6065833@pucc.UUCP (03/24/87)
In response to the question about whether open rings of interbreeding animal species exist, I know of one case not yet mentioned. There are a group of (garden?) snakes in the SE US, excluding Florida, forming a continuous population of 5 or so discrete varieties which interbreed, except in the west of the range. Here the 2 "end-point" varieties do not interbreed. Una Smith (6065833@PUCC.bitnet)