Theme 5A/B

Question 1

What is phylogeny?

Answer 1

The evolutionary history of organisms

Question 2

What is a phylogenetic tree?

Answer 2

• A branching diagram that shows the relationships between species, often according to the time since a common ancestor
• For each species/group of species, shows which other species/group of species it shares its most recent common ancestor with
• Provides hypotheses of evolutionary relationship

Question 3

What is anagenesis?

Answer 3

• When evolutionary changes accumulate slowly over time, a pattern of gradual phyletic change
• Does not increase biodiversity, is simply the gradual transformation of one species into another as its characteristics shift over time
• Depicted as a straight line on a phylogenetic tree

Question 4

What is cladogenesis?

Answer 4

• An ancestral species undergoes speciation, producing two descendant species, both of which are distinct from their common ancestor
• Does increase biodiversity
• Depicted by a branching pattern on a phylogenetic tree

Question 5

What is a phylogram?

Answer 5

A phylogenetic tree where the branch lengths represent the amount of inferred evolutionary change/time. (branching + evolutionary “time”)

Question 6

What is a cladogram?

Answer 6

A phylogenetic tree where all branches are of equal length. (just branching)

Question 7

What is a sister group?

Answer 7

• Two species (or groups of species) that share a common ancestor not shared by any other species or group

Question 8

Character states can be similar for one of two reasons:

Answer 8

• Homologous characters (homologies): shared because of common ancestry, shared ancestral and derived characters
• Analogous characters (homoplasies): shared because of convergent evolution

Question 9

What is homoplasy?

Answer 9

• Similarity in appearance but not in origin

Question 10

What is homology?

Answer 10

the similarity of the structure, of organisms based upon their descent from a common evolutionary ancestor

Question 11

How are homologies recognized?

Answer 11

• structural similarity
• relations between parts
• embryonic development

Question 12

The strongest hypothesis of evolutionary relationships is:

Answer 12

the tree with the fewest number of changes required b/c it minimizes the total number of independent origins of characters states

Question 13

What is the principle of parsimony?

Answer 13

The phylogeny requiring the fewest evolutionary changes is the best estimate of the true phylogeny = most parsimonious

Question 14

Each nucleotide in the DNA sequence or amino acid sequence of proteins:

Answer 14

can act as a trait

Question 15

What is the distance method?

Answer 15

• DNA sequence differences reflect time since the common ancestor (more time and difference = more distantly related)
• Can estimate degrees of relatedness from comparisons of DNA sequences

Question 16

What is a monophyletic group?

Answer 16

Includes a common ancestor and all of its descendants

Question 17

What is a paraphyletic group?

Answer 17

Includes a common ancestor and some, but not all, of its descendants

Question 18

What is a polyphyletic group?

Answer 18

Does not include the common ancestor

Question 19

What is adaptive radiation?

Answer 19

The rapid evolution of new species occupying new niches

Question 20

What is graduated evolution?

Answer 20

• Slow and steady gradual evolution

- Results in anagenesis

Question 21

What is punctuated evolution?

Answer 21

• Rare and rapid (on a geologic time scale) events of branching speciation
• Results in cladogenesis