Selective Breeding Flashcards
what is selective breeding
- when humans artificially select the plants or animals that are going to breed
- so that genes for particular characteristics remain in the population
why are organisms selectively bred
to develop characteristics that are useful or attractive
what are some examples of animals would be selectively bred to sustain and develop desirable characteristics
- animals that produce more meat or milk
- crops with disease resistance
- dogs with good gentle temperament
- plants that produce bigger fruits
what is the process of selective breeding
- from your existing stock select the ones which have the characteristics you are after
- breed them with each other
- select the best of the off spring then breed them together
- continue this process over several generations so the desirable trait gets stronger and stronger
- eventually all the off spring will have the characteristic
what is selective breeding also known as
artificial selection
is selective breeding a new thing and why
- no, people have been doing it for thousands of years
- it is how we ended up with edible crops from wild plants
- or the domestication of animals like cows and dogs
how is selective breeding used in agriculture and why is it important
- genetic variation means that some cattle will have better characteristics for producing meat or being larger
- to improve meat yields, farmers could select cows and bulls with these characteristics and breed them together
- after this select the best of the off spring for several generations
- the farmer would get cows with very high meat yields
how is selective breeding used in medical research and why is it important
- in several studies investigating the reasons behind alcoholism
- rats have been bred with either a strong or weak preference to alcohol
- this has allowed researchers to compare the differences between two types or rats
- including differences in their behaviour and how their brains work
what is the main problem with selective breeding
- it reduces the gene pool or the number of alleles in a population
- this is because the best animals or plants are always used for breeding so they are all closely related
- this in known as inbreeding
what can inbreeding cause and why
- health problems
- because there is more of a chance of the organism inheriting harmful genetic defects when the gene pool is limited
how do dogs suffer from inbreeding
- some dogs are suseptible to certain defects because of inbreeding
- such as pugs often having breathing problems
what is the ethical consideration of selective breeding
- people can think of it an unethical
- especially when animals are bred to have negative characteristics for research
why would there be a serious problem is a new disease appears in selectively bred organisms
- there is not much variation in the population
- so there is less of a chance of resistant alleles being present
- all of the stock are closely related to each other
- so if one is going to be killed by a new disease it is likely that all the others will succumb to it too
