Gene pool

A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survive bouts of intense selection. Meanwhile, low genetic diversity (see inbreeding and population bottlenecks) can cause reduced biological fitness and an increased chance of extinction, although as explained by genetic drift new genetic variants, that may cause an increase in the fitness of 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 particular phenotypic trait, the population is said to be 'monomorphic'. When the individuals show several variants of a particular trait they are said to be polymorphic.

The Russian geneticist Alexander Sergeevich Serebrovsky first formulated the concept in the 1920s as genofond (gene fund), a word that was imported to the United States from the Soviet Union by Theodosius Dobzhansky, who translated it into English as "gene pool."[1]

Harlan and de Wet (1971) proposed classifying each crop and its related species by gene pools rather than by formal taxonomy.[2]

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; hybrids are generally fertile with good chromosome pairing; gene segregation is approximately normal and gene transfer is generally easy.".[2] 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
   • chromosomes may pair poorly or not at all
   • recovery of desired phenotypes may 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."[2]
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, but gene transfer between them is impossible without the use of "rather extreme or radical measures" [2] such as:
   • embryo rescue (or embryo culture, a form of plant organ culture)
   • induced polyploidy (chromosome doubling)
   • bridging crosses (e.g., with members of the secondary gene pool).

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.

Hu et al. mostly focuses on the genetic breeding of specific plants to help with the rise of climate change and how this will affect crops. We focus on a the genus Brassica more specifically the plant Rapeseed and how changing and strengthening the gene pool of the plant has improved crop yields. The article also goes into greater depths on topics about the Rapeseed like genome structure, population-level differentiation, gene cloning, and more.[3]

Another example of gene pools in plants is Norwegian spruce trees are studied in a parks all across Moscow and trees found naturally in forested areas. What the researchers discovered is gene pool and genetic diversity greatly decreased between those planted in plant stands and those found naturally. Because of this decrease they found that multiple of the plant stands were in a critical state and one had even died out completely.[4]

Barker et al. go in depth about the relation between plants and insects. More specifically the writers speak about different plant traits and insect communities.[5]

Simonov speaks about the European Bison and how rising populations has increased the gene pool of the animal. There are different measurements of the wild bison compared to the domesticated species. They also speak about their dietary practices and how free ranging enables them to grow in different ways.[6] Kharkov et al. speaks about the genetic diversity and the gene pool of the Russian, Ukrainian, and Belarussian people. They speak of how the different groups really haven't been studied thoroughly and effectively enough. There are many tables/graphs in this article that show different alleles and loci that were studied to show the differences and similarities presented in the populations.[7] Cyranoski delves into the work of changing of genetic material and rewriting the gene pool. It speaks of how a biophysicist name He from China genetic birthed two girls with changed genes. There's a sentence in the article that stated the scientific community isn't sure if the alterations actually worked.[8]

Lara-Flores and Rivera-Arriaga talks about how genetic engineering has been thought of as an idea for the repopulating different fish stocks. They also speak of ways to manage these genetically modified species.[9] Mourkas et al. focus mostly on the mutation of a pathogen that has grown resistant to antibiotics. It's a food born pathogen that has been linked to livestock but the researchers aren't sure of how it spreads to humans. We're presented with multiple tests that looked for antibiotic genes and found multiple similarities between the two pathogens.[10]

Lara-Flores and Rivera-Arriaga also raise many questions on the effect that genetically engineering fish species might have. Questions like what are some possible mutations, are there existing rules and regulations for this change, and could there be any risks to the already existing ecosystems?[11]

Cyranoski is very heavy with the details of what He did in genetically changing the two girls that were born. It states that he could have done this illegally and may face criminal charges once the trial is over. We also see statements from different scientist that study in the same field and they speak on how this might cause drastic damage to gene editing.[12]

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