Facultative parthenogenesis in crayfish is an interesting finding that (perhaps) became more likely under adventive conditions, but the fact that it had not been observed previously does not mean it did not take place previously. Framing all this in terms of 'successful invasion' and 'capability' suggests that crayfish have considerable knowledge of geography, undertake coordinated efforts to take and hold territory formerly unoccupied, and deploy an otherwise unused mode of reproduction in doing so. None of those suggestions are necessary, and none of them are supportable by the data provided. The fact that crayfish can survive and thrive after transcontinental dispersal does not license (or licence, if you prefer) the assertion that they are 'invading'.
