Breed - Frustrated

There are many populations or lineages of cultivated plants and domestic animals that are classified as belonging to the same taxonomic species, but that are morphologically, physiologically, or ecologically different. Each of these is called a variety. Humans have cultivated and bred animals and plants for many years, either for use or as pets, and have isolated and fixed the mutations that arose during this process, and have created new lineages according to their purpose. The process of improving a variety to develop a new variety is called breeding, and methods such as pure lineage separation, lineage separation, crossbreeding, and the use and generation of polyploids and mutations have been used. In recent years, the remarkable development of manipulation techniques such as tissue culture and genetic recombination has made it possible to create new varieties or lineages for specific purposes, such as microorganisms. Research has been conducted on the increase and improvement of food and other production through crossbreeding between varieties with different advantages, and the generation of new mutations and polyploids through X-ray irradiation and chemical treatment, which have contributed greatly to the prosperity of humanity and the improvement of our lives, and further development is expected in the future.

Regional variations or local types seen in common plants and animals are sometimes called varieties, and ecological or physiological lineages within the same region are sometimes called varieties, but this is not appropriate.

[Takehiko Nakane]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

栽培植物や飼養動物には、分類学上では同一の種に属するが、形態的にあるいは生理・生態的に異なった多くの個体群ないしは系統が知られている。これらそれぞれが品種とよばれるものである。人間は長年にわたって動植物を、利用のため、あるいは愛玩(あいがん)用として、栽培・飼育してきたが、その間に生じた変異を分離して固定させ、さらに目的に応じて新しい系統をつくりだした。品種を改良して新しい品種を育成することは育種とよばれ、純系分離、系統分離、交雑、倍数体や突然変異の利用生成などの方法がとられてきたが、近年は組織培養や遺伝子組換えなど操作技術の著しい発達によって、微生物など目的に沿って新しい品種ないし系統をつくりだすことが可能となってきた。異なった長所をもつ品種間の交配や、X線照射・薬品処理などによる新たな突然変異・倍数体の生成により、研究が進められてきた食料その他の増産や改良などは、人類の繁栄や生活向上に大きな貢献をしてきたが、今後もさらに発展が期待されよう。

　一般の動植物にみられる地域的な変異、地方型のことを品種とよぶことがあり、また同一地域内の生態ないし生理的な系統を品種ということもあるが、適当ではない。

［中根猛彦］

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