chapter 7 animal classification, phylogeny, and organization

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Chapter 7 Animal Classification, Phylogeny, and Organization

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Page 1: Chapter 7 Animal Classification, Phylogeny, and Organization

Chapter 7

Animal Classification, Phylogeny, and Organization

Page 2: Chapter 7 Animal Classification, Phylogeny, and Organization

Classification of Organisms

• Systematics or taxonomy– Study of the kinds and diversity of

organisms and of the evolutionary relationships among them

Page 3: Chapter 7 Animal Classification, Phylogeny, and Organization

A Taxonomic Hierarchy

• Taxon– Any grouping of animals that shares a

particular set of characteristics

• Taxonomic categories– Hierarchically arranged (broader to

specific)– Domain, kingdom, phylum, class, order,

family, genus, species– Above species level there are no

definitions for each category

Page 4: Chapter 7 Animal Classification, Phylogeny, and Organization

Table 7.1

Page 5: Chapter 7 Animal Classification, Phylogeny, and Organization

Nomenclature

• Binomial system of nomenclature• International Code of Zoological

Nomenclature– Homo sapiens (H. sapiens)– Other naming rules

Page 6: Chapter 7 Animal Classification, Phylogeny, and Organization

Molecular Approaches to Animal Systematics

• Relatedness of animals reflected in proteins and DNA.– Nuclear and mitochondrial DNA– Ribosomal RNA

Page 7: Chapter 7 Animal Classification, Phylogeny, and Organization

Domains and Kingdoms

• Ribosomal RNA studies– Distant evolutionary relationships– Evolutionary conservation results in slow rates of change.

• Three major lineages (Domains)– Eubacteria

• Bacteria

– Archaea• Extremophile microbes

– Eukarya• Organisms with compartmentalized cells• Nuclear membranes mitochondrial and chloroplast membranes

• Horizontal gene transfer (HGT) common in early history of life and makes base of tree net-like

Page 8: Chapter 7 Animal Classification, Phylogeny, and Organization

Figure 7.2 Three lineages of life.

Page 9: Chapter 7 Animal Classification, Phylogeny, and Organization

Animal Systematics

• Goal– Arrange animals into MONOPHYLETIC GROUPS

using traits having a genetic basis and that can be measured (characters).

– Single ancestral species and all descendants

• Groupings reflecting insufficient knowledge– Members of a lineage found to have separate

ancestry• Polyphyletic groups

– Some, but not all, members of a lineage included• Paraphyletic group

Page 10: Chapter 7 Animal Classification, Phylogeny, and Organization

Figure 7.3 Evolutionary groups.

Page 11: Chapter 7 Animal Classification, Phylogeny, and Organization

Approaches to Animal Systematics

• Evolutionary systematics– Traditional approach– Homologies useful in classification– Phylogenetic trees depict relationships,

time, and abundance.

Page 12: Chapter 7 Animal Classification, Phylogeny, and Organization

Figure 7.4 Phylogenetic tree showing vertebrate phylogeny.

Page 13: Chapter 7 Animal Classification, Phylogeny, and Organization

Approaches to Animal Systematics

• Phylogenetic systematics (cladistics)– Homologies of recent origin are most

useful.– Ancestral characters

• Common to all members of a group• Symplesiomorphies

– Outgroup• Related group not included in study group• Used to help decide whether or not a character

is ancestral or more recently derived

Page 14: Chapter 7 Animal Classification, Phylogeny, and Organization

Approaches to Animal Systematics

• Phylogenetic systematics (continued)– Derived characters

• Arisen since common ancestry with the outgroup

• Synapomorphies

– Clade• Related subset within a lineage

– Cladogram• Depicts a hypothesis regarding

monophyletic lineage

Page 15: Chapter 7 Animal Classification, Phylogeny, and Organization

Figure 7.5 This hypothetical cladogram shows five taxa (1-5) and characters (A-H) used in deriving taxonomic relationships.

Page 16: Chapter 7 Animal Classification, Phylogeny, and Organization

Approaches to Animal Systematics

• Phylogenetic species concept– Group of populations that have evolved

independently of other groups of populations– Monophyletic– Share one or more synapomorphies

• Hierarchical nesting– Cladograms represent nested groups that

share synapomorphic characters.– Less inclusive nests contain closely related

organisms.

Page 17: Chapter 7 Animal Classification, Phylogeny, and Organization

Figure 7.6 Cladogram showing vertebrate phylogeny.

Page 18: Chapter 7 Animal Classification, Phylogeny, and Organization

Compare figures 7.4 and 7.6

1. What kind of information is common to both representations?

2. What kind of information is present in figure 7.4 that is not in figure 7.6?

3. What kind of information is present in figure 7.6 that is not in figure 7.4?

4. How are the relationships between reptiles, birds, and mammals represented differently in the two figures?

5. How do the differences in question 4 reflect differing approaches of evolutionary systematics and phylogenetic systematics?

Page 19: Chapter 7 Animal Classification, Phylogeny, and Organization

• Symmetry describes how parts of an animal are arranged around a point or axis.

Table 7.2

Page 20: Chapter 7 Animal Classification, Phylogeny, and Organization

Figure 7.7 Sponges display cell-aggregate organization and some sponges are asymmetrical (Monochora barbadensis).

Page 21: Chapter 7 Animal Classification, Phylogeny, and Organization

Figure 7.8 This coral polyp (Tubastraea sp.) is radially symmetrical.

Page 22: Chapter 7 Animal Classification, Phylogeny, and Organization

Figure 7.9 Bilateral symmetry is accompanied by the formation of a distinct head (cephalization).

Page 23: Chapter 7 Animal Classification, Phylogeny, and Organization

Table 7.3

Page 24: Chapter 7 Animal Classification, Phylogeny, and Organization

Other Patterns of Organization

• Unicellular (cytoplasmic) level of organization– Protists (unicellular)– Sponges (cell

aggregate)

• Diploblastic organization– Ectoderm (outer

cellular layer)– Endoderm (inner

cellular layer)– Mesoglea (noncellular)

Page 25: Chapter 7 Animal Classification, Phylogeny, and Organization

Other Patterns of Organization

• Triploblastic Organization– Mesoderm

• Third tissue later sandwiched between ectoderm and endoderm

• Supportive, contractile, and blood cells

– Body cavities often present• Organ development• Exchanges by diffusion• Storage• Hydrostatic skeletons• Elimination of wastes and reproductive products• Facilitate increased body size

Page 26: Chapter 7 Animal Classification, Phylogeny, and Organization

Figure 7.11 Triploblastic Organization.

a) Triploblastic acoelomate– Mesoderm forms solid mass.

b) Triploblastic pseudocoelomate– Body cavity not entirely lined by mesoderm. – Gut is not associated with muscle or connective tissue.

c) Triploblastic coelomate– Body cavity completely surrounded by mesoderm.– Mesenteries suspend visceral structures in body cavity.

Page 27: Chapter 7 Animal Classification, Phylogeny, and Organization

Higher Animal Taxonomy

• Animalia is monophyletic– Molecular and embryological evidence

• Four phyla originated independently• Bilaterally symmetrical phyla

– Protostome phyla• Spiral, determinate cleavage• Trochophore larval stage• Ecdysozoa

– Molt a cuticle

• Lophotrochozoa

– Deuterostome phyla• Radial, indeterminate cleavage

Page 28: Chapter 7 Animal Classification, Phylogeny, and Organization

Figure 7.12 Animal taxonomy.

Page 29: Chapter 7 Animal Classification, Phylogeny, and Organization

Figure 7.13 Developmental characteristics of protostomes and deuterostomes.