BIO SCI 94 Lecture Notes - Lecture 14: Metabolic Waste, Eutheria, Reptile

• School: UC-Irvine
• Department: Biological Sciences
• Course: BIO SCI 94
• Professor: Robin Bush

Document Summary

In our class, we will assume that segmentation evolved multiple times. Lungfish can venture onto land and breathe air for limited periods of time. The early vertebrate lineages look like fish and we refer to them casually as fish. On the tree, they appear as a series of independent monophyletic groups that form a grade. Grade - sequence of lineages that are paraphyletic. Amphibians are tetrrapods, but they are a transitional group. Most live on land, but they don"t have amniotic eggs and thus still need to lay their eggs in water. In many species, gas exchange occurs exclusively or in part through their moist, mucus-covered skin. Tetrapods were the first vertebrates that could breed in terrestrial environments. Three major evolutionary innovations gave tetrapods this ability: Only with the evolution of the amniotic egg did animals attain the capacity to remain on land all the time. Amniotic egg keeps embryo from drying out.