“I think the biggest disclaimer is not to take the paradigms too seriously and to think about other ways of thinking about the processes involved rather than the cartoons that are in that paper.”

“I think the core of this paper still holds, but how strongly so and whether it can really do so on its own, to the point that we get truly distinct species, is unknown. So, I think the paper is correct in terms of natural selection is part of the puzzle for understanding speciation, but the caveat would be that, I think it’s still unknown, in this system and in most systems actually, how far natural selection, on its own, can really push things. That would be the caveat. And that’s why, I guess, 15 years later, I’m happy I didn’t put ‘speciation’ in the title and that I used ‘reproductive isolation’ instead.”

“I think the most exciting studies are ones that show where it does and where it does not happen. In other words, just showing that it does happen someplace else is great. But I’m, in many ways, more interested in the ones that show that it does not happen, and wondering why is that. You know, what are the other things that are important? And even better are studies that perform these sorts of things in multiple locations, or under multiple types of conditions, and find that, well, in this area, it looks like it’s sort of confirmed,while in this area it looks like it’s not confirmed. Those sorts of multifactorial studies are very challenging to conduct, especially with diversity, because there are a lot of treatments involved. But I think those can be pretty powerful.”

“I think the only caveat I would add is that the circumstances under which we did our tests on females in sound attenuating chambers with males is very unnatural. And that it would be better to try to show it in the flock setting where there are more males and females present. We stopped doing work inside attenuating chambers because it just seemed like not a very good environment for the birds. I mean, the chambers are very large and they had a lot of room to fly and things like that, but it still isn’t the same as an outdoor facility, where the birds can decide who they want to be with and form groups of their own volition. We were forcing males and females together, and I think I would rather have them try to connect naturally. So that’s what I would say.”

“I think the paper is now remembered as representing the formal birth of the field of phylogeography. Of course, I couldn’t have fully anticipated this at the time, but I did certainly have a sense that it had the potential to become a landmark treatise.”

“I think the paper stands as it is. There is nothing I regret or where I think the results are not right. Work with other parasites of Daphnia done in my group are largely consistent with the first results. Studies in other systems also largely confirmed that the overall conclusion is sound. However, we know now that in some systems the story is much more complex. Maybe I was lucky that in my system the outcome was rather clear cut.”

“I think the results hold, and that’s nice to be able to say. My sense is that they were preliminary experiments, but due to my own work on radish for a couple years after that, as well as work other people have done in other systems, this seems to be a general phenomenon.”

“I think the whole approach just doesn’t work. This is ironic, because I published a paper – might have been part of my thesis – in 1992 where we reconstructed the order in which ecomorphs evolved, using parsimony methods. It was a cool paper. It suggested that the anoles on two islands had evolved following the same pattern. But I now think the whole exercise is hopeless, because when you have a group in which homoplasy is rampant, any kind of confidence in inferred ancestral character states is very limited. To infer ancestral states, you need there to be a strong phylogenetic signal. The assumptions of these methods simply aren’t met when these traits evolve relatively rapidly. I just think there are some questions we can’t answer with phylogenetic methods. This is one of those cases.”

“I think there’s definitely been a shift in the field, but I don’t think it was sparked by my paper. Hubbell’s book on Neutral Theory was definitely the spark that got people thinking more about drift and speciation and dispersal, to some degree. And then, as the term meta-community became widespread, that was a major impetus to get people studying dispersal in more detail. So, I don’t think my paper was the reason behind that at all. I would actually go as far to say that my paper is almost like a response to that. So you have neutral theory pushing people over there, meta-community theory pushing people over there, classic niche theory pushing people over there, and it’s quite difficult for a student to see how all of those things relate to one another. My goal was to do that. To see how do those things all fit together. And in the end, they fit together via a common framework that really isn’t that complicated. It’s not as complicated as we’ve typically made it out to be.”

“I think they [main conclusions of this paper] completely stand. This is an interesting story, too. In 2012, we published a paper in Journal of Animal Ecology where we, essentially, repeated the same analysis for four populations, and also with more modern statistics. Our previous analysis was a bit inappropriately focused on using ANOVA approaches, but in 2012 we were using mixed models, for example. We were able to confirm our results – effects of learning, the seasonal effects and level of repeatability - through studies in other populations. We were comparing all these parameters across four different populations. One major problem in science is that studies are, often, not replicated. So, we don’t know whether a result is specific to the population studied, or to the species, or maybe even to the researcher who collected the data. This is why I’m pretty happy about this sort of confirmation, based on much more data from many different populations.”

“I think this is a strong finding. In fact, this morning I was thinking that we should go back and update the analyses, because it’s been over 30 years. But I do know that the main patterns are still there. In the paper, we talked about the possibility that some species would become more common because of changes in water temperature and others would become rarer; I’m pretty sure that’s what’s happened.”

“I think this was a big home run and I was lucky to have it early in my career; this is pre-tenure. But when I tell the story of the next year, I always make a little joke out of the fact that I’d gotten this really slam dunk result in ’89, wrote it up and it was published in ’90. In summer ’90, I repeated the experiment and it totally failed. As I tell this in talks, I watch the faces of students or young academics .. you know, first everybody’s horrified if we can’t repeat our results. But in ecology, context can change everything. And that’s a lesson I want to convey: if you can’t repeat your work, why not? Figuring that out will enlarge your understanding of nature.”

“I think we’ve identified what the key drivers are. You may be able to refine things now.You may come up with a slightly different age structure, you may come up with different climatic drivers and what have you. But I don’t think the logic of that paper changes. I don’t see any reason why anyone would necessarily go back and do the same thing over and over again.”

“I think what has happened in the last 15 years is that people talk quite a lot about genetic architecture of sexual traits [...] and the, kind of, sexual conflict that can come about from these situations. So maybe, these days, if I was working on this, if I got this idea now, I might phrase it a bit more genetically. I might also phrase it a bit more in the conflict between males and females kind of angle. But I don’t have any major regrets. It’s just, like every paper, a bit of a product of their time.”

“I think what I was starting to get at then was a bit more of a patch dynamic approach to Community Ecology, where you think about colonization and extinction, and how there is the interplay between these processes that determine the number of species you observe in a patch. Eventually, I was able to take those ideas and develop it into a more spatially explicit version of food web ecology. The original paper was published in 1998, just a couple of years before the millennium when there were a whole bunch of new ideas around Metacommunity Ecology. I think I still think about communities in terms of colonization and extinction, and how the environment and the traits of species affect these two processes.”

“I think you would have to read it in a historical context, in the context of what was known at that time, and what were we trying to answer, that may be well-established now but that was not established then. What were the controversies at that time, what were the things we were trying to resolve, what was what were we doing, that was different than what had been done before? So, I think to think about things from the perspective of where we were coming from at that time. And then, why did it become influential, how did it change the way people were thinking about the problems we addressed and the subsequent direction of science since then? That would be an interesting thing to think about. But it’s very difficult to go back and think about how people saw things at that time and just the whole context. There was no Web of Science, there was no online access to papers, there was no email, there was no web, we didn’t have cell phones either. It’s hard to put yourself in that frame of mind, you know, how you would be thinking about problems and how you would be addressing and approaching things, when so many things were really different, were profoundly different about the way we were doing science,and certainly the way we were trying to make sense of scientific publications. Most importantly, a lot of the people reading this today weren’t even alive then, so it’s very hard to imagine how the world was before you are in it.”

“I will suggest they read one paper that is older and one paper that is more recent. I would suggest that they went back to some of the original ideas, to some of Preston’s ideas in the 1960s about how the number of individuals is related to the number of species. That had a strong influence on my thinking. I would also suggest that they go and look at some of the really cool new studies that have been done, where they’ve tried to use some really large databases to test some of these ideas. I was using experiments in a limited number of tree holes to test the underlying premises of the “more individuals hypothesis”, but structural equation models also allow the testing of on mechanisms on large observational datasets. A nice synthesis of both experimental and observational tests of the more individuals hypothesis is the 2018 Ecology Letters review by David Storch and colleagues.”

“I would ask them [students reading the paper today] to read it, and when reading it to imagine me working there, on foot, more than 40 years ago. And I would ask them to try not to find fault with it, because you can easily find fault with it, in retrospect.”

“I would ask them [students reading the paper today] to think about its [the paper's] importance in an historical context. What they should take from it is that it built long-lasting conceptual and empirical bridges between two formerly disconnected evolutionary arenas.”

“I would say it is a good example of how to link theory and experiment, but also that by today’s standards it is not a very sophisticated piece of work and much has been done since then to develop both the theory and experimental techniques.”