Complex sentence: The European edible frog appear a species, but is actually semi-permanent hybrids between pool frogs and marsh frogs, the edible frog population being dependent on the presence of at least one of the parents species to be maintained.
Split into simpler sentences: The European edible frog appears to be a species, but is a actually semi-permanent hybrid between pool frogs and marsh frogs. The edible frog population is dependent on the presence of at least one of the parents species to be maintained.