BCB705 Biodiversity: Chapter2 - Evolution of Biodiversity

Table of Contents

1. THE INFINITE VARIETY: THE BEGINNING OF LIFE
2. BUILDING BODIES: INVERTEBRATES OF THE OCEANS
3. THE FIRST FORESTS
4. THE SWARMING HORDES
5. THE CONQUEST OF THE WATER AND THE BIRTH OF THE VERTEBRATES
6. THE INVASION OF THE LAND
   1. The conception of lungs
   2. Possible ancestors
   3. Amphibians: The limitations
   4. A variety of habitats
   5. Colonizing the land
   6. A burrowing existence
   7. The accomplished jumpers
   8. The sticky tongue
   9. Sound production
   10. Amphibians: Mating
   11. A terrestrial environment for breeding
   12. Protecting the young
   13. Marsupial frogs
   14. Parental care: A step further
   15. Brooding in the stomach
   16. Effects of climatic conditions
   17. Moisture and development
   18. The water-holding frog
   19. Test Yourself
   20. Assignments
7. A WATER-TIGHT SKIN AND THE SHELLED EGG
8. LORDS OF THE AIR
9. EGGS, POUCHES AND PLACENTAS
10. THEME AND VARIATION
11. THE HUNTERS AND THE HUNTED
12. A LIFE IN THE TREES
13. THE COMPULSIVE COMMUNICATORS

THE INVASION OF THE LAND

The beginning of limbs

The first fish may have crawled onto land during Devonian times (350 million years ago) and probably did so, in response to drying swamps. This required that two problems must be overcome, how to move without the support of water and how to obtain oxygen from air rather than water. The mud skipper (eg Periophthalmus sobrinus which occurs in our mangrove swamps) suggest adaptations that ancestral fish may have developed in their quest to colonize land. Each pair of front flippers has a fleshy base supported internally by bones and is able to be used to lever the animal forward. Another animal which showed the beginnings of limbs is the Coelacanth, Latimeriachalumnae (order Crossopterygii), the living fossil that was thought to have been extinct for 70 million years.

Periophthalmus modestus (Mudskipper)

Each pair of front flippers has a fleshy base supported internally by bones and is able to be used to lever the animal forward

Coelacanth