Sadly this is the tenth and last in my series of the ten papers that had a great influence on my life as an ecologist. I’m going to cheat somewhat and actually discuss three papers. In my defence they are extremely closely linked and I am pretty certain that in today’s publishing world they would all have had to have been combined anyway. That aside, I really liked this experiment the first time I read about it and still rate it very highly. I would, however, love to be able to travel back in time and give them a couple of hints with the benefit of hind-sight, although as the authors are two of the greatest living ecologists, Dan Simberloff and E O Wilson, I might be a bit apprehensive doing so 🙂 In any case, much of what I would have said was addressed a few years later (Simberloff, 1976).
Wilson and Simberloff wanted to practically test the island biogeography theory famously described by McArthur and Wilson a few year earlier (MacArthur & Wilson, 1967). To do this they travelled to the Florida Keys and after due reconnaissance decided that the many mangrove “tree islands” would be ideal study sites (Figure 1). Then came the really cool bit.
Figure 1. Two of the experimental ‘islands’ from Wilson & Simberloff (1969)
They set about removing the arthropod animal life from nine of the islands (Figure 2), or as much as they could, by fogging with methyl bromide; not something we could do now. They then monitored the islands at frequent intervals for the next year. They had of course surveyed the islands before they fumigated them.
Figure 2. What a cool project; defaunation in progress – from Wilson & Simberloff (1969)
Figure 3. Island equilibria – from Simberloff & Wilson (1970)
The major finding from their study was that recolonization happened quite quickly and that a year later had pretty much reached an equilibrium position (Figure 3). Another important finding and one that has important implications for restoration and conservation strategies was that two years after the defaunation event, although the islands were well populated, the species composition, except for one island was less than 40% similar to the original inhabitants (Simberloff & Wilson (1970). Most species present were new to those islands. The analysis of the data presented in the two data papers is rather basic, some of the key island biogeographical premises are not addressed at all and I wondered why they had not done so. Their data are all shown in some detail so it is possible to do some more analysis, which I took the liberty of doing. The extra analysis shows why they did not discuss area effects per se . The only significant relationship that I could find was that between the number of species and the distance from the ‘mainland’ source (Figure 4), which as predicted by MacArthur & Wilson (1967) was negative. Sadly, island size did not correlate with species number (Figure5). Finally, there was a positive, but not significant relationship between the initial number of species found on an island and the number a year later (Figure 6).
Figure 4. Relationship between distance from ‘mainland’ source and the number of arthropod species present (R2 = 0.65, P <.0.05) Data from Simberloff & Wilson (1970).
Figure 5. Island diameter and number of arthropod species (not statistically significant, r2 = 0.19, although I am sure many politicians would view this as a positive trend). Data from Simberloff & Wilson (1970)
Figure 6. Initial number of species on an island and number of species present one year later. Although it looks convincing (r2 = 0.54), there are too few observations to reach statistical significance. Data from Simberloff & Wilson (1970)
Although this work was extremely influential, (my Bracknell roundabouts study owes a lot to it), there were two major flaws in the original experimental design. Firstly the number of islands was very low, but of course this is understandable, given the effort and complex logistics required to remove the arthropods safely (Figure 2). The other flaw was that the islands did not cover a large enough range of sizes, thus making it less likely for the species-area pattern to be detected which was a great shame.
As I mentioned earlier, these short-comings were not ignored by the authors, and a few years later Sinberloff (1976) reported the results of an enhanced study, again in the Florida Keys, where he was able to convincingly demonstrate the species-area effect. I guess that this was pretty satisfying as it tied up a number of loose strings. He also managed to get the phrase “flogging a dead horse” into his introduction 🙂
Of the three papers, Simberloff & Wilson (1969) is the most highly cited (according to Google Scholar, 618 to date) and became a “citation classic”* in 1984 at which time it had accumulated 164 citations. Simberloff & Wilson (1970) has attracted 252 cites with Wilson & Simberloff (1969) trailing in third with a mere 158 cites. As a point of interest, Simberloff (1976) has so far received 313 cites. To reiterate, the original mangrove island study, despite its flaws was a fantastic piece of work and Sinberloff and Wilson won the Mercer Award of the Ecological Society of America for this work in 1971.
I can think of no better person to explain why Simberloff & Wilson (1969) deserves its place in the Ecological Hall of Fame than Simberloff himself who in the commentary to the 1984 citation classic article wrote “I think the main reason it is cited, however, and its lasting contribution, is not so much that it supports the [equilibrium] theory, as that it reported a field experiment on ecological communities, and thus seemed dramatically different from the correlative approach that dominated this field”
MacArthur, R.H. & Wilson, E.O. (1967) The Theory of Island Biogeography Princeton University Press, Princeton.
Simberloff, D. (1976) Experimental zoogeography of islands: effects of island size. Ecology, 57, 629-648.
Simberloff, D. & Wilson, E.O. (1969) Experimental zoogeography of islands: the colonization of empty islands. Ecology, 50, 278-296.
Simberloff, D. & Wilson, E.O. (1970) Experimental zoogeography of islands: a two-year record of colonization. Ecology, 51, 934-937.
Wilson, E.O. & Simberloff, D. (1969) Experimental zoogeography of islands: defaunation and monitoring techniques. Ecology, 51, 267-278.
*Those of you who remember Current Contents will know what this means and here is the actual commentary.
“This is Simon Leather, he’s an ecologist, albeit an applied one” Thus was I introduced to a group of visiting ecologists by my then head of department at the Silwood Park campus of Imperial College. As you can imagine I was somewhat taken aback at this public display of the bias that ‘pure’ scientists have against those that they regard as ‘applied’. I was (and still am), used to this attitude, as even as an undergraduate doing Agricultural Zoology when we shared modules with the ‘pure’ zoologists, we were regarded as a slightly lower life form J Working in Finland as a post-doc in the early 1980s it was also obvious that there was a certain degree of friction between the pure and applied entomologists, so it was not a phenomenon confined entirely to the UK. To this day, convincing ecology undergraduates that integrated pest management is a suitable career for them is almost impossible.
I was an ecologically minded entomologist from early childhood, pinning and collecting did not interest me anywhere near as much as insect behaviour and ecology, but I knew that I wanted to do something “useful” when I grew up. Having seen my father in action as a plant pathologist and crop protection officer, it seemed to me that combining entomology with agriculture would be an ideal way to achieve this ambition. A degree in Agricultural Zoology at Leeds and a PhD in cereal aphid ecology at the University of East Anglia (Norwich) was the ideal foundation for my chosen career as an applied ecologist/entomologist.
I started my professional life as agricultural entomologist working both in the laboratory and in the field (cereal fields to be exact), which were easily accessible, generally flat, weed free and easy to manipulate and sample. In the UK even the largest fields tend to be visible from end to end and side to side when you stand in the middle or edge (even more so now than when I started as wheat varieties are now so much shorter, less than half the height they were in 1977).
Having fun as a PhD student – aphid ‘sampling’ in Norfolk 1978
I haven’t grown since I did my PhD so wheat must have shrunk 🙂
See the post script to see what wheat used to look like.
Laboratory experiments, even when working on mature plants were totally do-able in walk-in growth rooms, and at a push you could even fit whole earing wheat plants into a growth cabinet.
I then spent ten years working as a forest entomologist, where field sites were the exact opposite, and extreme measures were sometimes required to reach my study animals, including going on an official Forestry Commission tree climbing course.
Pole pruners – (of only limited use) and tree climbing (great fun but laborious)
Scaffold towers for really high work, but expensive (and scary on sloping hillsides).
And as for lab work, not a chance of using mature plants or even plants more than two to three years old. Excised branches and/or foliage (rightly or wrongly) were the norm*.
Doing field work was, despite the sometimes very physically challenging aspects, a lot of fun, and in my case, some very scenic locations. My two main field sites were The Spey Valley and
Sutherland and Caithness, both of which provided magnificent views and of course, a plethora of whisky distilleries
where I discovered what is now my favourite single malt 🙂
The real fun came when it was time to submit papers. Journal choice was (and is) very important. As Stephen Heard points out, journals have a ‘culture’ and it is very important to pick a journal that has the right editorial board and ethos. The laboratory work never seemed to be a huge problem, referees (perhaps wrongly) very rarely criticised the use of young plants or excised foliage. I was able to publish the output from what was a very applied project, in a range of journals from the very specialised to the more ecological. This selection for example, from 1985-1987 (Leather, 1985, 1986; Leather & Burnand, 1987; Leather et al., 1985), appeared in Ecological Entomology, Oecologia, Functional Ecology and Bulletin of Entomological Research respectively.
Papers reporting field-based work were a little bit harder to place in journals outside the mainstream forestry ones, particularly when it came to experimental work. One of the problems was that ecological referees unused to working in forests tended not to have a grasp of what was involved in setting up and servicing an experiment in a forest plantation or stand. A farmer has no great objection to an entomologist removing 100 wheat tillers a week from his 2 ha field (at 90 stems per metre2, even a 16 week field season would only remove a tiny fraction of his crop). A forest manager on the other hand with a stocking density of 3000 stems per hectare would look askance at a proposal to remove even 100 trees a month from a hectare plot, especially if this was repeated for seven years. Sample size was thus a problem, even when using partial sampling of trees, e.g. by removing say only one branch. When it came to field scale replication, to compare for example, three treatments and a control on two different soil types, where each treatment plot is a hectare, things get a bit difficult. The most that we could service, even with help (since we did not have huge financial resources), was three replicates of each treatment. In agricultural terms this seems incredibly low, where 10m2 plots or even smaller, are very often used (e.g. Staley et al., 2009; Garratt et al., 2011).
We thus ended up with our experimental papers in the really specialised forestry journals (e.g. Leather, 1993; Hicks et al., 2007). On the other hand, those papers based on observational, long-term data were easier to place in more general ecological journals (e.g. Watt et al., 1989), although that was not always enough to guarantee success (e.g. Walsh et al., 1993; Watt et al., 1991). Another bias that I came across (perhaps unconscious) was that referees appeared, and still do, think that work from production forests is not as valid as that coming from ‘natural’ forests, especially if they are tropical. We came across this when submitting a paper about the effects of prescribed burning on carabid populations in two sites in Portugal (Nunes et al., 2006). We originally sent this to a well-known ecological journal who rejected it on the grounds of low replication, although we had also replicated it temporarily as well as geographically. I was not impressed to see a paper published in this journal shortly after they had rejected our manuscript in which the authors had reported changes in insect communities after a one-off fire event in a tropical forest, without even the benefits of pre-fire baseline data. We had in the meantime, given up on general ecology journals and submitted our paper to a local forestry journal. Such is life.
I originally started this essay with the idea of bemoaning the fact that publishing studies based in production forests in more general journals was more difficult than publishing agriculturally based papers, but got diverted into writing about the way applied ecologists feel discriminated against by journals and pure ecologists. I may or may not have convinced you about that. To return to my original idea of it being more difficult for forestry–based ecologists to break out of the forestry journal ghetto than it is for agro-ecologists to reach a broader audience, I present the following data based on my own publication record, which very convincingly demonstrates that my original feeling is based on fact, albeit based on an n of one 🙂
Numbers of agricultural and forestry based papers published by me in different journal categories.
I might also add that being an entomologist also limits where you can publish, so being an applied entomologist is something of a double whammy, and when it comes to getting research council funding, don’t get me started!
Hicks, B.J., Aegerter, J.N., Leather, S.R., & Watt, A.D. (2007) Differential rates of parasitism of the pine beauty moth (Panolis flammea) depends on host tree species. Scottish Forestry, 61, 5-10.
Leather, S.R. (1985) Oviposition preferences in relation to larval growth rates and survival in the pine beauty moth, Panolis flammea. Ecological Entomology, 10, 213-217.
Leather, S.R. (1986) The effect of neonatal starvation on the growth, development and survival of larvae of the pine beauty moth Panolis flammea. Oecologia, 71, 90-93.
Leather, S.R. (1993) Influence of site factor modification on the population development of the pine beauty moth (Panolis flammea) in a Scottish lodgepole pine (Pinus contorta) plantation. Forest Ecology & Management, 59, 207-223.
Leather, S.R. & Burnand, A.C. (1987) Factors affecting life-history parameters of the pine beauty moth, Panolis flammea (D&S): the hidden costs of reproduction. Functional Ecology, 1, 331-338.
Leather, S.R., Watt , A.D., & Barbour, D.A. (1985) The effect of host plant and delayed mating on the fecundity and lifespanof the pine beauty moth, Panolis flammea (Denis & Schiffermuller) (Lepidoptera: Noctuidae): their influence on population dynamics and relevance to pest management. Bulletin of entomological Research, 75, 641-651.
Nunes, L.F., Silva, I., Pité, M., Rego, F.C., Leather, S.R., & Serrano, A. (2006) Carabid (Coleoptera) community change following prescribed burning and the potential use of carabids as indicator species to evaluate the effects of fire management in Mediterranean regions. Silva Lusitania, 14, 85-100.
Staley, J.T., Stewart-Jones, A., Pope, T.W., Wright, D.J., Leather, S.R., Hadley, P., Rossiter, J.T., Van Emden, H.F., & Poppy, G.M. (2010) Varying responses of insect herbivores to altered plant chemistry under organic and conventional treatments. Proceedings of the Royal Society of London B, 277, 779-786.
Walsh, P.J., Day, K.R., Leather, S.R., & Smith, A.J. (1993) The influence of soil type and pine species on the carabid community of a plantation forest with a history of pine beauty moth infestation. Forestry, 66, 135-146.
Watt, A.D., Leather, S.R., & Stoakley, J.T. (1989) Site susceptibility, population development and dispersal of the pine beauty moth in a lodgepole pine forest in northern Scotland. Journal of Applied Ecology, 26, 147-157.
The height of mature wheat and other cereals has decreased hugely over the last two hundred years. Cereals were originally a multi-purpose crop, not just providing grain for humans, but bedding straw for stock and humans, winter fodder for animals, straw for thatching and if really desperate, you could make winter fuel out of discarded straw**.
John Linnell – Wheat 1860 You wouldn’t have been able to see Poldark’s (Aidan Turner) manly chest whilst he was scything in this field!
Pieter Breugel the Elder – Die Kornernter – The Harvesters (1565) – Head-high wheat crops and not just because the average height was lower in those days.
*As I was writing this article I came across this paper (Friberg & Wiklund, 2016) which suggests that using excised plants may be justifiable. Friberg, M. & Wiklund, C. (2016) Butterflies and plants: preference/performance studies in relation to plant size and the use of intact plants vs. cuttings. Entomologia experimentalis et applicata, 160, 201-208
**My source for this is Laura Ingalls Wilder – Little House on the Prairie, to be exact 🙂
In the space of a week I came across three items that made me despair even more than I normally do for the healthy future of our planet. Coincidentally I was reading Neal Stephenson’s novel Seveneves, which is also about the environmental destruction of the Earth as we know it, albeit by an external disaster and not by our own efforts. In his novel, the World’s leaders come together to save some of humanity and the planet’s genetic resources, and not destroy it as we seem hellbent on doing.
Browsing in a local supermarket I came across what was to me, a new phenomenon, so-called Smartwater!
This is an example of how the fetish/obsession for bottled water has gone way over the top
Step 1 – find a natural spring
Step 2 – extract the water
Step 3 – distil the water to remove the natural ‘impurities’ (sodium, calcium carbonates etc. which are electrolytes) by steam distillation (requires energy, probably from non-renewable sources)
Step 4 – put back the minerals (electrolytes) that were removed by the distillation process
Step 5 – bottle in plastic (not glass) bottles
Step 6 – sell at inflated prices to mugs
What is wrong with tap water folks? 😦 If as some feel, that the tap water has a strong taste of chlorine, leave it overnight before using it.
The belief by some commentators and members of the UK electorate, that the European Union has environmental policies designed to thwart business rather than protecting the environment.
Not a beautiful morning, rather a sign writ large upon the sky, of how much environmental harm we are doing to the planet.
Rather than expanding runways and airports to encourage growth in air-traffic and the use of fossil fuels, we should be thinking of ways to cut it and reduce our carbon footprint. Cat Stevens was thinking about this very issue in 1971 in his fantastic song “Where do the Children Play?”
“Well you roll on roads over fresh green grass.
For your lorry loads pumping petrol gas.
And you make them long, and you make them tough.
But they just go on and on, and it seems that you can’t get off.
Oh, I know we’ve come a long way,
We’re changing day to day,
But tell me, where do the children play?”
On the plus side some nations seem to be taking a more responsible approach to the exploitation of finite resources. I am happy to say France, the location of our future retirement home, is leading the way in reducing the use of plastics. They are also way ahead of us in encouraging the use of solar energy by homeowners.
We are now officially in the Anthropocene Age which is probably not a good thing. It seems an appropriate moment to reflect on what we can do to halt, or at the very least, slow down, what seems to be an unstoppable race to extinction of most of the natural world. We all know what the principal causes are despite the obfuscation and prevarication that surrounds the debate. Equally, we are also aware of the mainly political and economic pressures that are preventing us from doing something to ease the pain and suffering we are inflicting on the world. I am not going to rehearse the arguments, but instead I will let the following speak to us all about why we need to keep and enhance what nature we have remaining.
“Though large herds of deer do much harm to the neighbourhood, yet the injury to the morals of the people is of more moment than the loss of their crops. The temptation is irresistible; for most men are sportsmen by constitution: and there is such an inherent spirit for hunting in human nature, as scarce any inhibitions can restrain” Gilbert White (1788)
They should know better – mind boggling and shocking
“Really I did deserve a chastisement for my intrusion into the meadow, the disastrous consequences of which I now had power to perceive to the full extent. I had bruised the tender stalks of springing grass, broken quantities of buds, and destroyed myriads of living creatures. In my stupid simplicity I had never had any suspicion of the pain I caused while perpetrating these evil deeds, and had been in a state of delight at the profound peace pervading the country, and the charms of solitude” E van Bruyssel (1870)
“We can never afford to lose sight of past and present human activities in their effects on the vegetation of countries which have been long inhabited and densely populated, like those of Western and Central Europe” A G Tansley (1923)
“On the favourable side of the balance, I think that I am superior to the common run of men in noticing things which escape attention, and in observing them carefully. My industry has been great as it could have been in the observation and collection of facts. What is far more important, my love of natural science has been steady and ardent” Charles Darwin (1929*)
“We have tried to conquer nature by force and by intellect. It now remains for us to try the way of love It is impossible to use the full resources of the soil except with a mixture of plants (either grown together as in pasture or mixed crops grown in succession as a in a proper rotation of crops). In monoculture it is impossible to keep disease at bay for long, and in addition it is impossible to feed animals properly except on a varied mixture” Lord Northbourne (1940)
“The soil is among Nature’s greatest marvels. A clod of earth, seeming simple and lifeless, is now known to be highly complex in structure, its particles most elaborate in their composition, with numerous invisible crevices inhabited by prodigious numbers of living organisms inconceivably small, leading lives of which we can from only the haziest conception, yet somehow linked up with our lives in that they produce the food of plants which constitute our food, and remove from the soil, substances that would be harmful to us” Sir John Russell (1957)
“Over increasingly large areas of the United States, spring now comes unheralded by the return of the birds, and the early mornings are strangely silent where once they were filled with the beauty of bird song” Rachel Carson (1962)
“I believe the strongest argument for keeping as much of the natural world as possible in the anthrosphere lies in the human need for variety, individuality, and the challenge of endeavouring to understand the nonhuman world. I believe, too, that emersion in the world of trees, flower, and wild creatures is needed to nourish human attributes now in short supply: awe, compassion, reflectiveness, the brotherhood we often talk about but rarely practice except on the most superficial of levels” Howard Ensign Evans (1966)
“I have heard it said more than once that the reason why there are more wire-worms afflicting the crops than in the past is that there are more tractors. The idea being that since the tractor-driven plough turns over three or four furrows at a time as against the horse-plough’s one furrow, the results is that birds get far fewer troughs in which to find worms, Thus more worms are left in the soil. It is an attractive theory, there is something cheering in the knowledge that Nature always hits back. Everything in nature has a meaning and a purpose. Everything is necessary to the universal scheme, every germ, every microbe, every pest. When anything ceases to serve the harmony it dies out” John Stewart Collis (1973)
“Humanity now co-opts something in the order of one-twentieth of all the photosynthesis – the primal driving process of life on the planet – for its own uses. And through its activities, Homo sapiens now threatens to alter the basic climatic patterns of the globe” Paul & Anne Ehrlich (1981)
“The rescue of biological diversity can only be achieved by a skillful blend of science, capital investment, and government: science to blaze the path by research and development; capital investment to create sustainable markets: and government to promote the marriage of economic growth and conservation” Edward Wilson (1992)
“Despite what developers will tell you about restoration, she said, once a piece of land is graded, the biologic organisms and understructure of the soil are destroyed. No one knows how to really re-create that, short of years of hand-weeding. Leaving land doesn’t work; the natives are overwhelmed by the invaders” Richard Louw (2005)
“Eventually some truth dawned: nature conservation is essentially concerned with mending the relationship between people and Nature, and is an expression of love for, and an interaction with, the beauty and wonder of the natural world, and with belonging in Nature” Matthew Oates (2015)
“Evidence shows that loss of interactions with nature changes people’ s attitudes toward nature, including the values they place on it, their beliefs concerning the environment, their perceived norms of environmental ethics, and their willingness to protect nature” Soga & Gaston (2016)
I could go on, and on, but I think you get the picture. We could have done so much so earlier.
Please share your favourite passages, be they gloomy or optimistic, by adding them to the comments.
Carson, R. (1962) Silent Spring, Houghton Mifflin, USA.
Collis, J.S. (1973) The Worm Forgives the Plough. Penguin Books
Darwin, C. (1929) Autobiography of Charles Darwin, Watts & Co., London (
Ehrlich, P. & Ehrlich, A. (1981) Extinction, Random House, New York.
Evans, H.E. (1966) Life on a Little-Known Planet, University of Chicago Press, USA.
Louw, R. (2005) Last Child in the Woods, Atlantic Books, London.
Northbourne, W.J. (1940) Look to the Land, J.M. Dent & Sons.
Oates, M. (2015) In Pursuit of Butterflies: A Fifty-Year Affair, Bloomsbury, London.
Russell, Sir, E.J. (1957) The World of the Soil, Collins, London.
Soga, M. & Gaston, K.J. (2016) Extinction of experience: the loss of human–nature interactions. Frontiers in Ecology and the Environment, 14, 94-101
Tanlsey, A.G. (1923) Introduction to Plant Ecology, George Allen & Unwin Ltd.
Van Bruyssel, E. (1870) The Population of an Old Pear Tree, MacMillan & Co. London
White, G. (1788) The Natural History of Selborne, Penguin Edition 1977.
Wilson, E.O. (1992) The Diversity of Life, The Belknap Press of Harvard University Press, USA.
Last year I wrote about my experience of being a tutor at the British Ecological Society’s Undergraduate Summer School at the Malham Tarn Field Studies Council site. I really enjoyed myself and also found it very refreshing to have the opportunity to interact with 50 bright young proto-ecologists. It appears that the students also enjoyed themselves as I was invited back this year to repeat my performance. I was very happy to accept the offer, after all, any chance to visit the county of my birth (Yorkshire) is not to be sneezed at and with the added bonus of being able to talk about entomology to a new audience thrown in I would have been made to turn it down. Thus it was that I headed up the dreaded M6 motorway on a sunny Monday afternoon (July 18th) with joy in my heart and a car boot full of entomological equipment and identification keys. The M6 did not disappoint and I spent an hour sweltering in the summer sunshine very slowly (very, very slowly) making my way through the inevitable road works. Luckily, being one of those people who likes to arrive early for appointments, I was only fifteen minutes late collecting my trusty assistant, Fran Sconce, from the very picturesque Settle Station and then heading up on to the FSC Malham Tarn site.
The weather on arrival was in marked contrast to last year.
We unloaded the car and just had time to set up 35 pitfall traps before heading in for the evening meal after which the students went on a long walk to Malham Cove.
The long walk
I walked part of the way back with them but turned back in time to get to the bar 🙂 for a very welcome drink, before retiring to bed.
The next day was even hotter, and we spent the morning setting up the labs and teaching areas.
This year, as well as the fifty undergraduates we had ten sixth form students from several different schools in London. Last year interacting with a class of fifty had posed certain difficulties, so this year we divided the students into two groups and ran the session twice, once on the Tuesday afternoon and then again on the Wednesday morning. This worked extremely well and meant that Fran and I and the PhD mentors assigned to us, were able to spend much more time with each student and also meant that we were not as rushed off our feet as we would have been otherwise. So a win/win outcome, although I did have to give the same lecture twice in 24 hours which was an interesting experience. On the Tuesday afternoon, I started with my lecture on why entomology is important and an overview of the insects.
I seem to have done a lot of arm waving
We then went outside and I demonstrated sampling methods while the students baked under, a by now, extremely hot sun, before sending them off to empty and reset the pitfall traps and collect other insects using nets and beating trays.
Being cruel to trees
Some of the stars of the day
Then it was back to the labs to identify the catches before the evening meal and refreshing drink or two in the bar*. After the bar closed we had the fluorescent beetle extravaganza. Last year I demonstrated the use of fluorescent dust on one hapless carabid beetle. This year I used ten, and two different coloured dusts. The beetles were then released after dark in
the courtyard outside the teaching labs where they were photographed fluorescing colourfully under my UV flashlight, as I ‘chased’ them around the arena, much to the delight of the watching students.
As the weather forecast was not very good for the Wednesday morning, we did the insect sampling first, in case the forecast rain was as heavy as predicted. As it turned out, apart from a short sharp shower, whilst I was demonstrating sampling methods, the sun came out and there were plenty of insects to collect before I did my lecture and we headed in to the labs for another ID session. All too soon the session was over, and Fran and I, after a hasty lunch, drove back down to Shropshire.
I think that the BES summer school is a superb idea and that the students get a great deal from it. I thoroughly enjoyed it and hope that I get the chance to be involved in any future summer schools. I was also greatly impressed by the 6th formers who certainly seemed to enjoy my entomology session, one of whom produced this excellent drawing.
Much better than anything I could draw
For those of you on Twitter #bestug16 will give you a flavour of the whole week.
*staffed that evening by the son of my best friend from school!
Solomon, M. E. (1949). The natural control of animal populations. Journal of Animal Ecology, 18, 1-35.*
According to Google Scholar there are 1149 (only 773 in 2013)citations to this paper, an average of 17.1 citations per year, compared with the 12.5 I reported back in 2013. Although influential, it had a slow start, only 383 citations being recorded for it between 1949 and 1993. Since 2000 it has averaged about 48 citations a year (760 in total), 225 of those since 2013.** To the modern reader this paper comes across as wordy and discursive, more like a popular article than a scientific paper. This does not, however, mean that the science and the man behind the article were not first class. Journals had less pressure on their space in those days and scientists had more time to think and read. If only it were so now. Despite the relatively low number of citations, this paper has had an immense influence on the study of population dynamics, although I will have to confess, that for my generation who were undergraduates in the 1970s, Solomon’s little Study in Biology*** book, Population Dynamics, published in 1969, was our main, if not only, encounter with his work.
Making sure that nobody could claim my copy of Population Dynamics
Here Solomon introduces the term functional as in a density related response
Nowadays we remember the paper as the first one to formalise the term ‘functional response’ although the early citations to this paper are in reference to density dependence, competition, population regulation and population variability e.g. (Elton 1949; Glen 1954; Southwick 1955; Bakker 1963). Interestingly, one of the earlier papers to cite Solomon, (Burnett 1951) presented functional response curves but did not mention the term (Watt (1959)). To add further insult to injury, Holling (1959) in the same year, in his classic paper in which he described and numbered the types of functional responses did not even refer to Solomon, rather deferring to Watt’s paper (loc. cit.). Since then, with the likes of Varley, Gradwell and Hassell (1973) and luminaries such as Bob May (May 1978), this paper has been cited often, and justifiably, and continues to influence us to this day, including the author of this eulogy (Aqueel & Leather 2012). This paper as well as being the first one to formalise the term ‘functional response’ was the first attempt to draw together the disparate conceptual strands of the first half of the twentieth century work on population dynamics in one coherent whole. Truly, a remarkable and very influential paper.
Aqueel, M. A., & Leather, S. R. (2012) Nitrogen fertiliser affects the functional response and prey consumption of Harmonia axyridis (Coleoptera: Coccinellidae) feeding on cereal aphids. Annals of Applied Biology, 160, 6-15.
A few months ago I was privileged to be given Robert Tillyard’s excellent The Insects of Australia and New Zealand (first published in 1926), by a former colleague of mine.
What made this even more special was that it had originally belonged to the great Maurice Solomon when he was a student, and contained some of his original annotations and revision notes.
*This is an expanded and updated version of the article I wrote as part of the British Ecological Society’s Centenary celebrations in 2013
**It is probably wishful thinking, but I might be tempted to think that by writing about this influential but somewhat overlooked paper, I increased the number of citations, so had a positive influence 🙂
***The Studies in Biology series, published by the then Institute of Biology (Now Royal Society of Biology), were excellent little books and the series on plant physiology were the main reason that I passed my first year plant physiology module as an undergraduate at Leeds University. I am reliably informed that there are plans to revive the series next year.
I think, that most, if not all entomologists, will confess to a bit of funding envy when talking with those of their colleagues who work with the “undeserving 3%”, the large charismatic mega-fauna and the modern dinosaurs. The terminology gives us away, although the evidence is overwhelmingly on our side (Leather, 2009). As entomologists, particularly those of us working in the field, we are used to reporting numbers collected in the tens of thousands (Ramsden et al., 2014 ), if not the hundreds of thousands (Missa et al., 2009) and even a short six-week study can result in the capture of thousands of ground beetles (Fuller, et al., 2008). Naming our subjects, much as we love them, is not an option, even if we wanted to. Even behavioural entomologists counting individual flower visits by pollinators are used to dealing with hundreds of individuals. In the laboratory, although numbers may be smaller, say tens, we still assign them alphanumeric codes rather than names, even though one might look forward to counting the number of eggs laid by the unusually fecund moth #17 or hope that aphid #23 will be dead this morning as she is becoming a pesky outlier for your mortality data 🙂
Our colleagues who work with mammals in the field, seem however to adopt a different strategy. It appears quite common for them to name their animals as the following examples from Twitter make clear.
Published data in McGraw et al., (2016) are from another study where the animals are not named.
Anthropomorphic judgement values
Anne being very involved with her cheetahs, although the paper (Hillborn et al., 2012) does not mention them by name.
Another example of subjects with names Hubel et al., 2016), but this time named in the paper.
Although in the description of methodology and results animals are referred to as subjects, the Table gives it away! (Allritz et al., 2016).
Another example of named subjects (Stoinski et al., 2003).
More named subjects (Dettmer & Fragaszy, 2000), but as these were captive the names almost certainly not chosen by the observers.
In this case (Blake et al., 2016), use no human-based names either in the methods or tables, so exemplary, although of course I have not seen their field note books 🙂
My concern, highlighted by these examples, is that by naming their study animals, the observers are anthropomorphising them and that this may lead them to inadvertently bias their observations. After all, the names have not been chosen at random, and thus could influence the behaviours noted (or ignored). I say ignored, because of two very specific examples, there are more, but I have these two to hand.
Victorians used birds as examples of good moral behaviour, erroneously believing them to be monogamous, probably because of seeing the way they fed their chicks cooperatively. Tim Birkhead (2000)* quotes the Reverend Frederick Morris who in 1853 preached “Be thou like the dunnock – the male and female impeccably faithful to each other,” and goes on to point out that despite a hundred years of ornithological science it was not until the late 1960s that the promiscuous behaviour of female birds was revealed, interestingly enough coinciding with the new moral code of the 1960s.
Descriptions of penguin homosexual behaviour and their penchant for acts of necrophilia so shocked George Levick’s publishers that they removed them from his 1915 report but printed them and privately distributed them to selected parties marked as “Not for Publication” (Russell et al., 2012). He also transcribed his descriptions of this ‘aberrant’ behaviour in Greek in his notebooks, presumably to make it less accessible.
AND NOW SOMETHING NEW for my blog, an embedded comment/riposte. I thought that it would be useful to get a response from someone who works on large charismatic mega-fauna and who names their subjects. Anne Hilborn, whom many of you will know from Twitter as @AnneWHilborn, has kindly agreed to reply to my comments. In the spirit of revealing any possible conflicts of interest I should say that I taught Anne when she was an Ecology MSc student at Silwood Park 🙂
Over to you Anne…..
“Hello, my name is Anne and I name my study animals.”
Decades ago this might have gotten me jeered out of science, the assumption being that by naming my study animals I was anthropomorphizing them and that any conclusions I drew about their behavior would be suspect. Thankfully we (at least those of us who have the privilege of working on megafauna) have moved on a bit in our thinking and our ways of doing science.
There are two parts to Simon’s concern about naming study animals. One is that naming leads to anthropomorphization, the second is that the anthropomorphizing leads to biased science. I would argue that the naming of study animals doesn’t necessarily increase anthropomorphism. On the Serengeti Cheetah Project we don’t name cheetahs until they are independent from their mother (due to a high mortality rate). During my PhD fieldwork I spent a lot of time following a young male known as HON752MC (son of Strudel). Several months after I started my work he was named Boke. My interest in his behavior, my chagrin at his failures and happiness when he had a full belly didn’t change when he was named. Many of us get emotionally attached on some level to our study animals, whether they have names or numbers.
An interesting thing to ponder is that if naming does lead to anthropomorphizing, does it only happen when human names are used? What human characteristics am I likely to attach to cheetahs named Peanut, Muscat, Strudel, Fusili, or Chickpea?
As to whether anthropomorphism leads to biased science… it definitely can if, as Simon points out, certain behaviors are not recorded because they do not fit the image of the animal the researcher had in their head. I don’t have any data on this, but I suspect this is extremely rare now days. Almost all researchers have had extensive formal training and know the importance of standardized data collection. I study cheetah hunting behavior, and I record how long a cheetahs spends spend stalking, chasing, killing, and eating their prey. I record the number of animals in the herd they targeted, how many second the cheetah spends eating vs being vigilant, and at what time they leave the carcass. No matter my personal feelings or attachments to an individual cheetah, the same data gets recorded.
Research methods have advanced a lot in the past decades and we use standardized methodologies and statistics expressly to prevent bias in our results. Anthropomorphism is just one possible source of bias, others include wanting to prove a treasured hypothesis, the tendency to place plots in areas where you suspect you will get the best results, etc..
As Adriana Lowe (@adriana_lowe ) puts it “Basically, if you’ve got a good study design and do appropriate stats, you can romanticise the furry little buggers until the cows come home and it won’t have a massive effect on your work. Any over interpretation of results would get called out by reviewers when you try to publish anyway.”
Simon points out examples of people being shocked when birds didn’t follow the dictates of contemporary human morality. I would like to think that biologists no longer place human values on animals. I can admire hyenas because the females are bigger bodied and socially dominant to males, but that doesn’t mean I draw parallels or lessons from them to human society (not in the least because the females give birth through their elongated clitoris and the cubs practice siblicide). As scientists we are capable of compartmentalizing, of caring deeply for our subjects, of shedding a tear when Asti turns up with one cub when previously she had five, without that changing the way we record data. In our training as biologists, we are taught not impose our own feelings or values on our study animals. We may find infanticide in lions (Packer and Pusey 1983), extra pair copulations in birds and primates (Sheldon 1994, Reichard 1995), or siblicide in boobies (Anderson 1990) to be repugnant, but we record, analyze, and try to publish on the phenomenon all the same.
To go on the offensive, there are ways naming study animals actually improves data collection.
Again, Adriana Lowe “If you’re doing scan sampling for instance, so writing down all individuals in a certain area every 10 minutes or so, names help. At least for me, it’s harder to remember if someone is M1 or M2 than Janet or Bob, particularly if you have a big study troop/community. So it can improve the quality of the data collected if you’re less likely to make identification errors.”
Because of our own training and peer review, assigning emotions or speculating about the intent on animals rarely makes it into scientific papers. However the situation is very different for those of us who wish to present our results outside of the ivory tower. While fellow scientists might be willing to wade through dry descriptions about how M43 contact called 3 times in 4 minutes when he was no longer in visual contact with M44, the public is not. Effective science communication needs a story and an emotional hook to draw people in. It is much easier to do that when you tell a story about Bradley and Cooper and not M43 and M44. I will admit this does get into grey areas with the type of language we use outside of scientific papers. I tell stories about the cheetahs in my blog posts and even assign emotions to individuals. But if I am answering questions from the media or the public, I am still very careful not to make any definitive claims about behavior that haven’t been backed up by statistical analysis.
Here I use language and make assumption in tweets that I never would in a scientific paper.
There are a lot of issues that negatively affect the objectivity of science ie. the majority of funding going to well established entrenched researchers, papers being reviewed primarily by people from the same school of thought, the increasing pressure to have flashy results that generate headlines, but naming of study animals is not high on the list.
So now, over to you the readers, what do you think? Please comment and share your views or at the very least, please cast your vote.
Allritz, M., Call, J. & Borkenau, P. (2016) How chimpanzees (Pan troglodytes) perform in a modified emotional Stroop task. Animal Cognition, 19, 435-449.
Birkhead, T. (2000) Promiscuity: An Evolutionary History of Sperm Competition and Sexual Conflict. Faber, London.
Blake, J.G., Mosquera, D., Loiselle, B.A., Swing, K., Guerra, J. & Romo, D. (2016) Spatial and temporal activity patterns of ocelots Leopardus pardalis in lowland forest of eastern Ecuador. Journal of Mammalogy, 97, 455-463.
Fuller, R. J., Oliver, T. H. & Leather, S. R. (2008). Forest management effects on carabid beetle communities in coniferous and broadleaved forests: implications for conservation. Insect Conservation & Diversity1, 242-252.
Hillborn, A., Pettorelli, N., Orme, C.D.L. & Durant, S.M. (2012) Stalk and chase: how hunt stages affect hunting success in Serengeti cheetah. Animal Behaviour, 84, 701-706
Kühl, H.S., Kalan, A.K., Arandjelovic, M., Aubert, F., Dâ€™Auvergne, L., Goedmakers, A., Jones, S., Kehoe, L., Regnaut, S., Tickle, A., Ton, E., van Schijndel, J., Abwe, E.E., Angedakin, S., Agbor, A., Ayimisin, E.A., Bailey, E., Bessone, M., Bonnet, M., Brazolla, G., Buh, V.E., Chancellor, R., Cipoletta, C., Cohen, H., Corogenes, K., Coupland, C., Curran, B., Deschner, T., Dierks, K., Dieguez, P., Dilambaka, E., Diotoh, O., Dowd, D., Dunn, A., Eshuis, H., Fernandez, R., Ginath, Y., Hart, J., Hedwig, D., Ter Heegde, M., Hicks, T.C., Imong, I., Jeffery, K.J., Junker, J., Kadam, P., Kambi, M., Kienast, I., Kujirakwinja, D., Langergraber, K., Lapeyre, V., Lapuente, J., Lee, K., Leinert, V., Meier, A., Maretti, G., Marrocoli, S., Mbi, T.J., Mihindou, V., Moebius, Y., Morgan, D., Morgan, B., Mulindahabi, F., Murai, M., Niyigabae, P., Normand, E., Ntare, N., Ormsby, L.J., Piel, A., Pruetz, J., Rundus, A., Sanz, C., Sommer, V., Stewart, F., Tagg, N., Vanleeuwe, H., Vergnes, V., Willie, J., Wittig, R.M., Zuberbuehler, K., & Boesch, C. Chimpanzee accumulative stone throwing. Scientific Reports, 6, 22219.
Leather, S. R. (2009). Taxonomic chauvinism threatens the future of entomology. Biologist,56, 10-13.
McGraw, W.S., van Casteren, A., Kane, E., Geissler, E., Burrows, B. & Dsaegling, D.J. (2016) Feeding and oral processing behaviors of two colobine monkeys in Tai Forest, Ivory Coast. Journal of Human Evolution, in press.
Missa, O., Basset, Y., Alonso, A., Miller, S.E., Curletti, G., M., D.M., Eardley, C., Mansell, M.W., & Wagner, T. (2009) Monitoring arthropods in a tropical landscape: relative effects of sampling methods and habitat types on trap catches. Journal of Insect Conservation, 13, 103-118.
Ramsden, M.W., Menéndez, R., Leather, S.R., & Wakkers, F. (2014) Optimizing field margins for biocontrol services: the relative roles of aphid abundance, annual floral resource, and overwinter habitat in enhancing aphid natural enemies. Agriculture Ecosystems and Environment, 199, 94-104.
Stoinski, T.S., Hoff, M.P. & Maple, T.L. (2003) Proximity patterns of female western lowland gorillas (Gorilla gorilla gorilla) during the six months after parturition. American Journal of Primatology, 61, 61-72.
I said that entomologists don’t name their study animals but they do name their pets. Some of our PhD students had an African flower
Soulcleaver; despite his name he seems quite cute when viewed side-on, perhaps even with a cheeky grin, although as an entomologist I couldn’t possibly say that 🙂
*note that Tim Birkhead also falls into the very trap that he describes by using the word promiscuous in the title of his book, a human judgemental term relating to moral behaviour, multiple mating would have been more appropriate.
This week (20th July) I have had the privilege of being able to interact with 50 undergraduates (mainly just finished their first year) under the auspices of the British Ecological Society’s new undergraduate summer school held at the Field Studies Council’s Malham Tarn Centre. The scheme enables aspiring ecologists to have “an opportunity to enhance their existing knowledge with plenary lectures from senior ecologists, fieldwork, workshops, careers mentoring and more at a week-long residential course” This was especially pleasurable for me because as a school boy and student I spent several enjoyable camping holidays at Malham and it gave me an opportunity to take part in a field course again, something I have missed since leaving Silwood Park where I ran the now defunct annual two-week long Biodiversity & Conservation field course. The programme included two ecological luminaries and old friends of mine, Sue Hartley from the University of York and plant scientist and author, Ken Thompson formerly of Sheffield University and also Clare Trinder from the University of Aberdeen. Also in the programme was conservation biologist, Stephanie Januchowski-Hartley, and additional input from the Chartered Institute of Ecology & Environmental Management (CIEEM), microbial ecologist, Dr Rob Griffiths from CEH and ecologist Dr Peter Welsh of the National Trust.
I arrived mid-morning of the Tuesday, having driven up from Shropshire to Yorkshire the night before, having taken the opportunity to stay in the old family home in Kirk Hammerton before it is put up for sale. Whilst there I also set a few pitfall traps to collect some insects that we might not catch otherwise. As it happened they were a dismal failure, returning mainly spiders, harvestmen and woodlice, plus one nice carabid beetle, more of which later. The weather didn’t look all that promising for an insect sampling session but I kept my fingers crossed and hoped that it wouldn’t rain as much as it did almost 40 years ago when my best friend from school and I aborted our camping holiday at nearby Malham Cove after three days of solid rain 😉
Malham Tarn – not quite raining
I was greatly amused on arriving to be greeted by a very large arachnid lurking on an outhouse.
We breed them big in Yorkshire!
Malham Tarn Field Studies Centre
After checking my equipment and locating suitable sampling sites I joined the students, Karen Devine, the BES External Affairs manager and some of the PhD mentors for lunch. After lunch it was my slot, a chance to infect (sorry, inspire), fifty ecologically included undergraduates with a love of insects. After being introduced by Karen I launched into my talk to a very full room of students.
Karen instilling order and attention 😉
Ready and waiting to be inspired
The undergraduates came from thirty different UK universities with a strong female bias, 34:16. Exeter University had four representatives, with Reading, Liverpool John Moores, UCL and Bristol with three each. I was sorry to see that there were no students from my Alma mater Leeds, or from my former institution, Imperial College, once regarded as the Ecological Centre of the UK, although UEA where I did my PhD, had two representatives. There was also one representative from my current place of work, Harper Adams University. Incidentally one of the students turned out to have gone to the same school that I did in Hong Kong, King George V School, albeit almost fifty years apart; a small world indeed.
I set the scene by highlighting how many insect species there are, especially when compared with vertebrates.
The importance of insects and plants
Or to put it another way
After a quick dash through the characteristics of insects and the problems with identifying them, exacerbated by the shortage of entomologists compared with the number of people working on charismatic mega-fauna and primates, I posed the question whether it is a sound policy to base conservation decisions on information gained from such a small proportion of the world’s macro-biota.
Then we were of into the field, although not sunny, at least it was not raining so I was able to demonstrate a variety of sampling techniques; sweep netting with the obligatory head in the bag plus Pooter technique, butterfly netting, tree beating and, as a special treat, motorized suction sampling, in this instance a Vortis.
With aid of the PhD mentors and Hazel Leeper from the Linnaen Society, the students were soon cacthing interesting things (not all insects) and using the Pooters like experts.
Getting close up with the insects
I also let some of the students experience the joy of the Vortis, suitably ear-protected of course. All good things come to an end and it was then time to hit the microscopes, wash bottles, mounted pins and insect keys.
Getting stuck in – picture courtesy Amy Leedale
I was very impressed with how well the students did at getting specimens down to orders and families and have every confidence that there are a number of future entomologists among them. After the evening meal, Kate Harrison and Simon Hoggart from the BES Publications Team introduced the students to the tactics of paper writing and publishing which I think they found something of an eye-opener. The students, after a rapid descent on the bar, enjoyed a Pub Quiz whilst I relaxed with a glass of wine until it was dark enough for me to demonstrate the wonders of using fluorescent dust to track our solitary carabid beetle using my UV torch before heading off to bed.
Glow in the dark carabid beetle – the bright lights of Malham Tarn – photo courtesy of Eloise Wells
I was sorry to have to leave the next morning, it would have been great fun to have stayed the full week, but next year I do hope to be able to be there for at least two days and nights so that we can do pitfall trapping and light trapping and of course, have more fun with fluorescent insects.
I hope the students found the whole week inspirational and useful, I was certainly inspired by their obvious enjoyment and interest and will be surprised I if do not come across some of them professionally in the future.
Well done BES and congratulations to Karen and her team for providing such a great opportunity for the students. I am really looking forward to next year and being able to see great Yorkshire features like this in the sunshine 😉
This year the AGM of the British Ecological Society (BES) was a joint affair with the Société Française d’Écologie (SFE) and was held in Lille in northern France just over an hour away from London by Eurostar. Given our love of France and in my wife’s case, Christmas markets, there was no way I was not going to attend this landmark meeting especially as the BES were willing to pay my registration fee in recognition of my role as an Associate Editor of the Journal of Animal Ecology. My mother-in-law is also a keen fan of Christmas markets so she decided to come along and keep Gill company.
We left London on a later train than originally planned (strike action in Brussels) and arrived in Lille mid –afternoon Monday to find that our hotel was a good 4 km away from the railway station and almost as far away from the Grand Palais where the conference was being held. Luckily my mother-in-law, although almost 86, is very spry and took the longish walk in her stride. We eventually found the hotel, on the way being amused by an Irish pub with a very non-Irish name 😉
An unusual name for an Irish Pub
Being a Monday in France, not much was open but we eventually found somewhere to eat for a reasonable price, and amusingly were served by an English waiter!
As the conference registration didn’t start until Tuesday evening we spent most of the day sight-seeing and bumping into fellow delegates.
The Christmas market was, however, somewhat disappointing, especially for those of us who were at the BES Birmingham meeting a couple of years ago.
The very small Christmas Market
The damp weather was also a bit off-putting. This was when I started to regret my decision to opt for a comfortable well-worn pair of Desert Boots with holes in the soles instead of a new pair.
Wet, cold feet
The state of my feet inspired me to tweet an appropriate Haiku 😉
Wet Pavements in Lille
Desert boots are great,
except when soles are holey;
then rain means wet feet
The BES and SFE did a great job – a very full programme kept us occupied from Wednesday 10th until late afternoon of Friday 12th December. (Gill and my mother-in-law managed to get to Brussels and Arras for their Christmas markets). My only gripe was that because it was such a popular meeting (over 1100 delegates) that there were a huge number of sessions (62) so I missed a lot of talks that I wanted to hear. This is why in some ways I much prefer smaller conferences such as the Royal Entomological Society annual meetings where there are generally only two parallel sessions. I have long ago given up trying to session- hop, so confined myself to the plenaries and complete sessions such as the Agricultural Ecology, Pest & Pesticides session, where one of my favourite talks was given by Victoria Wickens from the University of Reading on local and landscape effects on aphids and their natural enemies; she was supported in the audience by her identical twin, Jennifer (also a PhD student at Reading and who spoke later in the Plant-Pollinator Interactions session). I first meet Jennifer and Victoria at the BES AGM in Leeds when they were MSc students and student helpers. It was only towards the end of that conference that I realised that there were actually two of them 😉
With careful planning I managed to fit in the Urban Ecology session, the Ecology & Society session, the symposium session on plant-insect-microbe interactions, and a session on herbivory. There were a lot of really good talks and I learnt a lot. I made sure that I attended the Friday morning talk by Grrl Scientist who spoke about the use of social media and crowd funding in ecology. I was somewhat embarrassed (and flattered) to have my blog publicly cited as an example of what other ecologists should be doing. It was lucky that it was dark in the auditorium as I was blushing rather a lot.
The influence of the SFE was definitely felt; the catering was much, much better than we normally get at the normal BES meetings and it was great to see so many French ecologists.
and the free beer at lunch time was a welcome innovation that went down very well with the English delegates 😉
The organisers of the meeting next year in Edinburgh must be feeling somewhat nervous 😉
Very many thanks to the BES and SFE and their local organisers for putting on such a splendid meeting; a veritable scientific and gastronomic delight.
The infamous Desert boots – back home and ready to be put to rest!
Nineteen-Sixty-One was a momentous year for entomology and ecology, although at the time I suspect few realised it. Skip forward to 2013 when The British Ecological Society published a slim volume celebrating the 100 most influential papers published in the Society’s journals. The papers included in the booklet were selected based on the opinions of 113 ecologists from around the world, who were then asked to write a short account of why they thought that paper influential. I was disappointed not to be asked to write about my nomination but instead asked to write about Maurice Solomon’s 1949 paper in which he formalised the term functional response.
The paper I had wanted to write about was included, but John Lawton had the privilege of extolling its virtues, and given the word limits did a pretty good job. I do, however, feel that given its importance to ecology and entomology it deserves a bit more exposure, so I am taking the opportunity to write about it here. I could have included this post in a series I have planned, called Ten Papers that Shook My World, but given the impact that this paper has had on entomologists I felt it deserved an entry in my Entomological Classics series.
For those of you who haven’t come across this paper before, this was an astonishingly influential paper. Basically, Southwood, who despite his later reputation as one of the ecological greats, was an excellent entomologist, (in fact he was a Hemipterist), wanted to explain why some tree species had more insect species associated with them than others. He made comparisons between trees in Britain, Russia and Cyprus and demonstrated that those trees that were more common and had a wider range had more insect species associated with them (Figure 1).
From Southwood 1961. I was surprised to see that he had committed the cardinal error in his Figure caption of describing it as Graph and also including the regression equation in the figure pane; two things that I constantly reprimand students about!
Importantly he also showed that introduced trees tended to have fewer insects than native species. He thus hypothesised that the number of insects associated with a tree species was proportional to its recent history and abundance and was a result of encounter rates and evolutionary adaptation. He then tested this hypothesis using data on the Quaternary records of plant remains from Godwin (1956) making the assumption that these were a proxy for range as well as evolutionary age.
He commented on the outliers above and below the line suggesting that those above the line were a result of having a large number of congeners and those below the line either as being taxonomically isolated and/or very well defended.
He then went on to test his ideas about the evolutionary nature of the relationship by looking at trees and insects in Hawaii, (ironically this appeared in print (Southwood, 1960), before the earlier piece of work (Journal of Animal Ecology obviously had a slower turnaround time in those days than they do now).
Figure 2.Relationship between tree abundance and number of insect species associated with them (drawn using data from Southwood 1960).
Considering the research that these two papers stimulated over the next couple of decades, what I find really odd, is that Southwood, despite the fact that he was dealing with data from islands and that Darlington (1943) had published a paper on carabids on islands and mountains in which he discussed species-area relationships and further elaborated on in his fantastic book (Darlington, 1957), did not seem to see the possibility of using the species-area concept to explain his results. It was left to Dan Janzen who in 1968 wrote
“It is unfortunate that the data on insect-host plant relationships have not in general been collected in a manner facilitating analysis by MacArthur and Wilson’s methods (as is the case as well with most island biogeographical data). What we seem to need are lists of the insect species on various related and unrelated host plants, similarity measures between these lists (just as in Holloway and Jardine’s 1968 numerical taxonomic study of Indo- Australian islands), knowledge of the rates of buildup of all phytophagous insect species on a host plant new to a region, where these species come from, etc. Obviously, the insect fauna must be well known for such an activity. The English countryside might be such a place; it has few “islands” (making replication difficult) but a very interesting “island” diversity, with such plants as oaks being like very large islands and beeches being like very small ones, if the equilibrium number of species on a host plant (Elton, 1966; Southwood, 1960) is any measure of island size.”
In 1973 Dan Janzen returned to the subject of trees as islands and cited Paul Opler’s 1974 paper in relation to the fact that the number of herbivorous insects associated with a plant increases with the size of the host plant population (Figure 3), and further reiterated
Figure 3.Opler’s 1974 graph showing relationship between range of oak trees in the USA and the number of herbivorous insect species associated with them.
his point about being able to consider trees as ecological islands. Opler’s 1974 paper is also interesting in that he suggested that this approach could be used for predicting pest problems in agricultural systems, something that Don Strong and colleagues did indeed do (Strong et al., 1977; Rey et al., 1981), and that the concept of habitat islands and the species-area relationship could be used when designing and evaluating nature reserves, something which indeed has come to pass.
Again in 1974 but I think that Strong has precedence because Opler cites him in his 1974 paper, Don Strong reanalysed Southwood’s 1961 data using tree range (based on the Atlas of the British Flora) as the explanatory variable (figure 4) to explain the patterns seen.
Figure 4. Strong’s reworking of Southwood’s 1961 insect data using the distribution of British trees as shown in Perring & Walters1 (1962).
The publication of this paper opened the floodgates, and papers examining the species-area relationships of different insect groups and plant communities proliferated (e.g leafhoppers (Claridge & Wilson, 1976); bracken (Rigby & Lawton, 1981); leaf miners (Claridge & Wilson, 1982); rosebay willow herb (McGarvin, 1982), with even me making my own modest contribution in relation to Rosaceous plants (Leather, 1985, 1986).
Although not nearly as popular a subject as it was in the 1980s, people are still extending and refining the concept (e.g. Brändle & Brandl, 2001; Sugiura, 2010; Baje et al., 2014).
Southwood (1961) inspired at least two generations of entomologists and ecologists, including me, and is still relevant today. It is truly an entomological (and ecological) classic.
Baje, L., Stewart, A.J.A. & Novotny, V. (2014) Mesophyll cell-sucking herbivores (Cicadellidae: Typhlocybinae) on rainforest trees in Papua New Guinea: local and regional diversity of a taxonomically unexplored guild. Ecological Entomology39: 325-333
Brändle, M. &Brandl, R. (2001). Species richness of insects and mites on trees: expanding Southwood. Journal of Animal Ecology70: 491-504.
Claridge, M. F. &Wilson, M. R. (1976). Diversity and distribution patterns of some mesophyll-feeding leafhoppers of temperate trees. Ecological Entomology1: 231-250.
Claridge, M. F. &Wilson, M. R. (1982). Insect herbivore guilds and species-area relationships: leafminers on British trees. Ecological Entomology7: 19-30.
Darlington, P. J. (1943). Carabidae of mountains and islands: data on the evolution of isolated faunas and on atrophy of wings. Ecological Monographs13: 37-61.
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The Atlas of the British Flora by Perring and Walters (1962) was an iconic piece of work, although not without its flaws. As with many distribution atlases it is based on a pence or absence score of plant species within one kilometre squares. So although it is a good proxy or range it does not necessarily give you an entirely reliable figure for abundance. A dot could represent a single specimen or several thousand specimens. Later authors attempted to correct for this by using more detailed local surveys e.g. tetrads. It must have been particularly galling for Southwood that the Atlas didn’t appear until after he had published his seminal papers, but he later made up for it by reanalysing and extending his data from that original 1961 paper (Kennedy et al., 1984).
Those of us working in this area using the original Atlas had to count the dots by hand, a real labour of love especially for those widely distributed species; the new edition (Preston et al., 2002) actually tells you how many dots there are so the task for the modern-day insect-plant species-area relationship worker is much easier 😉
A summary of research projects and publications dealing with mosquitoes, wetlands and urban ecology (as well as other Medical Entomology activities) by Dr Cameron Webb (University of Sydney & Pathology West)