Chapter 2 



Importance of Biological Diversity 



HIGHLIGHTS 



Biological diversity benefits human welfare directly, as various organisms are 

 used to satisfy basic human needs, and indirectly, as diversity supports many 

 processes essential to human survival and progress. 



The constituency for maintaining biological diversity is large but fragmented 

 because many groups focus on various aspects of biological resources rather 

 than on diversity per se. Constituents w^ho are politically articulate in support 

 of diversity are usually motivated by its intrinsic values rather than its sub- 

 stantial economic values. 



Human welfare is inextricably linked to, and 

 dependent on, biological diversity. Diversity is 

 necessary for several reasons: 1) to sustain and 

 improve agriculture, 2) to provide opportunities 

 for medical discoveries and industrial innova- 

 tions, and 3) to preserve choices for address- 

 ing unpredictable problems and opportunities 

 of future generations. Actual and potential eco- 



nomic uses range from subsistence foraging to 

 genetic engineering. The essential services of 

 ecosystems, such as moderating climate; con- 

 centrating, fixing, and recycling nutrients; pro- 

 ducing and preserving soils; and controlling 

 pests and diseases are also dependent on bio- 

 logical diversity. Finally, diversity has esthetic 

 and ethical values. 



DEFINITION 



Biological diversity refers to the variety and 

 variability among living organisms and the eco- 

 logical complexes in which they occur. Diver- 

 sity can be defined as the number of different 

 kinds of items and their relative frequency in 

 a set [97]. Items are organized at many levels, 

 ranging from complete ecosystems to the chem- 

 ical structures that are the molecular basis of 

 heredity. Thus, the term encompasses the num- 

 bers and relative abundance of different eco- 

 systems, species, and genes. (Box 2-A describes 

 major components of biological diversity.) 



Species diversity, for example, decreases 

 when the number of species in an area is re- 

 duced or when the same number exists but a 

 few become more abundant while others be- 

 come scarce. When a species no longer exists 

 in an area, it is said to be locally eliminated. 



The extreme effect of species diversity loss is 

 extinction— when a species no longer exists 

 anywhere. 



Biological diversity is the basis of adaptation 

 and evolution and is basic to all ecological proc- 

 esses. It contributes to research and education, 

 cultural heritage, recreation and tourism, the 

 development of new and existing plant and ani- 

 mal domesticates, and the supply of harvested 

 resources (table 2-1). The intrinsic importance 

 of biological diversity lies in the uniqueness of 

 all forms of life: each individual is different, 

 as is each population, each species, and each 

 association of species. Major functional and 

 utilitarian benefits of ecosystem, species, and 

 genetic diversity are described in the next five 

 sections; evaluation of diversity and the con- 

 stituencies of diversity are discussed in the fi- 

 nal sections. 



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