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Flashcards in Phylogenetics Deck (29)
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1

Ancestral State

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

2

Branches

Represent the evolution of taxa over time.

3

Character

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

4

Character State

The form that a character takes.

5

Chronogram

Branch lengths are proportional to absolute time.

6

Cladogram

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

7

Data Matrix

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)

8

Derived State

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

9

Homology

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

10

Homoplasy

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

11

Ingroup

group of taxa you are analyzing

12

Monophyly

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

13

MRCA

Most Recent Common Ancestor

14

Node

Represent the MRCA of 2 or more descendants of taxa.

15

Outgroup

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

16

Paraphyly

include the MRCA but exclude one or more descendants.

17

Parsimony

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

18

Phylogeny

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

19

Phylogram

Branch lengths are proportional to amount of genetic change.

20

Polyphyly

Combine organisms that lack a MRCA.

21

Polytomy

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))

22

Root Branch

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

23

Root Node

common ancestral taxa, origin

24

Rooted tree

shows there is an MRCA

25

Sister group

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.

26

Speciation

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

27

Synapomorphy

Shared derived state; they define monophyletic groups.

28

Taxa

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

29

Unrooted Tree

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