Category Archives: Evolution

A fossilised flower in amber – with its pollinator!

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There have been only a handful of occasions in my professional life when I’ve been sent a manuscript to review that has caused my jaw to hit the floor with amazement.  The last time it occurred was July 2016 when I received a request to review a study that claimed to have found a fossil flower in amber, with an associated pollinator.  Not only that, but the flower appeared to belong to a species of asclepiad (Apocynaceae subfamily Asclepiadoideae) – the plant group on which I have focused a good deal of my attention over the years.  Even better, the study was by George Poinar, the originator of the idea to extract DNA from amber-encased fossils, thus inspiring Jurassic Park.  George is also the author of two books (Life in Amber and Quest for Life in Amber) that made a big impression on me when I was a PhD student and young post-doc*.

An asclepiad in amber?  From George Poinar?  How could I possibly refuse?!

One of the almost unique features of the asclepiads is that they disperse their pollen as discrete packages – pollinia – that attach en masse to their pollinators.  Only the unrelated orchids do anything similar, which means that identifying the pollinators of asclepiads is much more straightforward than for most plants, making them an ideal model group for studying plant-pollinator interactions.  I’ve had a deep interest in the asclepiads, and particularly their pollination ecology, for over 30 years. Over that time I’ve occasionally daydreamed that perhaps a fossil asclepiad flower in amber might be discovered in my lifetime, or an insect with a pollinarium attached, but I was amazed to see that this study had discovered both in the same piece of amber.  In the image at the top of this post, L and C point to some significant features of the flower, whilst T marks the pollinator.  And T stands for….

….a termite!  Termites are rare overall as pollinators and unknown in that role in relation to the asclepiads; P in this image points to the pollinia attached to the front of the head of the termite:

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You can get a better sense of the relationship between the flower and the pollinator from the photograph at the end of the this post.

After reading and re-reading and re-re-reading the manuscript I came to the conclusion that assigning the flower to a living group of asclepiads was problematical.  So (with the Editor’s permission) I solicited the views of a few colleagues with more experience than I of some of the less well-known groups of asclepiads, and related Apocynaceae s.s., the morphology of which may shed light on this intriguing fossil.  Without going into the technical details (which I’m happy to discuss with anyone who is interested) we concluded that the flower may well represent a transitional taxon as it has features of a number of different extant asclepiad lineages.  This amber, from the Dominican Republic, is estimated to be between 15 and 45 million years old, so it’s perhaps not unexpected that the set of floral features in this flower appear rather odd from a modern perspective: plants, and their flowers, evolve, just like all other organisms.

George has assigned the flower to a new genus and called it Discoflorus neotropicus  – the “different flower from the Neotropics”.  Millions of years ago this flower bloomed in the tropical forest that covered that part of the world, and attracted a worker termite to feed on its sweet nectar, pollinating the flower in the process.  Before that could take place both flower and pollinator found themselves entombed in the sticky sap being exuded by a leguminous tree called Hymenaea protera.  Many asclepiads are climbers so it’s quite possible that Discoflorus neotropicus was climbing through the branches of that tree when it got stuck.  A fateful day for flower and insect that has come down to the present day as an all-too-rare insight into ancient plant-pollinator interactions: the first fossil asclepiad flower and the first fossil asclepiad pollinator.

The study is published as follows, with a link to the journal:

Poinar Jr, G.O. (2017) Ancient termite pollinator of milkweed flowers in Dominican amber.  American Entomologist 63: 52-56

My sincere thanks to George for allowing me to highlight his research, and use his images, on my blog.  All images are (c) George O. Poinar Jr.

 

*I have a life-long interest in palaeontology that goes back to my youth, collecting fossils on the shale heaps produced from coal mining in the north of England (heaps, incidentally, that my father, grandfather, and paternal uncles had helped to create – all were coal miners in the area).  I very nearly became a professional palaeontologist but the lure of living ecosystems overcame my interest in those that are dead, though my fascination with fossils continues, particularly those in amber and (as I’ve related previously) human ancestors.

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Filed under Biodiversity, Evolution

Generalist pollination can evolve from more specialised interactions: a new study just published

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There’s a long-standing idea in biology that ecological specialisation is an evolutionary “dead end” from which species can never emerge.  In other words, if a species becomes so adapted to a particular ecological strategy (could be feeding or habitat requirements or how it interacts with other species ) then no amount of natural selection will result in its descendants evolving different strategies, thereby diversifying into new species.  In particular it’s traditionally thought that evolving broader, “generalist” strategies from narrower, “specialised” ones is highly unlikely.

This has been much discussed in the literature on the ecology and evolution of pollination systems, where traditionally this “dead end” scenario has been accepted.  However a small number of case studies have shown that generalised pollination systems can evolve within much more specialised clades, beginning with Scott Armbruster and Bruce Baldwin’s study of Madagascan Dalechampia (Euphorbiaceae), published in Nature in 1998.

To this limited body of examples we can now add another case study: in the genus Miconia (Melastomataceae), generalist nectar/pollen rewarding strategies can evolve within a clade of plants that predominantly uses a more specialised, buzz-pollinated strategy involving just bees.

The work is part of the PhD research of Vinicius de Brito who is one of the researchers I was privileged to do some field work with in Brazil when I was there in 2013 – see my post: “It’s called rainforest for a reason, right?  Brazil Diary 6“.  Vini is the guy on the left of the photo accompanying this post.  Here’s the citation and a link:

de Brito, V.L.G., Rech, A.R., Ollerton, J., Sazima, M. (2017) Nectar production, reproductive success and the evolution of generalised pollination within a specialised pollen-rewarding plant family: a case study using Miconia theizans. Plant Systematics and Evolution doi:10.1007/s00606-017-1405-z 

Here’s the abstract:

Generalist plant–pollinator interactions are prevalent in nature. Here, we untangle the role of nectar production in the visitation and pollen release/deposition in Miconia theizans, a nectar-rewarding plant within the specialised pollen-rewarding plant family Melastomataceae. We described the visitation rate, nectar dynamics and pollen release from the poricidal anthers and deposition onto stigmas during flower anthesis. Afterwards, we used a linear mixed model selection approach to understand the relationship between pollen and nectar availability and insect visitation rate and the relationship between visitation rate and reproductive success. Miconia theizans was visited by 86 insect species, including buzzing and non-buzzing bees, wasps, flies, hoverflies, ants, beetles, hemipterans, cockroaches and butterflies. The nectar produced explained the visitation rate, and the pollen release from the anthers was best explained by the visitation rate of pollinivorous species. However, the visitation rates could not predict pollen deposition onto stigmas. Nectar production may explain the high insect diversity and led to an increase in reproductive success, even with unpredictable pollen deposition, indicating the adaptive value of a generalised pollination system.

As always, I’m happy to send a PDF to anyone who wants a copy, just drop me an email.

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Filed under Bees, Biodiversity, Brazil, Butterflies, Evolution, Hoverflies, Mutualism, Pollination, Wasps

The bee that lives on a volcano!

Nature can adapt to even the most unpromising and uncompromising of physical environments, from deep oceans to arid deserts.  And now we have a bee that lives in close proximity to an active volcano!  The work is by one of my former PhD students, Dr Hilary Erenler (who is still a Visiting Researcher at the University of Northampton), and is featured in a big news story in the journal Science.

Here’s a link to the story.

The full reference for the study, with a link to the journal, is:

Hilary E. Erenler, Michael C. Orr, Michael P. Gillman, Bethan R. B. Parkes, Hazel Rymer and Jean-Michel Maes (2016) Persistent nesting by Anthophora Latreille, 1803 (Hymenoptera: Apidae) bees in ash adjacent to an active volcano. Pan-Pacific Entomologist 92:67-78.

Well done Hils, it’s a great study!

 

 

 

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Filed under Bees, Biodiversity, Evolution, University of Northampton

Pollinators and pollination – something for the weekend #9

The latest in an (ir)regular series of posts to biodiversity-related* items that have caught my attention during the past few weeks; this one’s focused on pollinators and pollination because there’s been so much emerging on this recently it’s been impossible to decide what to write more fully about!

 

Feel free to recommend links that have caught your eye.

*Disclaimer: may sometimes contain non-biodiversity-related items.

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Filed under Bees, Biodiversity, Birds, Brazil, Ecosystem services, Evolution, Honey bees, Macroecology, Pollination

Virtual Conference on Pollinators, Pollination and Flowers

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Academic conferences are an important part of what makes science function, via the exchange of ideas and information, publicly and in person.  The act of sitting and listening to both established and early career researchers discussing their most recent work, sometimes before it’s in print, is stimulating and exciting, and will never be replaced by digital technology. We’re social animals and conferences, as much as anything else, are social events.

But conferences are becoming more expensive, more frequent, and increasingly out of reach to researchers with limited budgets.  They are also getting larger: how many times have you attended a big conference and been torn between which of two (or three or four) talks to go to in parallel sessions?  Wouldn’t it be nice to be able to see all of them?  Or to go back and hear again the talks that you most enjoyed?  Likewise, wouldn’t it be great if your students or members of the public could also see what such conference presentations are like?

With this in mind, some time ago I dreamed up the idea of “virtual conferences” in as an experiment that aims to bring together into one place the most interesting recorded seminars, webinars, conference talks and public lectures that are freely available, and present them as a series of themed mini-conferences.  All of the videos in these collections are available on sites such as YouTube* and my role is just to curate them and present them in one place for convenience, as a showcase for some of the best research in biodiversity, evolutionary biology, ecology and conservation, very broadly defined, including inter-disciplinary and policy-related presentations.  And just as at a conference, there’s an opportunity to discuss the talks in the comments section on each post and to provide links to other talks on the same topic.

As well as being a service to the research community and the wider public, I hope that these conferences will be a useful teaching resource at advanced undergraduate and postgraduate level.

If anyone is interested in guest-curating a set of presentations in their own subject area on this blog, please do get in touch and I’ll be happy to talk about it.

So here’s the first virtual conference, on (naturally) pollinators, pollination and flowers:

 

Judith Bronstein (University of Arizona)

The conservation biology of mutualism

 

Peter Crane (University of Chicago)

The origins of flowers

 

Jeffery Pettis (USDA Bee Research Laboratory, Maryland)

The role of pesticides in declining pollinator health

 

Linda Newstrom (Landcare Research, New Zealand)

Pollinator systems in New Zealand and sustainable farming fund

 

Mace Vaughan and Eric Mader (Xerces Society/USDA/University of Minnesota)

Pollinator habitat assessment and establishment on organic farms

 

Carlos Vergara, Rémy Vandame, and Peter Kevan (Universidad de las Americas-Puebla/El Colegio de la Frontera Sur/CANPOLIN)

Coffee pollination in the Americas

 

Claire Kremen (University of California, Berkeley)

Restoring pollinator communities in California’s agricultural landscapes

 

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

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Filed under Bees, Biodiversity, Ecosystem services, Evolution, Honey bees, Mutualism, Pollination, Royal Society

Are tropical plants and animals more colourful? Not according to a new study!

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The notion that tropical ecosystems are somehow “different” to those at higher latitudes is a pervasive one in ecology and biogeography, that has its roots in the explorations of 18th and 19th century Europeans such as von Humboldt, Darwin, Wallace, and Belt.  All of these authors expressed their amazement at the biological riches they observed in their tropical explorations, and how different these habitats were to those they knew from home.

In many ways the tropics are special, of course and we know that they contain many more species than most other parts of the world; indeed my own work has shown that the tropics have significantly more types of functionally specialised pollination systems, and that the proportion of wind pollinated species is lower in tropical communities.  However tropical plants are not, on average, more ecologically specialised (that is, they do not use few species of pollinator) and, as the recent guest blog on Dynamic Ecology argued, there is a growing body of evidence to say that overall tropical interactions between species are not stronger and more specialised than those in the temperate zone (though there are others who dispute this and it’s an ongoing debate).

One of the central tenets of the “tropics are special” idea is that the tropics are more colourful; or rather that the biodiversity of the tropics tends to be more garish, gorgeous, and spectrally exuberant, than that of other parts of the globe.   Now a new study by Rhiannon Dalrymple, Angela Moles and colleagues, published in the journal Global Ecology and Biogeography, has challenged this idea for flowering plants, birds, and butterflies in Australia, using sophisticated colour analysis rather than relying on human impressions. Following that link will take you to the abstract and you can read it yourself; however I wanted to summarise their findings by quoting from the first section of the discussion in the paper:

Contrary to predictions…[our]…results have shown that tropical species of birds, butterflies and flowers are not more colourful than their temperate counterparts. In fact…species further away from the equator on average possess a greater diversity of colours, and their colours are more contrasting and more saturated than those seen in tropical species.”

It’s a really, really interesting study that, as the authors say, runs counter to all of our expectations.  Gradually ecologists and evolutionary biologists are testing some long-standing assumptions about the tropics and the results are proving to be a challenge to preconceived ideas about patterns in the Earth’s biodiversity.

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Full disclosure: senior author on the paper Angela Moles was my co-author on that Dynamic Ecology blog, based on which we’ve written a short review article that (hopefully) will be published soon.  Other than that I have no vested interest in the study.

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Filed under Alfred Russel Wallace, Biodiversity, Birds, Butterflies, Charles Darwin, Evolution, History of science

“one of the referees says floresianus actually means ‘flowery anus’ so it should be floresiensis

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In a parallel universe I work as a paleoanthropologist, a topic that has fascinated me ever since as a teenager I read Donald Johanson’s account of the discovery of Lucy (Australopithecus afarensis).  At university I took a short human evolution course and could easily have been swayed into doing research in that area were it not for my fascination with plants and ecological interactions (there are also parallel universes in which I’m a marine biologist, palaeontologist, gardener, sound engineer, etc….you get the picture).  I still keep half an eye on the paleoanthropological literature and enjoyed reading this interview on the Nature website with the discoverers of Homo floresiensis, the so-called “hobbit” fossil hominids, which added significantly to our understanding of the biodiversity of the human evolutionary lineage.

The line that “one of the referees says floresianus actually means ‘flowery anus’ so it should be floresiensis“, and some of the other anecdotes, give lovely insights into how science works, and the way it often follows a random, haphazard path, not at all the clear and logical route that non-scientists assume.  And it shows how the peer-review process can pick up and correct errors in a manuscript that could haunt any scientist’s career…..

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Travelling west to go north (BES Macroecology meeting day 1)

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Birmingham New Street, with its subterranean platforms accessed by narrow concrete gullets, must be one of the ugliest and most unpleasant major railway stations in Britain.  It’s also, thanks to the redevelopment work currently being carried out, one of the most confusing for the traveller who only occasionally passes through.  Ugly and unpleasant I can handle if it functions well: but ugly and unpleasant AND confusing is not good.  It’s a huge contrast to Milton Keynes station which I went through last week on the way to Chester, where the open, airy platforms look out onto embankments covered in wild flowers (see the photo above).  While waiting for the train at Milton Keynes I spotted butterflies and bees visiting flowers only feet from passing high-speed engines.

As I start this post I’m sitting on Platform 9A at Birmingham waiting for a train at 0949 to Nottingham where I’m attending the British Ecological Society’s Macroecology Special Interest Group’s annual conference.  In fact I should be on the train which left platform 12A at 0919, but trying to find the unsignposted 12A, followed by a detour to pick up a coffee, meant that I missed the train by about a minute.  Not to worry, gives me an opportunity to rant about Birmingham New Street station.

The BES Macroecology SIG has been established for three years and I blogged about the inaugural meeting in London back in 2012.  I missed last year’s meeting in Sheffield so thought I’d make a special effort to get to the Nottingham event this year, even though it involves heading west (to Birmingham) to travel north (to Nottingham).

Day 1 of the meeting started with the first of two keynote addresses by Catherine Graham from Stony Brook University.  Cathy focused on her work on that most charismatic of flower visitors, the hummingbirds.  In the first talk she dealt with the importance of thinking about phylogenetic scale when conducting analyses.  Lots of thought provoking ideas and a huge amount of information to digest.

As I’m speaking on the second day I could relax and listen to some interesting talks by established and early career researchers, and PhD students, most of whom have been given 7 minutes (!) to present their work.  It’s been a challenge to whittle the final part of the talk I gave in Copenhagen last week into such a short format, but we’ll see how I get on tomorrow.  Highlights of day 1 for me included Joe Bailey talking about urbanisation, climate and alien vascular plants in the UK; Nova Mieszkowska’s work on inter-tidal species; Sive Finaly on whether Madagascan tenrecs are an example of an adaptive radiation (answer = “maybe”); and Guy Harrington on studying fossils in a macroecological manner.  But really but all the talks were good and I learned something from each of them.

As I mentioned in that post back in 2012, defining “macroecology” is problematic and there are still those who see it as synonymous with biogeography.  Perhaps one difference is that biogeography has traditionally tended to focus on patterns (e.g. how species richness changes as one moves form the poles to the tropics) whereas macroecology also seeks to explain those patterns in terms of processes, using very sophisticated statistical and mapping approaches.  But even that fails to fully appreciate biogeography which has a tradition of also trying to infer processes (for example Joseph Hooker’s 19th century work on the distribution of plants included hypothetical explanations), though without the modern analytical tools that are available to the macroecologist.  It’s a debate that will no doubt go on, though perhaps it’s a sterile one.  Does it matter what we call it as long as the science is sound?

 

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Filed under Biodiversity, Biogeography, Evolution, History of science, Macroecology, Urban biodiversity

Rational explanations

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It has been a week for rational explanations, for assessing evidence in a logical way, a subject on which I have posted in the past and which goes to the heart of the scientific endeavour.

There was a lot of media attention about a study published in PNAS that claimed to show that hurricanes with female names (Katrina, Sandy, etc.) cause more damage than those with male names, because (to quote the abstract of the study) “hurricane names lead to gender-based expectations about severity and this, in turn, guides respondents’ preparedness to take protective action”.  In other words, people take feminine words less seriously than masculine words.  Is that true?  Are people really that socially attuned to gender-specific language?  Turns out that the original study may have made too many assumptions with regards to data and the statistical model they used, according to a re-analysis by Bob O’Hara and GrrlScientist on the Guardian science pages.  However in a further twist, a re-analysis of the re-analysis by Florian Hartig on the Theoretical Ecology blog found some (although very, very weak) support for a gender effect.  Florian makes an interesting point, however, that “the authors would have probably found it much more challenging to place this study in [a top science journal such as] PNAS if they would have done a more careful and conservative statistical analysis”.  In other words, science is certainly not immune to the effects of hyperbole and controversial findings.

Speaking of “hyperbole and controversial findings”, Richard Dawkins made headlines by apparently suggesting that reading fairy tales to children is not in their best interest: “Is it a good thing to go along with the fantasies of childhood, magical as they are? Or should we be fostering a spirit of scepticism?” Not surprisingly there was a big backlash against Dawkins who clarified his views on Twitter (!) and claimed they had been taken out of context. Perhaps so, but he has a track record of increasingly controversial views that he surely knows will raise his profile.  But then he’s an author with books to sell, who long ago gave up being a practising scientist by not publishing any peer-reviewed papers in science journals for over 30 years.  Dawkins’ role at Oxford was as Professor for Public Understanding of Science and unfortunately he gives the impression that scientists are all about rational thought and logical arguments in every facet of their lives. Which we’re not, I can assure you: I possess a whole raft of personal, irrational idiosyncrasies, including sending a little prayer to the Gods of Science every time I submit a new manuscript to a journal.  Which they often ignore, the f**kers.

There was also an odd quote from Dawkins in relation to the logic of fairy tales, that there is “a very interesting reason why a prince could not turn into a frog – it’s statistically too improbable”.  Nope, it’s not statistically improbable – it’s biologically impossible!  “Statistically too improbable” suggests that it could happen, given enough time.  Not sure that this helps with public understanding of science….

Something which is statistically improbable, but which does happen occasionally, is finding new fossils which make us rethink our understanding of the biodiversity of species interactions.  Such a find was published recently in the journal Biology Letters:  a 47 million year old fossil bird of a previously undescribed group that provides the earliest evidence of flower feeding, and possibly pollination by a birds.  The evidence in this case is the presence of pollen grains preserved in the gut area of the fossil, which could also represent flower eating (a range of birds do this, for example bullfinches) rather than nectar feeding and legitimate pollination.  Nonetheless it’s a stunning find and links nicely with a February post of mine.

Another new discovery this week, for me at least, was that (contrary to rumours, errr, started by me….) Dr Georges Aad does indeed exist.  Apologies to him, though it was fun while it lasted.

Finally to the intriguing photos that grace the start and end of this post.  I took these from the garden a couple of evenings ago. It shows a plane apparently flying into a dark tunnel that stretches out ahead of it (click on the images for a better view).  We watched the plane for several minutes and the “tunnel” appeared to be moving ahead of the plane as it travelled across the sky.  Karin had a plausible explanation, that what we were seeing was the shadow of the contrail because of its position relative to the low angle of the setting sun.  This was confirmed by a web site showing other examples of this phenomenon, which apparently is not uncommon, though judging from the comments on the site, some people prefer US government covert chemical spraying as a rational explanation.  Evidence and data will always be open to interpretation.

 

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Guest blogging: Are species interactions stronger and more specialized in the tropics?

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In hushed tones the narrator describes the intricate details of yet another highly specialized relationship between one species of indescribable beauty and a second species with intricate behaviour that is about to eat/infect/cooperate with/exploit it [delete as appropriate].

The camera view pulls back to reveal the green cathedral of a tropical rainforest: 

“The tropics” continues the narrator “are special…….…”

 

Yes, the tropics are special.  But how special?  Or more to the point, how different are tropical communities to temperate communities?  Over at the Dynamic Ecology blog, Jeremy Fox has invited Angela Moles and myself to contribute a guest blog on the subject of whether the idea that species interactions are always stronger and more specialized in the tropics is outmoded and not backed up by the evidence.  In Jeremy’s parlance, is it a zombie idea?

The subject of latitudinal variation in species interactions is one that has interested me for a while and I’ve written a few papers on the topic, especially in relation to how plant-pollinator interactions vary with latitude.  You’ll find references to some of them in the Dynamic Ecology piece, plus a fuller over view of our arguments.

So what are you doing reading this?  Get over to Dynamic Ecology and read that!

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