Category Archives: Pollination

There ain’t no b(ee) in Starbucks

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I do love a road trip.  Karin and I are just back from a drive too and from her homeland of Denmark, via ferry from Harwich to Hook of Holland, in order to pick up a porcelain dinner service that belonged to her grandparents.  It was a great trip and I hope to put up some photos from that shortly.  But before then I thought I’d write a short post about a key element of any good road trip:  coffee.

If I drive for two hours or so I have to take a break and top up with at least a coffee, possibly also a snack, certainly lunch at the appropriate time.  Last Friday, en route to Harwich, we stopped off at a motorway service station that had a Starbucks.  Whilst waiting for my coffee (Americano, no milk, thank you very much) I noticed that there was quite a lot of text on the walls all about where and how coffee grows, its cultivation and harvesting, and so forth.  Being the sort of ecologist who is interested in how plants flower and set fruit I focused on the relevant text (see the photo above).  It’s a little indistinct but, in essence, this is what it says:

“Coffee plants flower once a year…..the flowers are jasmine scented….and then some magic happens….and nine months later you get coffee fruit”

Okay, I made up the bit about “magic” but, seriously, that’s what is implied by this text: that by some hocus pocus, coffee flowers turn into the coffee fruit that contain the beans.  No mention made of the fact that pollinators (mainly wild and managed bees) are important in this process.  Although coffee can self pollinate (which is fairly magical I suppose) without the pollinators we would have much less coffee of poorer quality.

In my recent review of pollinator diversity and conservation I did some back-of-the-envelope calculations of coffee production to illustrate the dependence of modern human society on animal pollination. Here’s what I wrote:

“Coffee is pollinated by a range of wild insects (mainly bees) and managed honeybees (Ngo et al. 2011), is second only to oil in terms of its value as a commodity, and supports millions of subsistence farmers. Global coffee production in 2016 amounted to 151.624 million bags, each weighing 60kg (International Coffee Organisation 2017). One coffee bean is the product of a single fertilisation event following the deposition of at least one pollen grain on a flower’s stigma. The mean weight of a single coffee bean is about 0.1g which means there are approximately 600,000 beans in a 60kg bag. The total number of coffee beans produced in 2016 is therefore 151.624 million bags multiplied by 600,000 beans per bag, which equals 90,974,400,000,000, or >90 trillion coffee beans. However coffee is on average 50% self pollinating (Klein et al. 2003) and a single bee visit may pollinate both ovules in each coffee flower, so we can divide that figure by four: nonetheless global coffee production requires at least 22 trillion pollinator visits to flowers. Clearly the global coffee market is supported by many billions of bees that require semi-natural habitat as well as coffee plantations in order to survive”.

I don’t want to pick on Starbucks, it just so happens that that’s where we stopped, and I have certainly seen similar displays in Costa, for instance, with again no mention of bees.  Apparently Starbucks et al. don’t want to acknowledge the role of these bees in supporting their (very lucrative) industry, at least not in the cafes themselves.  If you Google “Starbucks pollinators” then you find some information online about how the company values bees, etc. etc.  But come on coffee sellers, you’re better than this, let the public know in the places where the public goes!  If you need advice from an expert, someone to write some text for you, I’m more than happy to act as a consultant.

References

International Coffee Organisation. 2017. Coffee production statistics for 2016. http://www.ico.org/prices/po-production.pdf Accessed 20th June 2017

Klein AM, Steffan-Dewenter I, Tscharntke T. 2003. Fruit set of highland coffee increases with the diversity of pollinating bees. Proc. R. Soc. B. 270: 955–961

Ngo HT, Mojica AC, Packer L. 2007. Coffee plant – pollinator interactions: a review. Can. J. Zool. 89:647–660

 

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

The evolution of pollination systems in one of the largest plant families: a new study just published – download it for free

Figure 1 JUNE revision

Interactions between flowering plants and the animals that pollinate them are known to be responsible for part of the tremendous diversity of the angiosperms, currently thought to number at least 350,000 species.  But the diversity of different types of pollination system (bird, bee, moth, fly, etc.) is unknown for most large, related groups of plants (what systematists term “clades”) such as families and subfamilies.  In addition we know little about how these interactions with pollinators have evolved over time and in different parts of the world.  Only a handful of groups of flowering plants have been studied with respect to questions such as:

How much do we currently know about the diversity of pollination systems in large clades?

How is that diversity partitioned between the smaller clades (e.g. subfamilies, tribes, genera) of a family, and what are the evolutionary transitions between the major groups of pollinators?

Do these pollination systems vary biogeographically across the clade’s range?

These sorts of questions have been addressed for the massive, globally distributed Apocynaceae (one of the top 10 or 11 largest angiosperm families with more than 5,300 species) in a study just published using a new database of pollinators of the family.  What’s more, the work is open access and anyone can download a copy for free.  Here’s the citation with a link to the paper:

Ollerton, J., Liede-Schumann, S., Endress, M E., Meve, U. et al. [75 authors in all] (2018) The diversity and evolution of pollination systems in large plant clades: Apocynaceae as a case study. Annals of Botany (in press)

In this study we have shown that (among other things):

  • The family is characterised by an enormous diversity of pollination systems involving almost all of the major pollen vectors and some that are nearly unique to the Apocynaceae.
  • Earlier diverging clades have a narrower range of pollination systems than those that evolved later.
  • Transitions from one type of pollination system to another are evolutionarily constrained, and rarely or never occur, whereas others have taken place much more often, e.g. between wasp and beetle pollination.
  • There is significant convergent evolution of pollination systems, especially fly and moth pollination, by geographically and phylogenetically distinct clades.

You’ll notice that there are 75 (!) authors on this paper.  That’s because we’ve pulled together a huge amount of previously unpublished data and used some state of the art analyses to produce this work.  It was a monumental effort, especially considering that my colleague Sigrid Liede-Schumann and I only decided to push ahead with this project about a year ago when we chatted at the International Botanical Congress that I posted about at the timeIn truth however the origins of this paper go back over 20 years to 1997 when when Sigrid and I published a study of what was then known about pollination systems in the Asclepiadaceae (the asclepiads).

In that paper we said that the research “is intended to be ongoing…[we]…hope to re-review asclepiad pollination within the next decade”.  At the time I didn’t think it would actually take more than 20 years!  However over that period a lot has changed.  For one thing the Asclepiadaceae no longer exists, broken up and subsumed within a much larger Apocynaceae.  Also, I’ve done a lot of work in the field and in the herbarium on some of the smaller groups within the family, such as CeropegiaOthers, including many of my co-authors, have also been working on different groups in various parts of the world.  Finally the level of sophistication of the analyses we are now able to do has increased beyond recognition compared to what we could achieve in the mid-1990s.  All of this means that now is the right time to produce this study.

Having said all of that, this is still a work in progress.  Our Pollinators of Apocynaceae Database contains a sample of just over 10% of the species in the family.  So lots more data on plant-pollinator interactions needs to be collected before we say we fully understand how pollination systems have evolved in this most remarkable family.  I’d be happy to talk with anyone who is interested in the family and being involved in future data collection.

The database will be freely available to anyone who wants to use it – lots more can be done with this information and, once again, I’m happy to chat with potential collaborators.

I was recently interviewed about the study, and about plant-pollinator interactions and the Apocynaceae more generally, for the In Defense of Plants podcast – here’s a link to that interview.

Finally, I’d like to express my sincerest thanks to my co-authors on this study – I really couldn’t have done it without you guys!

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Filed under Apocynaceae, Biodiversity, Biogeography, Evolution, Pollination, Wasps

British phenological records indicate high diversity and extinction rates among late-summer-flying pollinators – a recently published study

Balfour et al Figure 1

Natural history records of plant flowering and pollinator foraging, much of them collected by well informed amateurs, have huge scientific importance. One of the values of such records to ecology is that it allows us to document where these species occur in space and when they are active in time. This can be done at a range of spatial and temporal scales, but large-scale patterns (for example at a country level) are, I think, especially useful because they provide scientific evidence that can inform national conservation strategies.

During 2017 I collaborated with a young early career researcher at the University of Sussex, Dr Nick Balfour, on an analysis of the phenologies of British pollinators and insect pollinated plants.  That study was recently published (see citation below) and I think that the results are fascinating.

Nick did most of the leg work on this, which involved assessing more than one million records that document the activity times of aculeate wasps, bees, butterflies and hoverflies held in the databases by three of the UK’s main insect recording organisations, the Bees, Wasps and Ants Recording Society (BWARS), the UK Butterfly Monitoring Scheme (UKBMS) and the Hoverfly Recording Scheme (HRS).  Information on flowering times was taken from a standard British flora (Clapham et al. 1990 – Flora of the British Isles. Cambridge University Press).

As well as looking at annual flight periods and flowering trends for these organisms we also focused on pollinator and plant species that were endangered or extinct. Here are some headline results and thoughts on what the work shows:

  • About two-thirds (62%) of pollinator species peak in their flight times in the late summer (July and August), though there was some variation between the different groups – see the figure from the paper above).  Particularly noticeable was the double peak of the bees, with the first peak denoting the activity of many early-emerging solitary bees, such as species of the genus Andrena, whilst the second peak is other solitary bees plus of course the bumblebees which by that time have built up their colonies.
  • A rather fixed phenological pattern with respect to different types of plants was also apparent, which I was not expecting at all: insect pollinated trees tend to flower first, followed by shrubs, then herbaceous species (again, refer to the figure above). This might be because larger plants such as trees and shrubs can store more resources from the previous year that will give them a head start in flowering the following year, but that idea needs testing.
  • Putting those first two points together, what it means is that trees tend to be pollinated by those earlier emerging bees and hoverflies, whereas the herbs are mainly pollinated by species that are active later.
  • When looking at the extinct and endangered pollinators, the large majority of them (83%) were species with a peak flight times in the late summer, a much larger proportion than would be expected given that 62% of all species are active at that time. However this was mainly influenced by extinct bee species and the same pattern was not observed in other groups.
  • The obvious explanation for that last point is that historical changes in land use have led to a dramatic reduction in late summer flowering herbaceous species and the subsequent loss of floral resources has been highly detrimental to those bees. But intriguingly no such pattern was apparent for the endangered pollinators and clearly there are complex reasons why pollinators should become rare or extinct, a point that I have discussed previously on the blog.
  • The lack of late summer flowering resources for pollinators is a contentious issue however as plant conservation groups have in the past recommend that meadows and road verges are cut in late summer to maximise plant species richness.  Mowing road verges once or twice a year certainly benefits plant diversity, as this recent review by Jakobsson et al. (2018) demonstrates.  But there’s very little data available that assesses how timing of cutting can affect pollinators.  The only study that I know of (and if I’ve missed any, please let me know) that has considered this is the PhD work of one of my former students, Dr Sam Tarrant who looked at pollinators and plants on restored landfill sites compared to nearby nature reserves.  In a paper that we published in the journal Restoration Ecology in 2012 we showed that on restored landfill sites the abundance of pollinators in autumn surveys (conducted September-October) was just as high as for summer surveys.  On nature reserves, which are routinely cut from mid-July onward, this was not the case.

Here’s the full citation of Nick’s study with a link to the publisher’s website, and a copy of the abstract is below.  If anyone wants a PDF, drop me a line:

Balfour, N., Ollerton, J., Castellanos, M.C., Ratnieks, F.L.W. (2018) British phenological records indicate high diversity and extinction rates among late-summer-flying pollinators. Biological Conservation 222: 278-283

Abstract:

The long-term decline of wild and managed insect pollinators is a threat to both agricultural output and biodiversity, and has been linked to decreasing floral resources. Further insight into the temporal relationships of pollinators and their flowering partners is required to inform conservation efforts. Here we examined the
phenology of British: (i) pollinator activity; (ii) insect-pollinated plant flowering; and (iii) extinct and endangered pollinator and plant species. Over 1 million records were collated from the historical databases of three British insect monitoring organisations, a global biodiversity database and an authoritative text covering the national flora. Almost two-thirds (62%) of pollinator species have peak flight observations during late-summer
(July and August). This was the case across three of the groups studied: aculeate wasps (71% of species), bees (60%), and butterflies (72%), the exception being hoverflies (49%). When species geographical range (a proxy for abundance) was accounted for, a clear late-summer peak was clear across all groups. By contrast, there is marked temporal partitioning in the flowering of the major plant groups: insect-pollinated tree species blossoming predominantly during May (74%), shrubs in June (69%), and herbs in July (83%). There was a positive correlation between the number of pollinator species on the wing and the richness of both flowering insect pollinated herbs and trees/shrubs species, per calendar month. In addition, significantly greater extinctions occurred in late-summer-flying pollinator species than expected (83% of extinct species vs. 62% of all species). This trend was driven primarily by bee extinctions (80% vs. 60%) and was not apparent in other groups. We contend that this is principally due to declines in late-summer resource supplies, which are almost entirely provisioned by herbs, a consequence of historical land-use change. We hypothesize that the seasonality of interspecific competition and the blooming of trees and mass-flowering crops may have partially buffered spring flying pollinators from the impacts of historical change.

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Filed under Bees, Biodiversity, Butterflies, Hoverflies, Macroecology, Pollination, Wasps

Pollinators, landscape and friends: our recent trip to the Danish island of Sejerø

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This is not the first time I’ve written about the beautiful Danish island of Sejerø – see my post “Why do bumblebees follow ferries?“.  It’s home to our friends Pia and Stephen Valentine (Stephen is the very talented artist who produced the fabulous study of waxwings that Karin commissioned for my birthday last year).  Earlier this month we traveled over to stay with them and to explore some more of the island.  Here are some photos and thoughts from that trip.

Despite the hot, dry weather that northern Europe has been experiencing recently there were pollinators aplenty.  Thistles and knapweeds (both groups from the daisy family Asteraceae) are well known to be drought tolerant and attract a lot of insect interest.  This is a Pantaloon Bee (Dasypoda sp.)  If it was Britain I’d say that it was D. hirtipes, but there are other species on the continent so I can’t be sure.  These bees are well named: the “pantaloons” are found only on the females and are used to collect pollen, especially from Asteraceae.

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I believe that this is the male of this species; note the absence of the pollen-collecting hairs on the rear legs and the yellow face, typical of many male bees:

The flower heads of the knapweeds were highly sought after; on this one, two different bumblebees (Bombus spp.) were competing with two Silver Y moths (Autographa gamma):

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Sometimes the bumblebees got an inflorescence to themselves, though the photobombing Silver Ys were never far away:

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It’s been a good year for the Silver Y, large numbers have migrated northwards from southern Europe and we’ve had lots in our garden too.  On Sejerø they were everywhere, on all kinds of plants: 

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The butterfly is one of the Blues (Lycaenidae), possibly Common Blue (Polyommatus icarus), but again this being Denmark they may have other species that I’m not familiar with.  Note the Silver Y photobombing once more…:

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Wild carrot (Daucus carota) was common on the island and always attracts a wide range of flies, wasps and beetles:

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Close to home we found a huge cherry tree laden with the fruits of pollination and collected a couple of kilos for Stephen to make into jam.  Stoning them was messy but fun and a nice opportunity to sit and chat about nature and people:

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I was very impressed with Stephen’s up-cycled general purpose baskets, made from plastic containers he finds on the beach, wire, and lengths of old hosepipe:

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Along the shore another edible plant, Sea Kale (Crambe maritima) was attracting a lot of attention from white butterflies (Pieridae) whose caterpillars feed on this and other members of the cabbage family (Brassicaceae):

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I tried a piece of raw leaf; it tasted ok, salty and a little bitter.  Apparently it’s very nice if you blanch the young leaves.  It’s a distinctive and impressive component of the beach flora:

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Amidst the greens, buffs and browns of the beach landscape we encountered the occasional scarlet of a patch of poppies (Papaver sp.):

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Everywhere on the island we saw evidence of the link between life on land and in the sea, and the cycles and processes upon which that life depends.  Sand martins (Riparia riparia – an apt name – “riparian” refers to the interface between land and water) are common and their nest excavations speed up the return of sediments back to the sea:

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Favoured rocks have been used by gulls and other sea birds for generations, their guano helping to enrich these coastal waters and fueling the primary production of seaweeds and diatoms, which in turn feed other shore life:

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Evidence of human activities was never far away, though, concrete and steel blending with nature:

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Wheat fields merging with the sky:

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Thanks to Pia and Stephen, and of course Zenja, for making this such a wonderful trip and allowing us to join them in exploring their home island:

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Filed under Bees, Biodiversity, Birds, Butterflies, Moths, Pollination

Academic job interviews: don’t feel obliged to do everything you said you’d do

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Last month I cleared out my office in preparation for our move to the University of Northampton’s new Waterside Campus.  Going through files I’d not opened in decades was a cathartic and occasionally emotional experience.  In one file I came across a box of OHP transparencies from the presentation I gave at my job interview in 1995!  (For younger readers, OHPs were just like PowerPoint, but you carried them around in a box….)

Anyway, the presentation (see photo above) at what was then Nene College of Higher Education set out what my research plans were going to be if I was offered the job. It’s interesting to look back on these research themes and consider whether I did actually do what I said I was going to do (go to my Publications page for details of the papers I’m referring to):

Flowering phenology” – This was a large part of my PhD, which I had completed two years earlier.  At Northampton I did a bit of work,  including a big meta analysis with Mexican colleagues Miguel Munguia-Rosas and Victor Parra-Tabla, but nothing further, though I do have a lot of unpublished data that one day may see the light of, err, day….

Pollination systems in the Asclepiadaceae” – I’ve done a lot of work on this plant family, including field work in South America and Africa, particularly with my German colleague Sigrid Liede-Schumann.  However Asclepiadaceae no longer exists as a separate family (it’s now a subfamily of Apocynaceae).  I have a large paper in press at the moment which assesses the diversity of pollination systems in the Apocynaceae; more on that when it’s published.

Specialisation and generalisation in pollination systems” – yes, done lots on this too, including contributing to the Waser et al. (1996) Ecology paper that’s now racked up >1550 citations, plus assessing latitudinal trends in specialisation.  Still a major focus of my research, it’s an area where there are lots of questions still to be answered.

Reproductive output [in plants]” – very little done since my doctoral work, though questions of annual variation in reproductive allocation were a big part of my PhD.  Has fallen by the wayside rather.

Seed predation” – ditto – it was a major component of my PhD and I published a couple of things but then hardly touched the topic.  A shame in some ways as I still think it’s a fascinating topic.

Pollinator behaviour” – I’ve done some work, mainly on birds and bees rather than the butterfly model system I proposed at the time, which was to work with Dave Goulson on a follow-up of a paper we published on floral constancy in Small Skipper butterflies.  This field has moved on hugely though, with some extremely sophisticated work being done with captive bumblebee colonies for instance.

Overall I think I’ve worked on about 50% of what I said I would do, which I’m more than comfortable with.  Because I’ve also done a whole bunch of stuff I never mentioned at interview, including work on pollinator conservation and interaction network analyses, both of which were hardly thought about in 1995.  There’s also research on the history of science that I was thinking about in the early 90s but which I didn’t present as a major research theme.

The moral of this story for anyone preparing for a job interview for an academic position is: Don’t think that you have to do all of the research that you say you’re going to do in the presentation.  Opportunities come and go, and interests wax and wane.  What is currently seen as exciting research may well, in 10 years time, be seen as old hat or a dead end, or have evolved in ways that provide you with fewer opportunities to contribute.  Prepare to be flexible, but don’t lie about your intentions.  In fact, as recently highlighted on the Dynamic Ecology blog, don’t lie about any aspect of getting an academic job!

One other thing: be realistic.  In retrospect I was too ambitious in the range of areas in which I wanted to do research, though they were all linked.  But over the course of 23 years it’s impossible to say how your research career will develop.  I’m looking forward to the next 23…. 🙂

 

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Filed under Apocynaceae, Pollination, University of Northampton

Hunting the Chequered Skipper: an encounter with England’s latest species reintroduction project

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If you have been following recent conservation news on social media you’ll know that this week was an important one for invertebrates.  The Chequered Skipper, a butterfly last seen in England in 1976, has been reintroduced to the country as part of the Back From the Brink initiative.  The Chequered Skipper project is led by Butterfly Conservation and a team travelled to a site in Belgium earlier in the week where about 40 skippers were captured.  These insects were transported back to the UK where they were held overnight in mesh cages at a secret location in order to acclimatise them, then released into the wild.  The release was filmed as part of next week’s BBC Springwatch series – look out for it.

The exact location of the reintroduction is secret.  However I can tell you that it’s occurred in the Rockingham Forest area of north Northamptonshire, in habitat that (over the past couple of years) has been managed specifically for this reintroduction, in order to create a network of sites across which the species could disperse in the future.  This area was the last stronghold of the species in England prior to its extirpation.  No one knows why it went extinct here, but hung on and did well in Scotland, but it may relate to climate: 1976, as many of the middle-aged will remember, was a very hot, dry summer, and this butterfly likes it warm and humid.

Yesterday I had the privilege of seeing this reintroduction first hand when I visited the site with my colleague Dr Duncan McCollin.  Duncan and I are supervising a PhD student, Jamie Wildman, along with Prof. Tom Brereton, Head of Monitoring at Butterfly Conservation (BC), and the University of Northampton’s Visiting Professor in Conservation Science.  Jamie’s project will focus on understanding the habitat requirements for Chequered Skipper, and monitoring the success of the reintroduction.  I’m also hoping that it might be possible for Jamie to assess the role of this species as a pollinator of the plants it visits.  Butterflies as pollinators is a very under-researched area.

Here’s a shot of the Four Mus-skipper-teers* just before we set off to help BC volunteers to locate the skippers and record their behaviour:

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The day started unpromisingly.  It was cool and overcast, and little was flying except some hardy Common Carder Bees.  But around lunchtime things began to warm up and gradually the sun broke through and we started to see flying Lepidoptera that we excitedly chased, only to be disappointed by yet another Mother Shipton or Silver Y.  But no skippers.

As we encountered some of the BC volunteers who were also tracking the insects we were told that we had “just missed one” or that they “saw one down that ride, we marked the spot”.  One volunteer wanted to show me a photo of a Chequered Skipper that he’d just taken “so I could get my eye in”.  I politely refused; I wanted to see the real thing and didn’t want to jinx it with a digital preview.

Finally, our efforts were rewarded and we found the first skipper of several we later encountered.  The image at the head of this post is that butterfly, a sight that has not been seen in England in more than 40 years.  An exciting and privileged encounter.  The county Butterfly Recorder, David James (on the right in this next shot), is ecstatic that the reintroduction has occurred “on his patch” but also nervous at the responsibility it represents:

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Later we spent time helping Jamie follow a female skipper who was showing egg-laying behaviour, moving slowly for short distances along a shrubby edge, occasionally nectaring on Bugle, and diving deep into the vegetation to (we hope) oviposit on grass leaves:

 

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Although I’ve over-cropped this next image of the skipper on Bugle, I thought I’d leave it as I like the different textures and patterns, and the slightly blurry ambience:

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The primary aim of Butterfly Conservation’s project is to return a small part of England’s lost biological heritage.  But it’s about more than just the Chequered Skipper.  It’s also about understanding how managing a network of sites for this flagship species can benefit other organisms.  The wide woodland rides that have been created are packed with plant species, amongst them at least five grasses that could be used as caterpillar food sources for the skippers, plus more than 20 nectar sources were flowering that they (and other flower visiting insects) could use.  Those other insects were plentiful too: over the day I spotted five species of bumblebees, several different day flying moths, lots of Dark-edged Bee Flies, and a few different solitary bees and syrphids flies.  We heard calling cuckoos, and four different warblers: chiffchaffs, garden warbler, whitethroats, and blackcaps.  Red kites (another incredibly successful species reintroduction) floated overhead skimming the treetops as they their cried to one another.

Rockingham Forest is a lovely part of Northamptonshire, well worth a visit.  The Chequered Skipper will be a wonderful addition to its biodiversity.  Of course there are no guarantees that the reintroduction part of the project will be a success, but if it isn’t it won’t be because of a lack of commitment from the people involved.  If the population does become established then in the future the location will be made public and butterfly enthusiasts will be able to come and pay homage to one of the few butterflies with a pub named after it.

 

*You get the puns you deserve on this blog…..

 

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Filed under Bees, Biodiversity, Birds, Butterflies, Pollination, University of Northampton

The explosion in orchids as houseplants: what does it tell us about how flowers evolve?

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One of the major trends in horticulture over the last 20 years or so has been the rise in popularity of orchids as house plants.  Orchids used to have a reputation as being delicate, choosy, costly things that needed expensive glasshouses, heating, and humidity systems to grow.  Some groups of orchids are certainly like that, but many are not (Orchidaceae is one of the two largest families of plants, after all).  These days it’s impossible to walk into any supermarket or department store and not see orchids for sale at a reasonable price, orchids that are tough and can withstand the relatively dry, centrally heated houses in which most of us in Britain live. 

The majority of these orchids are varieties of Phalaenopsis, the moth orchids.  Intensive hybridisation by commercial growers has meant that there is an almost inexhaustible range of flower colours, shapes, sizes and patterning available.  Take a look at this gallery of images and you’ll see what I mean, or go into a shop that sells such orchids and observe that almost no two are alike.

This is the stuff of natural selection: genetic variation in the phenotype that can be acted upon by a selective agent.  In this case it’s the growers of orchids who choose the most attractive types to sell and discard the others.  If this variation emerged in wild populations most of it would disappear over time, but some, just occasionally, would be selected for by a different group of pollinators and go on to form a new species.  This is much more likely to happen if the individuals with this variation are isolated from the rest of the population in time or space, for example if they flower later or have been dispersed to a distant valley or mountaintop (termed allopatric speciation).  But it can also happen within populations – sympatric speciation.

Back in 1996, near the start of this orchid explosion, one of my earliest papers was a speculative commentary in Journal of Ecology called “Reconciling ecological processes with phylogenetic patterns: the apparent paradox of plant-pollinator systems”.  It generated some interest in the field at the time and has picked up >250 citations over the years, mostly other researchers using it as supporting evidence for the discrepancies we see when trying to understand how flowers evolve within a milieu of lots of different types of potential pollinators selecting for possibly diverse and contradictory aspects of floral form.  In that paper I made a passing comment that I expected the reviewers to criticise, which they did not.  Once it was published I thought that perhaps other researchers in the field would critique it or use it as a jumping off point for further study, which has not really happened either.  This is what I wrote:

         “It appears that pollination systems are labile and may evolve quite rapidly….plant breeders can obtain a fantastic range of horticultural novelties through selective breeding over just a few generations.”

This is horticulture holding up a mirror to the natural world and saying: “This is how we do it in the glasshouse, look at the variety we can produce over a short space of time by selecting for flower forms; can nature do it as quickly, and if so what are the mechanisms?”  

I still believe that pollination ecologists could learn a lot from horticulture and there’s some fruitful (flowerful?) lines of enquiry that could be pursued by creative PhD students or postdocs.  Here’s one suggestion: part of the reason why these Phalaenopsis orchids are so popular as house plants is that they have very long individual flower life times, often many weeks.  Now we suspect that floral longevity is under strong selection; see for example research by Tia-Lynn Ashman and Daniel Schoen in the 1990s.  This showed that there is a negative correlation between rate of pollinator visitation and how long flowers stay open.  Plants with flowers that are not visited very frequently stay open much longer, for example the bird-pollinated flowers of the Canary Islands that may only be visited once or twice a day, and which can remain open for more than 20 days.  Is the floral longevity shown by these orchids (or other groups of plants that have been horticulturally selected) beyond the range found in natural populations?  If so, what are the underlying physiological mechanisms that allow such extreme longevity?  If not, does this mean that there is an upper limit to the lifespan of flowers, and if so, why?  

In the mean time I’m going to enjoy the orchids above that sit on our kitchen windowsill.  They actually belong to my wife Karin who has developed something of an interest in them in recent months.  The big spotty one is a late birthday gift for her that I picked up this morning from a local flower shop, and which stimulated this post as I was walking home.  I’d bet that we never see another one like it!

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Filed under Biodiversity, Biodiversity and culture, Birds, British Ecological Society, Evolution, Gardens, Personal biodiversity, Pollination

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

Wageningen poster.jpg

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

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Filed under Biodiversity, Biogeography, Macroecology, Pollination

Can pollinators survive sudden changes in the weather?

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 6th 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 16th 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”.

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Filed under Bees, Biodiversity, Butterflies, Gardens, Pollination, Urban biodiversity

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

P1080615

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.

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