Category Archives: Pollination

Plant-pollinator networks in the tropics: a new review just published.


As an ecologist who has carried out field work in the temperate zone (UK), the subtropics (Tenerife and South Africa) and the tropics (parts of South America, Africa and Australia)  I’ve always found the idea that the study of ecology can be divided into “tropical” and “non-tropical” a bit odd.  It’s as if the way that the natural world works somehow changes at about 23 degrees north or south of the equator, making things “different” around the equator.  The tropics are a very special, diverse place, it’s true, but so are many places outside the tropics.

With this in mind I was pleased when I was asked by some of my Brazilian colleagues to contribute to a chapter in a new book entitled Ecological Networks in the Tropics. It was an opportunity to review what is known about plant-pollinator networks in the tropics and the ways in which they are very similar to such networks at lower latitudes. Here’s the details of the chapter, followed by the abstract.  If anyone wants a copy please drop me an email:

Vizentin-Bugoni J, PKM Maruyama, CS Souza, J Ollerton, AR Rech, M Sazima. (2018) Plant-pollinator networks in the tropics: a review. pp 73-91 In Dáttilo W & V. Rico-Gray. Ecological networks in the Tropics. Springer.


Most tropical plants rely on animals for pollination, thus engaging in complex interaction networks. Here, we present a global overview of pollination networks and point out research gaps and emerging differences between tropical and non-tropical areas. Our review highlights an uneven global distribution of studies biased towards non-tropical areas. Moreover, within the tropics, there is a bias towards the Neotropical region where partial networks represent 70.1% of the published studies. Additionally, most networks sampled so far (95.6%) were assembled by inferring interactions by surveying plants (a phytocentric approach). These biases may limit accurate global comparisons of the structure and dynamics of tropical and non-tropical pollination networks. Noteworthy differences of tropical networks (in comparison to the non-tropical ones) include higher species richness which, in turn, promotes lower connectance but higher modularity due to both the higher diversity as well as the integration of more vertebrate pollinators. These interaction patterns are influenced by several ecological, evolutionary, and historical processes, and also sampling artifacts. We propose a neutral–niche continuum model for interactions in pollination systems. This is, arguably, supported by evidence that a high diversity of functional traits promotes greater importance of niche-based processes (i.e., forbidden links caused by morphological mismatching and phenological non-overlap) in determining which interactions occur, rather than random chance of encounter based on abundances (neutrality). We conclude by discussing the possible existence and direction of a latitudinal gradient of specialization in pollination networks.



Filed under Bees, Biodiversity, Biogeography, Macroecology, Mutualism, Pollination

XI International Symposium on Pollination, Berlin, April 16th -20th, 2018


From the organisers:

Dear Pollination Biologists,

The International Commission for Pollinator-Plant Relationships (ICPPR) invites you to attend, and possibly submit abstracts for. the XI International Symposium on Pollination TO BE HELD IN BERLIN, GERMANY, APRIL 16-20 2018.

Please take advantage of the early-bird registration opportunity.

The deadline for Abstract submissions is MARCH 1ST, 2018



Carlos H. Vergara



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Filed under Bees, Biodiversity, Ecosystem services, Honey bees, Pollination

Something for Blue Monday – the only known blue flowered asclepiad

Tweedia caerulea - OBG 2014-11-06 11.33.14

Today is Blue Monday – reckoned to be the most depressing day of the year, though I’m in a very good mood: just back from a great 9am seminar with my final year students taking the Biodiversity & Conservation module.  They presented some really interesting, diverse and thought provoking papers as part of their assessment for this module; it’s a great group to teach.

But if you are suffering from the blues this morning, here is a photograph to cheer you up.  As far as I am aware Tweedia caerulea (also known as Oxypetalum coeruleum)  is the only known blue flowered asclepiad (that’s to say, a member of the family Apocynaceae subfamily Asclepiadoideae – what used to be the family Asclepiadaceae*).

No one is sure why blue is such a rare colour within the asclepiads (and indeed the Apocynaceae as a whole) and it may be connected to the pollination system of this plant.  However we don’t know what pollinates Tweedia caerulea in the wild so it’s hard to test that idea; other species within this group are variously pollinated by wasps, bees, flies, moths, etc.  Truly blue flowers (as opposed to some shade of purple or violet) are relatively uncommon generally amongst the flowering plants and the source of much interest and excitement in those groups where they do occur, for example the Himalayan Poppies (Meconopsis).

Tweedia caerulea is easy to grow from seed but not so easy to get through the winter in the UK, so in the past I’ve grown it as an annual in the garden.  Apart from the colour, one of the other reasons I like this plant is that it’s named after the 19th century plant collector John Tweedie whose life I’ve been researching over the past 20 years or so – see this paper for example.



*The asclepiads are my favourite group of plants, and one that I’ve published quite a bit of research on, so I was a bit miffed when the taxonomic rank of the family was relegated to subfamily.  But it makes evolutionary sense and now gives me a much larger family of plants on which to research, so every cloud etc. etc.


Filed under Apocynaceae, Biodiversity, Gardens, John Tweedie, Pollination

The holly, the mistletoe, and the pollinators: an update on an old story


Holly and mistletoe are two of Europe and Scandinavia’s most iconic plants, steeped in folklore and cultural significance, and redolent of the dark days of mid-winter and its festivities.  Last year, together with my colleagues Jim Rouquette and Tom Breeze, I published a study of the value that pollinators add to the wholesale auction prices of these two plants using data from the UK’s largest holly and mistletoe auction that has been held in the town of Tenbury Wells for 160 years.

Holly and mistletoe are excellent subjects for a study of the added value that pollinators bring to a crop as they are 100% reliant on pollination by a range of wild bees, flies and other insects.  This is because both species are dioecious with separate sex plants, therefore any berries produced on a female plant must be due to the activities of pollinators.

Here’s a link to last year’s blog post about that paper and here’s the reference for the paper itself, with a link to the journal where you can download it for free:

Ollerton, J., Rouquette, J.R. & Breeze, T.D. (2016) Insect pollinators boost the market price of culturally important crops: holly, mistletoe and the spirit of Christmas. Journal of Pollination Ecology 19: 93-97

The data set in that paper only developed the story up to 2015 as the 2016 auctions took place too late to include within our analyses.  However I’ve collected the auction reports for 2016 and 2017 and added them to the data set.  The results are graphed below*.

The auction price for holly with berries is rather volatile, but on average over this time period, berried holly has twice the commercial value of holly without berries.  Indeed in the last auction of 2017, holly without berries failed to sell, hence the value of £0.00.  The very wintry weather on the auction day reduced the number of buyers, but nonetheless, to have no one bidding for the unberried holly was unprecedented.

Holly auction prices plot

The pattern for mistletoe is rather similar, but in this case the value of berried material is less volatile than that of holly, and the average value is around three times greater than for auction lots of unberried plants.

Mistletoe auction plot

This data set offers a unique insight into the value of pollinators for two culturally important crops (all other such studies have focused on food or, rarely, fibre crops).  I’ll continue to archive the auction reports and to update these analyses every few years in the run up to Christmas.  If anyone is interested in accessing the data, please drop me a line.

If you want to learn more about the botany of different types of mistletoe follow this link to Mike Fay’s blog post on the Kew website.

Also worth checking out is Manu Saunders’ recent piece highlighting some old Christmas-themed blog posts.

Yesterday was my last day in the office, I’m now officially on leave and looking forward to a restful Christmas and New Year break.  Season’s greetings to all of my readers and thank you for your continued support and interest in biodiversity!



*There are three auctions each year and therefore three data points per annum, except for 2016 when only two auction reports were produced.


Filed under Biodiversity and culture, Ecosystem services, Pollination

Local and regional specialization in plant–pollinator networks: a new study just published

Euphorbia canariensis pollinators 2016-04-29 17 58 00

A fundamental feature of the natural world is that no species exists in isolation: all organisms interact with other organisms during their lives. These interactions take many forms and the outcome varies with the type of interactions. For example predator-prey interactions are clearly negative for the prey species, but positive for the predator. Other interactions result in positive outcomes for both species, including relationships between pollinators such as bees, birds and flies, and the flowers that they pollinate. An important feature of such interactions is how specialized or generalized it is; that is, how many different pollinators are actually involved in pollinating a particular type of flower, or how many types of flower does a specific pollinator visits.

In a newly published study, I have collaborated with colleagues from Denmark and Brazil to assess how local specialization (within a community) relates to regional specialization (across communities) using two separate data sets from the Brazilian rupestrian grasslands and Canary Island/North African succulent scrub vegetation.

Here’s the citation with a link to the paper (drop me a line if you can’t access it and need a PDF):

Carstensen, D.W., Trøjelsgaard, K., Ollerton, J. and Morellato, L.P.C. (2017) Local and regional specialization in plant–pollinator networks. Oikos (in press) doi:10.1111/oik.04436

The abstract is as follows:

“Specialization of species is often studied in ecology but its quantification and meaning is disputed. More recently, ecological network analysis has been widely used as a tool to quantify specialization, but here its true meaning is also debated. However, irrespective of the tool used, the geographic scale at which specialization is measured remains central. Consequently, we use data sets of plant–pollinator networks from Brazil and the Canary Islands to explore specialization at local and regional scales. We ask how local specialization of a species is related to its regional specialization, and whether or not species tend to interact with a non-random set of partners in local communities. Local and regional specialization were strongly correlated around the 1:1 line, indicating that species conserve their specialization levels across spatial scales. Furthermore, most plants and pollinators also showed link conservatism repeatedly across local communities, and thus seem to be constrained in their fundamental niche. However, some species are more constrained than others, indicating true specialists. We argue that several geographically separated populations should be evaluated in order to provide a robust evaluation of species specialization.”

This is what those two different habitats look like:

If you would like more information on plant-pollinator networks, including details of an edible game for Christmas (!), follow this link to the standingoutinmyfield blog.

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Filed under Bees, Biodiversity, Biogeography, Brazil, Macroecology, Mutualism, Pollination, Tenerife

Pollinators, flowers, natural selection and speciation: a virtual conference

Ashy Mining Bee 2017-06-17 10.55.45

It’s been a couple of years since I posted my previous “virtual conferences” on Pollinators, Pollination and Flowers and Ecology and Climate Change, a lapse that has largely been due to lack of time (my default excuse for most things these days….).  However Judith Trunschke at Uppsala University in Sweden has risen to the challenge of guest-curating her own virtual conference*.  The theme here is how pollinators impose (or sometimes don’t impose) natural selection on flowers that results in the formation of new plant species:

Timo van der Niet (IIASA 2010): Plant-diversification through pollinator shifts

Timo van der Niet (Congresos UCA 2014): Disentangling the contribution of pollinators in shaping angiosperm orchid genus Satyrium

Anne Royer (Evolution 2016): Plant-pollinator association doesn’t explain disruptive selection & reproductive isolation

Brandon Campitelli (Evolution 2016): Pollinator-mediated selection and quantitative genetics

Yuval Sapir (Evolution 2016): Rethinking flower evolution in irises: are pollinators the agents of selection?

Ruth Rivken (Evolution 2014): The mechanisms of frequency-dependent selection in gynodiocious Lobelia siphilitica

Gonzalo Bilbao (Botany 2017): Pollinator-mediated convergent shape evolution in tropical legumes

My grateful thanks to Judith for curating this great set of talks; if anyone else would like to do the same, please get in touch.

Feel free to discuss the talks in the comments section and to post links to other talks on the same topic.


*I’m assuming that, as all of these videos are in the public domain, none of the presenters or copyright owners objects to them being presented here.  If you do, please get in touch and I’ll remove it.

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Filed under Bees, Biodiversity, Birds, Butterflies, Evolution, Honey bees, Hoverflies, Mutualism, Pollination, Wasps

Pollinator biodiversity and why it’s important: a new review just published – download it for free


In a new review paper that’s just been published in the Annual Review of Ecology, Evolution and Systematics I have looked at the question of just how diverse the pollinators are, and why pollinator biodiversity is ecologically important and therefore worthy of conservation.  I’ve taken a deep time and wide space approach to this, starting with what the fossil record tells us about when animal pollination evolved and the types of organisms that acted as pollinators in the past (the answer may surprise you if you’re unfamiliar with the recent paleontological literature on this topic).  Some of the most prominent biogeographical patterns have been highlighted, and I have tried to estimate the global diversity of currently known pollinators.  A conclusion is that as many as 1 in 10 described animal species may act as pollen vectors.

As well as this descriptive part of the review I’ve summarised some recent literature on why pollinator diversity matters, and how losing that diversity can affect fruit and seed set in natural and agricultural contexts.  Extinction of pollinator species locally, regionally, and globally should concern us all.

Although I was initially a little worried that the review was too broad and unfocused, having re-read it I’m pleased that I decided to approach the topic in this way.  The research literature, public policy, and conservation efforts are currently moving at such a fast pace that I think it’s a good time to pause and look at the bigger picture of what “Saving the Pollinators” actually means and why it’s so important.  I hope you agree and I’d be happy to receive feedback.

You can download a PDF of the review entitled Pollinator Diversity: Distribution, Ecological Function, and Conservation by following that link.

Pollination ecologists should also note that in this same volume of Annual Review of Ecology, Evolution and Systematics there’s a review by Spencer Barrett and Lawrence Harder called The Ecology of Mating and Its Evolutionary Consequences in Seed Plants.  If you contact those authors I’m sure they’d let you have a copy.


Filed under Apocynaceae, Bees, Biodiversity, Biogeography, Birds, Butterflies, Climate change, Ecosystem services, Evolution, Honey bees, Hoverflies, IPBES, Macroecology, Mammals, Moths, Mutualism, Neonicotinoids, Pollination, Urban biodiversity, Wasps

The only way is Norway! Reflections on SCAPE 2017


It’s been a busy few days of science, eating great Norwegian food, catching up with old friends, and meeting new ones:  The Scandinavian Association for Pollination Ecology’s 31st annual meeting is over.  As I’ve reported in previous years – for example here and here and here –  it’s been a whirlwind of great presentations and interesting discussions, far too much to summarise in a single blog post.  But here’s my top 5 personal list of things that I discovered during SCAPE 2017:

  • The hills are alive with microclimatic heterogeneity!  Lisa-Maria Ohler introduced us to how variable ground temperature can be on a very local scale and how this might influence plant-pollinator diversity.  Especially impressive was the fact that this was based on Lisa’s BSc thesis!


  • Removal of abundant and well connected plant species (“hubs”) from a plant-pollinator network can affect insect visitation rates and pollen deposition (Paolo Biella).  It was particularly good to catch up with this project as I’m one of the collaborators on it!


  • Several very interesting talks discussed scent variation between Lithophragma populations and how this does not seem to correlate with flower shape and with the moth and bee pollinators, including this one by Mia Waters:


  • Some invasive plants have much higher levels of pollen protein content than native plants which may be a reason why they are so successful – they attract more pollen-collecting visitors (Laura Russo).
  • Old ideas of why heteranthery (flowers with two different types of anthers) have evolved may not be correct (Kathleen Kay).  This is a question that vexed Darwin and still seems to be vexing pollination ecologists!

I also got some really useful ideas and feedback on my own presentation, which is one of the best things about small conferences such as SCAPE: just over 70 people took part.  Next year will mark a break in tradition for SCAPE when, for the first time in its history, the 32nd meeting will take place outside of Scandinavia, in Ireland.  Watch this space for more details next year!

Thanks to our Norwegian hosts for making the conference so welcoming; I’ll finish with some general photos of the conference and of the lovely town of Drøbak, where the meeting took place, and its aquarium:








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Filed under Biodiversity, Pollination

A bad botanical pun

fucksia not fewsha 20171012_080602_001_preview

Not all of the poetry that I write – such as these pieces – is serious and high-minded, some of it is whimsical, funny, or just plain dumb.  Today I taught a morning class on flower structure and pollination, so in its honour here’s an example of the latter:


A Bad Botanical Pun

“Don’t become a gardener – there’s no fuchsia in it!”

Not a great pun, but I’ve heard worse.

However, it may be pedantic, but I have to point out

That the genus Fuchsia was named in honour of Leonard Fuchs

(A sixteenth century Bavarian botanist, as you ask).

His name is pronounced as a definite, Germanic “fucks”,

Not a prim, Victorian “fewsh”.

So, don’t become a botanist – it’ll Fuchsia!


Students in the pollination practical 20171012_111355_preview


Filed under Biodiversity, Gardens, Poetry, Pollination, University of Northampton

The Buzz Club: citizen scientists protecting pollinators

Buzz Club 1.png

This is a guest post by Charlie Dance who is Development Officer at The Buzz Club.

It’s hard to over-stress the importance of pollinators. Not only do they play an indispensable role in global food security, they’re also essential in maintaining the diversity of plant species in natural habitats, thus supporting nature as a whole. The UK is home to thousands of different pollinators including bees, wasps and hoverflies. However, while many of these species seem to be declining or disappearing, we know surprisingly little about the majority of them. Why are some disappearing, and how quickly is it happening? What can we do to help? How can we turn our gardens into pollinator havens? It was to help answer questions like these that the Buzz Club was founded in 2015.

Run by volunteers at the University of Sussex, The Buzz Club is a citizen-science charity using the power of the public to provide important data on pollinators. We run a variety of nationwide surveys and experiments suitable for all ages and ideal for wildlife and gardening enthusiasts. Furthermore, we provide information about how to make our urban landscapes more pollinator friendly.

For more information and for a list of current projects, please visit our website:

As a membership-based organisation, we rely on the small donation of £2 per month from members, all of which goes directly towards running the charity. Not only do new members receive a complementary welcome pack containing a specially designed seed mix, bee identification chart, pollinator-friendly gardening guide, magnifying lens and stickers (see photo below), they also get to learn more about pollinators whilst helping to generate useful data that can be used in our projects.

We believe that with your help we can find out how best to conserve bees and other pollinators. Our ultimate goal is to ensure that we look after insects, giving them and us a future.

Join the Buzz Club here:



From Jeff:  if citizen science is your thing, don’t forget that the Ivy Pollinators project will run again this year:


Buzz Club 2.png

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Filed under Bees, Biodiversity, Butterflies, Ecosystem services, Gardens, Hoverflies, Moths, Pollination, Urban biodiversity, Wasps