Ch. 14: Phylogeny

Question 1

What is phylogeny?

Answer 1

The study of the evolutionary history of a species or group of organisms. It describes the relationships between organisms, such as which organisms an organism is thought to have evolved from and which species it is most closely related to. Allows us to make classifications

Question 2

What is a lineage?

Answer 2

a series of ancestor and descendant populations

Question 3

Describe the components of a phylogenic tree.

Answer 3

Question 4

What can a phylogenic tree portray?

Answer 4

• all life forms
• major evolutionary groups
• small groups of closely related species
• individuals
• populations
• genes

Question 5

What is a taxon?

Answer 5

any group of species designated with a name

Question 6

What is a clade?

Answer 6

any taxon that consists of all the evolutionary descendants of a common ancestor

Question 7

What does homologous mean?

Answer 7

Any features shared by two or more species that descended from a common ancestor are said to be homologous

Question 8

What is a synapomorphy?

Answer 8

Derived traits that are shared among a group and are viewed as evidence of the common ancestry of the group are known as synapomorphies

Question 9

What are homoplastic traits?

Answer 9

Similar traits generated by convergent evolution and/or evolutionary reversals are called homoplastic traits or homoplasies

Question 10

Concerning a phylogenic tree, what is an ingroup?

Answer 10

the group of organisms of primary interest

The root of the tree is located between the ingroup and the outgroup

Question 11

Concerning a phylogenic tree, what is an outgroup?

Answer 11

species or group known to be closely related to, but phylogenetically outside of, the group of interest

The root of the tree is located between the ingroup and the outgroup.

Question 12

What if a trait is present in both the ingroup and the outgroup?

Answer 12

the trait must have evolved before the origin of the ingroup and thus is ancestral for the ingroup. traits present in only somemembers of the ingroup must be derived traits.

Question 13

What are the steps to constructing a phylogenic tree?

Answer 13

1) select a group of organisms to classify (the ingroup) and an appropriate outgroup.

2) choose the characters that will be used in the analysis and identify the possible forms (traits) of the character.

3) determine the ancestral and derived traits

4) distinguish homologous from homoplastic traits

Question 14

What are applications of phylogenetic trees?

Answer 14

• reconstructing past events
• forensic investigations that involve viral transmission
• compare and contrast living organisms
• reveal convergent evolution
• reconstructing ancestral states
• molecular clocks
• understanding zoonotic diseases

Question 15

What is a molecular clock?

Answer 15

a molecular clock uses the average rate at which a given gene or protein accumulates changes to gauge the time of divergence

Question 16

As it concerns a phylogenic tree, what does monophyletic mean?

Answer 16

containing and all descendants of that ancestor, and no other organisms (a clade). a true monophyletic group can be removed from a phylogenetic tree by a single “cut.”

Question 17

As it concerns a phylogenic tree, what does polyphyletic mean?

Answer 17

a group that does not include its common ancestor

Question 18

As it concerns a phylogenic tree, what does paraphyletic mean?

Answer 18

a group that does not include all the descendants of a common ancestor