Ch. 2— Importance of Biological Diversity • 45 



Photo credit: J. Cohen, National Zoo 



The armadillo is one of only two animal species known to contract leprosy. 

 Ttiese animals now serve as research: models to find a cure. 



sponge. Three derivatives of this com- 

 pound have been patented as antiviral and 

 anticancer drugs (10). 



Genetic Diversity 



Genetic variabihty is one of the characteris- 

 tics of fruit flies, tree snails, and butterflies that 

 makes them so useful for research. The unusual 

 range of diversity among the races, varieties, 

 and lines of corn contributes to its enormous 

 value for basic biological research. One exam- 

 ple is the discovery and analysis of regulatory 

 systems that control gene expression, wrhich 

 added a new dimension to the study of in- 

 heritance (21). 



The genus Nicotiana has also been used 

 widely in genetic and botanical research largely 



because of the great variation among its spe- 

 cies (84). The varied reactions to specific viruses 

 characteristic of many Nicotiana species pro- 

 vide a potential tool for separating and iden- 

 tifying viruses. Nicotiana species have been 

 involved in numerous discoveries of virus re- 

 search (e.g., virus transmissibility, purification, 

 and mutability) (35). 



Special genetic stocks are essential research 

 tools. For example, inbred lines of chickens de- 

 veloped at the University of California at Davis 

 are used worldwide for research on immunol- 

 ogy and disease resistance of chickens. Mutant 

 stocks of chickens also serve as genetic models 

 for scoliosis (lateral curvature of the spine) and 

 muscular dystrophy in humans (58). 



