Changing the living world. Selective Breeding Humans use selective breeding to pass desired traits...
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Transcript of Changing the living world. Selective Breeding Humans use selective breeding to pass desired traits...
Changing the living world
Selective Breeding• Humans use selective breeding to pass desired
traits on to the next generation of organisms:• Nearly all domestic animals and most crop
plants have been produced by selective breeding
Tools for selective breeding
• Hybridization: crossing dissimilar individuals to bring together the best of both organisms
- e.g. Shasta daisies, got its large, white appearance from hybridization by a scientist named Luther Burbank
• Inbreeding: the continued breeding of individuals with similar characteristics
- e.g. Many breeds of dogs are maintained by inbreeding: golden retriever
Risk of inbreeding• Most of the members of a breed are
genetically similar:- Because of this, there is always a chance that
a cross between two individuals will bring together 2 recessive alleles for a genetic defect
Increasing Variability
• Breeders can increase the genetic variation in a population by inducing mutations, which are the ultimate source of genetic variability
• Breeders can increase the mutation rate by using radiation and chemicals
Increasing Variation• Producing new kinds of bacteria: scientists have
been able to develop hundreds of useful bacteria strains
e.g. bacteria that can digest oil• Producing new kinds of plants: scientists use
drugs to produce cells that have double or triple the normal number of chromosomes (polyploid)
e.g. production of bananas