Biodiversity - Biodiversity Types/Functions of Biodiversity December 19, 2017 Biodiversity Types The word “biodiversity” is an abbreviated version of “biological diversity”. The Convention on Biological Diversity defines biodiversity as: “the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part; this includes diversity within species, between species, and of ecosystems.” Thus, Biodiversity refers to the variety of forms – the different plants, animals and micro-organisms. It also includes the genes they contain and the ecosystem they form. It deals essentially with dynamic processes and increases when new genetic variation is produced and decreases on the loss of genetic variation or species extinction. TYPES OF BIODIVERSITY There are three distinct levels of bio-diversity though all of them are components of a much intricate web. • Genetic Diversity: a) It refers to variation of genes within species. b) This variation can exist between different populations of the same species as well as between individuals within a population. c) Genetic diversity provides organisms and ecosystems with capacity to recuperate after change has occurred. d) Thus Genetic diversity is a level of biodiversity that refers to the total number of genetic characteristics in the genetic makeup of a species. It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary. e) Genetic diversity plays a great role in the adaptability and survival of a species. A species that has a large degree of genetic diversity among its individuals will have more variations from which to choose the most fitting allele. • Species Diversity: a) Species diversity is a measure of the diversity within an ecological community that incorporates both species richness (the number of species in a community) and the evenness of species’ abundance. b) Species diversity can be measured in terms of: i. Species richness – refers to the number of various species in a defined area. ii. Species abundance – refers to the relative numbers among species. For example, the number of species of plants, animals and microorganisms may be more in an area than that recorded in another area. iii. Taxonomic or phylogenetic diversity – refers to the genetic relationships between different groups of species. c) Species diversity is not evenly distributed across the globe. The overall richness of species is concentrated in equatorial regions and tends to decrease as one moves from equatorial to polar regions. d) In addition, biodiversity in land ecosystems generally decreases with increasing altitude. The other factors that influence biodiversity are amount of rainfall and nutrient level in soil. In marine ecosystems, species richness tends to be much higher in continental shelves. • Ecosystem Diversity: a) It refers to the presence of different types of ecosystems. For instance, the tropical south India with rich species diversity will have altogether different structure compared to the desert ecosystem which has far less number of plant and animal species. b) Likewise, the marine ecosystem although has many types of fishes, yet it differs from the freshwater ecosystem of rivers and lakes in terms of its characteristics. So such variations at ecosystem level are termed as ecosystem diversity. • Functional Diversity: a) Functional diversity refers to the diversity of ecological processes that maintain and are dependent upon the other components of diversity. b) Functional diversity includes the many ecological interactions among species e.g. competition, predation, parasitism, mutualism, etc. as well as ecological processes such as nutrient retention and recycling. c) It also includes the varying tempos and intensities of natural disturbances that many species and communities require if they are to persist.