Epigenetic evolution

Question 1

developmental hierarchy

Answer 1

from simple phenotype to complex phenotype

Question 2

epigenetic landscape

Answer 2

introduces tresholds to how the genome translates to the phenome

the deeper the “valleys” the more stable / canalised the genetic determination of the phenome is

Question 3

canalisation

Answer 3

The degree of the wall steepness in epigenetic landscapes
How constrained the “marble” is

Canalization can be considered a buffering of developmental pathways such that minor mutations would not greatly affect the course of development

As a trait or phenotype is becoming more fixed and less variable, its epigenetic landscape is becomming more canalized

Question 4

phenotypic plasticity

Answer 4

A range where phenotypes can change over different environments
(Evo-Devo-Eco)

for ex: daphnia water fleas changing the morphology of their “heads” depending on the presence of predators in their environment

Question 5

epigentic treshold, meaning of cryptic and realised

Answer 5

Cryptic (above threshold) is not normally seen
Realised is what can be more commonly observed

Question 6

hsp90 treatment, what was the main takeaway?

Answer 6

testing phenotypic plasticity

What does Hsp90 do: reconform proteins, saving proteins if they become altered

Process of the test:
Hsp90 knockout for a few generations while selecting for a specific trait
and then stopped the knockout of Hsp90
and noted that the trait had become fixed in the genome !

Question 7

impact of stresses during development

Answer 7

some parts of development are not regulated by the genome but by stresses

for example : muscle contractions during human development

if a human is born paralyzed, its skeleton will look weird

the muscle contractions help forming our skeleton

for example: the loss of jaw musculature , leafding to reduced faces and the problem of wisdom teeth

Question 8

quantic evolution

Answer 8

perhaps there can be quantic evolution jumps accross adaptive landscape fitness peaks

for example:
the origin of tetrapods , the jump to terrestrial locomotion so from fins to limbs (-410-400 Ma)
a transformation that was accompanied by whole changes in phenotypes

Question 9

How can phenotypic plasticity be a driver for genetic change and the origin of phenotypic novelties

Answer 9

The example of Hsp 90

What does Hsp90 do: reconform proteins, saving proteins if they become altered

Process of the test:
Hsp90 knockout for a few generations while selecting for a specific trait
and then stopped the knockout of Hsp90
and noted that the trait had become fixed in the genome !

Question 10

origins of tetrapods (Polypterus)

Answer 10

polypterus was the first walking fish!
- could do air breathing (paired ventral lungs)
- Lobed fins
- “neck”
ventro lateral based fins

its shoulder nusculature allowed it to rotate its fins (high mobility)

this was possible thanks to developmental plasticity!
(phenotypic plasticity which then allowed traits to get fixed in genome (more robust articulation, smaller bones))

Question 11

how does phenotypic plasticity (in response to envr) impact macro-evolutionary change

Answer 11

• origin of phenotypic novelties
• guides genotypic change