morphology to be diagnosed as separate species by morphological characters alone

23. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-23 Species Biological species concept Biological species concept Lacks an explicit temporal dimension Lacks an explicit temporal dimension Gives little guidance regarding the species status of ancestral populations relative to their evolutionary descendants Gives little guidance regarding the species status of ancestral populations relative to their evolutionary descendants Proponents of the biological species concept Proponents of the biological species concept Disagree on the degree of reproductive isolation necessary for considering two populations separate species Disagree on the degree of reproductive isolation necessary for considering two populations separate species

24. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-24 Species The biological species concept has received strong criticism The biological species concept has received strong criticism A species has limits in space and time A species has limits in space and time Boundaries between species may be difficult to locate. Boundaries between species may be difficult to locate. Interbreeding is not an operational definition in asexual organisms Interbreeding is not an operational definition in asexual organisms

25. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-25 Species Evolutionary Species Concept Evolutionary Species Concept Simpson proposed the evolutionary species concept in the 1940s Simpson proposed the evolutionary species concept in the 1940s Concept persists but with modification Concept persists but with modification An evolutionary species An evolutionary species A single lineage of ancestor-descendant populations that maintains its identity from other such lineages and that has its own evolutionary tendencies and historical fate. A single lineage of ancestor-descendant populations that maintains its identity from other such lineages and that has its own evolutionary tendencies and historical fate. Definition accommodates both sexual and asexual forms as well as fossils Definition accommodates both sexual and asexual forms as well as fossils

26. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-26 Species Phylogenetic Species Concept Phylogenetic Species Concept Phylogenetic species Phylogenetic species An irreducible (basal) grouping of organisms diagnosably distinct from other such groupings and within which there is a parental pattern of ancestry and descent. An irreducible (basal) grouping of organisms diagnosably distinct from other such groupings and within which there is a parental pattern of ancestry and descent. Both asexual and sexual groups are covered Both asexual and sexual groups are covered Phylogenetic species is a single population lineage with no detectable branching Phylogenetic species is a single population lineage with no detectable branching

27. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-27 Species Main difference in practice between the evolutionary and phylogenetic species concepts Main difference in practice between the evolutionary and phylogenetic species concepts The latter emphasizes recognizing as separate species the smallest groupings of organisms that have undergone independent evolutionary change The latter emphasizes recognizing as separate species the smallest groupings of organisms that have undergone independent evolutionary change Discerns the greatest number of species but may be impractical. Discerns the greatest number of species but may be impractical. Disregards details of evolutionary process Disregards details of evolutionary process

28. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-28 Species Dynamism of Species Concepts Dynamism of Species Concepts Disagreement is a sign of dynamic research Disagreement is a sign of dynamic research Should not be considered discouraging Should not be considered discouraging Cannot predict which species concepts will remain useful in the future Cannot predict which species concepts will remain useful in the future Possible that disagreements regarding species boundaries may identify interesting cases of evolution in action Possible that disagreements regarding species boundaries may identify interesting cases of evolution in action No one concept is comprehensive or final; No one concept is comprehensive or final; All need to be understood to understand future concepts All need to be understood to understand future concepts

29. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-29 Taxonomic Characters and Phylogenetic Reconstruction Major goal of systematics Major goal of systematics Infer the evolutionary tree or phylogeny that relates all extant and extinct species Infer the evolutionary tree or phylogeny that relates all extant and extinct species Accomplished by identifying organismal features called characters that vary among species Accomplished by identifying organismal features called characters that vary among species Characters are any feature used to study variation within and among species Characters are any feature used to study variation within and among species Identified by observing patterns of similarity of morphological, chromosomal, and molecular features Identified by observing patterns of similarity of morphological, chromosomal, and molecular features Less frequently, behavioral and ecological features are used Less frequently, behavioral and ecological features are used

30. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-30 Homology Homology Character similarity resulting from common ancestry Character similarity resulting from common ancestry Similarity does not always reflect common ancestry Similarity does not always reflect common ancestry Homoplasy Homoplasy Character similarity that misrepresents common descent Character similarity that misrepresents common descent Taxonomic Characters and Phylogenetic Reconstruction

31. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-31 Using Character Variation to Reconstruct Phylogeny First step is to determine which variant form of each character was present in the common ancestor of the entire group First step is to determine which variant form of each character was present in the common ancestor of the entire group The character state present in the common ancestor The character state present in the common ancestor Ancestral character Ancestral character All other variant forms of the character arose later within the group All other variant forms of the character arose later within the group Evolutionarily derived character Evolutionarily derived character Taxonomic Characters and Phylogenetic Reconstruction

32. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-32 Polarity of a character Polarity of a character Refers to identifying which one of its contrasting states is ancestral and which one(s) is derived Refers to identifying which one of its contrasting states is ancestral and which one(s) is derived Outgroup comparison Outgroup comparison Method used to examine the polarity of a variable character Method used to examine the polarity of a variable character Outgroup Outgroup Group that is phylogenetically close but not within the group being studied Group that is phylogenetically close but not within the group being studied Infer that any character state found both within the group being studied and the outgroup is ancestral for the study group Infer that any character state found both within the group being studied and the outgroup is ancestral for the study group Taxonomic Characters and Phylogenetic Reconstruction

33. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-33 Organisms or species that share derived character states Organisms or species that share derived character states Form subsets within the study group called a clade Form subsets within the study group called a clade Derived character shared by members of a clade Derived character shared by members of a clade Synapomorphy of that clade Synapomorphy of that clade Syapomorphies are used as evidence of homology Syapomorphies are used as evidence of homology Infers that a particular group of organisms forms a clade Infers that a particular group of organisms forms a clade A clade corresponds to a unit of evolutionary common descent A clade corresponds to a unit of evolutionary common descent Taxonomic Characters and Phylogenetic Reconstruction

34. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-34 Includes all descendants of a particular ancestral linage Includes all descendants of a particular ancestral linage Pattern of derived states of characters within study group Pattern of derived states of characters within study group Forms a nested hierarchy of clades within clades Forms a nested hierarchy of clades within clades By identifying the nested hierarchy of clades or branches By identifying the nested hierarchy of clades or branches Patterns of common descent can be formed Patterns of common descent can be formed Character states ancestral for a taxon are plesiomorphic for that taxon Character states ancestral for a taxon are plesiomorphic for that taxon Sharing of ancestral states is termed symplesiomorphy Sharing of ancestral states is termed symplesiomorphy Taxonomic Characters and Phylogenetic Reconstruction

35. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-35 Identifying the level at which a character state is a synapomorphy may identify a clade Identifying the level at which a character state is a synapomorphy may identify a clade Cladogram Cladogram Nested hierarchy of clades Nested hierarchy of clades To construct a phylogenetic tree To construct a phylogenetic tree Additional information concerning ancestors, duration of lineages, and amount of evolutionary change must be included Additional information concerning ancestors, duration of lineages, and amount of evolutionary change must be included Taxonomic Characters and Phylogenetic Reconstruction

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37. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-37 Sources of Phylogenetic Information Sources of Phylogenetic Information Comparative Morphology Comparative Morphology Examines shapes, sizes and development of organisms Examines shapes, sizes and development of organisms Skull bones, limb bones, scales, hair and feathers Skull bones, limb bones, scales, hair and feathers Living specimens and fossils are used Living specimens and fossils are used Taxonomic Characters and Phylogenetic Reconstruction

38. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-38 Comparative Biochemistry Comparative Biochemistry Analyzes sequences of amino acids in proteins and nucleotides sequences in nucleic acids Analyzes sequences of amino acids in proteins and nucleotides sequences in nucleic acids Recent studies show comparative biochemistry can be applied to fossils Recent studies show comparative biochemistry can be applied to fossils Comparative Cytology Comparative Cytology Examines variation in number, shape and size of chromosomes Examines variation in number, shape and size of chromosomes Used almost exclusively on living specimens Used almost exclusively on living specimens Taxonomic Characters and Phylogenetic Reconstruction

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40. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-40 Theories of Taxonomy Two currently popular theories of taxonomy Two currently popular theories of taxonomy Traditional Evolutionary Taxonomy Traditional Evolutionary Taxonomy Phylogenetic Systematics (cladistics) Phylogenetic Systematics (cladistics) A relationship between a taxonomic group and a phylogenetic tree or cladogram important in both theories Relationship can take on one of three forms A relationship between a taxonomic group and a phylogenetic tree or cladogram important in both theories Relationship can take on one of three forms Monophyly Monophyly A monophyletic taxon includes the most recent common ancestor and all descendants of that ancestor A monophyletic taxon includes the most recent common ancestor and all descendants of that ancestor

41. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-41 Paraphyly Paraphyly A taxon is paraphyletic if it includes the most recent common ancestor of all members of a group and some but not all descendants of that ancestor A taxon is paraphyletic if it includes the most recent common ancestor of all members of a group and some but not all descendants of that ancestor Polyphyly Polyphyly A taxon is polyphyletic if it does not include the most recent common ancestor of all members of a group A taxon is polyphyletic if it does not include the most recent common ancestor of all members of a group The group has at least two separate evolutionary origins The group has at least two separate evolutionary origins Theories of Taxonomy

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43. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-43 Both evolutionary and cladistic taxonomy Both evolutionary and cladistic taxonomy Accepts monophyletic Accepts monophyletic Rejects polyphyletic groups Rejects polyphyletic groups Differ on accepting paraphyletic groups. Differ on accepting paraphyletic groups. Difference has important evolutionary implications Difference has important evolutionary implications Theories of Taxonomy

44. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-44 Traditional Evolutionary Taxonomy Traditional Evolutionary Taxonomy The two main principles The two main principles Common descent Common descent Amount of adaptive evolutionary change Amount of adaptive evolutionary change A particular branch on an evolutionary tree A particular branch on an evolutionary tree Considered a higher taxon if it represents a distinct adaptive zone Considered a higher taxon if it represents a distinct adaptive zone Distinct “way of life” Distinct “way of life” A taxon that represents an adaptive zone is a grade A taxon that represents an adaptive zone is a grade Evolutionary taxa may be either monophyletic or paraphyletic Evolutionary taxa may be either monophyletic or paraphyletic By accommodating adaptive zones, nomenclature reflecting common descent is not as clear By accommodating adaptive zones, nomenclature reflecting common descent is not as clear Theories of Taxonomy

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48. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-48 Phylogenetic Systematics/Cladistics Phylogenetic Systematics/Cladistics Challenge to evolutionary taxonomy Challenge to evolutionary taxonomy Willi Hennig (1950) Willi Hennig (1950) First proposed cladistics or phylogenetic systematics First proposed cladistics or phylogenetic systematics Emphasizes common descent and cladograms Emphasizes common descent and cladograms Cladists avoid paraphyletic groups by defining a long list of sister groups to each more inclusive taxon. Cladists avoid paraphyletic groups by defining a long list of sister groups to each more inclusive taxon. Theories of Taxonomy

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50. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-50 Current State of Animal Taxonomy Current State of Animal Taxonomy Modern animal taxonomy Modern animal taxonomy Established using evolutionary systematics and recent cladistic revisions Established using evolutionary systematics and recent cladistic revisions Phylocode Phylocode New taxonomic system New taxonomic system Being developed as an alternative to Linnean taxonomy Being developed as an alternative to Linnean taxonomy Replaces Linnean ranks with codes that denote the nested hierarchy of monophyletic groups conveyed by cladograms Replaces Linnean ranks with codes that denote the nested hierarchy of monophyletic groups conveyed by cladograms The terms “primitive,” “advanced,” “specialized” and “generalized” The terms “primitive,” “advanced,” “specialized” and “generalized” Used for specific characteristics and not for groups as a whole Used for specific characteristics and not for groups as a whole Theories of Taxonomy

51. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-51 Major Division of Life Aristotle’s two kingdom system Aristotle’s two kingdom system Included plants and animals Included plants and animals One-celled organisms became a problem One-celled organisms became a problem Haeckel (1866) Haeckel (1866) Proposed Protista for single-celled organisms Proposed Protista for single-celled organisms R.H. Whittaker (1969) R.H. Whittaker (1969) Proposed a five-kingdom system to distinguish prokaryotes and fungi Proposed a five-kingdom system to distinguish prokaryotes and fungi Woese, Kandler and Wheelis Woese, Kandler and Wheelis Proposed three monophyletic domains above kingdom level—Eucarya, Bacteria and Archaea— based on ribosomal RNA sequences. Proposed three monophyletic domains above kingdom level—Eucarya, Bacteria and Archaea— based on ribosomal RNA sequences.

52. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-52 More revisions are necessary to clarify taxonomic kingdoms based on monophyly More revisions are necessary to clarify taxonomic kingdoms based on monophyly “Protozoa” “Protozoa” Neither animals nor a valid monophyletic taxon Neither animals nor a valid monophyletic taxon “Protista” “Protista” Not a monophyletic kingdom Not a monophyletic kingdom Most likely composed of seven or more phyla Most likely composed of seven or more phyla Major Division of Life

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54. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-54 Major Subdivisions of the Animal Kingdom Traditional groupings based on embryological and anatomical characters Traditional groupings based on embryological and anatomical characters Branch A (Mesozoa): phylum Mesozoa, the mesozoa Branch A (Mesozoa): phylum Mesozoa, the mesozoa Branch B (Parazoa): phylum Porifera, the sponges and phylum Placozoa Branch B (Parazoa): phylum Porifera, the sponges and phylum Placozoa Branch C (Eumetazoa): all other phyla Branch C (Eumetazoa): all other phyla

55. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-55 Grade I (Radiata): phyla Cnidaria, Ctenophora Grade I (Radiata): phyla Cnidaria, Ctenophora Grade II (Bilateria): all other phyla Grade II (Bilateria): all other phyla Division A (Protostomia): characteristics in Figure 10-12 Division A (Protostomia): characteristics in Figure 10-12 Acoelomates: phyla Platyhelminthes, Gnathostomulida, Nemertea Acoelomates: phyla Platyhelminthes, Gnathostomulida, Nemertea Pseudocoelomates: phyla Rotifera, Gastrotricha, Kinorhyncha, Nematoda, Nematomorpha, Acanthocephala, Entoprocta, Priapulida, Loricifera Pseudocoelomates: phyla Rotifera, Gastrotricha, Kinorhyncha, Nematoda, Nematomorpha, Acanthocephala, Entoprocta, Priapulida, Loricifera Eucoelomates: phyla Mollusca, Annelida, Arthropoda, Echiurida, Sipunculida, Tardigrada, Onychophora Eucoelomates: phyla Mollusca, Annelida, Arthropoda, Echiurida, Sipunculida, Tardigrada, Onychophora Major Subdivisions of the Animal Kingdom

56. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-56 Division B (Deuterostomia): characteristics in Figure 10-2 Division B (Deuterostomia): characteristics in Figure 10-2 phyla Phoronida, Ectoprocta,Chaetognatha, Brachiopoda, Echinodermata, Hemichordata, Chordata Major Subdivisions of the Animal Kingdom

57. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-57 Recent molecular phylogenetic studies have challenged traditional classification of Bilateria Recent molecular phylogenetic studies have challenged traditional classification of Bilateria Grade II: Bilateria Grade II: Bilateria Division A: (Protostomia): Division A: (Protostomia): Lophotrochozoa: phyla platyhelminthes, Nemertea, Rotifera, Gastrotricha, Acanthocephala, Mollusca, Annelida, Echiurida, Sipunculida, Phoronida, Ectoprocta, Entoprocta, Gnathostomulida, Chaetognatha, Brachiopoda Lophotrochozoa: phyla platyhelminthes, Nemertea, Rotifera, Gastrotricha, Acanthocephala, Mollusca, Annelida, Echiurida, Sipunculida, Phoronida, Ectoprocta, Entoprocta, Gnathostomulida, Chaetognatha, Brachiopoda Ecdysozoa: phyla Kinorhyncha, Nematoda, Nematomorpha, Priapulida, Arthropoda, Tardigrada, Onychophora, Loricifera Ecdysozoa: phyla Kinorhyncha, Nematoda, Nematomorpha, Priapulida, Arthropoda, Tardigrada, Onychophora, Loricifera Division B (Deuterostomia): Division B (Deuterostomia): phyla Chordata, Hemichordata, Echinodermata phyla Chordata, Hemichordata, Echinodermata Major Subdivisions of the Animal Kingdom

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