11.1.1 Classifying the Products of Evolution: Taxonomy

Question 1

Classifying the Products of Evolution: Taxonomy

Answer 1

• Phylogeny is the evolutionary history of a species or group of related species.
• The science of systematics involves categorizing species according to phylogeny.
• Modern systematics incorporates taxonomy and cladistics. Taxonomy involves describing and naming the various forms
of life. Cladistics is a type of taxonomy that classifies organisms based on degree of relationship.
• Phylogenetic trees and cladograms are graphic representations of the evolutionary relationship between organisms.
• Each branch (clade) of a cladogram represents a new divergence between species.

Question 2

Systematics

Answer 2

• the study of the relationships among the diversity of life-forms on the planet. The information about each organism comes from evolutionary history, genetics,
  and anatomy.

Question 3

Taxonomy

Answer 3

• the branch of systematics that creates a classification scheme for organisms.
• Two different approaches to taxonomy are phenetics and cladistics

Question 4

phenetics

Answer 4

• involves classifying organisms based entirely on
  measurable similarities and differences in phenotypic
  characteristics. Phenetics ignores the distinction between homologous and analogous structures
• Review: Homologousstructures are similar structures shared by species because of common ancestry. Analogous structures appear superficially similar, but do not reflect a common ancestry.
• Using phenetics, a scientist would compare anatomical
  characteristics between the bat, bird, and butterfly illustrated to the left. Naively considering analogous structures (wings), the three organisms might erroneously be classified as close relatives.

Question 5

Cladistics

Answer 5

• classifies organisms according to the order in time
  that branching occurs in a phylogenetic tree. This approach reflects evolutionary relationships. Relying on the fields of genetics, developmental biology, and anatomy, cladistic analysis uses shared homologous structures among organisms. Cladistics is the dominant approach in modern taxonomy.
• Cladistic analysis of the bat, bird, and butterfly to the left would consider homologies among the three. Based on cladistic analysis, butterflies are placed in a separate phylum from bats and birds.
• For a given group of organisms, a clade is an evolutionary branch. Clades can be organized into a phylogenetic tree called a cladogram.
• The cladogram on the left shows members of the taxonomic family Ursidae, which includes the black bear, grizzly bear, and giant panda. The scheme is based on information from molecular genetics, development, and morphology.

Question 6

True or false?

If two organisms have DNA that is 97% identical, then they are in the same species.

Answer 6

• false

Question 7

Each branch of a cladogram represents a new divergence betweeen species. These branches are also called

Answer 7

• clades

Question 8

Which one of the following was developed by Carl Linneaus?

Answer 8

• Binomial nomenclature

Question 9

What are two approaches to taxonomy?

Answer 9

• Cladistics and phenetics

Question 10

On what does phenetics base its conclusions?

Answer 10

• data concerning the similarities between organisms

Question 11

Which of the following is the best description of taxonomy?

Answer 11

• Classification of organisms based on systematics