Hybridisation in plants is probably the biggest single chunk of evidence gathered so far. Biological reproductive barriers are weaker in plants than they are other lifeforms, and are more likely to break - meaning plants of two different species can reproduce and produce a hybrid, which provided the conditions are correct can also reproduce, if the biological barriers are replaced, you have a totally new species that didn't exist before, this happens all the time and is well documented. There's also plenty of evidence with other hybrids such as some species of ducks, but it's far rarer.
I mention Hybridisation because it's to do with genetics, which is pretty rock solid evidence - there's tonnes of other pieces of evidence like whales with residual back legs, but if you're a creationist you'll probably go "SHOW ME A WHALE WITH LEGS"
To be honest, there's so much good and tested information out there - if you say there's no evidence, then you haven't tried very hard in looking, and have just formed a conclusion based on what you want, rather than what's actually going on.