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Lecture 35

BIOL 1001 Lecture Notes - Lecture 35: Neoteny, Heterochrony, Biostratigraphy

Course Code
BIOL 1001
Tamara Kelly

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March 10th Lecture Note- Molecular
Timing is Everything
Mutations in gene controlling development have major effect on morphology
Heterochrony: changes in timing of developmental events b/t two taxa
Ex: food growth in tree salamander stops sooner, while good growth in ground
salamander continues
Juveniles are differentiated from adults by their inability to reproduce not by specific
Rate of body cell (somatic) development may differ from reproductive (germ cell)
Many adults can maintain same morphology characterises of juvenile’s b/c rate of
somatic development may be slow. However, in reproductive development may be
faster. Thus species are more reproductively developed in adulthood than juveniles
Paedomorphosis: retention of juvenile characteristics in adults but able to reproduce
-rate of somatic cells slows down but reproductive rate continues.
- sexual development occurs faster
Paedomorphic is a type of heterochrony
Neoteny: rate of somatic development slows & larval form acquires ability to produce
-Change in gene expression such that somatic development slows
-Look like juveniles but are able to reproduce
Heterochrony: differences in timing & rate
Example: Pugs – they have flattened faced
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