QnAs with Geerat J. Vermeij

Geerat Vermeij, an evolutionary biologist and paleontologist, has spent a long and distinguished career studying paleoecology, marine ecology, and biogeography. Focusing on a variety of systems, including fossil and living molluscs, Vermeij has helped address important evolutionary questions, including how shells evolved their functional morphology; how competition and predation influence morphology, ecology, and evolution; and how the dominance of faunas has changed over geological time. In his Inaugural Article, Vermeij describes his recent work examining the circumstances in which adaptive innovations evolved in shells (1). Now an emeritus professor of paleobiology at the University of California, Davis, Vermeij was elected to the National Academy of Sciences in 2022.

Geerat Vermeij. Image credit: Reproduced with permission. ©The Regents of the University of California, Davis campus.

PNAS: How did you become interested in studying shells and their morphology?

Vermeij: I have been interested in molluscs and shells since I was a boy and have been collecting shells ever since, including as recently as this year. Another strand, also from boyhood, is a great interest in geography. Both of those interests were strongly encouraged by my parents as well as by my brother, and I became what I’d like to think of as a broadminded biological scientist. I’ve also been very interested in how shells work and what their characteristics are. This paper is in the long line of work I’ve done beginning more than 50 years ago...[on] the geography and distribution of traits.

As someone who has been blind from a young age, I’m also very attuned to characteristics that, quite frankly, many people might overlook. As one example, I care a lot about the sculpture, the ornamentation that is on the outsides of shells. And one of those is…imbrication, which is where the slopes of features toward the growing or moving end of the animal are steeper than the slopes in the other direction. In a survey that I’m doing at the moment of this kind of imbricate sculpture, I’ve discovered that almost no one has ever noticed this or documented it. And I think one of the reasons…is that I use my fingers, and if you rub across a shell, it’s rougher in one direction than in another, just as on a grass blade, for example. For me, this is far more natural than for a sighted person.

PNAS: How did you become interested in comparing shell traits between the Indo-West Pacific and Atlantic-East Pacific realms?

Vermeij: When I was a senior at Princeton in 1968, I took part in a graduate course which went down to Costa Rica and then we took a little side trip to Curacao, so I got to see the tropics for the first time. That same year, I also went to Hawaii for a course on molluscs. The contrast in shallow-water molluscs really hit me like a brick, and that got me really intrigued about why they were so different. That began one of several strands of research, and this paper is…the most recent culmination of it. When I started, one of the things that struck me was that the so-called Indo-West Pacific shallow-water species were far better armored in terms of their shell form or antipredator characteristics than the Caribbean species, and I wondered why. We also determined that these two great big realms differed in their histories.

PNAS: What did your studies reveal?

Vermeij: The tentative conclusion is that in the Indo-West Pacific, where extinction was much lower in magnitude, per-species innovations are at much higher frequency than in the Atlantic-East Pacific, where extinction was severe. It’s admittedly an n of 2, so we have to be somewhat circumspect here, although I have found the same thing in the temperate realms as well. I had done an earlier study in 2012, and I’m really amazed that with so much more data now the results from the preliminary study have remained unchanged (2). I’m one of these scientists who thinks about a paper for a year or two or three and gets an answer and then moves on. That’s been the pattern in my life, and sometimes I move back when I have something new to say, and I get fresh ideas when I do return. That was the case in the current paper. I left this for 12 years, and, in the intervening time, I had new ideas.

PNAS: Has your research raised any concerns about the ecological impact of global warming or overfishing?

Vermeij: Global warming is a problem, but I’m much more concerned about human destruction of ecosystems. We are overfishing the world’s oceans, and we have largely destroyed and will continue to destroy terrestrial ecosystems. In particular, I’ve been pushing very hard [on the] idea that…by overexploiting top consumers in the oceans as well as on land, we are taking away a lot of the natural selection that has operated for millions and millions of years. That might very well account for some of the extinctions in tropical America, for example. So I think that’s a really major problem.

PNAS: What are some key reflections from your research career?

Vermeij: Well, I’ve been…pleading with biogeographers for…decades to think not just about taxa and numbers of species or just diversity, which to my mind doesn’t get you very far. I think it is far more important to think about the geography of organisms in an ecological context. And I think it’s a far richer field that way and one that is remarkably unexplored. Organisms are trying to tell us not just their names, not just how many there are, but what are their characteristics and what those characteristics imply about their mode of life, the challenges of their life, and how those challenges have changed over time.

I think the thing that characterizes much of my work is that I try to synthesize and pull things together from extremely disparate and isolated sources, including extremely obscure ones as well as just my own cumulative experience with specimens in my own collections and in museums and in the field around the world. It’s taken a huge amount of effort. I read widely every day, and if I didn’t do that, I couldn’t do this work. And, likewise, I’ve created a large research collection, and I have visited many museums and field sites, and if I hadn’t done that, I couldn’t do this work. So it’s really a question of staying at it for decades…unrelentingly. It’s all been very enjoyable.