BIOL-UA 12 Lecture Notes - Lecture 8: Water Vascular System, Cambrian Explosion, Paleozoic
18 Mar 2016
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Ecdysozoans: two largest phyla = nematodes and arthropods cuticle: tough coat that covers the body. Body plan dates to cambrian explosion (=early paleozoic era) Point where a lot of new species came out of it. What distinguishes them from current day arthropods is no variation from segment to segment. Appearance of many major groups of living animals = sudden increase in diversity. This is a result of a rise in atmospheric oxygen and new predator-prey relationships. Diversity continued to increase but was then punctuated by mass. Homeotic genes (hox) control the identity of body parts. Hox family of genes is highly conserved, but can produced a wide diversity of morphologies. Studied in flies in which hox genes provide positional information during development. If expression is perturbed body parts can be produced in the wrong location. Ie. wild type of flies with normal eyes, and mutant type antennapedia with legs on the face/ eyes.
