Topic 4: Systematics and Phylogeny

Question 1

Systematics

Answer 1

The theory and practice of classifying organisms based on evolutionary history.

Question 2

Phylogeny

Answer 2

Shown as a phylogenetic tree which shows the evolutionary relationships among organisms.

Question 3

Phylogenetic Trees

Answer 3

Demonstrates the evolutionary relationships between species and a common ancestor.

Question 4

Branch Point (Node)

Answer 4

Represents the common ancestor of two lineages.

Question 5

Dichotomous Branching

Answer 5

Divides into two branches

Question 6

Speciation

Answer 6

The divergence of two species from a common ancestor.

Question 7

Internal Branches

Answer 7

Connects two nodes

Question 8

External Branches

Answer 8

Connect a node and a tip.

Question 9

Basal Taxon

Answer 9

Diverges early and originates near the common ancestor.

Question 10

Sister Taxa

Answer 10

Two descendants that split from the same node

Question 11

Polytomy

Answer 11

A branch which more than two groups emerge. They lack sufficient data to determine lineages.

Question 12

Root/Rooted

Answer 12

One branch that represents the common ancestor of all taxa.

Question 13

Clades

Answer 13

Groups that include an ancestor and all its descendants

Question 14

Types of Phylogenetic Trees

Answer 14

Cladograms and Phylograms

Question 15

Cladograms

Answer 15

Depicts evolutionary relationships where only the branching pattern is important.

Question 16

Phylograms

Answer 16

Depicts evolutionary patterns and branch length represents evolutionary change.

Question 17

Homology

Answer 17

The trait was present i the common ancestor of the two organisms and retained overtime.

Question 18

Analogy

Answer 18

The trait evolved independently in the two organisms as an adaptation to similar environments

Question 19

Ingroup

Answer 19

The group whose evolutionary relationship you are studying

Question 20

Outgroup

Answer 20

One or more taxa related to the ingroup but that diverged early.

Question 21

Telling the difference between analogy and homology

Answer 21

Homo. have similar anatomy, developmental pathways in embryonic development, genetics, and can be traced back through history.

Question 22

Trait Complexity

Answer 22

The more complex two similar structures are, the more likely they are homologous.

Question 23

Characters (Traits)

Answer 23

anatomical, physiological, or molecular features used to compare taxa.

Question 24

Character States

Answer 24

The observed variation of a character, which can be used to determine evolutionary changes

Question 25

Cladistics

Answer 25

A method used to infer evolutionary relationships using homologous characters that group taxa based on shared derived characteristics.

Question 26

Shared derived characteristics

Answer 26

Traits that evolved in the most recent common ancestor of a clade and are unique to that group.

Question 27

Shared Ancestral Characters

Answer 27

Ancestral traits shared by a taxa of a clade but are also present in taxa of earlier clades.

Question 28

Paraphyletic Grouping

Answer 28

consists of a common ancestor, but not all descendants of the ancestor.

Question 29

Polyphyletic Grouping

Answer 29

Includes distantly related taxa but does not include the common ancestor of all group members.