Category Archives: Pollination

How old are the flowering plants? A new study aims to reconcile the fossil and DNA evidence – but what does it mean for pollinators?

Yesterday I was contacted by a journalist to give a comment on a paper that’s just been published in Nature Ecology and Evolution:

Silvestro, D., Bacon, C.D., Ding, W. et al. (2021) Fossil data support a pre-Cretaceous origin of flowering plants. Nature Ecology and Evolution https://doi.org/10.1038/s41559-020-01387-8

I was happy to do so as it adds a fascinating twist to a long-standing interest of mine: when did the angiosperms evolve and what role did pollinators play in that evolution?

In the end they didn’t use the text that I sent back to them, so I thought that I’d share it on the blog:

The evolution of the angiosperms was arguably one of the most significant events in the history of life on Earth, but the timing of the origin of this group of plants remains a hotly debated topic, with conflicting evidence coming from the fossil record and molecular biology. This important new study has developed a novel statistical approach to reconcile these two lines of evidence, and comes down firmly on the side of the molecular evidence to conclude that angiosperms originated much earlier than the fossil record suggests. This will be sure to stir up further debate that can only be resolved by finding well preserved and accurately interpreted fossils of an appropriate age. In the future I would like to see Silvestro et al.’s technique applied to the major groups of pollinators such as bees and wasps (Hymenoptera) and butterflies and moths (Lepidoptera) where there is likewise a discrepancy between what the fossils and DNA are telling us. Pollinators have had a profound influence on angiosperm evolution and we might expect a close correlation between the origin and subsequent diversification of these different groups of organisms. This would certainly support the findings from Silvestro et al.’s study. It’s an exciting time for researchers in this field: a world without flowers and pollinators would look very different

Climate change history affects contemporary pollination systems – a new study just published

Illustration of Curatella americana and its pollinators by Pedro Lorenzo

The distribution of plants, animals and other organisms that we see around us is clearly influenced by climate: all species have limitations in terms of temperature, rainfall, etc., that affects where they can live and reproduce. As well as these contemporary “climatic niches” however, there are much more subtle effects of historical climate on species, and the ways in which they interact with one another. These are harder to study because it requires us to know about what climatic conditions were like in a particular region thousands or millions of years ago. But as our knowledge of paleoclimates grows, we can apply it to understand how contemporary ecology is shaped by the past. This in turn may tell us how species will react to future climate change.

In a new study that I’ve just published with Brazilian, Danish and American colleagues, we’ve shown that the frequency with which a South American savannah tree self-pollinates is determined mainly by the climatic stability experienced by a population since the Last Glacial Maximum. In contrast, and perhaps surprisingly, the current diversity and abundance of pollinators plays a much smaller role in how often plants self-pollinate.

The work was led by André Rodrigo Rech and formed part of his original PhD research. Here’s the full citation:

Rech, A.R., Ollerton, J., Dalsgaard, B., Jorge, L.R., Sandel, B., Svenning, J.-C., Baronio, G.J. & Sazima, M. (2021) Population-level plant pollination mode is influenced by Quaternary climate and pollinators. Biotropica (in press)

The abstract is below, first in English then in Portuguese. If anyone wants a PDF please add a comment or send me a message via my Contact page.

Abstract:

Patterns in ecology are the products of current factors interacting with history. Nevertheless, few studies have attempted to disentangle the contribution of historical and current factors, such as climate change and pollinator identity and behavior, on plant reproduction. Here, we attempted to separate the relative importance of current and historical processes on geographical patterns of the mating system of the tree species Curatella americana (Dilleniaceae). Specifically, we asked the following: (a) How do Quaternary and current climate affect plant mating system? (b) How does current pollinator abundance and diversity relate to plant mating system? (c) How does mating system relate to fruit/seed quantity and quality in C. americana? We recorded pollinators (richness, frequency, and body size) and performed pollination tests in ten populations of C. americana spread over 3,000 km in the Brazilian savannah. The frequency of self‐pollination in the absence of pollinators was strongly influenced by historical climatic instability and not by present‐day pollinators. In contrast, seed set from hand‐cross and natural pollination were affected by pollinators (especially large bees) and temperature, indicating the importance of current factors on out‐cross pollination. Two populations at the Southern edge of the species’ distribution showed high level of hand‐cross‐pollination and high flower visitation by large bees, but also a high level of autogamy resulting from recent colonization. Our results indicate that historical instability in climate has favored autogamy, most likely as a reproductive insurance strategy facilitating colonization and population maintenance over time, while pollinators are currently modulating the level of cross‐pollination.

Resumo:

Os padrões em ecologia são o produto de fatores contemporâneos interagindo a partir de uma bagagem histórica. Apesar desse reconhecimento, poucos estudos se ativeram em separar as contribuições dos fatores históricos e atuais como o clima, a identidade e comportamento de polinizadores sobre a reprodução de plantas. Neste trabalho nós decompomos a importância relativa dos processos contemporâneos e históricos no padrão geográfico do sistema reprodutivo da árvore comum no Cerrado, Curatella americana (Dilleniaceae). Especificamente nós perguntamos a) como o clima do presente e do quaternário afetam o sistema reprodutivo? b) Como a abundância e diversidade de polinizadores afeta o sistema reprodutivo da planta atualmente. c) Como o sistema reprodutivo se relaciona com a quantidade e qualidade dos frutos produzidos em C. americana? Para responder estas questões, nós registramos os polinizadores (riqueza, frequência e tamanho corporal) e realizamos testes de polinização em 10 populações de C. americana distribuídas em mais de 3.000 km de Cerrado no Brasil. A frutificação com autopolinização foi fortemente influenciada pela instabilidade climática do passado e não teve relação com os polinizadores no presente. Em contraste, a frutificação com polinização cruzada manual e natural foi afetada pelos polinizadores (especialmente abelhas grandes) e pela temperatura atual, revelando o papel de fatores ecológicos sobre a polinização cruzada. Duas populações na borda sul da distribuição de C. americana apresentaram alto nível de frutificação com polinização cruzada manual e altas taxas de visitação floral por abelhas grandes, mas também apresentaram alto nível de autogamia interpretadas como resultado da recente colonização dessas áreas. Nossos resultados indicam que a instabilidade climática do passado promoveu a autogamia como uma estratégia de segurança reprodutiva capaz de facilitar a colonização e manutenção de populações nesses locais com polinizadores imprevisíveis. Em contrapartida, nos locais com disponibilidade de polinizadores a polinização cruzada foi intensificada revelando a como processos históricos e contemporâneos atuam de forma sinérgica sobre o sistema reprodutivo das plantas.

Why did I write the book? An interview with NHBS

The nice people at NHBS recently did a wide-ranging interview with me about my new book Pollinators & Pollination: Nature and Society and what led me to write it. It covers a lot of ground, including climate change, food security, the UK Pollinator Monitoring Scheme, and growing up in Sunderland.

Here’s the link:
https://www.nhbs.com/blog/jeff-ollerton-pollinators-pollination

Flowers can be assholes – quite literally!

2003-572 s G Bochum

WARNING: There’s a high yuck factor to this post, it’s not for the squeamish or easily offended!

One of my Twitter contacts, Traci Birge in Finland, has been reading Pollinators & Pollination: Nature and Society, and making some very nice comments about it. I had to laugh at this one in which she describes some plants as “assholes” because of the way in which they deceive pollinators into visiting their flowers but offer no reward in return:

If you follow that thread you can see that Traci was closer to the truth than perhaps she realised: there are some plants with flowers that appear to mimic the anuses of dead mammals, particularly in the families Apocynaceae and Araceae. By their smell, texture, colour and hairiness they are fooling flies into visiting the flowers, because assholes, like any mammalian orifice, provide an entry point for maggots of carrion-feeding flies. Sometimes the deception is so great that the flies lay their eggs on these blooms, though of course the maggots starve.

A great example of an anus-mimicking bloom is the Dead Horse Arum (Helicodiceros muscivorus). Check out the image above: if that doesn’t look like a horse’s ass, I don’t know what does!

Other examples might be found within the stapeliads, especially the genus Huernia which often have a thickened annulus to the centre of the flower. However that could also be interpreted as mimicking an open, inflamed wound on the side of an animal:

As I point out in the book, you might imagine that there would be strong natural selection against flies visiting these flowers if they lose fitness by laying eggs on such an unsuitable substrate. But the flowers are tapping into really deep-seated behaviours and clearly the flies can’t distinguish the flowers from the real thing.

This is flower pollination that is far removed from the deliciously perfumed, cute-and-cuddly, heart-warming world of bees and flowers. Isn’t nature wonderful?

All photos from Wikipedia, as follows:

Helicodiceros muscivorus: Göteborgs botaniska trädgård (photographer: Ingemar Johansson) – http://www.mynewsdesk.com/se/pressroom/goteborgs_botaniska_tradgard/image/view/dracunculus-muscivorus-128973, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=19265330

Huernia zebrina: Enzo^ – Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=10963668

Huernia schneideriana: Juan Carlos Fonseca Mata – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=94705877

Plant-pollinator networks in Australian urban bushland remnants are not structurally equivalent to those in residential gardens – a new study just published

Towns and cities are ecologically complex environments where nature finds a home in all sorts of places, including both highly artificial gardens created by people, and the fragments of natural environment left behind when developments are built. In a new study that I’ve co-authored with Australian researcher Kit Prendergast we’ve for the first time compared and contrasted the pollinators, and the plants that they visit, in urban settings in the the biodiversity hotspot of Western Australia. Full disclosure: the field work was all done by Kit as part of her PhD. I just acted as an “adopted supervisor” (her words!) to help with data analysis and writing up of the work.

I think that it’s a great study, not least because it really highlights just how different gardens are to remnant natural vegetation. If we are to maintain the maximum possible pollinator diversity, and associated pollination services, we need to retain as much remnant vegetation as possible when designing and building new developments. Gardens alone are not enough.

The study details are:

Prendergast, K.S. & Ollerton, J. (2021) Plant-pollinator networks in Australian urban bushland remnants are not structurally equivalent to those in residential gardens. Urban Ecosystems https://doi.org/10.1007/s11252-020-01089-w

The abstract is below; if you’d like a PDF of the paper please use the form on the Contact page.

Abstract

Urbanisation is a prominent and increasing form of land-use change, with the potential to disrupt the interactions between pollinators such as bees and the flowering plants that they visit. This in turn may cause cascading local extinctions and have consequences for pollination services. Network approaches go beyond simple metrics of abundance and species richness, enabling understanding of how the structure of plant-pollinator communities are affected by urbanisation. Here we compared pollination networks between native vegetation (bushland) remnants and residential gardens in the urbanised region of the southwest Australian biodiversity hotspot. Across fourteen sites, seven per habitat, plant-bee visitor networks were created from surveys conducted monthly during the spring-summer period over two years. Extinction slope (a measure of how extinctions cascade through the network), and network robustness and nestedness were higher for bushland remnants, suggesting that networks in bushland remnants had greater functional integrity, but if disrupted, more cascading extinctions could occur. In contrast, niche overlap between pollinators was higher in residential gardens, suggesting greater competition for resources. Most species-level properties did not differ between habitats, except for normalised degree, which was higher in bushland remnants. In conclusion, it appears that pollination networks in managed residential gardens are not structurally equivalent with those in bushland remnants. This has implications for conservation of wild bee assemblages in this biodiversity hotspot, and suggests removal of remnant native vegetation for residential development could disrupt the integrity of plant-pollinator assemblages.

“Bee Together” with YDMT – pollinator online talks during January and February

As I write a slow haze of fine snow is falling, covering our garden with a thin white dusting. Spring feels a long way off, despite the emerging spears of daffodil leaves. But you can get a taste of what the new season will bring by signing up for a short series of free evening online talks on the topic of pollinators that has been organised by the Yorkshire Dales Millennium Trust – here’s the link for the Bee Together programme – and here’s more details of the talks:

Thursday January 28 at 7pm: Pollinators and Pollination: Nature and Society
An overview of the diversity of pollinators in Britain, why they are important, and the threats to that diversity with Jeff Ollerton.

Thursday February 18 (7pm): The B-Lines Project
Buglife’s B-Lines network is an imaginative solution to the problem of the loss of flowers and pollinators. B-Lines are a series of ‘insect pathways’ running through our countryside and towns, along which Buglife are restoring and creating a series of wildflower-rich habitat stepping stones. Catherine Jones talks about mapping the recently completed B-Lines map and some of the projects that have already created habitat for pollinators.

Thursday February 25 (7pm): The Hidden Lives of Garden Bees
Brigit Strawbridge Howard will explain some of the basic differences between bumblebees, solitary bees, and honeybees – including lifecycles and nesting behaviour; the problems they all face; and, most important, what we can do to help. Brigit is a wildlife gardener, amateur naturalist and advocate of bees. She writes and campaigns to raise awareness of the importance of native wild bees, and is the author of Dancing with Bees: A Journey Back to Nature.

I hope to see some of you there: Happy New Year everyone!

A Christmas discount for my new book and some recent social media comments

Pollinators are responsible for producing much of the traditional Christmas food that we enjoy at this time of the year, and add considerable value to the holly and mistletoe that decorates our homes in northern Europe and elsewhere. The link between pollinators and Christmas is something that I discuss in my new book Pollinators & Pollination: Nature and Society. As a special seasonal gift, the publishers (Pelagic) are offering a 30% discount on orders in the run up to Christmas. To claim the discount follow that previous link and use the code CHRISTMAS30 at the checkout. UPDATE: Apologies, the publisher tells me that the discount period has now passed.

Although the book has not yet been formally reviewed in any journal or other form of media, I’ve had some very nice (and unsolicited) comments about it via Twitter . Here’s some examples:

This new book is SUPERB. It contains everything I’ve spent the last 10 years trying to grasp, all in one book, AND written in a way I can understand! I cannot tell you how much I’m learning from it already. It makes such a difference to a non-scientist (like me) to be able to grasp the facts, and the science behind the facts, without having to first look up dozens of terms I don’t understand.

Brigit Strawbridge Howard – author of Dancing With Bees

Good to see discussions of ecology, culture and politics together.

Anon

I was delighted to receive this superb book over the weekend. It’s an extremely informative read for anyone interested in the subject of pollination!

Anon

Looking forward to reading this. I like the tone of what I’ve dipped into so far, really engaging and none of that turgid academic English that gives me a headache!

Steven Falk – author of Field Guide to the Bees of Great Britain and Ireland

Thanks everyone!

Finally, a physical copy of my book!

Yesterday I was delighted to finally receive an advance copy of my book Pollinators & Pollination: Nature and Society! It’s been over three years in the writing and production, much longer than I had anticipated. But, as I describe in its pages, the book is the culmination of >50 years of experience, study and research. So perhaps three years isn’t so bad…

If you’re interested in buying a copy you can order it direct from Pelagic Publishing and from most of the large online booksellers. Let me know what you think.

Why are bees like Bactrian camels? Because they both have two humps!

It was eminent bee biologist Charles Michener who first* pointed out that there was something odd about the global distribution of bees. In his 1979 paper Biogeography of the bees he writes:

“unlike many groups which abound in the tropics, bees attain their greatest abundance in warm temperate areas”

Think about that for a moment: in contrast to most other groups of insects, birds, mammals, flowering plants, fish, indeed the majority of the Earth’s biodiversity, bees are NOT generally at their most species rich in tropical areas. Rather, we have to move north and south of the equator to find them at their highest diversity. This is an odd pattern of distribution for such a successful (> 20,000 species), globally widespread and ecologically important group of organisms.

Some 15 years ago I was inspired by Michener’s comments when, together with colleagues Steve Johnson and Andrew Hingston, we wrote a chapter called Geographical variation in diversity and specificity of pollination systems for the 2006 Waser & Ollerton edited volume Plant-pollinator Interactions: from Specialization to Generalization. In that chapter we presented a rough analysis of how bee diversity per unit area in different countries changes with latitude. This, and a follow-up that appeared in my 2017 Annual Review of Ecology, Evolution and Systematics paper, confirmed Michener’s view that there’s an unusual relationship between bee diversity and latitude, with peak species richness outside of the tropics, in warm, dry environments.

What I really hoped over this time was that some serious bee biologists would follow up Michener’s insights and produce a full analysis of how bee diversity changes across the planet. Yesterday that hope was realised when Michael Orr, Alice Hughes, Douglas Chesters, John Pickering, Chao-Dong Zhu and John Ascher published the first analysis of bee diversity across the whole planet, and its underlying causes, in their open-access paper Global Patterns and Drivers of Bee Distribution.

Their analyses are based on a data set of >5,800,000 records of where bees occur and it’s been an incredible achievement to bring all of that together into a planet-wide view of where bees are found, and why. I highly recommend that you download and read it, it’s an impressive piece of work.

What have camels got to do with all of this? Well, as the authors show in their paper (from which the image above is taken), if you graph up the increase in bee species richness with latitude from the poles in each hemisphere, you get two humps at about 35 degrees north and south of the equator: like a Bactrian camel. In contrast, as I noted above, if you were to do the same for for most other species you’d get a single hump at the equator: like a dromedary camel.

One of the key drivers of this bimodal pattern seems to be the amount of rainfall in an environment – bees do not like it too wet, in contrast to their relatives the ants which do show the more typical tropical peak in diversity. As the authors put it:

“humidity may play a key role in limiting bee distribution, such as through spoilage of pollen resources”

One of the implications of this for the biogeography of plant-pollinator interactions is that we might expect there to be a greater diversity of different types of pollinators in areas where bees are not so abundant. And indeed that is exactly what we find: in that Ollerton, Johnson and Hingston book chapter I mentioned we showed that there’s a step-change in the diversity of functionally specialised pollination systems as one moves from the sub-tropics into the tropics. There could be many reason for that but I suspect that one is a relative lack of bees compared to the number of plants species; thus you get tropical “oddities” such as specialised cockroach pollination in some plants.

Orr et al.’s paper is a milestone in bee biogeography and opens up new opportunities for conserving these insects, and their vital relationships with the flowering plants. To give just one example: these analyses provide a framework for predicting bee diversity hotspots in parts of the world that have been poorly explored by bee taxonomists, but which are nevertheless severely threatened by habitat degradation and conversion to agriculture. It could also be used for predicting how climate change might affect future bee distributions, especially in parts of the world that are expected to become wetter. I’m looking forward to seeing how the team’s work develops in the future.

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*It’s always risky to state “first”, but Michener was certainly the first that I am aware of. Let me know if you’ve come across any precedents.

SCAPE 2020 by the numbers

Last Friday to Sunday I hosted the annual Scandinavian Association for Pollination Ecology (SCAPE) conference virtually. This is my first opportunity to report back as I took some time off and then tried to catch up with other tasks.

Running any scientific conference is hard work, and virtual ones are no exception! On Monday I was exhausted after a marathon long weekend of three 10-hour days in front of a computer chairing sessions, queuing up speakers and their talks, and generally making sure things ran as smoothly as possible. Of course before that there were literally weeks of preparation, and since then I have been doing follow up work of responding to emails, sending out certificates and receipts, etc.

It’s been quite a job and I couldn’t have done it with the help of my wife Karin (especially for the loan of her office space in the garden) and also Yannick Klomberg who was working on the website, dealing with the posters, etc., all on top of having a week old baby and his partner to look after! In addition I’m grateful to Paul Egan who ran the SCAPE Twitter account, and the session Chairs, keynote speakers, and participants who contributed to a really amazing conference. Our technical support crew from the University of Northampton were great too.

It was the largest SCAPE meeting so far held, no doubt because it was the first to be carried out virtually, with 352 participants from 41 countries listening to and chatting about 92 talks and viewing 39 posters. We also ran several well-attended evening discussion and poster sessions.

Long-standing SCAPEr Marcos Mendez kept a log of the number of participants in each of the sessions and I’ve graphed the data below, showing the broad themes of each group of sessions:

It’s pleasing to see that attendance was reasonably consistent over the course of the long weekend and that there was interest across the full spectrum of themes. The one downward blip was in session 5, which I can only surmise was due to it being the final session on Friday between 17:25 and 18:25.

As is traditional at SCAPE we announced the host of next year’s meeting at the very end. I’m delighted to announce that SCAPE 2021, the 35th annual meeting, will be held for the first time in Poland, where Marcin Zych will be the host. “Wider Scandinavia” just got wider….