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

3. More than 1.5 million species of animals are named
Linnaeus and Taxonomy
More than 1.5 million species of animals are named
Estimated that these account for
Less than 20% of all animals currently alive
Less than 1% of extinct animals
Taxonomy (aka - Systematics)
Formal system for naming and classifying species
Science of classifying organisms based on similarity, biogeography, etc.

4. Systematics 3 types of Systematics/Taxonomy Evolutionary Systematics
Grouping organisms that resemble ancestors
Numerical Taxonomy
Used mathematical models to group organisms according to overall similarities
Phylogenetic Systematics (cladistics)
Use “outgroups”, differences between taxa to make a subset called a clade (Greek - branch)
Most commonly used, measures variety of characteristics. *Discussed later*

5. Greek philosopher Aristotle first classified organisms (350 BC)
Linnaeus and Taxonomy
Greek philosopher Aristotle first classified organisms (350 BC)
Carolus Linnaeus designed the current system of classification (1750)
Swedish botanist with extensive experience classifying objects, especially flowers
Used morphology (study of form and structure) to develop a classification system of animals and plants
Divided animal kingdom into species and gave each a distinctive name
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

6. Carolus
Linnaeus

7. Linnaeus and Taxonomy
Hierarchy of taxonomic ranks now includes 7 major groups
Kingdom, phylum, class, order, family, genus, and species
Now, the new level of Domain is also used.
All animals are placed in Kingdom Animalia, or Domain Eukarya
Taxa (Taxon) - Groups of animals that share a particular set of characteristics.
Example: True Flies “Diptera” - single pair of wings
Each rank can be subdivided into additional levels of taxa
Superclass, suborder, etc.

9. Division of Life - Milestones

10. 3 Domains - current proposal
Based on ribosomal RNA sequences

11. Nomenclature: assignment of a distinctive name to each species
Taxonomy
Nomenclature: assignment of a distinctive name to each species
A scientific name of an animal consists of two words (binomial nomenclature)
First word is the genus and is capitalized
Second is the species written in lower case
Scientific name should be printed in italics or underlined if handwritten
Homo sapiens

12. Taxonomy
Some animals are subspecies, usually caused by Geographic locations. They are referred to as trinomials (3 names)
All three terms are in italics
Subspecies is also in lower case
Ex. Ensantina eschscholtzii (salamander) has many subspecies.
E.e. plantens, E.e. picta, E.e.croceater

14. Biological Species Concept
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.
Ability to successfully interbreed is central to the concept
10-14

15. Reproductive Community
Species
Biologists use certain criteria for identifying species
Common Descent
Reproductive Community
Member of a species must form a reproductive community that excludes members of other species

16. Taxonomic Characters and Phylogenetic Reconstruction
Cladogram
Diagram illustrating hierarchy of clades (groups of animals with common ancestry)
To construct a Phylogenetic tree
Additional information concerning ancestors, duration of lineages, and amount of evolutionary change must be included (compared to cladogram)

17. A cladogram
Amphioxus is the “outgroup” because it doesn’t share any of the defining characteristic with the other taxa. What characteristic separates Bass from Horses?

18. Taxonomic Characters and Phylogenetic Reconstruction
Sources of Phylogenetic Information
(What do we use to identify animals??)
Comparative Morphology
Examines shapes, sizes and development of organisms
Skull bones, limb bones, scales, hair and feathers
Living specimens and fossils are used

19. Taxonomic Characters and Phylogenetic Reconstruction
Comparative Biochemistry
Analyzes sequences of amino acids in proteins and nucleotides sequences in nucleic acids
Recent studies show comparative biochemistry can be applied to fossils
Comparative Cytology
Examines variation in number, shape and size of chromosomes
Used almost exclusively on living specimens

20. Phylogenetic Tree based
On Cytology:
Comparing base
substitutions on
Cyctochrome C
(a respiratory protein).
#’ s represent number of
Mutations that occurred.

21. Animal Kingdom Patterns of Organization
Symmetry
Asymmetrical (no central body point/axis) ex. sponge
Bilateral (if divided right/left sides are mirror image) ex. vertebrates
Radial (any plane cut through organism makes mirror image) ex. Sea anemone
Embryonic Tissue Layers:
Diploblastic - 2 tissues (ectoderm and endoderm)
Triploblastic - 3 tissue layers (also mesoderm)
Zygote Cleavage
Protostome - blastopore becomes mouth
Deuterostome - blastopore becomes anus

23. Major Subdivisions of the Animal Kingdom
Traditional groupings based on embryological and anatomical characters
Branch (Parazoa): phylum Porifera, the sponges and phylum Placozoa
Branch (Eumetazoa): all other phyla

24. Major Subdivisions of the Animal Kingdom
Branch Eumetazoa
Grade I (Radiata): phyla Cnidaria
Grade II (Bilateria): all other phyla
Division A (Protostomia): (subdivisions made by presence of coelom in embryo)
Acoelomates: phyla Platyhelminthes,
Pseudocoelomates: phyla Rotifera, Nematoda,
Eucoelomates: phyla Mollusca, Annelida, Arthropoda, Tardigrada,
Division B (Deuterostomia):
phyla Echinodermata, Chordata

25. Major Subdivisions of the Animal Kingdom
Recent molecular Phylogenetic studies have challenged traditional classification of Bilateria
Grade II: Bilateria
Division A: (Protostomia):(subdivisions made by molting/shedding)
Lophotrochozoa (non-molting): phyla platyhelminthes, Rotifera, Mollusca, Annelida,
Ecdysozoa (outer covering sheds or molts): phyla Nematoda, Arthropoda, Tardigrada,
Division B (Deuterostomia):
phyla Chordata, Echinodermata