Chapter 27 (Phylogenies & the History of Life)

Question 1

adaptive radiation

Answer 1

Rapid evolutionary diversification within one lineage, producing numerous descendant species with a wide range of adaptive forms.

Question 2

ancestral trait

Answer 2

A trait found in ancestors.

Question 3

branch

Answer 3

A part of a phylogenetic tree that represents populations through time.

Question 4

cladistic approach

Answer 4

A method for constructing a phylogenetic tree that is based on identifying the unique traits of each monophyletic group. Compare with phenetic approach.

Question 5

convergent evolution

Answer 5

The independent evolution of analogous traits in distantly related organisms due to adaptation to similar environments and a similar way of life.

Question 6

derived trait

Answer 6

A trait that is clearly homologous with a trait found in an ancestor, but which has a new form.

Question 7

homoplasy

Answer 7

Similarity among organisms of different species due to convergent evolution. Compare with homology.

Question 8

node

Answer 8

In a phylogenetic tree, the point where two branches diverge, representing the point in time when an ancestral group split into two or more descendant groups. Also called fork.

Question 9

outgroup

Answer 9

A taxon that is closely related to a particular monophyletic group but is not part of it.

Question 10

phenetic approach

Answer 10

A method for constructing a phylogenetic tree by computing a statistic that summarizes the overall similarity among populations, based on the available data. Compare with cladistic approach.

Question 11

phylogenetic tree

Answer 11

A diagram that depicts the evolutionary history of a group of species and the relationships among them.

Question 12

phylogeny

Answer 12

The evolutionary history of a group of organisms.

Question 13

short interspersed nuclear elements (SINES)

Answer 13

The second most abundant class of transposable elements in human genomes; can create copies of itself and insert them elsewhere in the genome. Are much shorter than LINEs, which move by a similar mechanism.

Question 14

synapomorphy

Answer 14

A shared, derived trait found in two or more taxa that is present in their most recent common ancestor but is missing in more distant ancestors. Useful for inferring evolutionary relationships.

Question 15

tip

Answer 15

The end of a branch on a phylogenetic tree. Represents a specific species or larger taxon that has not (yet) produced descendants—either a group living today or a group that ended in extinction. Also called terminal node.

Question 16

parsimony

Answer 16

The logical principle that the most likely explanation of a phenomenon is the most economical or simplest. When applied to comparison of alternative phylogenetic trees, it suggests that the one requiring the fewest evolutionary changes is most likely to be correct.