Phylogeny (Ch. 20)

Question 1

Phylogenies

Answer 1

• show the evoluntionary history of a group of organisms
• formal hypotheses identifying likely relationships amoung groups of modern organisms
• show relatedness within a large group or genera of species are related
• it can include both prehistoric and modern organisms
• essential for the comparative method that is used for evolution

Question 2

How to classify organisms

Answer 2

• morphology (traits)
• patterns of behaviour
• chromosomal anatomy
• details of physiology
• molecular sequences of nucleic acids/proteins

Question 3

robust phylogenetic trees

Answer 3

distinguish between similarities inherited from a common ancestor from those that have evolved independently in response to similar environments

Question 4

How are these trees created or analyzed (what is the purpose)

Answer 4

• analyzing the genetic changes that caused speciation/differentiation
• fossils are not all complete so must rely on the phenotype traits as indicators of genetic similarity/difference

Question 5

What are some things systematics try to avoid and and succeed in when creating the trees? why is this necessary?

Answer 5

• avoid differences based on environmental conditions
• must be genetically independent, reflecting different parts of organisms’ genome
• this is necessary because different organismal characters can have the SAME genetic basis

Question 6

Homologous characters

Answer 6

similar in evolution but not necessarily their function (ie. the limbs of a tetrapod - whales vs. humans)
- emerge from comparable embryonic structures and grow in similar ways during development

Question 7

Why are homologous characters useful in phylogenetic trees?

Answer 7

they reflect the underlying genetic similarities therefore it can indicate relatedness or common ancestry

Question 8

evolutionary development biology

Answer 8

reveals that some genetic controls of development pathways can be similar across a wide variety of organisms

Question 9

Analogous characters

Answer 9

characters that are different in animals that serve the same the same function

Question 10

Homoplasious

Answer 10

phenotypic similarities that have evolved in different lineages
(traits that have developed due to similar environments )
- however they are excluded from analysis because they provided no evidence

Question 11

Mosaic evolution

Answer 11

refers to the reality that in all evolutionary lineages, some characters evolve slow and other evolve fast
- every species displays a mixture of ancestral and derived characters

Question 12

ancestral character

Answer 12

old forms of traits

Question 13

derived character

Answer 13

new forms of traits

Question 14

what is useful about derived characters?

Answer 14

they provide the most useful information about evolutionary relationships because once a characters is established it usually persists in all that species descendants (i.e.backbone)
*any derived character is derived only in relation to what occurs in other organisms

Question 15

Out-group comparison

Answer 15

use to distinguish between derived and ancestral characters

(study the group with more distantly related species constituting a group otherwise not included in the analysis