Complex sentence: The subspecies "Bufo bufo gredosicola" is restricted to the Sierra de Gredos mountain range where it is facing predation by otters and increased competition from the frog "Rana perezi" which both seem to be extending their ranges to higher altitudes.
Split into simpler sentences: The subspecies "Bufo bufo gredosicola" is restricted to the Sierra de Gredos mountain range where it is facing predation by otters and increased competition from the frog "Rana perezi". Both otter and frog seem to be extending their ranges to higher altitudes.