L6

Question 1

Plasticity

Answer 1

Ability to generate multiple phenotypes from a single underlying genotype

Question 2

Developmental plasticity

Answer 2

Irreparable change in phenotype depending on early env

Question 3

Behavioural plasticity

Answer 3

Interchangeable phenotypes

Question 4

Why should phenotypes be plastic?

Answer 4

• efficient allocation of nutrients and energy
• traits can be costly if not needed
• consequences of having traits when needed are predictable
• needs are unpredictable in time and space and plasticity allows adaptation when needed

Question 5

What do we need for plasticity to be beneficial?

Answer 5

• env. must be INTERMEDIATELY and UNPREDICTABLY variable (if too variable, evolve one phenotype and hope for the best)
• there must be fitness consequences of being plastic

Question 6

Examples of behavioural plasticity

Answer 6

• seasonal plumage - develop at start of breeding season and can change next year
• (sneaker males to some extent - decision to be sneaker right now is behavioural BUT usually developmental because some morphological differences)
• antlers - can grow bigger or smaller next year

Question 7

Examples of developmental plasticity

Answer 7

• sneaker males IF involves morphological changes - sneaker and territorial males different phenotypes which are irreversible
• horns - can’t ungrow (although some beh. because can decide when to grow)
• turtle - temperature sex determination
• social insects - female ability to be Q rather than W depends on environment (although decision tor ear Q or W is behavioural)

Question 8

Paedomorphosis:

• neoteny
• progenesis

Answer 8

neoteny - somatic growth slowed but reproduction still comes in
progenesis - reproductive development hastened

Question 9

Heterochrony

Answer 9

Change in timing of developmental events

• acceleration vs neoteny
• hypermorphosis vs progenesis
• predisplacement vs postdisplacement

Question 10

Paedomorph hypothesis

Answer 10

Stable aquatic ecology surrounded by harsh terrestrial ecology selects against leaving the water except when pond dries up

Question 11

Why do newts always progress to adult form?

Answer 11

• aquatic env. stable in some ways (always wet)
• but terrestrial env. also stable
• so don’t stay in water because wouldn’t be able to spread and also run rsk of more predators if stay in ponds