Genetic mechanisms of morphological change

Question 1

TD, WGD

Answer 1

tandem duplication, whole genome duplication

Question 2

how does TD occur?

Answer 2

incorrect pairing up during meiosis- gamete with 3 copies of a gene is produced

Question 3

where have whole genome duplications occured

Answer 3

vertebrates (2R) and teleost fish (3R), smaller groups like goldfish (4R)

Question 4

ortholog

Answer 4

gene separated by a speciation event- e.g. the human version of whatever vs the frog version

Question 5

paralog

Answer 5

gene separated by duplication- e.g. the 2 genes descended from a single gene before the duplication

Question 6

example of a major transition which did not require WGD

Answer 6

leafy plants- seemed to just be a change of function thing, changes in aas, binding sites etc

Question 7

debate over how morphological change comes about

Answer 7

cis-regulatory changes vs changes in the proteins themselves

Question 8

how can we use breeding experiments to look at how morphological traits originate?

Answer 8

trait mapping- basically, is there a match between genes and morphology?

• e.g. the 3-spined stickleback thing, could map ‘small spine’ trait to a region next to the limb patterning gene Pitx1- concluded differences in expression pattern were important here

Question 9

how can we study wild populations to help us answer this question?

Answer 9

GWAS! get a population with variability in a trait and track where the changes are in the genome

-e.g. rabbits, found the agouti gene to be related to colouration which was kinda to be expected, but did show that this DNA is jackrabbit DNA which is interesting

Question 10

how can we look at domesticated species to answer this question?

Answer 10

we have a good record of morphological changes, so can form hypotheses about what might have changed

e.g. twin-tailed goldfish, guessed that maybe the chordin mutation responsible for twin-tails in zebrafish may be involved- it seems to be a partial phenotypw