BIODIVERSITY AND HUMAN HEALTH
Executive Summary, page 2
by Joseph Dougherty

Defining Biodiversity

Biodiversity can be divided into four broad categories:

• Genetic Diversity: the variety of alleles (different versions of the same gene) within a species. For example, humans have several different alleles for blood type, which are combined in varying ways to produce the many blood types expressed in humans. Other species have similar variances in their DNA, the genetic code that expresses how large they may grow, what color their fur may be, how fast they may run, or — perhaps most importantly — how effectively their immune systems may respond to a new pathogen.
• Species Diversity: the variety of species within a particular area. A species is the most fundamental level of scientific classification among organisms, though the boundaries of this category are often debated among professional biologists and many valid subdivisions (subspecies, races, variants, morphs, etc.) are recognized. The lines between species diversity and genetic diversity cannot be concretely drawn. For example, the right whale (Balaena glacialis) has distinct populations in the northern and southern hemispheres. Some scientists believe these are distinct races or genetically unique populations, while others believe them to be separate species entirely (the southern population, if separated from the northern, would be B. australis). Measuring species diversity is complicated because species distributions are highly variable from one biome to another, just as the territory covered by each organism varies from species to species. While the ranges of some species, such as the great whales and sea turtles, literally span the world’s oceans, the ranges of others may be restricted to a single mountaintop or tiny desert pool. Differing biomes vary in their species diversity, so when measuring the health of a particular area, it must be compared to similar habitats (i.e., rain forest to rain forest, desert to desert) or, preferably, to baseline data recorded in same location at an earlier time.
• Cultural Diversity: the variation in behaviors or customs among different groups of the same species. This is most prevalent among humans, but science has recorded distinct cultures in other species, too. For example, humpback whales demonstrate a type of culture in their seasonal songs, as do chimpanzees in their hunting behavior. Behavior variations are important because some behaviors may be more favored than others in the face of sudden evolutionary pressures.
• Ecosystem Diversity: the variety of communities of interacting organisms and the environments they occupy. This level of biodiversity is by far the most complex, consisting of the physical (nutrients, soil, water, atmosphere) and the biotic (individual organisms, communities of interacting species) components of the surrounding environment. This level is also complex because the very nature of an ecosystem is broadly encompassing, thus many varied habitats and sub-systems may fall into a larger system that is still in and of itself unique. A good example is the Florida Everglades, a vast wetland ecosystem containing many smaller habitats, such as pine barrens, cypress swamps, and mangrove communities. Eventually, all ecosystems, and by extension all life, on earth are interconnected and interdependent. The earth is enshrouded in a relatively thin mantle, its width extending from the bottom of the ocean to about seven miles up into the atmosphere, of habitat capable of supporting life, called the biosphere.
  

To the best of our knowledge, nothing lives outside of the biosphere, and — with the sole exception of the sun’s rays — everything we need to thrive and prosper must be obtained from this same biosphere... which is also where we must dispose of our waste. Wise and sustainable use of this limited resource is not only what is best for the other organisms who share this space with us, but it is crucial for our very survival as a species.

The physical and biotic components of all ecosystems are continually interwoven through nutrient cycling, the ingestion, absorption, excretion, and decomposition of materials in the environment. For most organisms, the oxygen, nitrogen, and carbon cycles are the most important, with the carbon cycle currently of particular interest to climatologists due to its role in global climate change. Entire ecosystems may interact through hydrologic cycling, the movement of water, which may bring life-giving moisture when clean or may rapidly contaminate a region if polluted.

Around the world, the regions with the richest biodiversity are often occupied by the poorest people, suggesting the strong possibility for poverty alleviation if the natural resources and indigenous knowledge in these biodiversity “hot zones” are properly managed.

Helping the rural poor to manage their resources more effectively will also help to ensure biodiversity. And while global economic forces may be driving the loss of biodiversity, the impacts of this loss are felt at the local level. The local knowledge that people have about their resources and how these resources should be managed provides a critical resource for all of humanity. Indigenous peoples who live in intimate contact with biodiversity could provide much of the intellectual raw material for a shift to sustainable societies, provided they are empowered to act in their own self-interest. Thus biodiversity and cultural diversity can be conserved together, enabling both to prosper. This is why biodiversity has become such a dominant theme in the global conservation movement.

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