Robin, I’ve never made the dressing without the poppy seeds, though I suppose you could leave them out. You could substitute black sesame seeds for them, thought I’d only use 1 tablespoon instead of the 2 called for in the recipe as I’m not sure how much they will affect the taste.
Also, you can omit the almonds altogether or substitute another nut for them. Pecans, walnuts, or even sunflower seeds would be equally delicious. Enjoy it!

Joyce, you can definitely substitute vegetable oil for canola oil in the dressing. Enjoy it!

Dorothy,
I have not made those substitutions to the poppy seed dressing, so not sure how it would taste. If you are going to do that, my suggestion would be to make half of the recipe, in case you shouldn’t like the outcome, and then if it works, make it again. If you do, I’d love to hear what you thought and your feedback would help others who might be interested in doing the same, so please report back!