Ch. 26: Phylogeny

Question 1

Phylogenies show

Answer 1

Evolutionary relationships

Question 2

Phylogenies are

Answer 2

Inferred from morphological and molecular data

Question 3

Shared characteristics are used to

Answer 3

Construct phylogenetic trees

Question 4

An organism’s history is

Answer 4

Documented in its genome

Question 5

Phylogeny

Answer 5

Classification system based upon evolutionary ancestral relatedness

Question 6

Phylogenetic tree

Answer 6

A graphical representation of a phylogeny
AKA evolutionary tree
-Parts: root, node, branch, outgroup, polytomy, tip

Question 7

Root

Answer 7

• Special node (1st node)

- A branch point within the tree represents the most recent common ancestor of all taxa in the tree

Question 8

Node

AKA Branch point

Answer 8

• Relationships often depicted as a series of dichotomies

- Each node represents the divergence of two evolutionary lineages from a common ancestor

Question 9

Branch

Answer 9

Connects a node and the Taxa

- usually dichotomous

Question 10

Outgroup

Answer 10

Not included into in a phylogeny that is being studied

Question 11

Polytomy

Answer 11

• More than two descendant groups emerge
• Three branches off of a node
• Not sure relatedness of which one is closer to which

Question 12

Ancestral trait

Answer 12

Character present in ancestor

Question 13

Derived trait

Answer 13

Modified character present in a descendent

Question 14

Cladistics

Answer 14

Willi Henry 1950

- relationships among species can be reconstructed by identifying shared derived traits, called Synapomorphy (homology)

Question 15

Synapomorphy (Homology)

Answer 15

Shared derived traits

Question 16

Sister Taxa

Answer 16

Groups of organisms that share an immediate common ancestor (branch point)

Question 17

Basal Taxa

Answer 17

A lineage that diverges early in the history of a group

Question 18

Clade (lineage)

Answer 18

Monophyletic group that includes an ancestral population and all its descendent, but NO others

Question 19

Monophyletic

Answer 19

Ancestral species (common ancestor) and all of its descendants 
AKA clade

Question 20

Paraphyletic

Answer 20

• Ancestral species and some, but not all, of its descendants
• Minus one branch

Question 21

Polyphyletic

Answer 21

• Ancestral species is NOT part of the group
• More branches than are apart of a monophyletic group
• One additional branch

Question 22

Homology

Answer 22

• Similarity due to common ancestry

- Character that is similar among to a group of organisms due to common ancestry

Question 23

Homoplasy

Answer 23

• Similarity due to reasons other than shared ancestry
• Converged Evolution
• Analogous structures that arose independently
• Similar structure or molecular sequence that has evolved independently in two species

Question 24

Length of branch

Answer 24

• Is a function of time
• Can be based on fossil records
• Genetically = molecular “clock”
• Shorter time = less mutations

Question 25

Endotherms are a

Answer 25

Polyphyletic group => homoplasy

Question 26

Morphological Homology

Answer 26

• Structured derived from a common ancestor used for the same function in the species in which it occurred
• anatomical feature
• i.e. hand, wing, fin

Question 27

Molecular Homology

Answer 27

Species placed in the same taxonomical group based on similar genetics (DNA, RNA, protein)

Question 28

Anole Lizard Example

Answer 28

1. Population grew, tree fell, some moved to the other side of the river
2. Tree decomposed, lizards stuck/isolated from one another, needed new ways of doing things
   * 3. Allopatric Speciation: mutation occurred because of isolation
3. Different mutations occurring continuously; one mutation accumulating in on population versus the other based on needed
4. Doolap color changed, sexual selection occurring
   [sexual selection, behavioral]

Question 29

1st branch point

Answer 29

oldest
2, 3, 4, 5, etc…
AKA node

Question 30

Parsimonious

Answer 30

simplest