Complex sentence: However, in the Bengalese finch, natural selection is replaced by breeding, in this case for colorful plumage, and thus, decoupled from selective pressures, stereotyped song syntax is allowed to drift.
Split into simpler sentences: However, in the Bengalese finch, natural selection is replaced by breeding, in this case for colorful plumage. Thus decoupled from selective pressures, stereotyped song syntax is allowed to drift.