13.4 selective breeding

what is selective breeding

plants/animals artificially selected so that genes for particular characterstic remain in population

what useful/attractive features are they bred for

1.animals that produce more meat/milk

2.crops with disease resistance

3.dogs with good ,gentle temperant

4.decorative plants wiht big or unusual flowers

process of selective breeding (4)

1. from existing stock ,slect those with charqacterstics ur after

2. breed them with each other

3. slect best of the offspring,then breed again

4. continue as desirable trait gets stronger and stronger until all offspring have the characterstic

how could this be used to improve meat yields

farmers could breed together cows and bulls with largest size,after several generations,farmers would get cows with very high yield.

what is the main problem with selective breeding

reduces the gene pool(number of differnt alleles(forms of a gene) in a population.

how does inbreeding happen eg.

when farmer breeds from all the ‘best’ cows together,inbreeding occurs as they are all closely related

issues with inbreeding

1.can cause health issues as theres more of a chance of organism inheriting harmful genetic defects when gene pool is limited-some dog breeds very susceptable

2.also serious problem if new disease appears,bc theres not much variation in population. all stock closely related so if one succumbs to illnes it is likely the rest will asw