http://www.farmersmarketmusic.com/images/horror/taken-dominated-1.php Sex and genetic shuffling.
Genetic drift. Natural selection. Natural selection at work. What about fitness? Sexual selection. Artificial selection. Selective breeding was practiced by the Romans. He noted the idea in his book titled India , which included various examples. The agriculturist selects his corn, letting grow as much as he requires, and tearing out the remainder.
The forester leaves those branches which he perceives to be excellent, whilst he cuts away all others. The bees kill those of their kind who only eat, but do not work in their beehive. Selective breeding was established as a scientific practice by Robert Bakewell during the British Agricultural Revolution in the 18th century. Arguably, his most important breeding program was with sheep. Using native stock, he was able to quickly select for large, yet fine-boned sheep, with long, lustrous wool. The Lincoln Longwool was improved by Bakewell, and in turn the Lincoln was used to develop the subsequent breed, named the New or Dishley Leicester.
It was hornless and had a square, meaty body with straight top lines. These sheep were exported widely, including to Australia and North America , and have contributed to numerous modern breeds, despite the fact that they fell quickly out of favor as market preferences in meat and textiles changed. Bloodlines of these original New Leicesters survive today as the English Leicester or Leicester Longwool , which is primarily kept for wool production. Bakewell was also the first to breed cattle to be used primarily for beef.
Previously, cattle were first and foremost kept for pulling ploughs as oxen  [ citation needed ] , but he crossed long-horned heifers and a Westmoreland bull to eventually create the Dishley Longhorn. As more and more farmers followed his lead, farm animals increased dramatically in size and quality. However, after his death, the Dishley Longhorn was replaced with short-horn versions. He also bred the Improved Black Cart horse, which later became the Shire horse. Charles Darwin coined the term 'selective breeding'; he was interested in the process as an illustration of his proposed wider process of natural selection.
Darwin noted that many domesticated animals and plants had special properties that were developed by intentional animal and plant breeding from individuals that showed desirable characteristics, and discouraging the breeding of individuals with less desirable characteristics. Slow though the process of selection may be, if feeble man can do much by his powers of artificial selection, I can see no limit to the amount of change, to the beauty and infinite complexity of the co-adaptations between all organic beings, one with another and with their physical conditions of life, which may be effected in the long course of time by nature's power of selection.
We are profoundly ignorant of the causes producing slight and unimportant variations; and we are immediately made conscious of this by reflecting on the differences in the breeds of our domesticated animals in different countries,—more especially in the less civilized countries where there has been but little artificial selection.
Animals with homogeneous appearance, behavior, and other characteristics are known as particular breeds, and they are bred through culling animals with particular traits and selecting for further breeding those with other traits. Purebred animals have a single, recognizable breed, and purebreds with recorded lineage are called pedigreed. Crossbreeds are a mix of two purebreds, whereas mixed breeds are a mix of several breeds, often unknown. Animal breeding begins with breeding stock, a group of animals used for the purpose of planned breeding.
When individuals are looking to breed animals, they look for certain valuable traits in purebred stock for a certain purpose, or may intend to use some type of crossbreeding to produce a new type of stock with different, and, it is presumed, superior abilities in a given area of endeavor. For example, to breed chickens, a breeder typically intends to receive eggs, meat, and new, young birds for further reproduction. Thus, the breeder has to study different breeds and types of chickens and analyze what can be expected from a certain set of characteristics before he or she starts breeding them.
Therefore, when purchasing initial breeding stock, the breeder seeks a group of birds that will most closely fit the purpose intended. Purebred breeding aims to establish and maintain stable traits, that animals will pass to the next generation. By "breeding the best to the best," employing a certain degree of inbreeding , considerable culling, and selection for "superior" qualities, one could develop a bloodline superior in certain respects to the original base stock.
However, single-trait breeding, breeding for only one trait over all others, can be problematic. The observable phenomenon of hybrid vigor stands in contrast to the notion of breed purity. However, on the other hand, indiscriminate breeding of crossbred or hybrid animals may also result in degradation of quality. Studies in evolutionary physiology , behavioral genetics , and other areas of organismal biology have also made use of deliberate selective breeding, though longer generation times and greater difficulty in breeding can make such projects challenging in vertebrates.
Plant breeding has been used for thousands of years, and began with the domestication of wild plants into uniform and predictable agricultural cultigens. High-yielding varieties have been particularly important in agriculture. Selective plant breeding is also used in research to produce transgenic animals that breed "true" i. Selective breeding in aquaculture holds high potential for the genetic improvement of fish and shellfish.
Unlike terrestrial livestock, the potential benefits of selective breeding in aquaculture were not realized until recently. This is because high mortality led to the selection of only a few broodstock, causing inbreeding depression, which then forced the use of wild broodstock. This was evident in selective breeding programs for growth rate, which resulted in slow growth and high mortality.
Control of the reproduction cycle was one of the main reasons as it is a requisite for selective breeding programs. Artificial reproduction was not achieved because of the difficulties in hatching or feeding some farmed species such as eel and yellowtail farming. The education of fish biologists paid less attention to quantitative genetics and breeding plans. Another was the failure of documentation of the genetic gains in successive generations.
This in turn led to failure in quantifying economic benefits that successful selective breeding programs produce. Documentation of the genetic changes was considered important as they help in fine tuning further selection schemes. Aquaculture species are reared for particular traits such as growth rate, survival rate, meat quality, resistance to diseases, age at sexual maturation, fecundity, shell traits like shell size, shell colour, etc.
The traits, for which the selection was done included growth rate, feed consumption, protein retention, energy retention, and feed conversion efficiency. The results showed Rainbow trout S. Her award-winning website is one of the most popular humor sites on the web today, with over , visitors a month and growing. REVIEWS AudioFile Magazine "A second volume continues the author's delightfully sadistic celebration of those who have 'improved our gene pool by removing themselves from it in a sublimely idiotic fashion.
The writing is light and witty; the narrator's delivery chirpy and reminiscent of a tabloid TV voice-over.
Gene Pool: Unnatural Selection - Kindle edition by R. A. Finlayson. Download it once and read it on your Kindle device, PC, phones or tablets. Use features like. Unnatural Selection book. Read 4 reviews from the world's largest community for readers. The first book in a four-part, science fiction series that explo.
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Oh, how I wish for her to wonder about the enormity of the sacrifice the monk has made in all that time, but none of that comes. The worn lid finally gives out, and the waters turn tornadic, a storm within the sea. It's people. BBC News: Are humans driving evolution in animals? Many extremists have expressed their disapproval with genetic manipulation, some due to religious beliefs, and others due to the fear of what this can due to the human race
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