Tag Archives: Conservation

The flower that’s pollinated by birds, bees….and the wind!

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In my new book Birds & Flowers: An Intimate 50 Million Year Relationship I spend a bit of time discussing the idea of the bird pollination syndrome that we refer to as ‘ornithophily’, its limitations, and the fact that it has two distinct meanings that are often conflated. One of the problems with ornithophily, and indeed all of the syndromes, is that historically it’s sometimes blinkered scientists to the extent that they only look at the flower visitors that are “right” for the syndrome, ignoring the rest or dismissing them as “secondary pollinators”, a term I dislike.

Why do I dislike that term? Because it fails to capture the complexity of flower-pollinator interactions and relegates an important component of plant reproduction to a subsidiary role. I could go on about this at some length, but if you’re interested in discovering more, look at pages 62-65 of Birds & Flowers. There I contrast the classical Most Effective Pollinator Principle with the equally valid (but much less well studied) Least Effective Pollinator Principle, with a segue into one of my favourite tracks from Led Zeppelin’s second album: What is and What Should Never Be.

But back to the real subject of this post – a flower that corresponds to the classical bird pollination syndrome BUT is also pollinated by bees and (very surprisingly) wind! It’s such an interesting paper by Brazilian ecologists Amanda Pacheco, Pedro Bergamo & Leandro Freitas – here’s the reference and a link to the study:

Pacheco, A., Bergamo, P.J. & Freitas, L. (2024) An unexpected case of wind pollination: ambophily in an ornithophilous tropical mountaintop Orobanchaceae. Plant Systematics and Evolution 310, 9. https://doi.org/10.1007/s00606-024-01890-6

For over 100 years the classical pollination syndromes have acted as a framework for understanding the ecology and evolution of plant-pollinator interactions. But we’ve long known that while they can be a useful shorthand, they do not fully reflect the complexity of how pollination systems evolve. That shouldn’t surprise us because, as I point out in my two recent books, we have data (of any quality) on no more than 10% of the 350,000 or so species of flowering plants!

In addition, those plants for which we do have good data are NOT a random subset of the flowering plants: they have been specifically chosen by researchers because they look to be good systems with which to address particular ecological or evolutionary questions.

Which is fine, but we MUST recognise that this imposes significant restrictions on our understanding of the biodiversity of plant-pollinator interactions. The authors of this paper expressed it very well when they wrote that assumptions about:

“predictability may cause researchers to take for granted that only birds pollinate ornithophilous flowers, hindering research on the contribution of other vectors.”

To which I’d add: it also hinders our understanding of how these interactions evolve over long time scales and across multiple populations.

An obvious question is: how frequent are these sorts of complex pollination systems, involving different pollen vectors of an apparently specialised flower? The answer is that we simply don’t know, because most researchers would have not gone into this level of detail. So a huge congratulations to the authors for a great study – I hope it stimulates others to look beyond the ‘expected’ pollinators of flowers.

Photos: Nathália Susin Streher from the original paper.

More from the WorldFAIR Project: Agricultural biodiversity FAIR data assessment rubrics for plant-pollinator interactions

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The final deliverable from the WorldFAIR Project with which I’m involved has recently been published and can be freely downloaded from Zenodo by following the link below. The report is called “Agricultural biodiversity FAIR data assessment rubrics” and in it we present the results from a series of six pilot studies that adopted the FAIR* standards and our recommendations from the previous report.

This document complements the previous one by giving examples and setting out guidelines that allow researchers and practitioners to ensure FAIRness in their plant-pollinator interaction data.

Here’s the full reference:

Drucker, D. P., Salim, J. A., Poelen, J., Soares, F. M., Gonzalez-Vaquero, R. A., Devoto, M., Ollerton, J., Kasina, M., Carvalheiro, L. G., Bergamo, P. J., Alves, D. A., Varassin, I., Tinoco, F. C., Rünzel, M., Robinson, D., Cardona-Duque, J., Idárraga, M., Agudelo-Zapata, M. C., Marentes Herrera, E., Taliga, C., Parr, C.S., Cox-Foster, D., Hill, E., Maués, M.M. Agostini, K. Rech, A.R., Saraiva, A. (2024). WorldFAIR (D10.3) Agricultural biodiversity FAIR data assessment rubrics (Version 1). Zenodo. https://doi.org/10.5281/zenodo.10719265

Although this is the last formal deliverable from our WorldFAIR work package, it’s not the final output that we have planned. I’ll report back on the journal paper(s) that we are writing as and when they are published.

*Findable, Accessible, Interoperable & Reusable (or sometimes Reproducible)

Leveraging Biodiversity Net Gain to address invertebrate declines in England – a new pre-print is available

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Back in October I posted about a report I’d written that considered Biodiversity Net Gain (BNG) and what it could mean for pollinators. The report generated some interest and has helped to inform a study by University of Oxford PhD researcher Natalie (Nat) Duffus that has just been posted as a pre-print entitled “Leveraging Biodiversity Net Gain to address invertebrate declines in England” – here’s the link to it: https://ecoevorxiv.org/repository/view/6667/

In this work, Nat has asked a group of us who are interested in this topic to assess the limitations of the current BNG system and how it might be improved to better support invertebrate populations. Please do read the study and comment either on the blog or directly on the pre-print. We’re interested in people’s views on this and whether we have missed anything important.

Here’s the abstract:

Meeting ambitions such as the Global Biodiversity Framework 2030 targets will require multiple conservation mechanisms that benefit the widest possible range of habitats and species. Using England as a case study, here we evaluate the likely impact of a novel and ambitious ecological compensation policy, Biodiversity Net Gain (BNG), on terrestrial insects, spiders, and other arthropods (‘invertebrates’), a functionally important but rapidly declining component of biodiversity. Current implementation of BNG in England sets out to provide a 10% uplift in biodiversity when infrastructure development (such as housebuilding) occurs. However, BNG is a habitat-driven approach, which risks overlooking important considerations relevant to invertebrate conservation, threatens to further reduce the size and quality of their habitats, and may increase habitat fragmentation. BNG – as currently implemented – therefore represents a missed opportunity to use a universally applied policy to benefit invertebrates and other functionally important components of biodiversity. We suggest ways forward to realign BNG with what we know to be crucial for successful invertebrate conservation, and with other policy mechanisms such as the National Pollinator Strategy. This will ensure that appropriate habitats and conditions for invertebrates are retained, enhanced, and created at a landscape scale, and that BNG is optimised to contribute to broader national conservation targets. As biodiversity accounting and offsetting schemes such as BNG are increasingly adopted around the world, the experience of BNG in England provides valuable insights into how ecological compensation programmes could be better designed, implemented, and monitored to ensure that benefits for a wide variety of taxa are achieved.

Key tropical crops at risk from pollinator loss due to climate change and land use – a new study just published

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PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) is one of the most important sources of data for large-scale modelling of how changes in land use is impacting biodiversity. Marry that with future climate models and you have a powerful tool for understanding how these two major factors in global change will shape both biodiversity and human society over the coming decades.

In recent years it’s been a privilege to be part of a project led by Joe Millard and Tim Newbold that’s using PREDICTS to model how pollinators and pollination services are likely to be impacted by human activities. The first paper from that work (which was Joe’s PhD) was entitled ‘Global effects of land-use intensity on local pollinator biodiversity’ and came out in 2021, as I documented on my blog at the time.

Yesterday a second paper was published, this time focused on how land use and anthropogenic climate change interact to potentially affect insect-pollinated crops across the world.

Our main finding is that it’s tropical crops, especially cocoa, mango, watermelon, and coffee, that in the future will suffer the greatest negative impacts from loss of pollinators. Although we can have perfectly healthy diets without consuming any of those, they currently support tens of millions of farmers across the tropics and are part of global supply chains worth billions of dollars per year.

Here’s the full reference with a link to the paper, which is open access:

Millard, J., Outhwaite, C.L., Ceaușu, S., Luísa G. Carvalheiro, da Silva e Silva, F.D., Dicks, L.V., Ollerton, J. & Newbold, T. (2023) Key tropical crops at risk from pollinator loss due to climate change and land use. Science Advances 9, eadh0756

Here’s the abstract:

Insect pollinator biodiversity is changing rapidly, with potential consequences for the provision of crop pollination. However, the role of land use–climate interactions in pollinator biodiversity changes, as well as consequent economic effects via changes in crop pollination, remains poorly understood. We present a global assessment of the interactive effects of climate change and land use on pollinator abundance and richness and predictions of the risk to crop pollination from the inferred changes. Using a dataset containing 2673 sites and 3080 insect pollinator species, we show that the interactive combination of agriculture and climate change is associated with large reductions in insect pollinators. As a result, it is expected that the tropics will experience the greatest risk to crop production from pollinator losses. Localized risk is highest and predicted to increase most rapidly, in regions of sub-Saharan Africa, northern South America, and Southeast Asia. Via pollinator loss alone, climate change and agricultural land use could be a risk to human well-being.

Biodiversity Net Gain and what it could mean for pollinators – read the new report

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Biodiversity Net Gain (or BNG) promises to transform the way that we approach nature conservation in the UK. I’ve been giving a lot of thought to what this might mean for insect pollinators and have produced a new report that summarises the opportunities that BNG presents and how we can make the most of them. You can download a copy of that report by following this link.

This is meant to be a working document and as BNG progresses, and our understanding of its impacts on pollinators increases, I will update it. In the meantime, please do feel free to comment.

“Enemy release” of invasive plants is unpredictable – a new study just published

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The summer of 2019, before the COVID-19 pandemic turned the world on its head, feels like a very long time ago. Early in that summer, as I recounted on this blog, Zoe Xirocostas joined my research group for a while in order to collect data for her PhD on the comparative ecologies of plants that are native to Europe but invasive in Australia. That work has proven to be very successful, and the latest paper from Zoe’s PhD has just been published.

The paper focuses on the “enemy release hypothesis” (ERH), a well-studied concept in invasion ecology that nonetheless generates significant debate and disagreement. In essence, the ERH posits that the reason why so many species become invasive is that they leave their consumers, pathogens and parasites behind when they move to a new locality. Those “enemies” would normally reduce the fecundity of the invader, putting a brake on their population growth. But in their absence, the invader can become far more successful. Of course, as well as leaving “enemies” behind the invader also loses its “friends”, such as pollinators, seed dispersers, and defensive or nutritional partners. This “Missed Mutualist Hypothesis” is something that I’ve recently explored with Angela Moles, who was Zoe’s main supervisor, and other collaborators in Australia. Expect to hear more about this from Zoe’s work in the near future.

But back to the enemies. Drawing on the most extensive set of standardised comparisons yet collected of the same plants in native and invasive habitats, Zoe found that plants in the invasive populations suffer on average seven times less damage from insect herbivores, as predicted by the (ERH). Rather remarkably, however, the amount of enemy release enjoyed by a plant species was not explained by how long the species had been present in the new range, the extent of that range, or factors such as the temperature, precipitation, humidity and elevation experienced by the native versus invasive populations.

In other words, it’s extremely hard to predict the extent of enemy release based on historical and ecological considerations that one might expect to impose a strong influence.

The study has just appeared in Proceedings of the Royal Society series B and is open access. Here’s the reference with a link to the paper:

Xirocostas, Z.A., Ollerton, J., Tamme, R., Peco, B., Lesieur, V., Slavich, E., Junker, R.R., Pärtel, M., Raghu, S., Uesugi, A., Bonser, S.P., Chiarenza, G.M., Hovenden M.J. & Moles, A.T. (2023) The great escape: patterns of enemy release are not explained by time, space or climate. Proceedings of the Royal Society series B 290: 20231022.

Here’s the abstract:

When a plant is introduced to a new ecosystem it may escape from some of its coevolved herbivores. Reduced herbivore damage, and the ability of introduced plants to allocate resources from defence to growth and reproduction can increase the success of introduced species. This mechanism is known as enemy release and is known to occur in some species and situations, but not in others. Understanding the conditions under which enemy release is most likely to occur is important, as this will help us to identify which species and habitats may be most at risk of invasion. We compared in situ measurements of herbivory on 16 plant species at 12 locations within their native European and introduced Australian ranges to quantify their level of enemy release and understand the relationship between enemy release and time, space and climate. Overall, plants experienced approximately seven times more herbivore damage in their native range than in their introduced range. We found no evidence that enemy release was related to time since introduction, introduced range size, temperature, precipitation, humidity or elevation. From here, we can explore whether traits, such as leaf defences or phylogenetic relatedness to neighbouring plants, are stronger indicators of enemy release across species.

Should honey bee hives be placed on or near conservation sites?

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Earlier this week, the East Midlands Environment Agency proudly tweeted that they had placed honey bee hives on an ecologically important site that they own. As you might imagine, the response from pollinator experts such as myself, conservation NGOs, and some beekeepers, was not positive, as you can see if you look at the comments beneath my tweet:

By coincidence, overnight I received a message from someone in the USA asking for advice. Here’s a redacted version of their message:

My community has a 4 acre serpentine barren site that is part of a larger string of these unique barrens ….. Honey bee hives have recently been located adjacent to the barrens. Can you advise me as to the best way to determine whether there are, and to document any, adverse effects to the serpentine barrens native pollinators?

The question of how managed honey bees can impact wild pollinators and the pollination of wild plants is one that frequently comes up in the talks and training that I do. Many beekeepers share these concerns – see for example this very detailed blog post by Mark Patterson.

Going back to the question of how to assess any impacts, the simple answer is that it’s not easy and it relies on having good data. This was my response to my American correspondent:

Ideally you would need to take a before-and-after approach where you have data on things like number of native pollinator species, their abundance (including nest sites), rates of visitation of different pollinators to flowers, and fruit or seed set from particular plants. You’d then compare what was going on before the hives arrived with what’s occurring since their arrival.

If you don’t have the “before” data it’s much more difficult to assess if there has been an impact from the honey bees. However, the advice of most conservation groups is to adopt the “precautionary principle” and not site hives on or adjacent to areas of nature conservation value, especially if they are relatively small areas. See for example the Bumblebee Conservation Trust’s advice: https://www.bumblebeeconservation.org/managed-honeybees/

The precautionary principle is a well established concept across a range of areas, including health and engineering, as well as nature conservation. In the latter it needs to be more widely applied, especially when it comes to questions of where to site honey bee hives, and how many.

Managing railway assets for biodiversity – new guidance just published

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Last year I posted about the work that I’ve been doing on railways and biodiversity with UIC – the International Union of Railways – and the UK Centre for Ecology & Hydrology. That work is now complete and the second of our two reports called UIC Guidelines on Managing Railway Assets for Biodiversity is now out.

UKCEH has produced a press release and I’m copying it verbatim below:

New guidelines for the management of Europe’s railway network to protect and enhance biodiversity have been published.

The UK Centre for Ecology & Hydrology (UKCEH) has worked with the International Union of Railways (UIC), the professional association representing rail companies across the world, to provide technical recommendations and key design features for incorporating and enhancing habitats within the existing European network and new line upgrades, providing examples of best practice.

The UIC European region comprises 118-member companies from 39 countries, amounting to 350,000 kilometres of rail network.

Professor Richard Pywell, Head of Biodiversity at UKCEH who is one of the lead authors of the report, said: “We worked closely with railway companies across Europe to distil the best available knowledge on managing railway assets to benefit nature. For each asset, we considered the most effective measures to protect and restore biodiversity, and how to monitor the outcomes of these interventions.”

Another report author, independent consultant Professor Jeff Ollerton, added: “Working with UIC on this project has revealed just how important the land managed by Europe’s railway companies is for nature. The next step is to better understand how nature supports Europe’s economy, and the health and wellbeing of its people.”

The authors used the widely-adopted mitigation hierarchy approach which guides, developers on protecting existing habitats and ecosystems where possible.

The new UIC Guidelines for Managing Railway Assets for Biodiversity have been drawn up as part of the REVERSE project, in which UIC has worked with its members and UKCEH to formulate a collective vision for protecting and enhancing biodiversity across the European rail network. They now form part of the European Railways: Strategy and Action Guide to ensure management for biodiversity is embedded at every level of the railway business, alongside safety, performance and sustainability. The adoption of the guidelines by member companies will be promoted through various UIC meetings and online events.

The REVERSE project comprises more than 20 European rail companies including Network Rail and SNCF as well as WWF (Worldwide Fund for Nature).

In 2021, UKCEH worked with Network Rail to draw up the rail company’s Biodiversity Action Plan to inform lineside habitat management across the UK. This involved using high-resolution imagery from satellites and aircraft to produce a detailed national map of all the habitats alongside the rail network.

Plant-based diets are a problem for bees! A new study of the significance of the ratio of food K:Na in bee ecology and evolution

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At the moment Karin and I are in the UK for a couple of weeks. I had work to do as an external examiner at the University of Swansea, plus we wanted to catch up with some family and friends. Our main base has been the home of our mates Ian and Simone and we’ve enjoyed some warm, muggy evenings sitting in their garden chewing the fat. Every now and again my eyes have been drawn to the activities of bumblebees as they move in and out of the foliage of a small Silver Fir. The bees are attracted to the large colonies of an aphid that is feeding on the tree’s trunk, from which they are collecting honeydew, as you can see in the photograph above.

When we think of the diets of bees we automatically think “nectar and pollen”. Honeydew, as a sugar-rich fluid, fits broadly into this concept, though as far as I know there’s been little study of its relative importance as a food source for bees. Aside from a few “vulture bees”, all of the 20,000 or so species are vegetarian. And therein lies a problem. Bees evolved from carnivorous wasps and so the evolution of bees, and their complex ecologies, is tied into this profound dietary shift toward a plant-based diet.

A particular issue that has hardly been investigated until recently is that the ratio of elements within meat is very different to that of plants. In particular, animal tissue has a high ratio of sodium (Na) relative to potassium (K), whereas for plants the ratio is reversed – high ratio of K:Na.

In a new conceptual review paper with my colleagues Zuzanna Filipiak and Michał Filipiak, we have explored the implications of this difference in elemental ratios for bee ecology and evolution, and for the conservation of these important insects. The paper is open access and you can download a copy by following a link in this reference:

Filipiak, Z.M., Ollerton, J. & Filipiak, M. (2023) Uncovering the significance of the ratio of food K:Na in bee ecology and evolution. Ecology e4110. https://doi.org/10.1002/ecy.4110

Here’s the abstract:

Bees provide important ecological services, and many species are threatened globally, yet our knowledge of wild bee ecology and evolution is limited. While evolving from carnivorous ancestors, bees had to develop strategies for coping with limitations imposed on them by a plant-based diet, with nectar providing energy and essential amino acids and pollen as an extraordinary, protein- and lipid-rich food nutritionally similar to animal tissues. Both nectar and pollen display one characteristic common to plants, a high ratio of potassium to sodium (K:Na), potentially leading to bee underdevelopment, health problems, and death. We discuss why and how the ratio of K:Na contributes to bee ecology and evolution and how considering this factor in future studies will provide new knowledge, more accurately depicting the relationship of bees with their environments. Such knowledge is essential for understanding how plants and bees function and interact and is needed to effectively protect wild bees.

Pesticides and pollinators: please sign this petition!

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As part of our roles as ambassadors of the new conservation organisation Restore (more of which later this year), several of us including Dave Goulson, George McGavin, and myself, are promoting this online petition to get the government to take the issue of neonicotinoid pesticides seriously. Here’s some text from Dave explaining the situation with a link to a petition that you can sign:

“For three years in a row our government has granted farmers special permission to use banned neonicotinoid pesticides on sugar beet. This is contrary to the expert advice of their own Expert Committee on Pesticides, who specifically recommended that permission should not be granted.  It also flies in the face of a huge body of scientific evidence showing that these chemicals are phenomenally toxic to all insect life, and that their use on any crop contaminates soils, hedgerow plants, and nearby streams and ponds for years to come. We are in a crisis, with insect populations in freefall. It is about time our government woke up to this, and acted accordingly. This petition https://petition.parliament.uk/petitions/631948 is a necessary means of holding the government to account. Please sign and share, as signing will ensure the issue is debated in Parliament.”

This petition now has more than 15,000 signatures which ensures that it gets a response from the Government. If it reaches 100,000 mark, it will trigger a debate in Parliament. Please sign and promote this important initiative!