Lecture 20 Phylogenetics 1

Question 1

Homoplasy

Answer 1

Trait evolves more than once; common in Biology
Incongruence among characters due to convergence between lineages or reversal to ancestral state

Question 2

Reversal

Answer 2

Evolve back to ancestral state

Question 3

synapomorphie

Answer 3

Shared derived characters

Question 4

Pleisomorphy

Answer 4

Ancestral trait
Not basis for grouping things

Question 5

As a species diversifies…

Answer 5

All of its descendants collectively from a clade

Question 6

Phylogenies are

Answer 6

Sets of hypotheses

Question 7

If a new character state evolves in a species

Answer 7

That state will be passed down to all descendants species

Question 8

Character states are

Answer 8

Alternative conditions of a character

Question 9

That character state then becomes a new

Answer 9

homology

Question 10

apomorphy

Answer 10

A derived trait (new homology)

Question 11

synapomorphy

Answer 11

If the trait is shared by multiple species

Question 12

Synapomorphies are evidence for

Answer 12

Phylogenetic relationship

Question 13

Nested pattern

Answer 13

When another character transforms within one of the daughter lineages; As clades diversify and evolve, a nested hierarchy is created among characters

Question 14

Clades

Answer 14

Are the same if they contain exactly the same members, no more, no less (clades are defined by who the descendants are coming from a common ancestor)

Question 15

The Principle of Parsimony

Answer 15

Occam’s razor: given more than one equally good explanation, the simplest should be preferred

Question 16

“Ad hoc” hypothesis

Answer 16

Each time we conclude that a trait evolved twice
We want minimize these because they lack direct evidence and typically makes it more complicated

Question 17

Most parsimonious tree is that

Answer 17

With the fewest hypothesized character transformations, or in other words, the shortest tree

Question 18

“traveling salesman problem”

Answer 18

No analytic solution, must examines all possible answers.
A difficulty arises when the number of species increases.