Types of Biological Diversity

Biodiversity may be defined in five different ways. Genetic diversity, species diversity, and ecosystem diversity describe biological systems made of plants or animals, or both. Ecological diversity and functional diversity describe the Earth’s biota in large systems, such as biomes. Most people with some idea of biodiversity tend to think of species diversity, which is the number and variety of species on Earth. Biodiversity actually ranges from the molecular level within a species’ genome to a much larger scale that encompasses the entire environment.

Genetic diversity occurs at the molecular level within deoxyribonucleic acid (DNA) and in an individual’s genes. Genetic diversity causes differences between individuals within a population and, in many cases, a specific set of genes possessed by one animal enables it to survive when others in its group cannot. The idea of genetic diversity becomes clear by considering specific examples to show how this type of biodiversity gives certain individuals an advantage over others within a population.

» Cheetahs that run faster than others have a better chance at catching prey.

» Bull walruses that are bigger and stronger than other males have a better chance of breeding with females.

» The brightest colored male cardinal has the best chance of attracting females.

» Wildebeests that maneuver the best over the African savanna have a good chance of escaping lions.

» Salamanders colored in the most deceptive camouflage have an increased chance of going unnoticed by predators.

An animal’s traits come from its genotype, which is the collection of genes that make an animal look and behave as it does. Gene analysis provides information about adaptations such as speed, strength, and camouflage that enable certain individuals to thrive while others succumb. Genotypes also describe the relatedness of members in a population and between populations. Relatedness may in turn indicate declining population size, interrupted migration routes, destruction of breeding grounds, or disrupted habitat. This is because when populations become fragmented or decline in size, the diversity of the group’s members begins to decline; the individuals making up the group become more related to each other over a few generations.

Genetic diversity studies begin by taking tissue, blood, or hair samples from animals. The biologist then determines the nucleic acid sequence of the sample’s DNA to define the animal’s genotype. Any unique pattern in DNA’s gene sequence may indicate a specific trait that gives an animal favorable characteristics. Genotype can be more complicated than this simple description, however. No single gene gives a cheetah its extraordinary speed, but it may be possible to find a finite set of genes that determine a salamander’s camouflage pattern. Conservation biologists may one day be able to inject into an animal genes that will confer advantages for the animal’s survival. The pathologist John H. Wolfe at Pennsylvania’s School of Veterinary Medicine has said in a campus newsletter, “Through gene therapy, we replace a ‘broken’ gene . . . with the correct, functioning copy.” This technology may take a long time to enter conservation biology, but the fast rate of species loss demands that new technologies move quickly to save the world’s critically endangered species. Such gene manipulation will also prompt arguments from those who denounce this practice because it goes against nature and the new transgenic animal may carry potential and unknown dangers. The debate about genetically modified species continues to unfold, and no conclusions have yet come from these discussions.

Species diversity consists of two important components: richness and evenness. Species richness comprises the number of species living in a region or a community; species evenness relates to the abundance of individuals within a select species. Biologists estimate species diversity by manually counting animals in the wild within a specific region, and then illustrating the results on a map of the region. Species diversity maps almost always provide mere estimates rather than exact numbers because most animal species can be difficult to count. One technique to estimate animal numbers involves counting small groups, such as a herd or a flock, and then extrapolating those results to estimate the total population size. Though biology now has accumulated fairly accurate estimates for easy to count animals like elephants, rhinoceroses, pandas, or golden eagles, counting secretive species or ones that live in hard-to-reach habitats— snow leopards, whales, white sharks, or birds in jungle canopies—still present unique challenges.

Ecosystem diversity encompasses all of the various ecosystems known to biology. Some examples of different ecosystems are marine kelp forests, coral reefs, the African savanna, and pine forests. Ecosystem diversity also refers to the variations within ecosystems. For example, a freshwater lake is an ecosystem, but it also contains subecosystems at the lake bottom, at mid-depth, at the water’s surface, and along its banks.

Ecology is the study of ecosystems and how they relate to each other. Ecology contributes to the study of biodiversity by helping biologists gain an understanding of biomes, including the types of plants living in them, their terrain, their physical features, and their climate. The health of biomes influences the status of many of the individual species native to those biomes. For example, land that 50 years ago supported grassland contained grassland ecosystems, soil ecosystems, and possibly aquatic ecosystems in ponds and streams. After a prolonged drought due to climate change, for instance, the grassland may turn into a dry plain (desertification) and the grassland ecosystems yield to desert ecosystems. All of these events have a profound effect on the biodiversity in these places and contribute to ecological diversity.

Ecological diversity comprises the variety of forests, wetlands, grasslands, lakes, oceans, riparian areas, and other biological communities that interact with their living and nonliving environment. (A biological community is the collection of animal and plant populations living and interacting in a particular area. The populations of species that lived on the vast plains of the western United States before the 1800s are an example of a biological community.) Air and ground surveys help biologists assess ecological diversity, which in turn gives a clearer picture of ecosystem diversity.

The final type of biodiversity is functional diversity, which is the variety of biological and chemical processes (called biogeochemical cycles) that make energy and nutrients available for biota. In other words, functional diversity provides various ways for the energy-matter cycle to operate.

Source of Information : Green Technology Biodiversity (2010)