Animal Classification and Phylogeny

Question 1

What is the fundamental basis by which organisms are classified?

Answer 1

Taxonomy and Systematics

Question 2

Taxon

Answer 2

Grouping of animals

Question 3

Taxonomy and Systematics

Answer 3

Study of naming and grouping diversity based on their evolutionary traits

Question 4

Who was the first person to come up with a scientific scheme of classification?

Answer 4

Carolus Linnaeus

Question 5

What is the binomial system of nomenclature?

Answer 5

Linnaeus’ system of arranging specimens into a hierarchical system- an ascending series of groups of increasing inclusiveness.

Question 6

Characteristics of binomial nomenclature

Answer 6

a. Two words printed in italics
b. First name genus (capitalized), second name species (lowercase)
c. Two different genera cannot have the same name, but two species in different genera can have the same name (Sitta carolinensis, Anolis carolinensis, Poecile carolinensis)

Question 7

Mandatory taxonomic categories

Answer 7

Kingdom, Phylum, Class, Order, Family, Genus, Species (woo!)

Question 8

What is an outgroup and how do you use outgroup comparison to construct a cladogram?

Answer 8

An outgroup is closely related to a group being studied, but not within the group itself. The outgroup provides another species that has common ancestry with all of the other groups, but does not share the characteristics with the groups being compared. It makes identifying ancestral traits possible.

Question 9

What are the different ways taxa could be grouped?

Answer 9

Evolutionary Taxonomy and Cladistics

Question 10

How does evolutionary taxonomy classify animals? Who came up with it?

Answer 10

ET groups taxa based on characters that are either homologous or analogous. It recognizes a group as a distinct taxon if it represents a distinct “adaptive zone”- a fundamental change in organismal structure and behavior. Results in taxa that are either monophyletic or paraphyletic. Developed by George Simpson and Ernst Mayr.

Question 11

How do cladistics classify animals? Who came up with it?

Answer 11

Emphasizes every organism’s descent from a common ancestor (homology). All taxa must be monophyletic, no room for paraphyly. Produces a nested hierarchy that is consistent with Darwin’s idea of evolution being a branching process. Developed by Willi Hennig.

Question 12

What are the major disagreements between ET and cladistics on classifying animals?

Answer 12

ET uses both monophyletic and paraphyletic taxa, while cladistics uses only monophyletic. Cladistics asserts that all organisms have a common ancestor. Cladistics asserts that the evolutionary tree is not a ladder-like progression of increasing complexity, because evolution has also resulted in reduced complexity.

Question 13

What are the major concepts for what constitutes a species? What are the pros and cons of each concept?

Answer 13

1. Typological or Morphological Species concept- species considered a fixed entity, defined by a few essential morphological features (before Darwin). Designated by a type of specimen that represented the essential features for the species. Small differences from the type specimen were considered “noise.” Does not take into account evolutionary change, does not deal with variation within a species.
2. Biological species concept- Species is a population reproductively isolated from others. Accounts for common descent and variation within species. BUT lacks temporal dimension- how to decide whether an ancestral population is a distinct species relative to its descendants and cannot deal with species that reproduce asexually.
3. Phylogenetic Species Concept- a group of populations that has an independent evolutionary history. Emphasizes monophyly.