Evolution Notes B

Question 1

Describe significant questions to ask regarding Evolution

Answer 1

• Which taxa is/are more closely related?
• Origin of traits
• Due to convergent evolution or shared common ancestor?
• Change in traits from deep in time towards present day

Question 2

Name 3 types of evolutionary relatedness

Answer 2

o Monophyly
o Paraphyly
o Polytomy

Question 3

Why are the types of evolutionary relatedness important?

Answer 3

• They are hypotheseses of relatedness
• They can help us understand what is ancestral (old) vs derived (new)
• They can help us understand how changes have occurred, starting from deep in the past towards the present
• They can help us distinguish between homology and homoplasy

Question 4

Monophyly

Answer 4

developed from a single common ancestral form

Question 5

paraphyly

Answer 5

taxonomic group that descended from common ancestor, but does not include all descendants of common ancestor

Question 6

polytomy

Answer 6

• when a node has more than two descendants (NOT bifurcated!)
• represents uncertainty in evolutionary relationships

Question 7

Convergent evolution

Answer 7

• characteristics developed independently when in similar/shared environments, not developed from relation
• Homoplasy (NOT HOMOLOGY!!)
• So much more than organisms looking similar to be in relation
• Only homologous characters can be used for phylogenetic reconstruction

Question 8

Tiktaalik

Answer 8

• Autopodium (hand or foot) consists of small nodular bones (wrist or ankle) and long bones (digits)
• Very important transitional fossil because it has small nodular bones but not digits
• Small nodular bones are the earliest endoskeletal elements distalto the zeugopodium
• still considered lobe-fin fish since no autopodium, but has wrist bones