Evolution and development

Question 1

Difference between vertebrate and arthropod (drosophila) body plan?

Answer 1

INVERTED
drosophila- nerve cord on ventral side
vertebrate- nerve cord on dorsal side

Question 2

What signals are involved in specifying the dorso-ventral axis in drosophila- what are they homologues of?

Answer 2

DPP- patterns the dorsal side
SOG- patterns the ventral side and it counteracted by DPP
DPP- BMP, Sog- Chordin
(In vertebrates BMP patterns the ventral side)

Question 3

When do more specific characteristics of a group appear?

Answer 3

Occur later

Question 4

How does diversity develop generally?

Answer 4

Through changes in control regions of control & target genes
-Modifications of existing mechanisms-

Question 5

What is the most important thing in driving evolution?

Answer 5

Changes in the timing and level of gene expression

Question 6

Which 2 animals show where changes in hox expression have generated changes?

Answer 6

Pythons- loss of limbs- anterior expansion of hoxc6 and hoxc8
Butterfiles- changes in upstream regions of genes important for wing development- not repressed by Ubx in the haltere- 2 sets of wings

Question 7

What are changes in time, place and level of expression important for?

Answer 7

Driving evolution- in comparison to changes in protein function

Question 8

The change in level and duration of which gene formed the basis of evolution of beak size and shape?

Answer 8

BMP4

Question 9

2 examples of developmental constraints

Answer 9

1. Animals- maximum of 5 digits, pattern of humerus, ulna/radius and digits largely conserved
2. Blind cave fish

Question 10

What is heterochrony- give an example

Answer 10

A change in the time/rate of developmental events

Marsupial embryos- anterior limb is developed v quickly in comparison to mouse- allows embryo to crawl into pouch

Question 11

What is neoteny- give an example

Answer 11

An animal reaches sexual maturity in a larval stage- before metamorphosis
Axolotl