Selective Breeding

Selective Breeding

What is selective breeding? Definition: Selective breeding is where humans select (chose) 2 animals with desired traits & breed (mate) them trying to produce offspring with the desired traits of both parents Selective Breeding Typically,

strains which are selectively bred are domesticated Over many generations, the practice leads to the development of strains with the desired characteristics Examples of selective breeding Intentionally mating 2 dogs in order to achieve or eliminate a specific trait A farmer saves seed from a hearty

crop to replant the next year Dogs are bred for competition or for hunting Cows can be bred to increase muscle mass or milk production Examples of Selective Breeding Dogs are a good example of selective breeding. Gamekeepers who hunted birds for leisure in the 1800s wanted a dog that didnt

actually exist. So, they selectively breed a mastiff and a bulldog to get the qualities that they wanted. Mastiffs were big, strong & good companions, but they lacked in speed and aggression. The bulldog however was aggressive and fast but lacked in strength. The selective breeding process eventually produced a bullmastiff which was large, quick, strong, & aggressive Bullmastiff Big, strong & good companion

(not aggressive or fast) Aggressive & fast (not big & strong) When selective breeding these 2 dogs, we get a Bullmastiff Large, quick, strong & aggressive dog Example of Selective Breeding in Cattle

Brahman cattle: good resistance to English shorthorn cattle: good beef, but poo heat, but poor meat heat resistance When selecting to breed these 2 animals we get a Santa Gertrudis cattle Result = good beef AND resistant to heat Selective Breeding in Crops

Selective Breeding of Lions & Tigers: LIGER Ligers are the worlds biggest cats Larger than their parents with the strength of a lion and speed of a tiger combined An average male liger stands almost 12ft on its hind legs & weigh up to half a ton (twice the weight of a wild lion or tiger)

How did the liger appear? If the father is a lion & the mother is a tiger, the offspring are known as ligers and the pairing results in gigantism Strong but lacks speed Fast but not as strong Ligers are fast & strong & twice as big as parent

Why do people selectively breed animals & plants? To make animals grow bigger, faster, prettier & stronger To make plants grow bigger, faster, prettier & produce more crops Pros of Selective Breeding Benefits: Farmers can produce crops with higher

yield More fruit or vegetables on a stalk Farmers can produce animals that grow more meat, more milk, more eggs, faster & stronger Can produce friendlier and prettier pets Cons of Selective Breeding Disadvantages: Loss of genes in a population

By not allowing some animals to breed, their genes could be lost forever in a population Take Hitler for example, he tried to kill all Jews, therefore, trying to eliminate the genes and all Jews from the planet Animal discomfort Farmers breed cows to have large utters, so now some cows have difficulty walking & have health problems Some chickens are too heavy to stand, so they have to lay

down all the time Can lead to inbreeding In order to create a certain type of animal through selective breeding, sometimes brothers & sisters of a population will mate to pass on favorable traits, and this can lead to bad health problems for children of inbreeding GENETIC ENGINEERING Genetic

engineering is a lot like selective breeding but a much faster process Definition: taking favorable genes from one organism and implanting it into another organisms DNA This can only be done in a laboratory with special equipment Examples of Genetic Engineering 1.

People have taken the insulin making gene from humans and inserted it into bacteria causing bacteria to make human insulin Why? Bacteria can reproduce quickly causing them to produce insulin at a much faster rate Examples of Genetic Engineering 2.

People have taken bad genes (genes which cause cancer and other diseases) out of a person and inserted healthy genes into a person to cure them of diseases However, they may be cured of that disease but get another worse disease because of being implanted with the other gene Examples of Genetic Engineering

3. People have taken a weed resistant gene and inserted the gene into certain crop plants Now farmers can spray weed killer on the crops to kill the weeds, but the spray will not affect the crops. The crops will grow better and bigger because weeds do not take away sunlight, nutrients, and water

However, this gene has leaked over into the weed population sometimes and caused the weeds to be resistant to herbicides (weed killer spray) 4. Examples of Genetic Engineering People have inserted genes into crops to make the crops resistant (poisonous) to pests, but are

harmless to humans (we think) Genetically Engineered Fish We have inserted genes into fish to make them grow twice as big and twice as fast Genetically Engineered Chickens We

have inserted genes into chickens to make them grow twice as big and twice as fast. They are so big they cant walk. Genetically engineered crops Humans have injected genes into crops to make them grow in colder environments Humans have injected genes into crops to make them grow in dry

(drought) environments Genetically Engineered Pigs Humans inject genes into pigs DNA in order for the pig to grow human-like organs, so people can transplant these organs into people who need them Genetically Engineered Mice Humans

inject genes into mice to make the mice grow human ears for cosmetic purposes Genetically Engineered Vaccines Genetically engineered vaccines may be safer because they do not use live viruses like traditional vaccines do Genetic Engineering

Genetic engineering may work wonders but it is all a process of manipulating the natural The Pros & Cons of Genetic Engineering Pros Include: 1. 2.

3. Humans have made crops with better taste, nutrition, and growth rate Humans have made pest resistant crops and crops with longer shelf life Humans have been able to produce new foods Foods which couldnt be reproduced in nature 4. 5.

Humans can help cure certain disease Boosts positive traits and suppress negative ones Cons Include: 1. 2. 3. By making plants bigger, taste better, and

better appearance we have accidentally made some crops allergenic to people By making plants bigger, taste better, and better appearance we have accidentally made some crops have less nutritional value Accidental gene transfer Such as when we inserted genes into crops to make them resistant to pest or herbicides, the genes leaked over into weeds and made them resistant to pest and herbicides too Cons Include: 4.

Genetic engineering in human beings can have certain side effects While treating one defector disease, the genetic engineering may lead to another disease which could be worse 5. Whats next? Will people try to insert genes into babies to have children which are smarter, muscular, prettier, certain color eyes, certain color hair,

and talente

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