Category Archives: Climate change

Monarchs and Milkweeds Workshop summary, Oak Spring, Virginia, June 2019

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As I recounted in my last post about a train ride through American climate change, my wife Karin and I have been in the USA for the past couple of weeks, visiting colleagues in the west and ultimately heading eastwards to Virginia for a workshop on monarch butterflies and their milkweed hosts.  The meeting was organised by Anurag Agrawal, professor at Cornell University and author of the recent book Monarchs and Milkweed, highly recommended to anyone interested in the natural history of plants and insects.  The monarch (Danaus plexippus) is an iconic migrating  species that travels from Mexico to Canada and back, over the course of a few generations.  This behaviour, and their vast over-wintering assemblages, have become the focus of intense efforts to understand their ecology and biology.  Their caterpillar host plants are mainly milkweeds (Asclepias spp.) and bringing together both plant and animal scientists is important for gaining a fuller over view of the issues facing the monarchs and the milkweeds, and how both can be conserved in a time of anthropogenic change.

The venue for the workshop was Oak Spring, Upperville, the former home of Paul and Rachel (“Bunny”) Mellon which has been turned into the base of operations for a philanthropic foundation specialising in plant science, horticulture, and botanical art.  The Oak Spring Garden Foundation (OSGF) is “dedicated to inspiring and facilitating scholarship and public dialogue on the history and future of plants, including the culture of gardens and landscapes and the importance of plants for human well-being”.  The OSGF generously funded the workshop, including accommodation and travel for participants.  This brought together a small group of scientists from the USA, the UK and Brazil, together with an artist, a milkweed horticulturalist, and two science writers.  Their brief was to discuss the latest developments in our understanding of monarch butterflies, their decline and conservation, and the taxonomy, evolution and ecology of milkweeds and the wider groups of Lepidoptera and the plant family Apocynaceae to which these organisms belong.  My invitation to take part was due to the research on the pollination ecology of this family I’ve conducted, spanning about twenty five years and culminating in a recently published assessment of the diversity of pollination systems in Apocynaceae.

First things first: Oak Spring is one of the most tranquil, beautiful, and inspiring places where it’s ever been my privilege to stay.  Here’s a few photographs, but they really do not do justice to the buildings and garden, their setting, nor to the unique atmosphere of Oak Spring.

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So to the science.  The workshop started with a set of short presentations on our recent research findings and the motivations for our interests in these organisms.  On the second day we then moved on to discussing ideas for future collaborations between the participants and how that work might be funded in the future.  Presentations and discussions were mainly held in the Basket House, named for obvious reasons:

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Each of us was also interviewed on camera to build an online archive of the work we do and why we do it.

The advantage of face-to-face meetings such as this, and why Skype and so forth can never fully replace them, is the free-flowing conversations that occur within the formal sessions and outside them.  Among the many things that I learned from presentations and discussions were:

  • The California monarch population has declined by almost 90% this year and there’s an urgent need to understand why this has happened.  Climate change has been implicated, especially in relation to the increased frequency of wildfires in this region.
  • Existing methods of nectar extraction from milkweed flowers may strongly underestimate the volume available to flower visitors, and overestimate the sugar concentration.  Using a small centrifuge to spin out the nectar seems to be the most effective method.
  • Asclepias arrived in the Americas (probably from Africa) some 10 million years ago (mya).  However Danaus only arrived about 3.7 mya, so there was a long period of time in which the plant was not co-evolving with one of its major herbivores.
  • There is strong evidence of migrations along the Andes by a close relative of the monarch, Danaus erippus.  Migrations in this group of butterflies therefore extends beyond the iconic D. plexippus.
  • Sonoran Desert Asclepias are sister group to the rest of the New World Asclepias spp.  The exact route by which the African ancestors made it to the Americas is unknown, it could be via Asia and the Bering Strait, or across the Atlantic by way of island stepping stones.  Either way, the phylogenetic position of the Sonoran milkweeds implies that a lot of Asclepias species have gone extinct over the past 10 million years.
  • Climate change seems to be resulting in more complex and unpredictable windows of opportunity for monarch egg laying and caterpillar development.  The monarchs are most successful in late spring and late summer, but not in all years.
  • Likewise, extreme precipitation of the kind I recently documented in the USA is also likely to have a negative impact on the monarchs and their host plants.
  • There is molecular evidence that monarch butterflies went through a huge genetic bottleneck in the 1960s-1970s, for reasons that are not altogether clear.

All of these findings, and more that there isn’t space to document, point to a need for further research to better understand these organisms if we wish to secure their futures.

By the end of the workshop we had made some concrete decisions on future steps:

  •  The African members of the genus Asclepias, plus about 20 other closely related genera, require more critical taxonomic and phylogenetic assessment in order to understand their systematic relationship to the North and South American Asclepias species.
  • A poster (or possibly series of posters) will be produced that explain the ecology of the monarch, its relationship with milkweeds, the patterns of migration, and the value of milkweeds as nectar sources for a diverse range of pollinators.
  • We will explore a multi-agency grant application to further develop the collaborations between participants.

The final day of the workshop involved a field trip around Virginia to see some of the local milkweed species, many of which live in woodland.  That surprised me: I always envision Asclepias spp. as grassland or desert plants.  The leader of the field trip, Mark Fishbein, had a hit list of 8 species that he wanted us to see and in the end we located all of them, including a rare hybrid population of A. syriaca x A. exaltata, plus the tropical milkweed Asclepias curassavica planted in the OSGF garden, plus the distant relative dogbane Apocynum cannabinum.  Here are some images from that day:

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Searching for milkweeds along Skyline Drive, Shenandoah National Park


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Poke milkweed – Asclepias exaltata


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Hunting that elusive hybrid milkweed!


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Caterpillar of the monarch butterfly feeding on a milkweed


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Alessandro Rapini intent on getting a good photo of the A. syriaca x A. exaltata hybrid


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A bumblebee and a butterfly visiting A. exaltata


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Purple milkweed – Asclepias purpurascens


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Common milkweed – Asclepias syriaca – with a visiting skipper butterfly


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Climbing milkvine – Matelea obliqua – a member of a largely fly-pollinated group of New World asclepiads


Thanks to my fellow workshoppers for such a stimulating and enjoyable meeting, and to all the staff at Oak Spring for making us feel so welcome.  Particular thanks go to Prof. Sir Peter Crane who, as President of the Oak Spring Garden Foundation, was hugely supportive of the workshop, and to Angie Ritterpusch, Head of Events and Guest Services, for logistical and organisational support.




Filed under Biodiversity, Biogeography, Butterflies, Climate change, Evolution

A train ride through American climate change

For the past week Karin and I have been travelling in the USA, starting in Denver, driving to Gunnison, then on to Grand Junction, Colorado, to catch the Amtrak California Zephyr train for a 36 hour trip to Chicago. Our final destination is a workshop on conservation of monarch butterflies and their milkweed host plants near Washington DC next week.

I’ll post something about the Gunnison leg of our journey at a later date, and of course the workshop.  But as I write the first draft of this post, we are passing through flooded Iowa farmland and I wanted to get some thoughts down about a repeating theme of our travels so far: climate change.

Our original destination in Colorado was the Rocky Mountain Biological Laboratory (RMBL), an almost legendary research venue for pollination ecologists. We were meeting up with my long-time friends and colleagues Nick Waser and Mary Price, with whom I’ve collaborated on various papers since the mid-90s. However we never made it to RMBL: unseasonably late snow had not yet been ploughed from the road up to the site and the only way in and out was with skis or snowshoes. Some hardy researchers were already there, but the limited time we had in Colorado made it impractical for us to make the journey:

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Unseasonable snow does not, of course, climate change make; but that was our first hint that there’s something odd about the weather in North America at the moment.

Fast forward a few days and we picked up the Zephyr in Grand Junction, the start of an incredible journey through spectacular Rocky Mountain scenery and then down into the flat agricultural lands of Nebraska and Iowa. We had a sleeping cabin and, following a stop in Denver, we drifted off to the slow chug-a-chug of the Zephyr’s wheels and the occasional distant whistle from the front engine – it’s a loooong train!

The next morning we were still in Nebraska and it was then that things started to get both interesting and worrisome. One of the conductors gave us a running commentary about the heavy rainfall that had caused flooding in this region during May and June – see this recent account from NASA’s Earth Observatory.  As you can see from the images below (snapped from the train as we passed, so excuse the quality), flooding is still an issue along the Platt and Missouri Rivers, both of which had over-topped their adjacent levees at various points. A conservation area, the Fontanelle Forest Preserve, had turned from woodland into wooded swamp:

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This is not the river Missouri – it’s actually about quarter of a mile beyond those trees:

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Adjacent farmland was completely flooded shortly after corn crops had been planted. Farm buildings were washed out and their occupants had been forced to leave with little notice. These are areas that do not normally flood and the impact of this heavy rain has been significant and will last long into the future:2019-06-05 09.51.37

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Infrastructure such as roads and bridges were also damaged.  The Union Pacific rail bridge across the Platt was partly washed away and has had to be rapidly rebuilt, but only after a new access road was established:

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Everywhere we looked there was flooding:

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A nearby industrial estate and trailer park had also been flooded, with a lock-up garage of classic American cars under seven feet of water, and the residents and businesses have been told to leave permanently. This area cannot be guaranteed flood-free in the future and will be leveled and allowed to return to nature:

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A local portaloo company was also flooded out and we observed the plastic toilets washed up along a lakeside that used to be a field of corn.  Superficially amusing, until you realise that this represents the loss of someone’s livelihood:

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Along the train tracks ballast had been piled up to begin a programme of raising the track bed. Residents of the nearby town of Pacific Junction (population about 470) have been told to either sell their homes to the government, and move out, or face ever-rising costs of flood insurance – see this recent local newspaper article. Pacific Junction used to be an important rail terminus and some of the families have been there for generations.   Let’s be clear what this means for these people – they are displaced from their homes, they are climate refugees in their own country.

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After we had passed through this area I chatted with one of the train stewards who mentioned that his Louisiana home had been flooded out in August 2016. He was forced to pay $400 per year flood insurance to protect his belongings and home from future events, in a part of the state that had no prior history of flooding.  “But your President says that climate change is not a problem” I probed.  He gave me a look that said more than words could ever convey. “Don’t get me started on that” he replied. A nearby passenger, a young guy, chimed in: “We’d be here all day!”  Trump’s rhetoric is changing slightly and, if anything, becoming less coherent and more deranged as he talked yesterday of “good climate” and “weather going both ways”.

All along the train route to Chicago we saw the same thing, over hundreds of miles and hour after hour – partially or completely flooded fields, crops washed away or submerged under water.  Large ponds in otherwise pristine, planted fields of parallel lines where the first growth of wheat was showing:

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Karin tells me that the flooding around the Mississippi was even worse, but I’m afraid that I slept through it; long train journeys are wonderful, but tiring!

This is just a snap shot of what climate change is doing to the USA at the moment; it’s creating climate refugees in a number of states – see this article for instance. Wildlife seems to be the only thing that’s benefiting as nature reclaims farmland and urban areas: the flooded fields we passed were full of herons, wildfowl, and other water birds. But in the longer term who knows what these changing weather patterns will bring for biodiversity and human society. The only certainty is that change is coming.


Filed under Biodiversity, Climate change

Biodiversity and climate change: a hierarchy of options

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The related issues of how to conserve biodiversity and reduce the impacts of climate change have never had such a high public profile as they do at the moment.  The activities of Extinction Rebellion caught the attention of the media around the world, for example here in London.  Numerous organisations, cities, regions and countries have declared a Climate Emergency.  And IPBES – the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Serviceshas released a summary of its first global assessment with the full report due later this year, and explicitly makes the link between conservation of biodiversity and reducing the effects of climate change.

Timed to coincide with all of this, the University of Cambridge has announced that it is setting up a Centre for Climate Repair in order to explore hi-tech “fixes” to climate change, such as spraying sea water into the atmosphere in order to reduce warming at the poles, and sucking CO2 out of the air using large machines.  I think it’s fair to say that this was met with some scepticism on social media; here’s some examples:

Other people have pointed out that nature-based solutions are the most likely to be successful, and provide a boost for biodiversity at the same time:

All of this reminds me of the Waste Hierarchy in its various iterations – you know the sort of thing – “Reduce > Reuse > Recycle”, where reduction in waste produced is best, followed by reuse of waste resources, with recycling being the least good option (but still better than just land-filling the waste).  As far as the link between conservation of biodiversity and reduction of the effects of climate change goes, there’s a parallel hierarchy – see the image at the top of this post – that sets out the order of priorities:

PROTECTION of ecosystems using the full force of national and international laws and conventions has got to be the top priority.  Otherwise any of the other activities will result in, at best, humanity running to catch up with what the world is losing.  Let’s stop cutting down ancient forests and degrading peatlands that have accumulated millions of tons of carbon over thousands of years!

FIX – by which I mean the kind of hi-tech solutions proposed above – should be the lowest priority: they do little or nothing directly for biodiversity and there is no compelling evidence that they will even work as intended.

Between these two are RESTORATION of currently degraded habitats (such as re-wetting peatlands as in the Great Fen Project) and PLANTING of trees, which can be a form of habitat restoration under some circumstances.  Large scale examples of this include

Grain for Green – China’s attempt to restore vegetation to abandoned farmland to reduce soil erosion and flooding.

Great Green Wall – a multinational initiative in Africa aimed at restoring the vegetation on the southern edge of the Sahara to combat desertification and mitigate climate change.

While doing a bit of research for this blog post* I became aware that a Conservation Hierarchy has already been developed by the Convention on Biological Diversity but that really only deals with habitat destruction, mitigation of destructive activities, etc.  What I’m suggesting is related more to the direct link between conservation of biodiversity and mitigation of climate change.  So what to call this particular hierarchy?  Perhaps the BioCC Hierarchy?  Can anyone suggest a better name?  Maybe it doesn’t need a name at all, it just needs people to be aware of it and for governments to act logically.


*I googled the term “Conservation Hierarchy” – you get the quality of research you pay for on this blog….



Filed under Biodiversity, Climate change, Ecosystem services, IPBES

Is pollination really an ecosystem service?

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Yesterday on Twitter Prof. James Bullock from the Centre for Ecology and Hydrology posted a slightly provocative tweet asking: “why pollination is so often called an ecosystem service. To my mind it is an ecosystem process which can, in some circumstances (e.g. crop pollination), support services such as food provision”.

I confess to being a bit surprised to see this; I’d always referred to pollination (at least by animals) as an ecosystem service, and it’s classified in that way in large status-and-trend reports such as the Millennium Ecosystem Assessment and (more recently) the IPBES Assessment Report on Pollinators, Pollination and Food Production which describes animal pollination as “a regulating ecosystem service that underpins food production and its contribution to gene flows and restoration of ecosystems”.

The crux of James’s question is illustrated in this diagram from a paper by Prof. Georgina Mace and colleagues in 2012 entitled Biodiversity and ecosystem services: a multilayered relationship.  However note that even here, pollination straddles the line between ecosystem processes and services:

Mace ES image

My initial response to James’s tweet was that animal pollination is really a community process as the interaction, and its outcomes, between animal and crop plant is dependent mainly on species diversity and abundance.  Remember, an ecosystem is the sum of the biotic (i.e. community) plus abiotic (e.g. energy, water, mineral nutrients, etc.).  So as far as crop pollination is concerned, the abiotic components of an ecosystem don’t really come into it except in as much as they influence diversity and abundance of all life on Earth.  This is in contrast to more strictly ecosystem processes that link directly to the abiotic factors, such as primary productivity and soil formation, that then support ecosystem services.

It’s further complicated by the fact that many of the plants that perform ecosystem services, such as carbon capture by trees, are themselves dependent upon animal pollination to maintain their populations.  It’s the plants that are providing the ecosystem services but the animals are playing an important role in supporting that.

If you’d like to follow that discussion, which has some interesting contribution from a range of people, here’s the link:


But ultimately I feel that these are fairly arbitrary definitions across a continuum of causes and effects: we know what animal pollination of crops and wild plants is and why it’s important, so what we call it doesn’t really matter, does it?  Other things are much more concerning.  At the moment the UK is experiencing unprecedented weather: for the first time ever, earlier today, a temperature of in excess of 20 Centigrade has been recorded in winter.  It currently feels more like late April or early May than February.  I’m already seeing a lot of pollinator activity in the garden and beyond, and each day more plants come into flower, far earlier than expected.

The current and future effects of such changes in the climate are far more important than discussions of the semantics of processes versus services, however interesting that might be.


Filed under Bees, Biodiversity, Climate change, Ecosystem services, IPBES, Pollination

Should environmentalists be optimistic in a time of uncertainty?


Over at the Ideas for Sustainability blog Joern Fischer posted a really interesting piece on 1st January called “A new kind of hope” about the current state of the world and whether, from an environmental perspective, there’s really anything to be optimistic about.  If environmental collapse via climate change and over-exploitation is inevitable, the collapse of civilization is not far behind.  Joern’s piece is well worth reading, lots to think about in there, and I highly recommend that you take a look.

I posted a comment there which I’m going to copy here and add to because I think it bears repeating.

Going back to at least my student days I always thought that there was only a slim chance of our civilization making it to the end of the 20th century without some kind of catastrophe wiping us out.   So it was a surprise to celebrate the millennium as December 1999 segued into January 2000. Since then, whilst I think there’s lots to be optimistic about such as the increase in renewable energy, large-scale habitat restoration in some regions, and a growing recognition of the environmental damage of biocides and plastics, there’s also the nagging fear that it’s too little, too late.

These days I alternate between wild optimism and deep depression over the fate of humanity and of the planet. It’s so easy to get sucked into the vortex of negative environmental narratives and ignore the positive ones. Especially so if you actively use social media.  So I try hard to be optimistic and resist the urge to just give up, but the political situation across much of the world makes that difficult. As I learn more about the natural world through my own research and that of others’, and as world events such as Brexit and the rise of the Far Right unfold, I realise how little any of us really know about anything at all. Thus I have a deep suspicion of anyone who spouts certainties, whether they be moral, philosophical, religious, scientific, political, or artistic. All we can do is feel our way into the future, cautiously.

With respect to the question that Joern poses of “If we have to re-build something after some kind of collapse … do we have ideas for what that something will be?”, this is the rationale behind the Dark Mountain Project, a loose collaboration of writers, artists, thinkers, etc., who are trying to look for new narratives for humanity and the planet we depend upon. I’ve written a couple of pieces for their journal, most recently for issue 10 where I discussed the role of poetry in science.  And although I don’t buy into their certainty that there will be a collapse, I think it’s an important project for understanding where we are now, where we’ve been, and where we might be going to.  Here’s a link to the project’s website.

The discussion over whether we should be optimistic about the future of the planet that supports us, and how that optimism will play out, is important for scientists, and society at large, to be having.  By coincidence as I was writing this post the map above started circulating on Twitter.  It’s a Russian teaching aid from 1928 showing the different biomes of the USSR and can be downloaded from this site.

What really struck me about this graphic was the certainty with which it represents the natural world, as if all of this could never change. There are polar bears on ice flows and a frozen tundra in the far north; water still fills the Aral Sea, hyenas feast in the steppe, snow leopards haunt the mountains, Siberian tigers prowl the pine forests.  And an optimistic looking whale heads towards Japan.  Some of this is gone, some will almost certainly change, but a lot of it we could save, if we want to, saving ourselves in the process.


Filed under Biodiversity, Biodiversity and culture, Climate change, Dark Mountain Project

Climate change at Christmas: did the hot, dry summer of 2018 cause the record-breaking prices of holly and mistletoe?

Over the past two festive seasons I have posted about the research we published assessing the auction prices of holly and mistletoe, two culturally important seasonal crops that are 100% pollinator dependent for berry production.  The first post was called Insect pollinators boost the market price of holly and mistletoe: a new study just published; the second was The holly, the mistletoe, and the pollinators: an update on an old story.

Follow those two links to get the full background to this research and a link to the original paper published in the Journal of Pollination Ecology.

I’ve collated the auction prices for the 2018 season and added them to the time series data set, and it’s clear that something very interesting has occurred.  Both berried holly and mistletoe have achieved record-breaking average prices, whilst auction prices for material without berries have hardly changed at all.  Here are the updated graphs; each data point is the average price per kilo paid at an auction:

Holly and mistletoe prices 2018

So what’s gone on this year?  What could have affected the auction prices?  One interesting possibility is that the long, dry summer of 2018, a likely consequence of climate change, has negatively affected berry production in these two species.  This could come about if the holly or the mistletoe host trees are water stressed and shed part of their berry crops.  It’s unlikely to be a consequence of too few pollinators as these species flower too early in the year to have been affected by the dry weather.   We have more work planned in the future using these data and this will be an interesting question to address.

Yesterday I popped out to do some Christmas shopping and tried to buy mistletoe at a local garden centre.  That’s the second time I’ve tried this year (the first was at a nearby green grocer’s) and the second time that I’ve been told that they have none because it’s very expensive this year and not worth stocking.  That seems predictable from the wholesale auction results I’ve just described.  Has anyone else in the UK had similar experiences this year?

The British holly and mistletoe market is relatively small and clearly seasonal, and probably not worth more than a few millions of pounds each year.  However it seems to be very sensitive to external factors and may be a microcosm for how some crops, at least, might respond to future extreme weather brought about by climate change.  Brexit might also have an effect in the coming years as we import a large amount of mistletoe from northern France.  But then Brexit is going to have an effect on large areas of British society…..

On that sour note, Happy Christmas to all of my readers, however you voted in the referendum.  I hope you have a restful holiday, spending it as you wish, with the people you want to!  And if you, or someone you know, are spending the festive season on your own this year, take a look at Karin’s latest blog post:  Preparing a Christmas Just For You.


Filed under Biodiversity, Biodiversity and culture, Climate change, Ecosystem services, Journal of Pollination Ecology, Pollination

A once in a lifetime sunset?

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It’s been a curious year in the UK, weather wise, with an early, mild spring interspersed by sudden cold snaps that may (or may not) have had a profound impact on pollinators, and then a summer that was hotter and drier than any in living memory.  There’s been some amazing thunderstorms and torrential rains, and weeks when there was no rain at all.  Then, on Thursday evening, as Karin and I were coming back from a walk around Abington Park (via a quick stop in the pub) the heavy, rain-bloated skies conspired with the setting sun to produce, for a brief period, a display of light and clouds that was more vibrant and gorgeous than any I’ve ever seen.  The sky reflecting from the rain-soaked pavements of Northampton added further drama to what may well be a once in a lifetime experience.

Here are a few shots I managed to take using the camera on my phone; I’ve not altered the colour or played with images in any way, but they do partial justice to the quality of the light that evening.

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Filed under Biodiversity, Climate change

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

Have we broken the planet?


A graph showing this year’s figures for area of global sea ice, in comparison with the same data for the past c. 40 years, was widely shared on Twitter yesterday, resulting in a lot of discussion and consternation.  I’m not on Twitter (yet…) and picked this up from Terry McGlynn’s Facebook feed.  The graph shows an anomalously low extent of sea ice compared with what we would expect at this time of the year, in fact a drop of about 25%.

As you can see, something looks to be seriously wrong.  For more discussion about the graph, see this piece over at The Verge.

I’ve not discussed climate change much on this blog, it’s not my area of specialism and there are plenty of other good bloggers out there who are far more knowledgeable than I.  But graphs like this are hugely worrying because they not only suggest that aspects of our climate may be at a tipping point where they change from one state/predictable pattern to another.  That’s a concern on a global level, because it’s strong evidence for global warming.  However the reduction in sea ice also has huge implications for the biodiversity that depends upon the ice.

If I hear any more news on this I’ll post it, but in the meantime it’s worth pondering whether perhaps the UK’s signing up for the Paris Climate Agreement this week is a bit too late.  As my colleague Duncan McCollin put it: “we’ve broken the planet”.  I hope he’s wrong.


Filed under Biodiversity, Climate change

The macroecology of animal versus wind pollination – a new study just published

In collaboration with colleagues in Brazil, Denmark, and elsewhere in the UK, we’ve just published a new research paper which looks at the global spatial distribution of wind and animal pollinated plant species, and the underlying historical and contemporary ecological causes of that distribution.  It’s a study that builds on my “How many flowering plants are animal pollinated?” paper in Oikos, and has been a long time in its gestation.  We’re very excited by its findings and plan to develop this project in the future.

As a bonus we made the cover of the journal with the amazing image below!  Big thanks to Pedro Viana and Jesper Sonne for the photos.

Here’s the citation with a link to the publisher’s website; the abstract is below.  If anyone wants a PDF copy, please ask.

Rech AR, Dalsgaard B, Sandel B, Sonne J, Svenning J-C, Holmes N & Ollerton J (2016) The macroecology of animal versus wind pollination: ecological factors are more important than historical climate stability. Plant Ecology & Diversity 9: 253-262



Background: The relative frequency of wind- and animal-pollinated plants are non-randomly distributed across the globe and numerous hypotheses have been raised for the greater occurrence of wind pollination in some habitats and towards higher latitudes. To date, however, there has been no comprehensive global investigation of these hypotheses.

Aims: Investigating a range of hypotheses for the role of biotic and abiotic factors as determinants of the global variation in animal vs. wind pollination.

Methods: We analysed 67 plant communities ranging from 70º north to 34º south. For these we determined habitat type, species richness, insularity, topographic heterogeneity, current climate and late-Quaternary climate change. The predictive effects of these factors on the proportion of wind- and animal-pollinated plants were tested using correlations, ordinary least squares (OLS) and logistic regression analyses with information-theoretic model selection.

Results: The proportion of animal-pollinated plant species was positively associated with plant species richness and current temperature. Furthermore, in forest, animal pollination was positively related to precipitation. Historical climate was only weakly and idiosyncratically correlated with animal pollination.

Conclusion: Results were consistent with the hypothesised reduced chance for wind-transported pollen reaching conspecific flowers in species-rich communities, fewer constraints on nectar production in warm and wet habitats, and reduced relative effectiveness of wind dispersal in humid areas. There was little evidence of a legacy of historical climate change affecting these patterns.



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Filed under Biodiversity, Biogeography, Brazil, Climate change, Macroecology, Pollination