The helpful folks over at rOpenSci have come up with exactly the tool I needed, exactly when I needed it.
Here’s a rough graph of germination rate from field collected seed of the invasive weed I work on, Centaurea diffusa (seen here). Each point represents a different maternal plant from 57 different populations, with native individuals in red and invasive individuals in black. I have collections that were up to 8 years old when I ran this trial, and no decrease in germination rate! That’s just silly! I’m sure it doesn’t hurt with the being invasive and all.
It is the favorite past time of every invasion biologist since H. G. Baker in the 1960s to make lists of traits which distinguish invaders. We’ve been doing it for at least 50 years, and yet, no list ever seems to satisfy. There are always exceptions – a majority of cases seem to be exceptions, really. And maybe that’s because we need to think about it in more dimensions.
Common question: Why should we worry about species moving around, anyway, haven’t they always done that? A forest is a just a forest and a grassland is just a grassland after all. What are you getting so worked up about? Aren’t humans the worst invasives?
Answer: Yeah, humans are the worst invasives, but I can’t really justify mass extirpations for humans. Not yet, anyway. Though limiting birth rates probably isn’t a terrible idea.