qMany species only appear to have
been distributed as far north as the central Sahara whereas some species only
spread south from the Maghreb to this point
qIn particular, deepwater species
such as the hippo, and the Nile Perch have this distribution, whereas species
that can survive with less water make it across the desert
qSo, elephant, giraffe, cichlids, the
Nile rat etc. can subsist with shallow pools
qThis line appears to be the
‘watershed’ in the central Sahara