The earliest records of maize indicate that the plant was developed in southern Mexico 6,, years ago from a grass called teosinte. Scientists believe that early farmers selected only the largest and tastiest kernels of teosinte for planting, rejecting punier kernels. This process allowed the farmers to develop corn very quickly, as small changes in the plant's genetic makeup had dramatic effects on the grain's taste and size. Despite their physical dissimilarities, teosinte and corn only differ by about five genes.
Today, corn is a staple in diets across the world. Averaged over the years from to , million tons of maize was produced each year around the world, primarily in the United States, China, and Brazil. Without selective breeding, many of the plants and animals on earth today would not exist.
However, there are some disadvantages of artificial selection, especially in the case of inbreeding. Through inbreeding, two closely related organisms reproduce to yield a purebred with desired traits. However, these organisms may also have undesirable traits due to recessive genes found in both parents. Thus, purebred dogs are sometimes born with health defects like hip dysplasia and have shorter life spans than other mixed-breed dogs.
Janssens, Luc, et al. Boyko, Adam R. Forest Service. Tigchelaar, Michelle, et al. Farrell, Lindsay L, et al. Actively scan device characteristics for identification. Use precise geolocation data.
Select personalised content. Create a personalised content profile. Measure ad performance. Select basic ads. Create a personalised ads profile. In other words, DNA acts like a set of instructions that enable cells to assemble the building blocks of all living things!
We inherit half of our genes from each parent. However, the specific combination of genes we inherit is almost completely random. This means that DNA is mixed up with every generation.
What controls whether we inherit a specific trait? Some traits are controlled by many different genes, and we might not inherit them all. So, how can understanding DNA be useful in agriculture? Modern genetic techniques allow farmers to identify the specific gene or genes that controls a desirable trait. Using these techniques, breeders can quickly identify which organisms have desirable genetics without having to wait for them to reach adulthood and display specific traits.
This is particularly useful for traits that are difficult to measure, such as disease resistance, or those that are largely controlled by the environment. It also means that multiple genes can be identified at the same time.
This makes it easier to select for traits controlled by several different genes, or to select organisms with a combination of different traits. However, even with these molecular tools, selective breeding can only get us so far. The new varieties may be economically important. For example, they may provide more or better quality food.
Selective breeding Selective breeding or artificial selection is when humans breed plants and animals for particular genetic characteristics. Main steps involved Selective breeding takes place over many generations. These are the main steps for both plants and animals: Decide which characteristics are important enough to select. Choose parents that show these characteristics from a mixed population.
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