In North America,many Kinds of Birds Have Closely Related Eastern

In North America,many kinds of birds have closely related eastern and western counterparts species or subspecies)that sometimes produce hybrid offspring where their ranges overlap.Eastern and western meadowlarks are virtually indistinguishable from each other in appearance,and yet,despite the fact that their ranges overlap throughout much of the Midwest,there are few documented cases of the meadowlark counterparts mating with each other and producing hybrid offspring.Propose mechanisms that would prevent cross- breeding between eastern and western meadowlarks,thus maintaining the counterparts as separate species.