Why do animals of southern latitudes and tropics, as a rule, have more protruding body parts than animals

Why do animals of southern latitudes and tropics, as a rule, have more protruding body parts than animals of northern latitudes and polar regions?

for example, elephants and desert foxes have enhanced heat transfer through their ears.
According to Alain’s rule, warm-blooded animals will have shorter protruding body parts in cold climates than related species in warm regions. Due to this, animals living in cold regions acquire a smaller body surface and, as a result, lose less heat. So, the smallest (relative to body length) ears and nose in the Canidae family are observed in the blue fox inhabiting the Arctic, and the largest in the fennec fox.