Phylogenetics

Question 1

Ancestral State

Answer 1

A character with the same state as the ancestor of a group has an ancestral state.

Question 2

Branches

Answer 2

Represent the evolution of taxa over time.

Question 3

Character

Answer 3

A heritable feature of an organism. Also known as a character trait. How we infer the phylogenetic history of a group.

Question 4

Character State

Answer 4

The form that a character takes.

Question 5

Chronogram

Answer 5

Branch lengths are proportional to absolute time.

Question 6

Cladogram

Answer 6

only the order of branching is shown; branch lengths have no meaning.

Question 7

Data Matrix

Answer 7

A hypothesis of homology; all characters are assumed to be homologous unless shown otherwise. (Morphology and behavior are coded numerically; DNA sequence data is coded by nucleotides)

Question 8

Derived State

Answer 8

A character with a different state as the ancestor of a group has a derived state.

Question 9

Homology

Answer 9

is similarity due to common ancestry. (Synapomorphies are homologous)

Question 10

Homoplasy

Answer 10

is similarity NOT due to common ancestry. It is due to convergent evolution.

Question 11

Ingroup

Answer 11

group of taxa you are analyzing

Question 12

Monophyly

Answer 12

(aka natural group) group of organisms consisting of their MRCA and all of its descendants.

Question 13

MRCA

Answer 13

Most Recent Common Ancestor

Question 14

Node

Answer 14

Represent the MRCA of 2 or more descendants of taxa.

Question 15

Outgroup

Answer 15

an ancestor that has some but not too much relation to ingroup taxa. Outgroups can be used to discover the starting conditions for your ingroup

Question 16

Paraphyly

Answer 16

include the MRCA but exclude one or more descendants.

Question 17

Parsimony

Answer 17

the best tree is the one with the fewest # of character changes.

Question 18

Phylogeny

Answer 18

Figures that represent the ancestor-descendant relationships among a group of organisms. (Horizontal, vertical, and circular).

Question 19

Phylogram

Answer 19

Branch lengths are proportional to amount of genetic change.

Question 20

Polyphyly

Answer 20

Combine organisms that lack a MRCA.

Question 21

Polytomy

Answer 21

Used when there is uncertainty in the branching pattern. (Soft: used when we have insufficient or conflicting data; hard: used when speciation happened so fast that there are no data that can resolve the relationships(rare))

Question 22

Root Branch

Answer 22

Leads to root node which is the MRCA of all descendant taxa on the phylogeny.

Question 23

Root Node

Answer 23

common ancestral taxa, origin

Question 24

Rooted tree

Answer 24

shows there is an MRCA

Question 25

Sister group

Answer 25

Two clades or species that are each other’s closest relatives, the two descendant taxa of a single node, originate as lineages at the same time.

Question 26

Speciation

Answer 26

The process whereby one species gives rise to two descendant species.

Question 27

Synapomorphy

Answer 27

Shared derived state; they define monophyletic groups.

Question 28

Taxa

Answer 28

Are at the tips; a taxon is any named group; taxa refers to multiple taxons.

Question 29

Unrooted Tree

Answer 29

a tree in which the root has been removed and relationships among taxa are more ambiguous ; remove root & straighten branch; shows branch splitting events but says nothing about the temporal sequence of these events ; no direction