Tag Archives: Science

A new study shows that even short-tubed flowers can specialise on hawkmoths as pollinators

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Of all of the “classical” pollination syndromes, flowers that are hawkmoth pollinated have one of the highest levels of predictability. If a flower is pale in colour, opens at night, is highly scented, and possesses a long tube at the bottom of which is a supply of nectar, there’s a very high likelihood that it’s pollinated by long-tongued hawkmoths (Sphingidae).

Indeed, one of the foundational stories about the development of our understanding of how pollination systems evolve, relates to Charles Darwin, the long-tubed orchid Angraecum sesquipedale and the hawkmoth Xanthopan morganii praedicta.

Fast forward 160 years and we now know that pollination syndromes are more complex than 19th and early 20th century scientists imagined – see my recent book Pollinators & Pollination: Nature and Society for a discussion of this topic. That’s not surprising because, as I point out, we probably have data on the interactions between plants and their pollinators for only about 10% of the estimated 352,000 species of flowering plants. There’s still much to be discovered!

As an example of how our understanding of specialised flower-hawkmoth interactions is developing, consider this recent study that I’ve just published with my Brazilian colleague Felipe Amorim and other collaborators. In it we have shown that, contrary to expectations, a species of Apocynaceae (Schubertia grandiflora) with a relatively short floral tube can specialise on hawkmoths with much longer tongues than we might predict.

The full reference with a link to the study is shown below, followed by the abstract. If you would like a PDF, please drop me a line via my Contact page:

Amorim, F.W., Marin, S., Sanz-Viega, P.A., Ollerton, J. & Oliveira, P.E. (2022) Short flowers for long tongues: functional specialization in a nocturnal pollination network of an asclepiad in long-tongued hawkmoths. Biotropica https://doi.org/10.1111/btp.13090

Abstract:

Since Darwin, very long and narrow floral tubes have been known to represent the main floral morphological feature for specialized long-tongued hawkmoth pollination. However, specialization may be driven by other contrivances instead of floral tube morphology. Asclepiads are plants with a complex floral morphology where primary hawkmoth pollination had never been described. We detailed here the intricate pollination mechanism of the South American asclepiad Schubertia grandiflora, where functional specialization on long-tongued hawkmoth pollinators occurs despite the short floral tube of this species. We studied two plant populations in the Brazilian Cerrado and recorded floral visitors using different approaches, such as light-trapped hawkmoths for pollen analysis, direct field observations, and IR motion-activated cameras. Finally, using a community-level approach we applied an ecological network analysis to identify the realized pollinator niche of S. grandiflora among the available niches in the pollinator community. Throughout a period of 17 years, long-tongued hawkmoths were consistently recorded as the main floral visitors and the only effective pollinators of S. grandiflora. Flowers rely on highly modified corona and gynostegium, and enlarged nectar chambers, to drive visitors and pollination mechanism. Despite its relative short-tube, network analysis placed S. grandiflora in the module including exclusively long-tongued hawkmoth pollinators and the most phenotypically specialized sphingophilous plants in the community. These results represent the first example of functional specialization in long-tongued hawkmoths in an asclepiad species. However, this specialization is uncoupled from the long floral tubes historically associated with the sphingophily syndrome.

The value of butterfly specimens for understanding species extinctions – a new study just published.

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The Chequered Skipper Reintroduction Project has featured in several posts over the last few years – see here and here – and University of Northampton PhD researcher Jamie Wildman has been working hard to complete his thesis under the less-than-ideal conditions imposed by the COVID-19 pandemic. The first paper from the project has just been published and it deals with Jamie’s monumental efforts to bring together all of the scattered data relating to preserved Chequered Skipper specimens held in museums and private collections. An existing database contained just 266 records; Jamie’s efforts increased that by an order of magnitude, adding a further 3,533 new records that document where and when specimens were collected, and by whom.

This 1,328 % increase in data means that we now know much more about the historical distribution of this butterfly and how that changed over time.

The Chequered Skipper went extinct in England in 1976 and this enhanced database will allow us to understand why that extinction occurred. This initial paper documents the strategy used to find the additional records as a road map for how others might proceed in the future. The full reference with a link to the paper is here:

Wildman, J.P., Ollerton, J., Bourn, N.A.D., Brereton, T.M., Moore, J.L. & McCollin, D. (2022) The value of museum and other uncollated data in reconstructing the decline of the chequered skipper butterfly Carterocephalus palaemon (Pallas, 1771). Journal of Natural Science Collections 10: 31-44

This is the abstract:

The chequered skipper butterfly Carterocephalus palaemon (Pallas, 1771) was declared extinct in England in 1976 after suffering a precipitous decline in range and abundance during the 20th Century. By searching and collating museum and other records, we show how a deeper understanding of this decline can be achieved, thus furthering conservation objectives. A preexisting Butterflies for the New Millennium (BNM) database of United Kingdom butterfly species records, created by Butterfly Conservation in conjunction with the Biological Records Centre (BRC), contained 266 historic C. palaemon records from England. United Kingdom (UK) museums and natural history societies were contacted for specimen data, and these sources added 2175 new records to the BNM. Owners of private specimen collections were also contacted, and these collections accounted for a further 465 records. Specimens originating from UK museums, other institutions, and private collections represent 2640 (71%) of total new records. Other sources, such as personal accounts held in museums, published and unpublished texts produced an additional 894 records. A further 437 records from museums, private collections, and other sources were considered partial and omitted from the data due to limited or misleading date and/or locality information. In summary, data from UK museums and other sources has infilled English C. palaemon distribution prior to 1976, offering further insight into potential environmental and anthropogenic drivers of decline at key sites. The quality and quantity of data obtained using the method outlined in this study suggests similar work could be carried out for other extinct or declining butterfly species to improve our knowledge of habitat requirements and historical distribution via modelling, identify causes of decline, and provide valuable information for potential reintroductions.

Join me on Thursday for a free talk!

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Join me this Thursday at a free online talk organised by Buglife where I’ll be giving an introduction to how flowers function and the ways in which their behaviour manipulates pollinators to ensure reproduction. I’ll be covering:

  • What are flowers and where did they come from?
  • How flowers function and reward pollinators.
  • Some case studies from my own research on flower and pollinator behaviour.
  • Why is it important that we understand floral biology?

Here’s the link to register for the event: https://www.buglife.org.uk/events/to-be-a-flower-with-professor-jeff-ollerton/

I look forward to seeing you there!

The value of nature, the value of guitars

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How we, as a society, value nature, and the tension between valuing (or appreciating) nature versus appreciating (or pouring money into) human cultural activities, have been consistent themes of this blog since I started it almost a decade ago; see for example my posts “How do we value nature? Costanza, Monbiot and the clash of concepts” and “Is the angry response of (some) environmentalists in the aftermath of the Notre Dame fire reasonable?“

Putting a monetary price on nature runs counter to the personal philosophies of many conservationists, which I completely understand: I have mixed feelings too. However there’s a whole field of research devoted to it called Ecological Economics and the valuation of natural capital and ecosystem services now plays a central role in the policies and strategies of both businesses and governments: see for instance the UK Government’s recent report on “The Economics of Biodiversity: The Dasgupta Review“. And whether we like it or not, the Earth’s ecosystems and the biodiversity that they contain support our global economy in very tangible ways, a point that I emphasise in my book Pollinators & Pollination: Nature and Society. If you’re reading this with a cup of coffee in your hand, you have to consider the ecological and financial impact of the billions of wild and managed bees that support the global coffee industry.

“What’s all of this got to do with guitars?” I hear you asking. Well, music, and especially guitars, are another constant theme of the blog, including my love of the songs of Crosby, Stills, Nash and Young, and my restoration of an old acoustic guitar back in 2020.

These themes converged together in a rather unexpected way just over a week ago. It was my birthday and as a present Karin had offered to buy me a new guitar. So off we went to Copenhagen for the day. One of the city’s best guitar shops is Akustikken and there I tried out several makes and models of acoustic guitar, of varying price and quality, before finally settling on an Epiphone Texan in an aged sunburst finish (see the image below). It plays very nicely, felt right in my hands, and was moderately priced despite its solid wood construction (cheap guitars often use laminated wood).

The guitar that really caught my eye, however, was the one in the photograph above: a Martin 045-S Stephen Stills Signature Model. Now, this is a serious, serious guitar. Based on a 1930s model owned by Stills himself, it was hand made in the USA in a limited edition of 91, of which this was number 48. The woods from which it’s made are rare and exceptional, including Adirondack spruce, Madagascar rosewood, and ebony, all species about which there are significant conservation concerns (see Richard Hobbs’s great blog The Nature of Music for more on this – highly recommended for anyone interested in the interface between human culture and ecological conservation).

The price tag for this guitar? A mere160,000 Danish kroner, about £18,000 or $20,000…..

That was WAY outside of our budget! But when the staff learned that it was my birthday they kindly took the Martin out of its humidity-controlled glass case and let me play it. I was a bit overwhelmed and very nervous if I’m honest, it was easily the most expensive guitar I have ever had in my hands! Karin took a short video of me strumming a few chords which I uploaded to Twitter:

Now, I’d played guitars up to around $2,000 in price that day, so a reasonable question is: did the $20,000 guitar sound ten times as good? Well, not in my hands it didn’t…. But in one sense it doesn’t matter, you’re not just paying for what it sounds like, you’re paying for the story, for the association with Stills, and the highly skilled crafting of the guitar – it is an exceptionally beautiful and fine-sounding instrument.

This brings us back to nature. We know from a lot of ecological experiments that have been conducted over the years that there’s a positive relationship between biodiversity (measured by the number of species in an ecosystem) and the way in which that ecosystem functions. So if you have more different kinds of plants in a grassland, for example, there tends to be greater carbon capture, more efficient use of water and uptake of nitrates from the soil, more resilience to events like drought and fire, and so forth. This is a strong and pervasive argument for conserving species within ecosystems: the more we have, the better the “health” of that ecosystem.

But, as with the sound of guitars, there’s probably an upper limit to this and ecosystems with ten times as many species probably do not function ten times as well. But they do function better. Having said that, this is a complex area of research with some competing ideas (and scientists) – this Wiki provides quite a good summary.

Regardless of the technical details, there’s no doubt that having more pollinators in an ecosystem, for example, increases the reproduction of a wider range of the plants that are present. Or that the presence of a greater diversity of dung beetles improves the rate of dung removal in grasslands.

But of course nature is more complicated than this. Just as a well made and high-value guitar is never going to sound good in the hands of a poor guitarist, likewise, species diversity in itself is insufficient. It is the interactions between those species that determines much of the way in which the ecosystem functions, and an ecosystem is never going to function well over the long term if it is inappropriately managed or if the processes that shape ecosystems, such as grazing by wild herbivores or natural fire regimes, are absent or have been altered.

Ecology is a hugely complex science but perhaps by exploring metaphors like this, some of that complexity can be made accessible to a wider range of people. Tell me what you think, does the metaphor work for you?

Leonard B. Thien (1938-2021) – botanist and pollination biologist

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I was saddened to learn recently of the death of Professor Leonard B. Thien of Tulane University who passed away at the end of October after a long illness. Although I didn’t know Professor Thien personally, I knew of his work in floral ecology, pollination biology and plant evolution, topics on which he had worked for since obtaining his PhD in 1968. Over the course of his career he published more than 80 articles on a huge range of botanical subjects, including ground-breaking work on mosquito pollination of orchids (Thien 1969). The orchid species Alaticaulia thienii is named in his honour.

The studies Leonard Thien published that really inspired me when I was first starting out on my journey as a researcher, however, involved his work on “relictual” angiosperms, i.e. flowering plants that have very long evolutionary histories and deep phylogenetic roots back to the early Cretaceous period, for example Magnolia and Illicium. Papers with titles such as “Patterns of pollination in the primitive angiosperms” (Thien 1980) piqued my interest and motivated me to work on Australian Piperaceae for a short while following my PhD (Ollerton 1996). It was a topic that I struggled to gain further funding for, and later molecular systematic studies changed many of our ideas about what constitutes the most basal groups of extant flowering plants. But nonetheless, the questions that Leonard inspired in me, regarding the ecologies of these relictual taxa, and whether we can infer the reproductive ecology of the earliest flowering plants from studies of their surviving descendants, are ones that intrigue me to this day (van der Kooi and Ollerton 2020).

Leonard Thien kept up this interest even as new DNA technologies over turned old ideas, and he was the first to study the reproductive ecology of Amborella trichopoda on New Caledonia, a species now considered to be the earliest surviving clade of flowering plants (Thien et al. 2003). This is just one part of a legacy of work that current and future generations will build upon as we develop our understanding of the relationships between pollinators, plants, and evolutionary processes.

I’m grateful to Peter Bernhardt for prompting this post and for sending me a copy of the In Memoriam article that he and and David White will publish in the Plant Sciences Newsletter in March, and to Lorraine Thien for providing the photograph that accompanies this post.

References

Ollerton, J. (1996) Interactions between gall midges (Diptera: Cecidomyiidae) and inflorescences of Piper novae-hollandiae (Piperaceae) in Australia. The Entomologist 115: 181-184

Thien, L.B. 1969. Mosquito pollination of Habenaria obtusata (Orchidaceae). American Journal of Botany 56: 232-237.

Thien, L.B. 1980. Patterns of pollination in the primitive angiosperms. Biotropica 12: 1-14

Thien, L.B., Sage, T.L., Jaffre, T., Bernhardt, P., Pontieri, V., Wesston, P.H., Malloch, D., Azuma, H., Graham, S.W., McPherson, M.A., Hardeep, S.., Sage, R.S. & Dupre, J.-L. 2003. The population structure and floral biology of Amborella trichopoda (Amborellaceae). Annals of the Missouri Botanical Garden 90: 466-490

van der Kooi, C.J. & Ollerton, J. (2020) The origins of flowering plants and pollinators. Science 368: 1306-1308

Earning a living as an independent academic and author: here’s what I’ve learned in my first year

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It’s just over one year since I stepped down from my full time professorship at the University of Northampton in order to work independently as a consulting scientist and author. It was a move precipitated by a number of factors, not least that after 25 years at that institution I needed some new challenges. I was starting to feel stale, jaded, and not a little burned out.

Since making the decision to leave the university (where I still hold a Visiting Professorship) Karin and I have down-sized our lives by selling our house, disposing of possessions that we didn’t need (though there’s still a lot in storage in the UK) and moving to Denmark, where we are renting a small apartment for the time being. Karin is Danish and, yes, both Brexit and the pandemic have played a role in our decision making.

A few people have asked me recently how I’m managing to earn a living as an independent academic so I thought I’d share with you my experiences so far. I’ve looked at my various sources of income over the past year and put them into four broad categories: Conservation, Research, Education and Writing. Then I worked out the proportion of my income that can be attributed to each area, keeping in mind that there’s overlap between them. This is the result:

Conservation-related activities accounted for the largest fraction, about 46% of my income. This includes direct advisory and consulting, on pollinator-related projects but also on wider, biodiversity-related topics. For example I worked with the Stanwick Lakes nature reserve in Northamptonshire, advising on how best to enhance and manage the site for pollinators.

It’s a site that I know very well but which was set up mainly because it’s important bird habitat. Seeing it from a pollinator’s perspective allowed me to make suggestions for improving the amount and timing of floral resources, opportunities for ground nesting bees, and so forth.

I’ve also been working with the Centre for Ecology and Hydrology (Wallingford) on a biodiversity strategy for the European railway network which I’ll write more about later this year when the final report is published.

Also included in the Conservation category are the many, many talks (mainly online) that I’ve done for various natural history, gardening and beekeeping groups, plus training sessions that I’ve done with ecological consultancies, estates departments, and local government. There’s a list of those available on my training and public speaking page.

Research projects funded by UK and international agencies accounted for about 32% of my income. Some of these are projects that started when I was still employed at the University of Northampton and which are paying for my time (including completing the supervision of my remaining PhD students), others are new ones. You can find a list of present and past projects on this page of my website.

I am a partner on several funding applications that are in the process of being assessed and I’ll report back when we know if they have been successful.

As well as my own research I’m also reviewing grant applications for funding organisations, advising research groups and departments on their research strategies, and working with the Turkish Journal of Botany to promote the work it publishes to a wider international audience.

Education is the third, very broad category that includes things such as external examining (both taught and research degrees), assessing staff applications for promotion, and doing the occasional online lecture. It accounted for 11% of my income, less than I might have expected given that I’ve spent over 30 years teaching in higher education, educational consulting is quite a crowded field and unless you’re a high-profile specialist, it doesn’t pay well.

Writing accounted for about 11% of my income. As well as royalties from my book Pollinators & Pollination: Nature and Society, I earned money from writing for magazines such as BBC Gardeners’ World Magazine, New Scientist, British Wildlife, and Bees & Other Pollinators Quarterly.

In addition I’ve done some advisory work for publishers, including reviewing text and making suggestions for a forthcoming children’s book about bees and other pollinators, and some paid manuscript editing.

At the moment the balance of my work feels about right; I’ll never stop being a scientist so working on research projects is, and always will be, an important part of my life. I wish that it was possible to earn more from writing, but outside of the best-seller lists it’s difficult for authors to earn a decent living. However I’m working on my next book at the moment, as is Karin whose Essential Companion to Talking Therapy has been well received.

Working independently in this way, and putting together what amounts to a “portfolio career”, is not for everyone. It’s hard work and there are lots of uncertainties along the way, especially with regard to month-to-month consistency of one’s income. However a career as a university academic has prepared me for this in ways which I’m only just beginning to discover. Aside from the obvious subject expertise, familiarity with literature searching, and confidence when giving talks, the uncertainties associated with the high proportion of unsuccessful funding applications and navigating the (often contradictory) requirements of peer reviews has been extremely valuable experience. And of course I’ve established a large and diverse network of colleagues with whom I can collaborate and go to for advice. The diversity of paid work with which I’m engaged, plus the pro bono activities such as peer reviewing for journals, ensures that there’s never a dull day. I have absolutely no regrets about this latest step in my career!

If you’re interested in working with me or want to discuss any aspect of what I’ve written about, please do get in touch via my Contact page.

Harnessing nature’s regenerative powers: more evidence that tree planting is not (always) the best solution

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An interesting study published this week in the journal Science has provided more evidence that natural regrowth of forests is faster and more efficient than tree planting for restoring habitats. Here’s the Guardian‘s take on it:

https://www.theguardian.com/environment/2021/dec/09/tropical-forests-can-regenerate-in-just-20-years-without-human-interference

Here’s a link to the original study in the journal:

https://www.science.org/doi/10.1126/science.abh3629#

And here’s a link to something that I wrote on this topic last year, arguing that pollinators and seed dispersers play a vital role in this process:

Forest restoration for climate change: don’t forget the pollinators and seed dispersers

Tree planting has its place, of course, especially as a way to get local communities engaged in positive action for the environment. But it’s not the solution for large-scale habitat restoration: in order to do that we need to harness nature’s own regenerative abilities.

Generating AI art from titles of scientific publications

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WARNING: huge time wasting potential ahead.

As regulars to my blog might know, I’m a sucker for computer-generated “stuff”, for example virtual ecological systems; see my 2020 post “a simple online ecosystem model: like Tamagotchi for the green generation“. Last night while browsing Twitter I came across a few people tweeting about app.wombo.art which uses words and phrases as a prompt for its AI to generate art in a variety of styles. For example, the image above is based on the title of my book Pollinators & Pollination: Nature and Society. The downloaded image always has “dream” at the top which is easy enough to crop, while “PROMPT” is the word or phrase that you entered, which can be turned off.

You can also use the titles of scientific articles – this one is my 1996 paper “Generalization in Pollination systems and Why it Matters” (I don’t think that it counts as a graphical abstract…):

A lot of people were submitting their thesis titles and I expect to see some of these used as frontispieces in PhDs in the near future. Here’s mine (from 1993) – “Ecology of flowering and fruiting in Lotus corniculatus“:

The other category that I had fun with was using scientific names – here’s the genus Ceropegia:

And here is Apocynaceae:

Can you guess what phrase I used to generate this one:

What’s really fascinating about this system is that every time you generate an image from the same phrase it returns something different. Go have fun, but be warned: it’s a bit of a rabbit hole and it’s possible to waste a lot of time playing around:

Life brings stability: biological crusts on sandy subsoil

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A couple of weeks ago we visited Karin’s family in Jutland and went for a couple of long walks around the area. One of these took us through some very nice mixed pine, oak, and birch forest close to a river. The forest was anchored into a thin horizon of mulchy topsoil, beneath which was almost pure sand, a post-glacial legacy of the wider, wilder rivers that ran through the region at the end of the last Ice Age.

Where our path ran parallel to the river I noticed that the exposed vertical sections were far from lifeless: the sandy faces had been colonised by algae, lichens, fungi, cyanobacteria, and mosses. These biological crusts had stabilised the sand and prevented it from eroding further back into the bank. On a miniature scale they were doing what forests and other vegetation does in mountainous areas all over the world: preventing landslides.

Biological crusts in turn provide opportunities for ferns and seed plants to germinate and gain a foothold: they are often the starting point for further ecological succession.

Not only are these crusts acting as substrate stabilisers and seed beds, but all of the usual ecological processes of photosynthesis, nutrient acquisition, decomposition, carbon storage, symbiosis and competition are taking place in just a few millimetres of biodiversity. There’s a lot going on in these thin veneers of life.

Heterospecific pollen deposition is positively associated with reproductive success in a diverse hummingbird-pollinated plant community: a new study just published

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Plants which live in diverse communities with other species may often share pollinators, which means that their stigmas can receive the pollen from different types of plants as well from individuals of their own species. This “heterospecific” pollen deposition may have consequences for plant reproduction if it clogs up the stigmas and prevents “conspecific” pollen from gaining a foothold. However there’s still relatively little published on this phenomenon and its impact on reproduction, particularly in highly diverse tropical communities across different seasons. In a new study just published in the journal Oikos and led by Sabrina Aparecida Lopes, we have shown that in a Brazilian hummingbird-flower community heterospecific pollen deposition (HPD) shows seasonal patterns. Contrary to expectations, we also found a positive relationship between HPD and reproductive success, which by coincidence has also been shown this month for a high-Andean plant community in this paper just published by Sabrina Gavini and colleagues.

Here’s the full reference and the abstract for our Oikos paper:

Lopes, S.A, Bergamo, P.J, Queiroz, S.N.P., Ollerton, J., Santos, T. & Rech, A.R. (2021) Heterospecific pollen deposition is positively associated with reproductive success in a diverse hummingbird-pollinated plant community. Oikos (in press)

Heterospecific pollen deposition (HPD) is ubiquitous across plant communities, especially for generalized species which use a diversity of pollinators, and may have negative effects on plant reproduction. However, it is unclear whether temporal changes in the co-flowering community result in changes in HPD patterns. Moreover, community-level studies are required to understand which factors influence HPD and how the reproduction of different species is affected. We investigated the temporal variation of HPD, its relationship with level of specialization on pollinators and floral phenotypic specialization, and its association with reproductive success (pollen limitation and fruit set) in 31 hummingbird-pollinated plant species in a tropical Campo Rupestre. We found seasonality in HPD, with species flowering in the dry season having greater diversity of heterospecific pollen on stigmas and a higher frequency of stigmas containing heterospecific pollen, compared to the rainy season. Stigmas of ecologically generalized species had more heterospecific pollen, while the relationship for ecologically specialized species depended on floral phenotype. Surprisingly, and in contrast to theory, we found a positive relationship between HPD and reproductive success. Our results indicate benefits of generalization and facilitation, in which sharing pollinators brings greater reproductive success via increased conspecific pollen deposition, even if it incurs more HPD. We demonstrated how assessing HPD at a community-level can contribute to understanding the ecological causes and functional consequences of pollinator sharing.

If you’d like a PDF, please use the Contact page to request one.