A number of levels of organization of living organisms can be estimated.
When the main concern of biologists is the loss of biodiversity, the estimation indices are less useful than they should be.
Measures of biodiversity, in terms of species diversity, may help focus efforts to preserve biologically or technologically important elements of biodiversity.
The Lake Victoria cichlids are an example of what we can learn from this.
In the 1980s, biologists discovered hundreds of species representing a variety of specializations to specialized habitat types and specific feeding strategies, such as eating plankton floating in the water.
Lake Victoria's cichlids are the product of an adaptive radiation.
The speciesradiates into different habitats.
The 15 species of finches on the Galapagos Island are an example of modest adaptive radiation.
The cichlids of Lake Victoria are an example of a spectacular adaptive radiation that used to include 500 species.
Some species quickly disappeared when biologists made this discovery.
The Nile perch, a large predatory fish, was introduced to Lake Victoria by the fisheries to feed the people living around the lake.
The Nile perch was introduced in 1963, but its populations did not begin to increase until the 1980s.
The Nile perch, declining lake water quality due to agriculture and land clearing on the shores of Lake Victoria, and increased fishing pressure were some of the factors that played a role in the extinction of 200 cichlid species in Lake Victoria.
Many of the species that were lost were never named.
The diversity is not what it used to be.
Contemporary rapid species loss that occurs all over Earth is caused primarily by human activity and is depicted in the cichlids of Lake Victoria.
At the rate of one out of 1 million species becoming extinct per year, extinction is a natural process of macroevolution.
There is a major difference between the previous mass extinctions and the current extinction.
There are three human activities that have a major impact: destruction of habitat, introduction of exotic species, and over-harvesting.
In the history of the planet, there have only been five extinctions on this scale, which were caused by catastrophic events that changed the course of the history of life.
The term "biodiversity" describes the number of species and their abundance on the planet.
Most biologists feel comfortable with the concept of species and are able to identify and count them in most contexts.
One of those concepts is genetic diversity.
The future potential of a species depends on the genetic diversity in the populations that make up the species.
The same is true for higher categories.
A group with different types of species will have more genetic diversity than a group with the same types of species.
The most genetically diverse of the genera is the one that has the greatest potential for evolution.
metabolic processes that keep organisms alive and reproducing are carried out by many genes.
One way to measure diversity that is important to human health and welfare is by using chemical diversity as a source of pharmaceuticals.
Humans have created a variety of organisms.
This diversity is also suffering losses because of migration, market forces, and increasing globalism in agriculture, especially in densely populated regions such as China, India, and Japan.
The human population depends on diversity as a stable food source, and its decline is troubling biologists and agricultural scientists.
Even if some of the species survive, whole ecosystems can disappear.
The loss of an ecosystems means the loss of interactions between species, the loss of unique features, and the loss of biological productivity.
The prairie ecosystem is an example of a largely extinct one.
Prairies once stretched from northern Canada down into Mexico.
Crop fields, pasture lands, and suburban sprawl replaced them.
The most productive agricultural soils in the United States are no longer created by the hugely productive ecosystem.
Native soils are disappearing or must be maintained at great expense.
There is a great diversity of species on Earth.
The knowledge of the species that live on the planet is limited because of a lack of financial resources and political will.
According to a recent estimate, less than 20% of the total number of species on the planet are known by science.
Estimates of the number of prokaryotic species are largely guesses, but biologists agree that science has only begun to catalog their diversity.
There is no way to be sure that the 1.5 million descriptions are accurate because there is no central repository of names or samples.
It is a guess based on the opinions of experts.
Science is very much in the same place as it was with the Lake Victoria cichlids, knowing little about what is being lost.
The internet is facilitating the effort to catalog accessible species.
According to the State of Observed Species Report, it will take close to 500 years to describe life on this planet.
The pursuit of naming and counting species may seem unimportant, but it's not just an accounting of species.
Biologists determine the unique characteristics of an organisms and whether or not it belongs to any other described species.
After the initial discovery, it allows biologists to follow up on questions about the biology of the species.
The unique characteristics of each species make it potentially valuable to humans or other species on which humans depend.
It's not evenly distributed on Earth.
Lake Victoria had almost 500 species of cichlids, ignoring the other fish families present in the lake.
The 500 species of cichlids were endemic because they were all found in Lake Victoria.
Highly restricted distributions are vulnerable to extinction.
The genera and families can be endemic.
Many of the fish found in Lake Michigan are found in other lakes in North America.
Lake Michigan is a recently formed lake while Lake Victoria is an ancient tropical lake.
The present form of Lake Michigan is about 7,000 years old, while the present form of Lake Victoria is about 15,000 years old.
Two factors, latitude and age, have been suggested as possible explanations for the diversity of the planet's flora and fauna.
In May, 20, 2012
The work of biogeographers is important to understanding our physical environment, how the environment affects species, and how environmental changes impact the distribution of a species.
Both ecology and biology need to be understood by biogeographers.
They need to know about evolutionary studies, soil science, and climatology.
There are three main fields of study under the heading of biogeography.
One of the oldest patterns in ecology is that species increase as latitude decreases.
The number of amphibian species across the globe is shown on the map.
The pattern is the same for most groups.
There is a lack of data in the study.
Scientists don't know why there is an increase in biodiversity closer to the equator.
The tropics have a greater age of the ecosystems than the temperate regions, which were largely devoid of life during the last glaciation.
The idea is that older people have more time for speciation.
It is possible that the tropics receive more direct energy from the sun than the polar regions.
More opportunities for coevolution, specialization, and perhaps greater selection pressures are provided by the greater heterogeneity.
The tropics have been seen as being more stable than the other parts of the world.
The tropics are assumed to be more stable than other environments and this might promote speciation into highly specialized niches.
Regardless of the mechanisms, it's true that the tropics have the greatest levels of biodiversity.
Knowledge of species is very low and there is a high potential for extinction because of the richness of diversity.