Category Archives: Pollination

Speaking about plant-pollinator research and science blogging in Wageningen in May

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If any of you are near Wageningen University on 31st May I’m giving a talk about some of our recent research called “The macroecology and macroevolution of plant-pollinator interactions”. It’s preceded by a workshop on the whys and hows of science blogging. Details are in the poster.

Here are the abstracts for the talk and the workshop:

Macroecology and macroevolution of plant-pollinator interactions

Plant-pollinator relationships are an ecologically critical form of interaction that ensures the long-term survival of the majority of the world’s plants species, and contribute to a large fraction of global agricultural output. In additiondiversity and abundance of biotically pollinated plant species can be an important determinant of the diversity of animals at higher trophic levels.

Despite that global significance, most studies of plant-pollinator interactions are done at a local level, involving populations and communities of species, over modest time scales. The ways in which these local sets of interactions scale up to produce global macroecological and macroevolutionary patterns, and the processes underpinning them, will be explored using two case studies.

The first is a data set of 67 plant communities, ranging from 70ºN to 34ºS, with which we investigated the roles of biotic and abiotic factors as determinants of the global variation in animal versus wind pollination. Factors such as habitat type, species richness, insularity, topographic heterogeneity, current climate and late-Quaternary climate change were investigated. The predictive effects of these factors on the proportion of wind- and animal-pollinated plants were examined (see: Rech et al. 2016 – Plant Ecology & Diversity 9: 253-262).

Since these results were published we have increased the number of plant communities in our database to >90, and our findings seem to be robust to these additional data. The dominant influence of contemporary climate on the relative importance of wind-pollinated species suggests that communities may be sensitive to future climate change. Communities in areas that are predicted to become drier may in time contain more wind-pollinated plants which may in turn reduce the diversity of pollinator species that are present. There may also be implications for the prevalence of human pollen allergies. Future work will focus on these two areas.

The second case study uses a newly assembled database of pollinators of the family Apocynaceae (one of the ten largest families of flowering plants), supported by a molecular phylogeny of the major clades. This database has been used to explore phylogenetic and biogeographic patterns of pollinator exploitation (Ollerton et al. in review). The findings from this study challenge some long-held assumptions about convergent evolution, the role of rewards such as nectar, and the notion that some specialised pollination systems are evolutionary “dead ends”. It also highlights the function of novel floral features in determining pollinator type and behaviour, such as the fused gynostegium and pollinia found in the subfamily Asclepiadoideae. In summary, Apocynaceae is emerging as an important model family for understanding the ecology and evolution of plant-pollinator interactions.

Blogging for EEB: why bother?

A growing number of scientists in Ecology and Evolutionary Biology (EEB) have their own blogs or post as guests on others’ blogs. In this workshop we will explore motivations and strategies for blogging, and its advantages for early career researchers. Why blog? What does it do for one’s career? Is it a distraction from actually doing science? How does one build a blog readership? We will also focus on two aspects that are sometimes seen as mutually exclusive: blogging as science outreach to the general public (sci-communication), versus blogging with other professional scientists in mind (sci-community). As preparation for the seminar please read Saunders et al. (2017) Bringing ecology blogging into the scientific fold: measuring reach and impact of science community blogs

Can pollinators survive sudden changes in the weather?

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Snow-Warm garden comparison

Just how pollinators cope with sudden changes in the weather early in the season is a bit of a mystery. Take 2018 as an example; my wife Karin spotted the first queen bumblebee in the garden on 6^th January, investigating a camellia flower just outside the kitchen. Over the course of the next few weeks I saw a few more at various sites, plus occasional hibernating butterflies such as the red admiral. The various social media outlets were reporting similar things, it looked as though we were going to have an early spring.

Then at the end of February “The Beast from the East” hit the UK, a weather system from Siberia that brought some of the coldest weather and heaviest snow the country had experienced for several years. That persisted for over a week then things got much milder. On 16^th March I was in the garden and spotted the first male hairy-footed flower bee of the year, plus a mining bee (Andrena sp.), and a brimstone butterfly, and a queen bumblebee, and a red admiral. Great I thought, spring really is here! The next day it snowed. A “Mini Beast From the East” had arrived, rapidly: the two pictures above making up the composite view of our garden were taken two days apart.

What happened to all of those insects I saw? Were they killed by the cold weather? Or did they survive? We have no firm data to answer that question – as far as I’m aware no one has ever tagged early emerging pollinators and followed their progress (I could be wrong – please let me know if I am). It would make an interesting, though labour intensive, project but could be done using non-toxic paint of various colours to mark the insects.

I suspect that some of the pollinators I saw were killed, but most were not and simply went back into hibernation for a short period, hunkering down in safe, sheltered spots. That makes much more evolutionary sense: any insects in the UK that cannot survive sudden changes in the weather would have gone extinct long ago. Another clue to support this idea is the fact that plants in flower early in the season, and in some cases the flowers themselves, usually survive the cold weather and come back as if nothing had happened. If the flowers can do it, and they have to stay where they are, surely the mobile pollinators can also do it?

As always I’d be interested in your thoughts on this topic, feel free to comment. And while we wait for the UK to thaw, here’s some topical and rather catchy music to listen to – The Beelievers singing “Mr Gove”.

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

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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.

Abstract:

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.

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

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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

MORE DETAILS AT:

http://www.icppr.com/xi-international-symposium-on-pollination.html

I HOPE TO SEE YOU IN BERLIN!

Carlos H. Vergara

CHAIR OF THE ORGANIZING COMMITTEE

Something for Blue Monday – the only known blue flowered asclepiad

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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.

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

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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.

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

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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.

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

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

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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.