Biodiversity means variety within and among living things. So far less than 2 million species have been described scientifically, but there are probably at least 10 million species on the planet.
Biological classification means putting living things in groups. There are several levels of classification. The largest category is the Kingdom: a very large group, for example all animals from jellyfish to worms to humans are in one Kingdom. There are 5 main kingdoms: Animals, Plants, Fungi, Protists (mainly single cells) and bacteria. Table 12.1.
Archaea are mainly found in extereme environments such as hot springs, and areas with very little oxygen. Many of them are killed by exposure to air. One is the source of the polymerase enzyme, which is used in PCR.
Kingdom Protista are organisms that have complex eukaryotic cells with a distinct nucleus and organelles such as mitochondria. Fig 12.8. One group of protists are the algae which includes seaweeds. They are photosynthetic, and produce chemicals like carrageenan which is a gel that is used in food, cosmetics and medicines.
The Animal kingdom is very diverse, with over 1 million species. Animals first evolved about 600 million years ago, and all take in their food and digest it inside their bodies. They range from simple sponges to roundworms, mollusks (snails, oysters, squid and octopus), annelid worms (including earthworms), arthropods (shrimp, insects and spiders), echinoderms (sea stars, sand dollars and sea urchins) and chordates ( like fish, birds, reptiles, mammals). Table 12.3 has photos and details. Many important chemicals are found in animals, such as a medicine for arthritis extracted from ants, and a protein from jellyfish that glows. Fig 12.12.
Fungi are made of thin, string like hyphae that release digestive enzymes into their surroundings. Fig 12.14. Fungi reproduce through single celled spores that blow around in the wind. Most fungi are decomposers that break down and digest dead plants and animals. Many fungi produce antibiotics that kill bacteria that compete with the fungus for food. Other medical products from fungi include cyclosporin which is given to transplant recipients to lower their immune system. Also statin drugs that reduce the risk of heart attack are obtained from fungi. Both of these drugs have sales of over $1 billion a year.
Some fungi, like mushrooms, are edible. Other important fungi include yeasts (used in baking and making beer and wine).
The Plant kingdom is the biggest source of medicines. Land plants are fairly recent, first evolving around 400 million years ago. Some plants like mosses and ferns reproduce using spores, but most plants produce much larger seeds, that can survive for many years until conditions are right for them to germinate. Table 12.5. Many drugs came originally from plants, like aspirin from willow trees, anticancer drugs from periwinkle, caffeine from coffee and tea, morphine from opium poppies. In addition almost all of our food (except for seafood) comes directly or indirectly from plants.
Phylogeny is the evolutionary relationship or history of a species. For example white-throated and white-crowned sparrows are more closely related to each other than they are to other species of sparrow. Fig 12.19. These evolutionary relationships can be used in bioprospecting to predict which species of plant or animal may have useful drugs. Traditional healers or shamans can also point out plants that are used in herbal medicine. Fig 12.20.
Last edited November 2006,
by David Byres, dbyres@fccj.edu