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Thread: Selective breeding

  1. #1 Selective breeding 
    Forum Freshman
    Join Date
    Apr 2011
    Posts
    29
    Hello; i am new to the forum.

    I would like to ask you about selective breeding and the chances of producing a Taurus (bull) that displayed favourable traits and phenotypes of 2 selectively-picked cattle; thus to produce a better offspring as a result.

    Taurus have 30 chromosome pairs; so what are the potential outcomes of the breeding?

    How do favourable phenotypes become dominant? is that just a result of the phenotype being heterozygous dominant?

    Am i correct in thinking that it is important to keep as many different phenotype combinations in genes as possible; as this allows for diversity within a species?!? if the potential phenotypic combinations were reduced; would this mean that the species would begin to look more and more alike with continued breeding?

    Thank you for your time and help; much appreciated.


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  3. #2  
    Forum Bachelors Degree
    Join Date
    Apr 2009
    Posts
    416
    you're using a lot of words that you don't know the meaning of. you really should take at least highschool biology, or if you're starting it now you should finish the chapter first.

    the phenotypic traits you're asking about could be controlled by one gene. in that case you could easily breed a population that all contained that trait through artificial selection. however if there are many alleles on the same gene or if there are many genes governing said trait(as there are for most all phenotypic traits) then it would be difficult to form a true breeding population of said trait.

    domminance is not a trait that changes over the evolution of a gene, only mutations in the gene might affect it and i have little experience in that area. a gene can become common in the population and have its phenotype expressed at higher rates than other genes whether its domminant or not. the gene that causes huntington's disease is dominant. if you have one copy of it you're pretty much screwed. however this gene is not expressed often in the population because the recessive allele(the one that prevents huntington's when it's homozygous) has grown in frequency due to natural selection on the human population.

    continued breeding in a stable environment always destroys phenotypic diversity. evolution tends toward one gene becoming fixed(having only the most reproductively sound allele). the biological force working against this is mutations in the genome. a gene with 2 alleles in a population could have 3 due to a point mutation in one of the alleles. this mutation could be beneficial and would likely be preserved, or be detrimental and would likely be erased. another force working against phenotypic uniformity is changes in the environment. if the environment never changed then one set of the best adapted would survive and replicate and all else would die out(on a very large timescale) but changes in environment change what is selected for and cause selection to change course throughout geologic time.


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