Dwarf elephants have appeared separately in multiple places and times when full-sized elephants got stranded somewhere and their habitat / food supply was restr

Dwarf elephants have appeared separately in multiple places and times when full-sized elephants got stranded somewhere and their habitat / food supply was restricted. There were dwarf mammoths in the California channel islands until pretty recently (a mammoth presumably swam from the mainland when the sea level was lower and they were one big island).