Chapter 26: Phylogeny and the tree of life (1)

Question 1

Define phylogeny.

Answer 1

Phylogeny is the evolutionary history of a species or group of related species

Question 2

Define systematics.

Answer 2

Systematics is a discipline focused on classifying organisms and determining their evolutionary relationship.

Question 3

What is taxonomy?

Answer 3

Taxonomy is the scientific discipline concerned with classifying and naming organisms.

Question 4

Explain the Linnaean classification of groups.

Answer 4

From broad to narrow:

• domain
• kingdom
• phylum
• class
• order
• family
• genus
• species

(DonKey Phl COFed on GiSel)

Question 5

A taxonomic unit at any level of hierarchy is called a _________

Answer 5

A taxonomic unit at any level of hierarchy is called a taxon.

Question 6

What are the parts of a phylogenetic tree?

Answer 6

1. Branch point
2. Sister taxa
3. Ancestral lineage(root)
4. Basal Taxon
5. Polytomy

Question 7

Define branch point.

Answer 7

Each branch point represents the divergence of two species

Question 8

Define sister taxa.

Answer 8

Sister taxa are groups that share an immediate common ancestor

Question 9

Define a rooted tree.

Answer 9

A rooted tree includes a branch to represent the last common ancestor of all taxa in the tree

Question 10

Define basal taxon.

Answer 10

A basal taxon diverges early in the history of a group and originates near the common ancestor of the group.

Question 11

Define polytomy.

Answer 11

A polytomy is a branch from which more than two groups emerge.

Question 12

Differentiate between homology and analogy.

Answer 12

Homology
- Homology is similarity due to shared ancestry

Analogy
- Analogy is similarity due to convergent evolution

Question 13

How does convergent evolution occur?

Answer 13

Convergent evolution occurs when similar environmental pressures and
natural selection produces similar adaptations in organisms from different evolutionary lineages.

Question 14

How can you sort out homologies from analogies?

Answer 14

Homology can be distinguished from analogy by
comparing
– (1) fossil evidence and
– (2) degree of complexity

• Physiology, and reproductive systems
  are very dissimilar in analogies.
• Another clue to distinguishing between homology and analogy is the complexity of comparing the characters.
  (For ex: human and chimpanzee skulls are made up of fused materials, this complexity makes it highly likely that they had the same ancestor)

Question 15

Define homoplasies from homologies.

Answer 15

Analogous structures or molecular sequences that evolved independently are also called homoplasies.

Question 16

Define molecular systematics.

Answer 16

Molecular systematics uses DNA and other molecular data to determine the evolutionary relationship

Question 17

Define cladistics.

Answer 17

Cladistics uses common ancestry as the primary criterion used to classify organisms.

Question 18

Define clade.

Answer 18

A clade is a group of species that includes an ancestral species and all its descendant

Question 19

Define monophyletic clade,

Answer 19

A valid clade is monophyletic, signifying
that it consists of the ancestor species and all its descendants

Question 20

Differentiate between paraphyletic and polyphyletic groups.

Answer 20

A paraphyletic grouping consists of an ancestral species and some, but not all, of the descendants

A polyphyletic grouping includes distantly related species but does not include their most recent common ancestor