Is there a term for when a detrimental gene can be positively selected for because of linkage to a very fit gene?
Genetic hitchhiking / genetic draft

From wikipedia


  Genetic hitchhiking, also called genetic draft or the hitchhiking effect, is when an allele changes frequency not because it itself is under natural selection, but because it is near another gene on the same chromosome that is undergoing a selective sweep.


The term "selective sweep" is used improperly in the wikipedia definition. One should replace the last sentence by [..] but because it is near another allele on the same chromosome that is undergoing positive selection or if we want to reuse the term "sweep", once could say [..] but because it is near another allele on the same chromosome that is sweeping to high frequency

Selective sweep

From wikipedia


  A selective sweep is the reduction or elimination of variation among the nucleotides in neighboring DNA of a mutation as the result of recent and strong positive natural selection.