Evolution - recent examples?

Here's one of my favorites, the study describes a single gene mutation leading to morphological and reproductive differences: The researchers witnessed a speciation event in a closed population they were studying, a single gene mutation changed the shell pattern of a snail, and the constraints of the new shell shape prevent the snails with the two types of shells from aligning their genitals to mate. But, the old-shelled snails could mate with the old-shelled, and the new-shelled could mate with other new-shelled snails.Thus snails with the shell-changing mutation are incapable of breeding with the ones without the mutation - even if they are sitting next to each other in the same pond. By most definitions this is considered speciation.I think the snail example is powerful: Humans witnessed it, it is based on a single gene mutation, that mutation prevents mating between those with and without the mutation (reproductive isolation), and the shell pattern is visibly different (morphology difference).