Prediction In Ecology And Evolution

I recently published a paper titled Prediction in Ecology and Evolution in BioScience. I was pretty sure the paper would get a lot of attention as I had six reviewers who provided more than 20 single-spaced pages of comments. In all cases, the reviewers were very interested and sincerely wanted to help improve the paper. Most of the criticisms focused on (1) what I should have paid more attention to, or (2) what I should have excluded. After publishing the paper, I immediately started getting emails making similar suggestions. This inspired me to start an exchange of ideas.

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To start, I provide the abstract of my paper, which is freely accessible on the journal website through the end of 2023. Then we will move to some commentaries/criticisms/suggestions. 

Prediction In Ecology and Evolution - by Andrew P. Hendry   

Prediction is frequently asserted to be the sine qua non of science, but prediction means different things to different people in different contexts. I organize and explain this diversity by addressing five questions. What does it mean to predict something? To answer this question, I describe concepts of prediction as prophecy, diagnosis, history, repeatability, and fate. What are we trying to predict? Here, I describe how predictions vary along several axes: general to specific, qualitative to quantitative, relative to absolute, point to range, and continuous to discontinuous. Where do predictions come from? In this case, I focus on deductive versus inductive reasoning. How do we test predictions? The answer here is not straightforward and I discuss various approaches and difficulties. How good are predictions? Not surprisingly, it depends on what is being predicted and how we judge success. Importantly, I do not espouse a “best”way to approach prediction but, rather, I outline its diverse manifestations so as to help organize practical thinking on the topic.

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1. From Predicting an Eclipse to Predicting Speciation

By Marius Roesti - University of Bern

In a separate post, Marius asks if we can move from a machine predicting an eclipse (use of an orrery to do so in the movie Pitch Black is shown below) a "machine" for predicting speciation in the post is here.

Excerpt from the post: In many life situations, we base our decisions and actions on their predicted consequences. Yet, predictions are also indispensable in fundamental sciences where interests center on understanding how our universe works, rather than assisting with practical life problems. We recently asked some colleagues why we want to predict things in science and often heard something like "because this will tell us whether we got it right or not". – This made us think. If true, what does this mean for a field of research still struggling with making accurate predictions?

The paper on which the post is based.

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2. Assessing Predictability in Ecology and Evolution

Daniel Ortiz-Barrientos, The University of Queensland, d.ortizbarrientos@uq.edu.au

 “We never actually prove any proposition in science; nor do we accept any proposition as ‘true,’ ‘finally true,’ or even ‘probable.’ But we do accept some propositions (or theories) as better tested, or better corroborated, than others.” - Lakatos (1978)

The paper “Predictability in Ecology and Evolution” (PIEE, Hendry 2023) comprehensively frames our understanding of the diverse applications of prediction in ecology and evolution. However, an emphasis on predictive ability can lead us to overestimate foresight given the complex and contingent nature of biological systems (Mayr 1961). Integrating a structured categorization of prediction in ecology and evolution with tailored best practices could add to the paper’s grounded perspective (Tables 1-2).

The taxonomy of PIEE encompasses concepts such as prophecy and repeatability and avoids a one-size-fits-all approach. This approach suits the complex context and aims of prediction in our research fields. However, predictions range on a continuum from universal principles to specific forecasts, each with distinct utilities and limitations (Table 1). This spectrum reflects the trade-offs among realism, precision, and generality (Levins 1966). General principles provide theoretical guides but can oversimplify nonlinear dynamics (Gould and Lewontin 1979), and detailed quantitative predictions often fail when extended beyond their inductive scope.

Practices like replicating studies, comparing models, and providing effect sizes (Table 2) should capture the relevant contexts we need for proper interpretation without demanding impossible generalities. Such a goal can ultimately reflect the role of contingency in evolution (Wiens and Donoghue, 2004). Also, conveying historical context and information on the sensitivity of evolutionary processes to initial conditions can help. In general, categorizing prediction into types that teach us about our own practice can prevent us from presuming universal accuracy while keeping our fundamental goal of finding rules in biology.

In conclusion, while the PIEE paper sheds light on the diverse role of prediction in ecology and evolution, it might overstate the predictive power achievable for researchers, given the complex realities of nature. Combining a structured prediction framework (Table 1) with adaptable methodologies (Table 2, Lakatos, 1978), can strengthen PIEE’s string conceptual foundation. It should also help us embrace unpredictability and sharpen our scientific rigor. Recognizing intrinsic limitations, as highlighted by Mayr (1961), can equip researchers with epistemic humility to navigate ecological and evolutionary complexity pragmatically.

References

Gould, S. J., & Lewontin, R. C. (1979). The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme. Proceedings of the Royal Society of London. Series B. Biological Sciences, 205(1161), 581-598.

Hendry, A. P. (2023). Prediction in ecology and evolution. BioScience, 73(3).

Lakatos, I. (1978). The Methodology of Scientific Research Programmes (Philosophical Papers Volume 1). Cambridge University Press.

Levins, R. (1966). The strategy of model building in population biology. American Scientist, 54(4), 421-431.

Mayr, E. (1961). Cause and effect in biology. Science, 134(3489), 1501-1506.

Wiens, J. J., & Donoghue, M. J. (2004). Historical biogeography, ecology and species richness. Trends in Ecology & Evolution, 19(12), 639-644.

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 YOUR COMMENT HERE!

A rejected analogy

Analogies can be useful ways of explaining complicated ideas - but they can also be problematic. Reviewers of a recent paper were having trouble understanding a rather intricate idea we were presenting. Thus, on revision, I attempted an analogy. I liked the analogy and found it helpful but - whether unfortunately or not - it didn't make it into the final paper. It was left on the cutting room floor, so to speak. Still, I kind of like it and so provide it here - with context.

Led by Sarah Sanderson, we recently conducted several studies that tested the hypothesis that populations living in areas with low levels of a limiting nutrient would show compromised performance for traits depending on that nutrient. Specifically, we first tested whether fish populations living in water with very low calcium levels would show reduced levels of calcium in their scales. This work was possible because several native species can be found across an environmental gradient in calcium levels, from "high" in the St. Lawrence to "low" in the Ottawa River (Figure  below).

To cut a long story short, we found NO EVIDENCE that the populations in low-calcium water had lower levels of calcium in their scales. The figure below shows that - for a given change in water calcium - scale calcium levels changed hardly at all.  At one level, this made sense - because calcium is what makes scales strong - and strong scales aid defense from predators and other environmental stressors. Yet experimentally exposing fish to similarly low calcium levels has been shown to compromise various aspects of performance - so how were these fish maintaining high-quality scales?

Our next hypothesis was that these fish really really need high-quality scales - and so prioritize that function when faced with low calcium availability. If so, they might show reduced functionality of other calcium-dependent traits - and so we next looked at various aspects of the skeleton. Again, we found no evidence that fish in low-calcium water show any compromise in this calcium-dependent structure. This result is summarized below, where the results for scale calcium from the earlier paper are in red and the results from various skeleton measurements are in green and blue. 

 

It seems, then, that populations in low-calcium water have somehow evolved to be better at obtaining calcium and/or building calcium-dependent structures - perhaps a classic case of "counter-gradient variation" (which would have to be confirmed using common-garden rearing). Yet, even in cases of counter-gradient variation, something else is often compromised - that is "Darwinian Demons" who are great at everything are unlikely. 

So where are the compromises then? We could always look at other calcium-dependent structures (although scales and skeletons are the most obvious) or perhaps the effort required to obtain calcium in low-calcium water has other costs, such as to growth or survival. But this is could be a wasted effort because ....

And now we come to the alternative idea for which I generated the analogy. Here it unfolds as written out in the draft version. The first paragraph is the analogy that was axed later and the rest of it was also modified for the final published paper. Perhaps you will like it or maybe you will hate it but, regardless, I bet you will remember it - even if only for short time.

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Perhaps trade-off payments during adaptation are “front loaded”

"We start with an analogy. When purchasing a mortgage for a home, the purchaser incurs an additional cost (beyond the cost of the home itself) in interest payments to the lender (usually a bank) – and most mortgages are structured such that those interest payments are front-loaded. As a result, payments early in a mortgage include a lot of interest payments (on the money loaned by the bank), whereas payments late in a mortgage almost entirely reduce the principal (because the interest was paid earlier). Thus, if one examines mortgage payments early on, this additional cost is apparent – and is a trade-off associated with purchasing a home via a mortgage. Later on, however, examining mortgage payments would suggest this cost was minimal – because the interest payments have become very small. In short, a strong trade-off (interest payments) can be evident early in the process of adaptation (getting a home) but are not evident later in the process (because they were paid early on).

From this analogy, we suggest that the costs of adaptation to a limiting nutrient might be absent in the present because they have been paid via selective mortality in the past. When an environment changes to become more stressful or difficult (e.g., colonizing an environment with limited resources, like calcium), selection for improved tolerance to that stressor is expected to be “hard” (as opposed to “soft”) – that is, by increasing mortality rates (Brady et al., 2019a). This increased mortality represents a cost in the form of “selection load” that stays high until evolution better adapts the population for the new stressful conditions. If population sizes are low during this period, an additional cost can be incurred through inbreeding that exposes “genetic load” (Crow, 1970). Once the population adapts and increases in abundance, however, it has paid those costs of selection (removing maladaptive alleles) and inbreeding (“purging” recessive deleterious mutations); and, hence, might perform better than the ancestral population in both environments. Indeed, populations adapted to stressful environments can show higher fitness (or at least not lower fitness) in all environments – both in laboratory adaptation studies and in field experiments (Reed et al., 2003; Rolshausen et al., 2015).

Applying this last scenario to our study system, adaptation to low-calcium water might have been extremely difficult at first – generating substantial mortality and strong selection. This expectation is supported by experiments that expose naïve fish to low-calcium water (Baldwin et al., 2012; Iacarella & Ricciardi, 2015) and by the failure of Ponto-Caspian invaders to colonize low-calcium water (Iacarella & Ricciardi, 2015; Jones & Ricciardi, 2005; Palmer & Ricciardi, 2005). During this initial period, trade-offs would be expected. During the period of intensive adaptation, selection would tend to remove individuals that showed the strongest trade-offs – or that suffered the most from them. Once the population passed through this period and became reasonably well adapted to the stressful conditions, the result could be a locally-adapted populations able to maintain homeostasis without incurring large costs. Time will tell whether invaders in the system will be able to pass through this same bottleneck.

We are not here suggesting that this selection cost is high every time a high-calcium fish population colonizes low-calcium water. Instead, a long history of native fishes occupying a diversity of calcium environments has probably maintained a pool of standing variation that facilitates rapid adaptation to new calcium conditions. The costs paid during this rapid adaptation would presumably be lower than the cost paid the first time that adaptation proceeded – that is, the first time a high-calcium fish lineage successfully colonized low-calcium conditions. Subsequently, alleles suitable for adaptation to low-calcium conditions might persist within the species as a whole – even when not in low-calcium water. An analog to this situation could be the ability of marine threespine stickleback to adapt repeatedly and rapidly to new freshwater habitats via standing genetic variation in the marine population that persists via gene flow from past and present freshwater populations (Roberts Kingman et al. 2021; Roesti et al., 2014; Schluter & Conte, 2009). We can see considerable value in applying these ideas to other systems where some fishes can occupy a broad diversity of habitats without obvious costs, whereas other fishes cannot."

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Histories of Stickleback Research - Tom Reimchen

Retrospection - by Prof. Tom Reimchen (University of Victoria, BC, Canada)

I was a second year undergraduate student at the University of Alberta in 1967 and interested in evolution but indecisive as to majoring in biology or geology. Students were given an opportunity to assist graduate students in summer projects.  I applied with Ric Moodie who was doing his PhD on Haida Gwaii (then called the Queen Charlotte Islands) studying the evolution of a giant black stickleback at Mayer Lake (I had read about stickleback in the journal Evolution). Other students applied for this position as well but I got the job. Ric later told me later that I was the only applicant who expressed no interest in sport fishing but a strong interest in evolution, so he hired me.

Ric’s research exposed me to methods of studying variation in natural populations. One of the techniques involved gill-netting cutthroat trout from the lake, extracting the stickleback from the stomachs and then measuring their size and various defense traits including the bony lateral plates on the side of the fish.  Ric got the impression that stickleback with seven lateral plates, which comprised the modal (most common) phenotype in the population, were captured by trout at a lower rate than stickleback with fewer or greater number of plates. He suspected that fish with different numbers of plates differed in their behaviour  and that this variation might account for the trends in trout stomach contents.  He assigned me the task of locating stickleback nests in the shallows of this large lake, after which we would capture the territorial males. Ric scored the males for nuptial colour, number of lateral plates on both sides, and body size. I did not really understand the rationale for this but it gave me the first exposure to the idea that individual phenotypes differing by a single lateral plate might be acting in different ways.

Over the three summers that I worked as Ric’s assistant, I found many nests and Ric scored many male stickleback. Ric thought it might be interesting to sample some of the neighbouring lakes to see if there were any other interesting stickleback. We hiked into the interior of the island across Sphagnum bogs and through forests using survey maps and compass bearings occasionally missing lakes altogether. One of these isolated lakes was much smaller than Mayer Lake, lacked littoral vegetation, and was appropriately named Drizzle Lake.  As we walked along the shoreline, speculating on whether there would be any fish in this small lake, I found a dead stickleback on the shore that looked superficially like the giant black Mayer Lake stickleback. I thought Ric had dropped a Mayer Lake stickleback to fool me into thinking that we had discovered another example of gigantism. He assured me that he had done no such thing. The genetic work years later showed that this was an independent origin of gigantism from that at Mayer Lake. On inspection of this dead stickleback, we could see that it had only 4 lateral plates, lower than the lowest plate count that Ric had ever seen at Mayer Lake, and we concluded (naively) that there would be minimal predation in the lake.

In my free time, I hiked to some additional unsampled lakes. One of these was the small Boulton Lake that lacked predatory fish. I put some traps in, waited a few hours, and when I checked them, to my absolute amazement, I found that most of the stickleback had no pelvis and many were missing some of the dorsal spines. Excitedly I returned to Mayer Lake to tell Ric who told me that such a stickleback had not been previously found in North America or Europe. We continued these lake surveys and got stickleback from 22 lakes, and many of the populations were distinctive to each lake. Such variability across such short distances exceeded the known morphological diversity of stickleback throughout Canada and Europe. The provincial environmental agency got wind of our ‘discoveries’ and asked us to recommend three lakes with unusual stickleback, one of which would be established as an Ecological Reserve for long term protection of the entire watershed and opportunity for research. We proposed Mayer Lake, where Ric was doing his study, Drizzle Lake, with the other giant stickleback in the north of the island, and Boulton Lake, which had stickleback with a missing pelvis. The government made a decision that Drizzle Lake would be established as an Ecological Reserve as it had the fewest administrative conflicts with other agencies. I was happy with this decision as the undisturbed lake was remote with no road access and had a small old log cabin near the lake that would provide a living place if I ever were to do research on the fish in this lake.

In May 1970, after completing my Zoology undergraduate degree at the University of Alberta, I convinced my friend Joe Rasmussen to come with me to Haida Gwaii for several weeks to sample more lakes for stickleback. During this trip, we discovered a small acidic bog pond with stickleback that were very unusual: not only were the lateral plates missing but the entire trunk was covered in a unique dinoflagellate parasite. We called this locality Rouge Lake as the nuptial colour of the males was outlandishly red;  it turned out with later studies to be also very atypical with respect to its genetic structure. On this expedition, I also made detailed collections of the Boulton Lake stickleback and saw that the relative expression of the pelvic girdle differed from one part of this lake to another, variation that I was later able to relate to spatial differences in the predation landscape.

During the spring of 1970, I started looking at samples of the giant stickleback from Drizzle Lake and noticed that some of the anterior lateral plates underlay the basal support structures for the dorsal and pelvic spines. One atypical fish had spines that were easily laterally deflected from their erect position. This fish was missing one of the lateral plates and it immediately became clear that the plates would buttress the dorsal and pelvic spines from lateral forces exerted during predator manipulation. I shelved my idea about this for several years, returning to it in the late 1970’s and  eventually publishing these observations in 1983 (Evolution 37: 931-946 - Figure 1).  

Figure 1: Relationships between lateral plates and spine supports.

Ric Moodie suggested I read EB Ford’s recent book on ecological genetics. This completely hooked me on studying adaptation and measuring selection in real time in the field. Fortunately, the University of Alberta had just hired Kennedy McWhirter, who was Ford’s colleague at Oxford. I took the courses Ecological Genetics and Population Genetics from Kennedy and this further cemented my interest in this emerging discipline. Kennedy encouraged me to do graduate work at the University of Liverpool in the UK where Arthur Cain and Philip Shepard had recently arrived from Oxford and were developing a graduate program in Ecological Genetics.  My subsequent four years in the UK resulted in a DPhil on the ecology and genetics of two sibling species of intertidal gastropods. This research greatly emphasized to me the importance of spatial and temporal scale for interpreting polymorphic variation within and among populations, an approach that would structure my subsequent studies on stickleback.

During my graduate program, I became friends with Paul Handford and Graham Bell who were both at Oxford;  over several years, we hatched an outlandish research plan in which we would go to Drizzle Lake on Haida Gwaii, and with our partners, live in an old log cabin, and undertake a multi-year study on the giant stickleback from the lake;  Paul would focus on the behavioural adaptations of the fish, Graham on the demography of the population and myself on predator-prey interactions in relation to phenotypic variability. Paul joined me on Haida Gwaii in late 1975 and 1976. Paul, who had just finished a post-doc on songbird dialect in the dry mountains of Argentina, did not take well to living in a small dark cabin in the midst of a wet and cool rainforest. Graham at this time had just finished his DPhil at Oxford and with Sue, his partner, initiated the process of immigrating to Canada. They got as far west as Edmonton where Paul was staying. It was clear that the logistics of potentially six of us living at Drizzle Lake were unreasonable. Paul and Graham got sensible and each got jobs, Paul at the University of Western Ontario and Graham at McGill University.

Figure 2a. Haida Gwaii with Drizzle Lake and research cabin (inset)

Not as well-anchored in reality, I took up residency at the Drizzle Lake cabin in 1976 (Figure 2a) and began the research program. I wanted to extend principles from some of my thesis work involving polymorphic traits and felt that sources of mortality and microsite adaptations might also be operating with traits that were continuous, such as lateral plates, rather than only discontinuous traits like the colour of  intertidal snails. With a $2000 support from the Ecological Reserves Unit (BC government) as well as similar amounts from Joseph Nelson at the University of Alberta, my partner Sheila Douglas and I equipped the 80 year old Drizzle Lake cabin with solar panels, a small wind generator, lights, microscopes as well as a ‘portable’ Osborne computer. In 1985, I was successful at getting an NSERC operating grant that allowed us to continue the research. 

Figure 2b. The lab at Drizzle Lake.

Our year round residency at Drizzle Lake from 1976 to 1985 and then summer residency from 1986 to 1990 yielded substantial evidence of repeatable temporal and spatial variation in the predation regime and the potential influence on the selection landscape affecting the stickleback population. Within several years, we had identified over 20 species of predators on stickleback in the lake, including 16 species of avian piscivores as well as resident salmonids (Figure 3). Most of these predators differed seasonally and they differed as to where they foraged in the lake and what size classes of stickleback they consumed. This high diversity of predators was not because the lake was a predator ‘hotspot’ but rather, evidence for this diversity emerged only as a consequence of the extended time duration (multiple years, multiple seasons) of the study. I summarized these data in a chapter for an Oxford publication that Mike Bell and Susan Foster put together in 1994. 

Figure 3: Predator assemblage at Drizzle Lake.

During the research program, Sheila and I circumnavigated Haida Gwaii several times and sampled about 800 lakes, ponds and streams, of which about 15% had stickleback, all of which were morphologically different from each other. Each lake offered a distinctive set of biophysical parameters (predators, diet, parasites, lake morphometry, spectra, etc) that had the potential of structuring the selective landscape (Figure 4).

Figure 4: Geographical survey of Haida Gwaii for stickleback with representative examples of habitats. Symbols: blue- stickleback present, black- stickleback absent

I was able to recruit some excellent students  including Carolyn Bergstrom on the role of asymmetry in defensive traits, Patrik Nosil on fluctuating selection and Mark Spoljaric on plasticity and predictability of body shape. We summarized the adaptive radiation of these 100+ allopatric populations in 2013 (Evolutionary Ecology Research 15: 241–269). Essentially, the selective landscape at each locality was defined by the relative importance of puncturing, compression or grappling piscivores combined with water spectra (reaction distance) and lake size (Figure 5).

Figure 5: Summary of major processes influencing the selective landscapes of Haida Gwaii stickleback defense structures. 

While it was clear to me that large differences in morphology, from fully-armoured to unarmoured among and within these populations, were adaptive; it remained ambiguous whether this represented genetic variation or plasticity. Axel Meyer had recently shown a major role of adaptive plasticity in jaw and skull morphology of central American cichlids, and such plasticity could not be ruled out for these divergent Haida Gwaii populations.  In 1989, I asked a new graduate student, Patrick O’Reilly, to examine the mtDNA of some of the most divergent populations of stickleback, including the unarmoured stickleback in small acidic ponds that I discovered back in 1970. It was reassuring that these unarmoured fish had a very distinctive mtDNA haplotype from most other stickleback populations (although it was similar to those in Japan), and were potentially relictual but this did not resolve whether the unarmoured phenotype was heritable. Subsequently, advances in DNA sequencing techniques allowed David Kingsley at Stanford to develop genome-wide SNP arrays for stickleback. My post-doc, Bruce Deagle, was able to use the arrays to show extensive genomic differentiation among the morphologically divergent populations, including three different lake-stream species pairs (Proc. Roy. Soc.  279 : 1732 1277), although this did still not rule out adaptive plasticity for divergence in morphological traits.

The repeated evidence for adaptive differentiation among and within populations would have more conceptual context if I had some  experimental data that allowed estimates of strength of selection and rates of change. In the mid-1980’s, I sketched out a plan to transplant limnetic giant stickleback with robust armour from a large lake into a small ‘barren’ fishless pond that differed in multiple ecological axes from the source lake. Ideally, I wanted to create a shift in the ecological theatre involving predation landscape (salmonids/birds to macroinvertebrates), trophic regime (limnetic/plankton to benthic/macrobenthos), spectral regime (dystrophic/heavily stained to eutrophic/non-stained waters) and water chemistry (lower to higher conductivity), expecting that subsequent generations might reveal phenotypic changes in the direction predicted from the differences I observed in the geographical surveys (Figure 6). Eventually, I identified four suitable barren ponds that generally met the criteria and in 1992 initiated the first of the transplant experiments. 

Figure 6: Transplant experiment from Mayer Lake with giant stickleback into a barren roadside pond.

The colonists successfully reproduced, yielding numerous generations that I sampled over time. In 2007, an outstanding student (Steven Leaver) began a graduate program with me and photographed and measured all the samples for meristic and metric traits. The results produced striking evidence for shifts in all defense and trophic traits over nine generations, all in the direction predicted. Some of the traits shifted in the first generation, consistent with adaptive plasticity, and other traits shifted across generations, more consistent with genetic changes (Biol. J. Linnean Society. 107:494-509 - Figure 7).  David Kingsley offered to do whole-genome sequences and I sent him 56 stickleback, including the source and transplant populations as well as representative stickleback from morphologically divergent Haida Gwaii populations. I needed a post-doc to do the genomics of these samples and fortunately Katie Peichel encouraged David Marques to apply. Remarkably skilled, David was able to complete the analyses of these fish identifying trait-specific genetic markers across the genome. These results gave novel insight into opsin evolution, as well as evidence for genome-wide shifts, all in the direction that were predicted by the genomic differences among the allopatric populations differing in ecological conditions. I feel this paper (Marques et al. 2017, Nature, Ecology and Evolution) has been the most substantive to emerge from my research program as it exemplifies the efficacy of natural selection and predictability of evolutionary changes among populations in remarkably few generations. This theme greatly contrasts to that of the famous orator, Stephen J. Gould, who concluded in 1985 that “….some geographic variation within a species is clearly adaptive, but much is a non-adaptive product of history."

Figure 7: Results of phenotypic shifts in the transplant population relative to the original colonists after 8 generations.

One of the important concepts  that emerged during our many years in the ecological theatre at Drizzle Lake and Haida Gwaii was the persistent reminder that inter- and intra population variability in defense morphology could not be reliably understood without context to age-specific sources of mortality. Presence of multiple species of piscivores that differed spatially and seasonally, as well as in their foraging and prey capture behaviour, creates an opportunity for diversifying selection on the traits that can differ spatially within populations and fluctuate over short periods of time. The tendency of researchers, including Ric and myself in the early formative years, to classify populations as either with or without predators was simply wrong. There were localities without predatory fish but there were none that lacked one or more species of piscivorous birds or macroinvertebrates (Figure 8). 

Figure 8: Routine morning observations of Common Loons foraging on stickleback at Drizzle Lake. Inset shows adult stickleback that escaped after capture by a Common Loon. These exhibit different lateral plate phenotype than uninjured fish and have elevated fitness relative to modal phenotypes (Evolution 2023, 77(4), 1101–1116).

Researchers, editors and reviewers still uncritically accept the flawed dichotomous characterization of the predation landscape (yes/no or high/low) despite the lack of evidence to warrant the dichotomy. While It is unlikely that  future researchers will embrace my approach -  living in an old cabin at the study lake for year-round observations on the abundance and behaviour of the predator assemblage,  I am optimistic for the future. New technologies, such as hi-resolution field cameras and e-DNA  will hopefully contribute to the understanding of the subtle but real temporal and spatial variability in selective landscapes, the motivation for the extended field studies on Haida Gwaii stickleback.

Sheila Douglas putting in the work.

Ole Kristian Berg - Memories

When a colleague and friend passes on, those of us left behind wish to honor them with some of our favorite memories. With Ole Kristian Berg, those memories are many and vivid. He was an excellent colleague and a genuinely wonderful man, who not only brought a creative originality to his (and our) research but also an undimmed sense of wonderment about the natural world, especially salmonid fishes (salmon, trout, and charr). Most importantly, he was someone who loved and lived life to the fullest, and never ceased to help us all remember how lucky we are to have careers and lives that can be so fun.

This post has memories from myself (Andrew Hendry), Sigurd Einum, Thomas Quinn, Trond Amundsen, Gunnbjørn Bremset, Jan Grimsrud Davidsen, Tor G. Heggberget, Sten Karlsson, Line Elisabeth Sundt-Hansen, and Eva Marita Ulvan - as well as (at the end) a collection of Ole's most cited papers. Note: many more remembrances from family, friends, and colleagues are HERE in Norwegian.

Ole Kristian Berg (11.04.1954 - 26.02.2023)

Andrew Hendry

I was a pretty green first-year graduate student in 1993 when I first met Ole - and I remained his close friend and collaborator for another 10 years. I worked with him four different years in Alaska (over the span of 10 years) and I spent months (over several trips) with his family in Trondheim, Norway. He was my first real international collaborator - and a more wonderful and personal entre into such collaborations could not have been imagined. Ole was an important and innovative scientist, with some truly influential work that you can peruse below. Ole was about so much more than science though, and he was such a fun and novel individual that capturing the spirit of who he was is perhaps best served by a series of personal anecdotes.  

Field work with Ole and his family

My most intimate experiences with Ole were during field work at a remote camp on Lake Nerka, Alaska, in 1995, 1996, and 2000. For much of that time, it was just me and Ole and Ole's family, and it was one of the most memorable and rewarding of times for me. We worked long hours, ate good food, and had lots to drink, while playing games and watching nature. And we laughed and laughed and laughed. And nothing made him laugh so hard as watching his young kids teach me how to swear in Norwegian. 

And then there was the electric drill. In 1995, Ole's main goal was to analyze the energy content of salmon and how it changed as they returned from the ocean to spawn in freshwater. To measure this energy content, we need to create a slury (or smoothie, if you will) of many many individual salmon. So Ole bought a Dewalt DW101 drill and hooked it up to a meat grinder. Powered by a generator, that amazing drill ran hours and hours each day making salmon smoothie. The result was a very influential paper (Hendry and Berg. 1999. CJZ 7:1663-1675). When he left Alaska, Ole proudly presented me with the drill, and it has been a valued household tool to this very day.

Ole's drill 27 years later.

I feel compelled to comment again about how creative Ole was as a scientist. We had written a series of papers about how natural selection influences female reproductive life span in salmon. That is, a female couldn't just lay her eggs and die because she had to live somewhat longer to defend her nest site against other females who might dig on top and thus displace and destroy the earlier female's eggs. Yet no one had a good estimate of this selection on life span due to "nest superimposition." Ole had the amazing idea to inject females with colored food dye, which would bind to the eggs. Then we could dig up the females' nests to see how many of the colored eggs remained depending on whether another female later dug her nest in the same spot. This study was one of my favorites to this very day (Hendry et al. 2004. PRSB. 271:259-266).

Ole digging up salmon nests (above) to look for dyed eggs (below).

Visiting Ole and his family in Trondheim. 

I have many memories of my trips to Norway, but two come immediately to mind and put a big smile on my face. The first was when we took a long hike up into the mountains to camp at a lake Ole and colleagues were studying. We arrived at dusk and crowded into a small one-room cabin, with beverages all round. Not having seen an outhouse, I eventually worked up the courage to ask "Where do I go to the bathroom"? Ole laughed and shouted "Oh, just go anywhere over in Sweden." It turned out we were right beside the cairns that marked the border with Sweden, and anywhere past that border was the outhouse. It was my first visit to Sweden. 

The other memory I want to share is how - when I spent several weeks staying with Ole and his family, they took great pleasure it introducing me to all of the traditional Norwegian "delicacies" - laughing at me as I tried them and telling stories about how Ole (and his kids) would weaponize food (mainly Surströmming) as practical jokes during military training (the whole barracks had to empty), at school (the police were called), and at athletic events (dropped on the opposing rowing team from a bridge above). Here is the menu and tasting notes that I generated from those days. Yes, they really cooked each of these dishes for me - mostly just to laugh at my reaction. 

Sigurd Einum

In remembrance of my dear friend and colleague Ole

It is now 30 years since I met Ole for the first time, I was a bachelor student in biology, and he was faculty. It’s funny how the teachers seemed old to me back then, he was only 38, and I’m now 50! Anyways, I already then noticed how he was able to establish a rapport with the students that few others did. I’m not sure how he did it, but I believe his rather informal manner and a good (or bad?) sense of humor was part of it. One of his more infamous pedagogic tricks was applied during lectures when he noticed students closing their eyes and appearing to fall asleep. He would then continue his lecturing in a normal voice while slowly approaching the unsuspecting student, and once there yell something really load and slamming his hands into the bench next to the sleeping head. Of course, he did this with a smile on his face, raising laughs, and it usually ended well. As another example, during a lecture on marine fish stocks in a class of about 100 students he, upon coming to a part about cod, got the students to participate in singing a kid’s song that describes components of the life-cycle and ecology of that species (Torskevise by Thorbjørn Egner). The thousands of students that experienced this probably remembers a thing or two about cod, and at the same time felt a bond to their professor that contributed to their motivation. While it is tempting to try to replicate this, I’m afraid that only someone with Ole’s personality can pull it off, and I would probably fail miserably.

Ole Kristian Berg in his element

When I joined our department in 2007 I came to know Ole as a colleague. He was incredibly helpful whenever I was having questions about how things were done in the department, and with respect to access to labs and equipment. We quickly initiated collaborations both with respect to teaching and science, and I have benefited greatly from his broad knowledge about, ecology, life and basically everything. In 2010 he invited me to join his expedition to Bear Island, which of course was excellently organized, well stocked with equipment, food and drinks, and required very little planning from my side. We also collaborated on our freshwater ecology course, and the annual field course at remote Lake Snåsa was always a highlight of the semester. I know Ole also appreciated these trips with the students, and he continued to participate on the field course after he retired. There we would teach coming generations of freshwater ecologists procedures for fish and plankton sampling and processing, water chemistry, and then at the end of a long day sit around the fire with a beer and watch the northern lights together. These moments will be deeply missed.

A good friend and incredibly generous and knowledgeable colleague has passed away, much too early. I had looked forward to further collaborations, and not the least more Christmas parties where he as usual was supposed to be responsible for the gløgg (mulled wine), and being the last one to leave the party. That did not happen. Instead, we will enjoy the good memories he has given us, and those are many! Ole continues to live on in the hearts of collaborators and students. My deepest condolences go to the family which has lost an amazing husband, father and grandfather.

Thomas Quinn

Ole (left) and Tom (right) in Alaska

Like all others who knew Ole Kristian Berg, I was shocked and saddened to hear of his passing, and extend my deepest sympathy to his family and friends. As sometimes happens in our profession, we became acquainted when I got an unexpected communication from him, indicating an interest in coming to meet and collaborate with me. Thankfully, I encouraged him. One thing led to another and 30 years ago, in the summer of 1993, he visited Seattle, stayed with me, and joined our field operations on Lake Aleknagik and Iliamna Lake, Alaska. The attached photo is from that year. I was immediately taken with his personal openness and friendly attitude, breadth of scientific ideas, and exceptional work ethic. Then, in 1995 and 1996 he came again, with his wife, children, and field technician, to work with Andrew Hendry, who was then my doctoral student. I was fortunate that a house across the street, owned by our neighbors and friends, Jim and Maxine Hinze, was vacant at the exact period when the Berg’s needed a place to stay. Otherwise, I am sure I would have squeezed them into my house, somehow! As always, he was lively, funny, kind, generous, and full of energy, but also full of mischief and tricks. Ole kindly invited us to a barbeque but then shocked us by revealing that he had smuggled minke whale meat into the US and that was what we were eating! Watching them all repacking their great volume of field gear among their bags to meet the weight requirements for luggage at the Seattle airport was something I will never forget.

Ole’s collaboration with Andrew Hendry resulted in a several important papers and a great boost to Andrew’s career, but it also provided an endless series of stories. The field camp where the Berg’s and Andrew were working, on Lake Nerka, was a long distance from the main field camp on Lake Aleknagik, which was accessible to stores for food, fuel, and other supplies. The Lake Nerka camp had what seemed like more than adequate food but in short order the unreliable old radio phone crackled with the news that they were running short of essentials. How could this be? Well, it seems that they ate in a week the supply of potatoes that would normally support a crew of that size for the whole season! Over on Iliamna Lake, the largest lake in Alaska, I will never forget wallowing in big waves in the middle of the night as we towed nets between two boats to sample juvenile sockeye salmon and sticklebacks. We barely escaped with our lives from the experience, but enjoyed a drink at 3 AM to celebrate our brush with death on the lake.

I raise a glass to a wonderful man – lively, loyal, experienced, wise, and kind.

Thrond Amundsen

Memories of Ole Kristian

It was so sad to hear that Ole Kristian had passed away so all too early. I’ve known Ole as an always supportive and friendly colleague ever since I started my job at NTNU, not so long after Ole was appointed himself, in the early 90s. I first and foremost think of Ole as a kind man, always interested, always supportive, always positive. These are qualities that don’t always thrive in modern academia but they mean a lot, and Ole’s kindness meant a lot to me.

For many years, up to Ole’s retirement and for longer than I can remember, I worked closely with Ole on our first-year course in Ecology, Behaviour and Evolution (BI1003). This is a special – and especially important – course for our department: it’s the first course for new NTNU students of biology, including lots of teachers and teaching assistants, and a large range of pedagogical tools and activities. In short, a cool course but a logistic nightmare to manage, requiring dedication ‘way beyond normal’. Ole put in enormous efforts and managed the course successfully for several years until his retirement two years back, to make it an enjoyable and successful course for students and teachers alike. Being the two old-timers of the course, Ole and I had many interesting chats on the smaller and bigger challenges of getting the course to work. I always felt that Ole appreciated my input and that of others and did his very best to make it a great course. Ole would have deserved much more praise for these efforts than he got. Last year, the course and its teachers were awarded the Teaching Excellence Award of the Faculty of Natural Sciences. Ole would truly have deserved to be part of the award-winning team – we who took over built the course on the foundation he laid down.

Ole was a true ‘fish person’, with a huge knowledge of fish biology and fish management. Other ‘fish people’ closer to his research can tell more about that then me. For me, who started dabbling with fish from a bird background, he was a rich source of knowledge and advice. And more importantly, he always showed a genuine interest and appreciation – he always had a kind and supportive word. I’m sure others can tell the same. To me, that meant more than he probably realized himself.

My last meeting with Ole was by accident, last fall, just outside the Natural Sciences building. I had only occasionally seen him since his retirement. Ole was in a good mood as always, and curious to hear about my stuff, including how things had worked out with my own group’s field work last summer (fortunately, for once, quite well!). On my part, I was curious how things were for him, and what he was up to at campus. Turned out he was on his way to talk to BI1003 students about how to present the projects they were about to complete, contributing as a ‘volunteer’. That’s typical of him – he loved that course, he loved engaging with students, and he was a very unselfish man, happy to help out when asked. On the private side, he told that he and his wife had spent the whole summer traveling Iceland, enjoying its splendid nature – and I believe culture, too. It sounded like they had had a great time up there, and we shared memories of Iceland’s natural riches.

When Ole has now so sadly passed away, that last meeting stands fresh in my memory, as typical of Ole – friendly, supportive, with a true love for nature and for educating the next generation about the value of nature. It makes me think that Ole lived his life to the full as a biologist, teacher, nature lover and family man until the very end. Even if that end came all too early.

Ole (left) was always happy - but never more so than when up to his wrists in fish guts.

Gunnbjørn Bremset, Jan Grimsrud Davidsen, Tor G. Heggberget, Sten Karlsson, Line Elisabeth Sundt-Hansen, and Eva Marita Ulvan

It is with great sadness we learned of Ole Kristian Berg's untimely passing. Most of us knew Ole Kristian from his time at the Zoological Institute at Rosenborg campus, where he devoted much of his research on the landlocked salmon (småblank) in River Namsen and River Mellingselva. It is especially our research collaboration on the småblank population in Upper Namsen that brought us together, where we mapped the status and distribution of småblank, as well as its unique genetical  and habitat use. Småblank was a natural study subject since Ole Kristian's father, Magnus Berg, was the first to describe the special salmon variant only found in the upper parts of the Namsen watercourse. Ole Kristian was very keen on preserving the original name of the landlocked salmon in Namsen, and it was therefore a great academic victory when "småblank" finally became the official nomenclature a few years back. Although småblank had a special place in his heart, there were many other areas of research that Ole Kristian worked on. Already in the 1980s, he focused on juvenile salmon that resided in atypical habitats, and together with graduate students, investigations were made in lakes on the west coast and in Namdalen, before later focusing on deeper lotic habitats in rivers in Nordmøre and Trøndelag. Ole Kristian was a pioneer in using modern analytical methods and was the first in Norway to conduct energetic analyses of juvenile salmonids in rivers such as River Homla and River Stjørdalselva. Many Norwegian fish researchers became interested in fish biology after Ole Kristian's lectures, and the number of students who have had him as a supervisor has gradually become extensive. In terms of personal qualities, we will especially highlight his good humor, infectious laughter, and unyielding optimism, and that he was very caring and generous towards his students and colleagues. His many antics during festive events at Rosenborg and the Natural Science Building are still being talked about, and we will never forget his performances with specially made dentures and glasses with special lenses. Ole Kristian will be deeply missed as a professional, colleague, and friend - and we will forever keep the memory of him in our hearts.

Ole's Most Cited Papers