Ecosystem Diversity

The variety of the biosphere's ecosystems is the third level of biological diversity. Each ecosystem has characteristic patterns of energy flow and chemical cycling that can affect the whole biosphere. For example, the productive pastures of phytoplankton in the oceans may help moderate the greenhouse effect by consuming massive quantities of carbon dioxide for photosynthesis and for building shells made of bicarbonate.

Genetic Diversity

Picture of Genetic Diversity In Peas

Genetic Diversity comprises not only the individual genetic variation within a population, but also the genetic variation between populations that is often associated with adaptations to local conditions. If one population becomes extinct, then a species may have lost some of the genetic diversity that makes microevolution possible. The loss of genetic diversity throughout the biosphere also has implications for human welfare. For example, if we lose wild populations of plants closely related to agricultural species, we lose genetic resources that could be potentially used to improve certain crop qualities, such as disease resistance, through plant breeding. 

Four Major Threats to Biodiversity

 Many different human activities threatens biodiversity on a local, regional, and global scale. Of this long list, most species loss can be traced to four major threats: habitat destruction, introduced species, overexploitation, and disruption of interaction networks such as food webs.
Habitat Destruction
Human alteration of habitat is the single greatest threat to biodiversity throughout the biosphere. Massive destruction of habitats has been brought about by agriculture, urban development, forestry, mining, and pollution. Habitat destruction may occur over immense regions. Sadly, 98% of the tropical dry forests of Central America nad Mexico have been cleared or cut down. Habitat loss is also a major threat to marine biodiversity. 93% of coral reefs have been damaged by human activities.
Introduced Species
Introduced species are species that humans move from native locations to new geographic regions. Free from predators, parasites, and pathogens, such transplanted species may spread through a new region at exponential rates.
Overexploitation
Overexploitation refers generally to the human harvesting of wild plants or animals at rates exceeding the ability of populations of those species to rebound. Species with restricted habitats are very vulnerable to overexploitation.
Disruption of Interaction Networks
The extinction of a keystone species can lead to the extinction of many other kinds of species.

Finding Biodiversity Hot Spots

A biodiversity hot spot is a relatively small area with an exceptional concentration of endemic species and a large number of endangered and threatened species. For example, nearly 30% of all bird species are confined to only about 2% of Earth's land area. And about 50,000 plant species, or about 17% of all known plant species inhabit just 18 hot spots that comprise a total of only 0.5% of the global land surface. Together, the hottest of the biodiversity hot spots total less than 1.5% of Earth's land but are home to a third of species and vertebrates.

Why is the Hawaiian Islands a Biodiversity Hotspot?

 The Hawaiian Islands is a biodiversity hotspot in that many species in the Hawaiian Islands are in fact endangered. The impact of invasive species which is purposefully or accidentally brought to the islands is the biggest threat. All of the ants in Hawaii are not native. Invasive rats threaten the native birds by getting into nests and eating the eggs and the young. Wild pigs also make puddles in the forest where mosquitoes breed. The mosquitoes carry pathogens that cause malaria in birds. Also, invasive plants are crowding out many of the native pant species.

The species diversity of a community- the variety of different kinds of organisms that make up the community- has two components. One is species richness or the total number of different species in the community. The other is the relative abundance of the different species or the proportion each species represents of the total individuals in the community.

Biodiversity is a hallmark of life. Biologists have so far identified and named about 1.8 million species. This enormous diversity of life includes approximately 5,200 known species of prokaryotes, 100,000 fungi, 290,000 plants, 52,000 vertebrates, and 1,000,000 insects. Researchers identify thousands of additional species each year. Estimates of the total species count range from about 10 million to over 200 million. Whatever the actual number, the vast variety of life make biology's scope very wide.