Implicationsof+Human+manipulation+of+gene+transfer

Human Manipulation of the genes chosen for future populations

either by Selective Breeding or by Transgenesis.

Humans choose which individuals' genes are passed on when using these techniques. This has Implications for the gene pools for future generations.

Effect on Genetic biodiversity.
What will happen to the range of alleles in a gene pool of a population if farmers only select some individuals for breeding? Other genes associated and possibly not known about will also be affected, for example cows native to hot climates are able to resist high temperatures, but probably can't make a lot of milk. If we start breeding them with high milk producing cows from temperate regions, then the high temperature ability may be lost, but alongside that gene may also be a gene for resisting a parasite, which is also lost from the population, and when the parasite attacks again, the gene pool no longer has the ability to fight that pest off. There is less diversity in the population when all the same individuals and their descendants are chosen for breeding.

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http://www.banglajol.info/index.php/PTCB/article/view/1114

Genetic Engineering to create specialist cows http://regentsprep.org/Regents/biology/units/heredity/engineering.cfm

Examples of the selected breeds of cattle that people have selectively bred. http://www.ansi.okstate.edu/breeds/cattle/

3 video clips explaining why cows gene pools have been so manipulated by humans. http://www.pbs.org/wnet/nature/lessons/the-perfect-cow/video-segments-holy-cow/1536/

A Dying Breed-selective breeding and indigenous cows. http://www.nytimes.com/2008/01/27/magazine/27cow-t.html?ref=world&_r=0

Sheep have also been manipulated to select for characteristics of different wool types or breeding twins so that the farmer can make more money. These flocks have been purebreeding for many generations so that no throwbacks occur. This creates a population with very similar alleles and therefore low variety in the gene pool.

What happens when a new trait is desirable in a population? Biotechnology learning hub describes a real New Zealand research example of Easy Care Sheep, created by selective breeding at Ag Research. http://biotechlearn.org.nz/focus_stories/easy_care_sheep.

The plan was to develop low cost sheep for farmers once the prices for wool and meat fell. New Zealand scientists were able to look overseas for sheep flocks that had been deliberately kept pure to find variations of sheep that had no wool on their faces or legs to create the 'easy care' sheep. Having these variations on genes available still was significant. If the populations had been selectively bred to be best for commercial purposes according to the consumer demands of the time, then variations like these might have been lost. New Zealand sheep have been bred for many generations for carpet wool, which is no longer in demand. Merino sheep are now being bred for fine wool for clothing.

Health of Individuals
https://www.youtube.com/watch?v=aCv10_WvGxo The Truth about Pure Bred Dogs (thanks to Sam for this link)

Some species have to have medical intervention to allow their offspring to be born. Belgian blue cattle for example are bred by breeding animals with the same mutation in their myostatin gene, which normally inhibits muscle growth. The mutation means the muscles don't stop growing.The double-muscling phenotype is a heritable condition which results in the increased number o f muscle fibers (hyperplasia) rather than the normal enlargement of individual muscle fibers (hypertrophy). [|3]] The extra muscle growth begins in the womb so calves are too big to be born, and have to be born by caesarian. In addition the double muscle females can have a narrower birth canal making calving even more difficult.

Evolution of Populations
The driving force behind successful populations is Natural Selection. In this process there is variation in a population,which allows a group to adapt to an environment through competition between offspring. If the environment changes, then the variants with the new best suited adaptations breed more successfully and the population's gene pool changes in the next generation. If people are manipulating the breeding, rather than competition for resources manipulating the successful offspring, the populations gene pool will be altered, perhaps in a way that means the group is not best suited to a natural habitat. It may mean the group can only survive if people maintain the protected environment.

The perfect cow in Africa is an example of this. (Selective breeding)

Flood tolerant rice is an example of this.(Selective breeding) (http://www.irinnews.org/report/82760/philippines-could-flood-resistant-rice-be-the-way-forward).

There is some concern that transgenic organism may breed with wild individuals and create non sex offspring, so that the populations future generations could become extinct. One study in transgenic fish has shown that the transgenic male is more successful at mating, but their offspring are not viable (can't breed), a pretty disastrous combination. (http://www.pnas.org/content/96/24/13853.full.pdf)

Survival of Populations
Conservationists need to be aware of inbreeding when they select individuals for conservation programmes.

And transgenic organism interbreeding with wild populations will have an effect in future gene pools, if their genes are successful. It won't be a matter of changing the frequency of an allele, it will be about a gene that did not exist before.

Sometimes the transgenic individuals can have other disastrous effects on long term futures of a species, see this article, http://www.pnas.org/content/96/24/13853.full.pdf, about a transgenic case that makes unsuccessful hybrids.