Presentation 7: Heterochrony

Question 1

Heterochrony

Answer 1

change in developmental timing
includes paedomorphosis (neoteny and progenesis)and Peramorphosis (hypermorphosis and acceleration)

Question 2

Paedomophosis

Answer 2

A type of heterochrony that includes neoteny and progenesis

Question 3

Neoteny

Answer 3

the retention of juvenile features in the adult animal (sexual maturity while still in larval state) ex. axolotl

Morphological Result: paedomorphosis
Somatic developmental timing: slowed
Reproductive developmental timing: unchanged
Size at sex. maturity: normal

Question 4

Progenesis

Answer 4

the speeding up of the germ line (reproduction occurs at what was ancestrally a juvenile stage) ex. annelids

Morphological Result: Paedomorphosis
Somatic developmental timing: normal
Reproductive developmental timing: sped up
Size at sex. maturity: small

Question 5

Hypermorphosis

Answer 5

total development time is extended leading to the addition of more stages (rate is unchanged) ex. chimp vs human brain

Morphological Result: Peramorphosis
Somatic developmental timing: normal
Reproductive developmental timing: slowed
Size at sex. maturity: large

Question 6

Acceleration

Answer 6

rate of development is sped up so more stages added to end ex. irish elk

Morphological Result: peramorphosis
Somatic developmental timing: sped up
Reproductive developmental timing: normal
Size at sex. maturity: normal

Question 7

Peramorphosis

Answer 7

Type of Heterocrony where there are extra stages at the end of the ancestral development line, includes acceleration and hypermorphosis

Question 8

Isomeric growth

Answer 8

Direct (grows proportionally, adult is just larger sized juvenile)

Question 9

Allometric growth

Answer 9

disproportionate growth, i.e. the head is much smaller in adult humans than in babies, - proportions change over time