Really. I do not understand where #327 indicates that lots of species have breeding members with differing chromosome counts. I'm not even sure what polyploid means. The first definition I saw said: "Having three or more (Gk. polys, many) sets of homologous chromosomes," and for homologous chromosomes it said: "A pair of chromosomes containing the same linear gene sequences, each derived from one parent. Humans normally have 22 pairs of homologous chromosomes [plus the XX or XY]." So what is this supposed to mean?
And doesn't this relate to plants? If there are "lots of species" with mixed-chromosome-count populations as you suggest, maybe you could identify two such animal species so I could go read about them.
ML/NJ
A link for the google impaired
This is just the first thing that came up. You may feel free to continue this search on your own. You showed initiative and curiosity with your professor. Continue down that line.
Fish, frogs, salamanders, lizards and chickens all have some polyploid species.