314 • Technologies To Maintain Biological Diversity 



The molecule is double stranded, with an exter- 

 nal "backbone" formedby a chain of alternating 

 phosphate and sugar (deoxyribose) units and an 

 internal ladder-like structure formed by nucleo- 

 tide base-pairs held together by hydrogen bonds. 



Domestication: The adaptation of an animal or 

 plant to life in intimate association with and to 

 the advantage of man. 



Ecology: A branch of science concerned with the 

 interrelationship of organisms and their envi- 

 ronment. 



Ecosystem: An ecological community together with 

 its physical environment, considered as a unit. 



Ecosystem diversity: The variety of ecosystems that 

 occurs within a larger landscape, ranging from 

 biome (the largest ecological unit) to microhabitat. 



Electrophoresis: Application of an electric field to 

 a mixture of charged particles in a solution for 

 the purpose of separating (e.g., mixture of pro- 

 teins) as they migrate through a porous support- 

 ing medium of filter paper, cellulose acetate, or 

 gel. 



Embryo transfer: An animal breeding technique 

 in which viable and healthy embryos are artifi- 

 cially transferred to recipient animals for nor- 

 mal gestation and delivery. 



Endangered species: A technical definition used 

 for classification in the United States referring 

 to a species that is in danger of extinction through- 

 out all or a significant portion of its range. The 

 International Union for the Conservation of Na- 

 ture and Natural Resources (lUCN) definition, 

 used outside the United States, defines species 

 as endangered if the factors causing their vul- 

 nerability or decline continue to operate. 



Endemism: The occurrence of a species in a par- 

 ticular locality or region. 



Equilibrium theory: A theory of island biogeogra- 

 phy maintaining that greater numbers of species 

 are found on larger islands because the popula- 

 tions on smaller islands are more vulnerable to 

 extinction. This theory can also be applied to ter- 

 restrial analogs such as forest patches in agricul- 

 tural or suburban areas or nature reserves where 

 it has become known as "insular ecology." 



Exotic species: An organism that exists in the free 

 state in an area but is not native to that area. Also 

 refers to animals from outside the country in 

 which they are held in captive or free-ranging 

 populations. 



Ex-situ: Pertaining to study or maintenance of an 

 organism or groups of organisms away from the 

 place where they naturally occur. Commonly 



associated with collections of plants and animals 

 in storage facilities, botanic gardens, or zoos. 



Extinct species: As defined by the lUCN, extinct 

 taxa are species or other taxa that are no longer 

 known to exist in the wild after repeated search 

 of their type of locality and other locations where 

 they were known or likely to have occurred. 



Extinction: Disappearance of a taxonomic group 

 of organisms from existence in all regions. 



Fauna: Organisms of the animal kingdom. 



Feral: A domesticated species that has adapted to 

 existence in the wild state but remains distinct 

 from other wild species. Examples are the wild 

 horses and burros of the West and the wild goats 

 and pigs of Hawaii. 



Flora: Organisms of the plant kingdom. 



Gamete: The sperm or unfertilized egg of animals 

 that transmit the parental genetic information to 

 offspring. In plants, functionally equivalent struc- 

 tures are found in pollen and ovules. 



Gene: A chemical unit of hereditary information 

 that can be passed from one generation to another. 



Gene-pool: The collection of genes in an interbreed- 

 ing population. 



Genetic diversity: The variety of genes within a par- 

 ticular species, variety, or breed. 



Genetic drift: A cumulative process involving the 

 chance loss of some genes and the disproportion- 

 ate replication of others over successive genera- 

 tions in a small population, so that the frequen- 

 cies of genes in the population is altered. The 

 process can lead to a population that differs ge- 

 netically and in appearance from the original 

 population. 



Genotype: The genetic constitution of an organism, 

 as distinguished from its physical appearance. 



Genus: A category of biological classification rank- 

 ing between the family and the species, compris- 

 ing structurally or phylogenetically related spe- 

 cies or an isolated species exhibiting unusual 

 differentiation. 



Germplasm: Imprecise term generally used to re- 

 fer to the genetic information of an organism or 

 group of organisms. 



Grow-out (growing-out): The process of growing 

 a plant for the purpose of producing fresh viable 

 seed to evaluate its varietal characteristics. 



Habitat: The place or type of site where an organ- 

 ism naturally occurs. 



Hybrid: An offspring of a cross between two ge- 

 netically unlike individuals. 



Inbreeding: Mating of close relatives resulting in 

 increased genetic uniformity in the offspring. 



