Four Models of Heterochrony (after Futuyma 1986)
Four Models of Heterochrony (after Futuyma 1986)
The ancestral
developmental pattern of
some feature y with respect to x (which may be a
general
size measure) shows positive allometry over a period extending
from
a
to B. Four possible evolutionary modifications of this
pattern
lead to different types of descendant organisms. (A)
Hypermorphosis:
extension of the period of growth results
in exaggerated adult features. (B) Progenesis:
early
cessation of growth results in retention
of juvenile features. (C)
Acceleration:
acceleration of development results in
exaggerated
adult features. (D) Neoteny:
deceleration of development result in
retention
of juvenile features. See lecture
notes for details.
