5.5: Types of Biodiversity
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- Differentiate among the types of biodiversity
Types of Biodiversity
Scientists generally accept that the term biodiversity describes the number and kinds of species in a location or on the planet. Species can be difficult to define, but most biologists still feel comfortable with the concept and are able to identify and count eukaryotic species in most contexts. Biologists have also identified alternate measures of biodiversity, some of which are important for planning how to preserve biodiversity.
Genetic diversity is one of those alternate concepts. Genetic diversity or variation is the raw material for adaptation in a species. A species’ future potential for adaptation depends on the genetic diversity held in the genomes of the individuals in populations that make up the species. The same is true for higher taxonomic categories. A genus with very different types of species will have more genetic diversity than a genus with species that look alike and have similar ecologies. If there were a choice between one of these genera of species being preserved, the one with the greatest potential for subsequent evolution is the most genetically-diverse one. It would be ideal not to have to make such choices, but, increasingly, this may be the norm.
Many genes code for proteins, which in turn carry out the metabolic processes that keep organisms alive and reproducing. Genetic diversity can be measured as chemical diversity in that different species produce a variety of chemicals in their cells, both the proteins as well as the products and by-products of metabolism. This chemical diversity has potential benefit for humans as a source of pharmaceuticals, so it provides one way to measure diversity that is important to human health and welfare.
Humans have generated diversity in domestic animals, plants, and fungi. This diversity is also suffering losses because of migration, market forces, and increasing globalism in agriculture, especially in heavily-populated regions such as China, India, and Japan. The human population directly depends on this diversity as a stable food source; its decline is troubling to biologists and agricultural scientists.
It is also useful to define ecosystem diversity: the number of different ecosystems on the planet or in a given geographic area. Whole ecosystems can disappear even if some of the species might survive by adapting to other ecosystems. The loss of an ecosystem means the loss of interactions between species, the loss of unique features of co-adaptation, and the loss of biological productivity that an ecosystem is able to create. An example of a largely-extinct ecosystem in North America is the prairie ecosystem. Prairies once spanned central North America from the boreal forest in northern Canada down into Mexico. Now, they have mostly disappeared, replaced by crop fields, pasture lands, and suburban sprawl. Many of the species survive, but the hugely-productive ecosystem that was responsible for creating the most productive agricultural soils is now gone. As a consequence, soils are disappearing or must be maintained at greater expense.
Current Species Diversity
Despite considerable effort, knowledge of the species that inhabit the planet is limited. A recent estimate suggests that the number of identified eukaryote species, about 1.5 million species, account for less than 20 percent of the total number of eukaryote species present on the planet (8.7 million species, by one estimate). Estimates of numbers of prokaryotic species are largely guesses, but biologists agree that science has only begun to catalog their diversity. Even with what is known, there is no central repository of names or samples of the described species; therefore, there is no way to be sure that 1.5 million is an accurate number. It is a best guess based on the opinions of experts in different taxonomic groups. Given that earth is losing species at an accelerating pace, science knows little about what is being lost.
There are various initiatives to catalog described species in accessible ways; the internet is facilitating that effort. Nevertheless, it has been pointed out that at the current rate of species description, which according to the State of Observed Species Report is 17,000 to 20,000 new species per year, it will take close to 500 years to finish describing life on this planet.
Naming and counting species may seem an unimportant pursuit given the other needs of humanity, but it is not as simple as counting. Describing species is a complex process by which biologists determine an organism’s unique characteristics and whether or not that organism belongs to any other described species. It allows biologists to find and recognize the species after the initial discovery, which allows them to follow up on questions about its biology. In addition, the unique characteristics of each species make it potentially valuable to humans or other species on which humans depend. Understanding these characteristics is the value of finding and naming species.
- A genus with a high variety of species will have more genetic diversity; the most genetically-diverse species will have the greatest potential for evolution and preservation.
- The loss of ecosystem diversity results in the loss of interactions between species, unique features of co- adaptation, and biological productivity.
- Human-generated species diversity has decreased due to migration, market forces, and agriculture.
- Humans have only been able to estimate the number of species that inhabit earth; this estimate accounts for about 20 percent of predicted species on the planet.
- Humans have only been able to estimate the number of species that inhabit Earth; this estimate only accounts for 20 percent of predicted species on the planet.
- genetic diversity: variety of genes in a species or other taxonomic group or ecosystem; can refer to allelic diversity or genome-wide diversity
- ecosystem diversity: variety of ecosystems in a biosphere or the variety of species and ecological processes that occur in different physical settings
- chemical diversity: variety of metabolic compounds in an ecosystem