After my nervousness last week, I'm going to talk today about a more relaxed (sure?) subject: genetic evolution of species. It is a general subject, valid for both plant and animal species.
What is it?
It’s the various natural or artificial ways that cause the evolution of species. At all times since the invention of agriculture, man has tried to adapt his environment, and his agricultural activities to his needs. He has felt the need to select species for their specific characteristics, thus providing improvements to what had hitherto existed.
It is the most simple process that will be used either alone or in combination to other methods.
It simply consists in observing a population of the same species, and chose the most interesting individuals to use them as parents, so try to transmit to their progeny, characters for which they were identified. For example, in apple, an old and almost extinct variety is Gala, bicolor variety that was achieved around 1920 in New Zealand. It is a variety whose general characteristics are very interesting, but the color does not correspond any more with current standards. In Gala orchards, trees producing the most colorful fruits were selected (in fact they are small natural mutations affecting only the color) to get the current Royal Gala variety. It is the same variety as Gala, but with a more intense red color. We proceed in the same way to select cows producing more milk, sheep producing more wool, running faster horses, or cats or dogs whose characteristics are the taste of the juries of beauty contests.
It is a very old method, which has been all time used by farmers and gardeners around the world, consciously or unconsciously.
This is a natural process, which is a genetic change of one or more characteristics. It is one of the main causes of the evolution of species.
It is a common phenomenon in plants, where you will find in a field either a plant or a branch with different characteristics. Thus it is usual, for example in my peach orchards, find a branch of nectarine, or a twig with fruits of different color or shape. It comes from a genetic change in the formation process of a bud that develops different characteristics. This new feature is set into the genome of the mutant individual or the mutant area and can then be transmitted to its progeny. If the mutant feature is interesting, it may either be used unchanged or it may be used as a parent in order to create a new progeny by a hybridization technique.
It is also possible to cause artificial mutations by controlled irradiation in specialized laboratories.
It is a very old method, based on the observation of characters, and their ability to combine to create a different characteristic. The breeding technique is normally done by natural ways, not allowing the breeding of naturally incompatible individuals. It is currently the main method for getting new varietal characteristics. If you cross a yellow flesh, small and early nectarine, with a late, white and bloody flesh flat peach, you will obtain a wide range of diverse fruit, which will combine in all possible ways, the original characters of parents. We generally consider that, in peach, a controlled crossing of two specific varieties can give a variability of about 500 different types.
It is in this way that, in recent years, appeared in the markets, flat peaches (paraguayo), and flat nectarines (platerines). The origin of the flat character in peach comes from a natural mutation, occurred 2000 years ago in China. Closer to us, there is an old variety, cultivated for many years in the region of Murcia, Spain, called Paraguayo, which is a small flat peach, rather shapeless, greenish, white and bloody flesh, slightly sweet but very aromatic (a type of vineyard peach, green and flat). It was used as parental in several breeding programs, allowing the current varieties diversity.
The technique is simple: you take a tree from a selected variety that will be the female parent (the receiver), and you substitute the natural pollination (normally made by bees) by a delicate fine brushwork, throwing on each flower pistil, pollen grains of the variety chosen as the male parent. It is also possible to proceed by isolating trees of both chosen varieties under a fine mesh net, under which a beehive is placed. Bees have no other choice but to interpollinate the two present trees.
Finally, there is the natural pollination, without human intervention, which simply consists of a carriage of pollen from a variety to the other, done by bees. This technique is not normally used for breeding, but it is widely used for pollination of self-sterile varieties, which means whose pollen is incompatible with its own flower (usual case in apricot, cherry, plum, apple and pear, for example).
Harvested fruits will be the same as the female original variety, because genetic changes are taking place in the seed, thus immediately invisible. It’s necessary to take all seeds and place them to germinate. Each seed has a set of combined characters from both parents.
The two most common breeding types are:
- Intraspecific breeding, which means crossing two varieties (in plants) or two breeds (animals) of the same species. This is for example, crossing a Golden apple with a Granny Smith apple or a German shepherd dog with a boxer dog. In humans, the process is called miscegenation.
- Interspecific breeding, which means crossing two related and compatible species. In plants, it is a cross between wheat and rye (triticale) or clementine and tangerine (clemenvilla) or apricot and plum (aprium or pluot). In animals, there are many cases. The best known is the mule, a cross between horse and donkey, but it is quite common in cats, or in open air pig farms, where sometimes introduce boars.
Remains the problem of F1 hybrids, concerning annual crops seeds. These seeds are produced by first generation artificial pollination whose agronomic characteristics are known, and generally interesting. But the progeny of these F1 hybrids (F2 hybrids) is very different. The farmer is forced to buy seeds every year to maintain the properties of the variety. Seed companies were accused of abusing the system. Although this is partially true (these are for-profit corporations), it should however be said in their defense, that the qualities of F1 hybrids are very difficult to obtain by other ways (stable varieties usually have lower agronomical performance and tend to degenerate over generations), in the other hand, varietal research is very expensive, and it is a way to get the investment back. Seed prices are calculated for mutual profit otherwise seeds companies could not sell anything. Farmers are not stupid, anyway.
It is a technique that can be applied both to animals and plants. It consists in the laboratory, to make an artificial modification on a specific gene, to change the behavior of the original organism. The technique allows us to imagine almost any modification or crossing, impossible in nature, especially interspecific crosses, unimaginable by natural ways.
It is obvious that there can be a serious ethical problem using this technique. Moreover, some companies used it as a very powerful economic weapon. It must also be said that the first GMOs varieties, commercialized on a large scale, were for the resistance to herbicides, sometimes causing overconsumption of these herbicides, and environmental problems. Ecologist organizations took it as a symbol of struggle against GMOs, without considering the potential benefits of the method. The anti-globalization organizations, for their part, combined the refusal of GMOs with the fact that these varieties are hybrid F1 too, to violently attack the seed companies, without trying to see the positive aspects of the system. Films have been made on this topic, and political campaigns as well, but without objectivity, playing on the fear of the unknown risk, and using perfectly the power of modern communication. And we know very well, from dictatorships to main political and economic crises, how high is the power of the mass media, and how easy it is to manipulate public opinion by shocking images.
However, it should be noted that this technique allows us to imagine some interesting solutions in specific conditions. For example, there are significant works in progress to create, by this method, crops adapted to saline soils of some regions of the world (and currently prohibiting any type of agriculture), or resistant to severe drought conditions, just to give two examples.
One of the main problems encountered since the first sale of GM crops, is the modification of some proteins in the plant, giving them a sometimes dangerous character to human health. But it seems clear, that if suitable work is done, researchers learn to control these risks. Investigation works are currently in progress in this way.
The technique has probably an important future, in the inevitable goal of feeding the world in the centuries to come, but it is essential to regulate its use.
"Science without conscience is but the ruin of the soul," wrote François Rabelais in 1532 in "Pantagruel". The formula is a bit dated, but it is really current in its meaning. Any new technique can lead to abuses. This is the case with GMOs. The first GM crops have flaws that emerged after their sale. That is not why we must drop the technique, especially because, as it is known, it will inevitably be recovered by not necessarily scrupulous people, who will make it a personal enrichment or domination tool.
However, this technique can provide very interesting answers, to many currently unresolved problems, and for the good of humanity.It is therefore preferable to continue working on it, to use it in a controlled way, but while establishing the political and legal means to prevent abuses.
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