Taxonomy

Question 1

What is Polytomy?

Answer 1

• A node on a phylogeny where more than two lineages descend from a single common ancestor
• Indicates
  We don’t know the relationship between the descendent
  lineages
  Descendent lineages spectated simultaneously

Question 2

How are species named?

Answer 2

• Common name
  Not generally standardized
  Multiple names for one species possible
  Multiple species for one name possible
  Varies across languages
• Scientific name
  Standardized and consistent around the world
  Changes with phylogeny

Question 3

Scientific Names

Answer 3

• Composed of two words
  Genus
  Species
• Underlined rather than italics if handwritten
• Sometimes the species is written as “sp” or
  “spp”
• Sometimes there is also a subspecies
  In this case we use trinomial nomenclature

Question 4

What is taxonomy?

Answer 4

• Study of the principles of scientific classification; systematic ordering and naming of organisms
• Who governs taxonomy?
  Nobody
  New species are decided via peer-review

Question 5

History of Taxonomy

Answer 5

• Linneaus : Father of Taxonomy
• First unified system for naming all plants and animals
  Based on shared characters among organisms
  Doesn’t consider evolution (predates evolutionary biology)
• Basic principles remain, but many of his classifications are drastically altered in modern taxonomy (based on evolution)
• We still follow a hierarchical system of classification

Question 6

Taxonomic Ranks

Answer 6

• Hierarchical system of classification based on Linnaean taxonomy
• Each species belongs to a single Genus, Family, Order, Class, Phylum, Kingdom and Domain
• Intermediate taxa are also possible
• Problematic in some ways

Question 7

Taxonomic Hierarchy

Answer 7

• 3 domains and 5-6 kingdoms
• Primary focus of this class is at the Phylum level
  Each lecture in Animal Diversity section focuses on a single
  Phylum
• Examples given at the species level

Question 8

Taxonomic Ranks (Domains)

Answer 8

Eukaryote (membrane-bound nucleus)
    Animals 
    Plants 
    Protists 
    Fungi 
Bacteria and Archaea 
     Prokaryotes (no nuclear membrane)

Question 9

5 Kingdom System

Answer 9

Animalia (Metazoan)
Plantae 
Fungi 
Protista 
Monera (all prokaryotes)

Question 10

6 Kingdom System

Answer 10

Animalia (Metazoa)
Plantae
Fungi
Protista
Bacteria
Archea

Question 11

Old vs New

Answer 11

modern usage only relies on evolutionary relationships, but keeps this old hierarchical structure

Question 12

Some problems with modern taxonomy

Answer 12

• Not governed by any international body
• Skewed towards pedagogical convenience rather than a true reflection of phylogeny
• Hierarchical ranks are difficult and outdated

Question 13

Metazoans and Protozoans

Answer 13

• Metazoa is a kingdom of multi cellular animals (also called Animalia)
• Protista is a kingdom of unicellular eukaryotes. Includes
  Protozoa: animal-like unicellular eukaryotes
  Protophyta: plant-like unicellular eukaryotes
  Fungus-like slime molds
  Not monophyletic

Question 14

What are Protozoa?

Answer 14

• Once considered to be a phylum
• No longer recognized as a monophyletic clade
• Understood to be spread throughout eukaryotic clades
  Unicellular eukaryotes are a paraphyletic group

Question 15

The group formerly known as Protozoa

Answer 15

• It is convenient to discuss these organisms as a group
• They have little in common from an evolutionary perspective
• Can be referred to as animal-like unicellular eukaryotes