L8

Question 1

Epigenome as both a fixed modifier and an experimenter

Answer 1

DNA methylation/histone modification - can be passed on so fixing based on inheritance

Alternative splicing/microRNA - more flexible allowing individuals to experiment with production of different proteins from same underlying genes

Question 2

Phenotypic accommodation

Answer 2

ability of a phenotype to become adapted without changes to existing genotype – eg Slijpers goat/fsh without tails etc

Question 3

Genetic accommodation/assimilation

Answer 3

selection on genes that fix alleles conferring evolutionary advantage

Question 4

Suggested Extended Synthesis

West-Eberhard 2003

Answer 4

Phenotypic evolution is result of four steps
1 trait origin - mutation/env change causes appearance of developmental variant which expresses a new trait
2 phenotypic accommodation to the new trait - made possible by inherent plasticity of developmental system
3 spread of new variant facilitated by recurrence in population if initial change in environmental (don’t have to wait for mutation to occur again)
4 genetic accommodation of novel phenotype as a result of standard selection

THEN
canalisation - production of consistent phenotype through selection

Question 5

Evolution of altruism

Answer 5

• one genetic mutation can’t cause altruism becayse will always lose if try to be cooperative
• if there is then a selection pressure for cooperation, individuals must override own selfishness - no genes for cooperation but individuals who cooperate reproduce better
• eventually gene for altruism/cooperation arises through random mutation - those individuals do better than those who are overriding own selfishness to cooperate