Gene pool

For the guitarist named Gene Pool, seeGreg Flesch.

Thegene poolis the set of allgenes,orgenetic information,in anypopulation,usually of a particularspecies.

Description

A large gene pool indicates extensivegenetic diversity,which is associated with robust populations that can survive bouts of intenseselection.Meanwhile, lowgenetic diversity(seeinbreedingandpopulation bottlenecks) can cause reducedbiological fitnessand an increased chance ofextinction,although as explained bygenetic driftnew genetic variants, that may cause an increase in thefitnessof organisms, are more likely to fix in the population if it is rather small.

When all individuals in a population are identical with regard to a particularphenotypictrait, the population is said to be 'monomorphic'. When the individuals show several variants of a particular trait they are said to bepolymorphic.

History

The Russian geneticistAlexander Sergeevich Serebrovskyfirst formulated the concept in the 1920s asgenofond(gene fund), a word that was imported to the United States from the Soviet Union byTheodosius Dobzhansky,who translated it into English as "gene pool."

Gene pool concept in crop breeding

Harlan and de Wet (1971) proposed classifying each crop and its related species by gene pools rather than by formal taxonomy.

1. Primary gene pool (GP-1): Members of this gene pool are probably in the same "species"(in conventional biological usage) and can intermate freely. Harlan and de Wet wrote," Among forms of this gene pool, crossing is easy;hybridsare generally fertile with good chromosome pairing; gene segregation is approximately normal andgene transferis generally easy. ".They also advised subdividing each crop gene pool in two:
   • Subspecies A: Cultivated races
   • Subspecies B: Spontaneous races (wild or weedy)
2. Secondary gene pool (GP-2): Members of this pool are probably normally classified as different species than the crop species under consideration (the primary gene pool). However, these species are closely related and can cross and produce at least some fertile hybrids. As would be expected by members of different species, there are some reproductive barriers between members of the primary and secondary gene pools:
   • hybrids may be weak
   • hybrids may be partially sterile
   • chromosomesmay pair poorly or not at all
   • recovery of desiredphenotypesmay be difficult in subsequent generations
   • However, "The gene pool is available to be utilized, however, if the plant breeder or geneticist is willing to put out the effort required."
3. Tertiary gene pool (GP-3): Members of this gene pool are more distantly related to the members of the primary gene pool. The primary and tertiary gene pools can be intermated, butgenetransfer between them is impossible without the use of "rather extreme or radical measures"such as:
   • embryo rescue (or embryo culture, a form of plantorgan culture)
   • inducedpolyploidy(chromosome doubling)
   • bridging crosses (e.g., with members of the secondary gene pool).

Gene pool centres

Gene pool centres refers to areas on the earth where important crop plants and domestic animals originated. They have an extraordinary range of the wild counterparts of cultivated plant species and useful tropical plants. Gene pool centres also contain different sub tropical and temperate region species.

See also

• Biodiversity
• Conservation biology
• Founder effect
• Gene flow
• Genetic drift
• Small population size
• Australian Grains Genebank