BIOL 1001 Lecture Notes - Lecture 35: Neoteny, Heterochrony, Biostratigraphy
26 Mar 2017
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Document Summary
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 morphology. Rate of body cell (somatic) development may differ from reproductive (germ cell) development. Many adults can maintain same morphology characterises of juvenile"s b/c rate of somatic development may be slow. 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. 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. Human evolution: fossil sequence shows gradual flattening of face & increase in brain size.
