5-6-13_limbs_pt_1

Gilbert 9e fig 198 heterochrony in ipper development

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ammals. Gilbert 9e, Fig. 19.8 Heterochrony in flipper development of the spotted dolphin may explain hyperphalangy Gilbert 9e, Fig. 19.8 Heterochrony is the phenomenon of expression of genes (or productino of a cell/tissue) at a different time in different species. Persistence of the AER’s signaling activity for a longer period of time may explain hyperphalangy. Snakes show differences in hindlimb AER vs. tetrapods Modern snakes don’t have forelimbs. Some snakes (e.g. constrictors such as pythons, boas, etc.) do have rudimentary hindlimbs (graspers). What about their AERs? Cohn and Tickle (1999). Nature 399, 474-479. Snake hindlimb AERs degenerate after a limb bud forms no AER The hindlimb AERs of modern snakes degenerate and cease FGF production after a rudimentary limb bud forms. Cohn and Tickle (1999). Nature 399, 474-479....
View Full Document

Ask a homework question - tutors are online