Life on Earth is extremely interesting, as most of us already know from television, if not from our own travels, and it becomes more so when each piece of the complex pattern fits understandably into the whole. One important goal of a biology curriculum should be to educate students about nature, in order to promote empathy and support for the natural world around us, and the interrelationship of all aspects of nature must be an integral part of the message delivered.

Biomes (bioclimatic zones) are appropriate divisions by which to organize the natural world, because the organisms that live in each of them possess common constellations of adaptations to them, in particular to the climate of each of the zones and to the characteristic vegetation types that develop in them. The primary elements to be dealt with under each zone were chosen because they are considered the basic elements at all levels, from the entire planet through each of its component physical environments to the species themselves.

The climate must be understood as perhaps the most important element in determining what kinds of organisms can live in an area and how they

DIVERSITY. Rain forests of this continent exhibit the lowest species diversity of the three major regions, presumably related to the relatively restricted size of the zone and the lack of major barriers promoting speciation. For example, there are only a few species of parrots, compared with the tremendous diversity of this group in South America and moderate diversity in southeast Asia. Single-locality forest bird lists perhaps reach 200 species. Nevertheless, there is still a wealth of species, including a noteworthy diversity of coexisting small antelopes and primates in a great array of sizes. There is much convergence in mammalian body form with comparable but unrelated taxa in South America, for example pygmy hippo with capybara, duiker with brocket, and chevrotain with paca.

DIVERSITY. Desert species diversity is very much dependent on rainfall and vegetative cover, with the fewest plant and animal species in the driest deserts. The Sonoran Desert is especially rich in species, with a substantial variety of distinct plant associations. The driest deserts (Atacama Desert of Chile/Peru, Sahara Desert of Africa) virtually lack living organisms in some areas. Some plant families are especially diverse in deserts, for example Chenopodiaceae, Crassulaceae, and Cactaceae. No major vertebrate taxa are confined to deserts, but some groups are quite well represented there, and many widespread genera have desert-adapted species. Lizards, snakes, and rodents are well adapted to dry environments, where they are diverse out of proportion to other groups that occur in deserts. Aquatic animals are lacking except where occasional water bodies persist, except for groups such as fairy shrimp that live in ephemeral pools. Amphibians are not very diverse, but some frogs occur even in very dry deserts, as long as rainfall is adequate for breeding at least occasionally.

Some topics in this essay:
PLANT ADAPTATIONS, HUMAN EFFECTS, ADAPTATIONS Animal, Sonoran Deserts, South America, ADAPTATIONS Animals, CLIMATE Temperate, WORLD CLIMATE, North America, ANIMAL ADAPTATIONS, rain forest, tropical rain, south america, rain forests, tropical rain forest, human effects, species diversity, animal adaptations, plant adaptations, tree species, plant species, diversity species diversity, tropical rain forests, plant animal species, asian rain forests,