Sibley’s findings in P2 distinguish between vultures from Europe and vultures from North or South America, not storks from different locations. The passage just talks about storks in general; we don’t know how to classify storks from different locations.

Sibley’s findings in P2 distinguish between vultures from Europe and vultures from North or South America, not storks from these locations. The passage just talks about storks in general; we don’t know how to classify storks from different locations.

Sibley’s findings show that North American vultures are more closely related to storks than to European vultures. If we classify storks and vultures as different species, Sibley probably doesn’t think that vultures from North America are the same species as vultures from Europe, since the North American vultures are more closely related to storks than they are to the European vultures.

Sibley’s findings don’t challenge this assertion because Sibley found that South American vultures are less closely related to European vultures. If we say that vultures and storks are different species, then Sibley would agree that vultures from South America are probably a different species from vultures from Europe.

The passage doesn’t distinguish North American vultures from South American vultures, so we don’t know whether or not Sibley’s findings challenge this assertion.