This is a short guest post by Dr Peter Bernhardt who recently retired as a professor at St Louis University and continues to be active in pollination biology.
Each of the 50 American states has its own flag. On Election Day in November 2020 the citizens of the state of Mississippi will vote on whether they want a new flag featuring the flower of their state tree, the southern magnolia or bull bay (Magnolia grandiflora). Of the eight Magnolia species native to the continental United States six have natural distributions including the state of Mississippi.
By voting in the magnolia flag Mississippians drop its 126-year old predecessor, which incorporated an emblem (the stainless banner) adopted by southern states during the American Civil War (1861-1865). This will also mean that Mississippi will be the only state with a flag depicting a flower in which tepals, stamens and carpels are all arranged in a continuous spiral and is pollinated by beetles (see Leonard Thien’s study published in 1974).
The popularity of M. grandifora far exceeds silviculture in the American south as successful exports stretch over two centuries and its cultigens are found as far as China and Australia.
Politics in America have turned floral in the last months of 2020: kamala, as in vice-presidential candidate Kamala Harris, is an Indian word for sacred lotus (Nelumbo nucifera).
To which Jeff adds: the flag above is the one that Mississippi citizens will be voting on – follow the link at the start to get the full story of the competition that was run to select a new flag.
The latest paper from Paolo Biella‘s PhD work, on which I collaborated and that I’ve discussed before on the blog, has just been published in the journal Functional Ecology. It’s entitled “An empirical attack tolerance test alters the structure and species richness of plant–pollinator networks“. The paper presents more of Paolo’s work showing how the experimental removal of the floral resources provided by the more generalised plants in a community can significantly (and negatively) affect the patterns of interaction between flowers and pollinators that we observe. It’s another piece of evidence that demonstrates how important it is to not neglect the common plants that attract a lot of flower visitors when considering how to manage a habitat.
If anyone has trouble accessing the PDF, drop me a line and I will send it to you.
Here’s the reference:
Biella, P., Akter, A., Ollerton, J., Nielsen, A. & Klecka, J. (2020) An empirical attack tolerance test alters the structure and species richness of plant-pollinator networks. Functional Ecology DOI: 10.1111/1365-2435.13642
Here’s the abstract:
Ecological network theory hypothesizes that the structuring of species interactions can convey stability to the system. Investigating how these structures react to species loss is fundamental for understanding network disassembly or their robustness. However, this topic has mainly been studied in‐silico so far.
Here, in an experimental manipulation, we sequentially removed four generalist plants from real plant–pollinator networks. We explored the effects on, and drivers of, species and interaction disappearance, network structure and interaction rewiring. First, we compared both the local extinctions of species and interactions and the observed network indices with those expected from three co‐extinction models. Second, we investigated the trends in network indices and rewiring rate after plant removal and the pollinator tendency at establishing novel links in relation to their proportional visitation to the removed plants. Furthermore, we explored the underlying drivers of network assembly with probability matrices based on ecological traits.
Our results indicate that the cumulative local extinctions of species and interactions increased faster with generalist plant loss than what was expected by co‐extinction models, which predicted the survival or disappearance of many species incorrectly, and the observed network indices were lowly correlated to those predicted by co‐extinction models. Furthermore, the real networks reacted in complex ways to plant removal. First, network nestedness decreased and modularity increased. Second, although species abundance was a main assembly rule, opportunistic random interactions and structural unpredictability emerged as plants were removed. Both these reactions could indicate network instability and fragility. Other results showed network reorganization, as rewiring rate was high and asymmetries between network levels emerged as plants increased their centrality. Moreover, the generalist pollinators that had frequently visited both the plants targeted of removal and the non‐target plants tended to establish novel links more than who either had only visited the removal plants or avoided to do so.
With the experimental manipulation of real networks, our study shows that despite their reorganizational ability, plant–pollinator networks changed towards a more fragile state when generalist plants are lost.
2 More than just bees: the diversity of pollinators
3 To be a flower
4 Fidelity and promiscuity in Darwin’s entangled bank
5 The evolution of pollination strategies
6 A matter of time: from daily cycles to climate change
7 Agricultural perspectives
8 Urban environments
9 The significance of gardens
10 The shifting fates of pollinators
11 New bees on the block
12 Managing, restoring and connecting habitats
13 The politics of pollination
14 Studying pollinators and pollination
As you can see it’s a very wide-ranging overview of the subject, and written to be accessible to both specialists and non-specialists alike. To quote what I wrote in the Preface:
“While the book is aimed at a very broad audience, and is intended to be comprehensible to anyone with an interest in science and the environment, and their intersection with human societies, I hope it will also be of interest to those dealing professionally with plants and pollinators. The subject is vast, and those working on bee or hoverfly biology, for example, or plant reproductive ecology, may learn something new about topics adjacent to their specialisms. I certainly learned a lot from writing the book.”
The book is about 100,000 words in length, lots of illustrations, and there will be an index. My copy editor reckons there’s 450 references cited, though I haven’t counted. I do know that they run to 28 pages in the manuscript, and that’s with 11pt text. All going well it will be published before Christmas.
No, it’s not safe. It’s a really, really dumb idea. Oleander is VERY poisonous and you could die. Do not do it.
OK, that was the short version; here’s the longer version. Oleander (Nerium oleander) is a plant belonging to the plant family that’s been the focus of much of my research for the past 30 years: Apocynaceae. The plant is widely grown in warm temperate and subtropical areas as an ornamental shrub or small tree and there are cultivars with flowers in a diverse palette of colours. In the Mediterranean, where it’s native, it’s a pollination generalist and pollinated by large bees, hawkmoths, and small flies. However, visitation to flowers is infrequent because, as Javier Herrera showed in this study, the flowers produce no nectar. It’s a rare example of a species of Apocynaceae with rewardless flowers in a family with very diverse pollination systems, as we showed in our study last year.
Although it’s very beautiful, oleander is also extremely poisonous. Many members of the family Apocynaceae are toxic: they are crammed full of alkaloids, cardiac glycosides, and other nasty chemicals that defend the plant against all but the most specialised of herbivorous insects, such as monarch butterflies (Danaus plexippus). But even in a family renowned for its toxicity, oleander stands out as being especially lethal.
The Scandinavian Association for Pollination Ecology (SCAPE) now has a dedicated website: https://scape-pollination.org/
The site includes some history of the conference and links to old programmes and abstract booklets, and we will use this for all future conference announcements. SCAPE2020 will be online and registration to give a talk or just attend is now open. If you’re tweeting about it please use the hashtag #SCAPE2020
My thanks to Yannick Klomberg for developing and maintaining the website.
The Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire has invited me to run my Introduction to Pollinators and Pollination workshop again this year, but of course it will all be online. Details for signing up are on the images, or you can follow this link.
Here’s a description of the workshop:
Pollination of flowers ensures the reproduction of most British wild plants and many of our agricultural crops. This session will provide an introduction to the natural history of pollinators and how they interact with the flowers that they pollinate. The main groups of pollinators will be introduced, with guidance on how to identify them, and their ecology and behaviour will be explored. The session will also consider why conserving these species is so important, followed by a Q and A discussion showing what individuals can do to help ensure their future diversity and abundance.
This year’s Missouri Botanical Garden/St Louis University John Dwyer Public Lecture in Biology will be given by Alan Mosswho researches Himalayan bumblebees and their interactions with flowers. The lecture is being live-streamed on YouTube – details are in the flyer above.
As I near completion of the copy-editing phase of my forthcoming book it’s frustrating to see all of the great research that’s been produced in recent weeks that I probably won’t be able to cite! Here’s a few things that caught my eye:
Damon Hall and Dino Martins have a short piece on Human dimensions of insect pollinator conservation in Current Opinion in Insect Science. My favourite line is: “any call to ‘save the bees’ must be a call to stabilize agriculture”. Amen to that.
In the journal New Phytologist, Rhiannon Dalrymple and colleagues, including Angela Moles who hosted me during my recent stay in Australia, have a great study entitled Macroecological patterns in flower colour are shaped by both biotic and abiotic factors. The title pretty much sums it up: in order to fully understand how flowers evolve we need to consider more than just their interactions with pollinators. It’s another demonstration of how we must look beyond simplistic ideas about pollination syndromes to fully understand the complexities of the relationship between flowering plants and pollinators…..
…..talking of which, again in New Phytologist, Agnes Dellinger asks: Pollinationsyndromes in the 21st century: where do we stand and where may we go? It’s an insightful and far-reaching review of a topic that has intrigued me for more than 25 years. There are still a lot of questions that need to be asked about a conceptual framework that, up until the 1990s, most people in ecology and biology accepted rather uncritically. One of the main unanswered questions for me is how further study of largely unexplored floras will reveal the existence of new pollination systems/syndromes. Which leads nicely to….
…..an amazing paper in Nature this week by Rodrigo Cámara-Leret etal. showing that New Guinea has the world’s richest island flora. The described flora includes 13,634 plant species, 68% of which are endemic to New Guinea! And the description of new species each year is not leveling off, there’s still more to be discovered. A commentary on the paper by Vojtech Novotny and Kenneth Molem sets some wider context to the work, and quite a number of media outlets have covered the story. Why is this relevant to pollinators and pollination? Well, we actually know very little about this critical aspect of the ecology of the island: there’s only a handful of published studies of plant-pollinator interactions from New Guinea, mostly focused on figs, bird-flower interactions, and a couple of crops. For such a biodiverse part of the world that’s a big gap in our understanding.
Finally, James Reilly, Rachael Winfree and colleagues have a paper in Proceedings of the Royal Society series B showing that: Crop production in the USA is frequently limited by a lack of pollinators. Most significant findings to me were that of the seven crops studied, five of them have their yields limited by lack of pollinators, and that even in areas of highly intensive farming, wild bees provided as much pollination service as honeybees.
That’s a few of the things that I spotted this week; what have you seen that’s excited or intrigued you? Feel free to comment.
At the time scientists and the media were suggesting that perhaps half a billion reptiles, mammals and birds had been killed, a figure that provoked a strong public reaction when accompanied by images of fire-scorched koalas. This was then revised upwards to 1 billion. But it turns out that even a billion is nowhere close to the real number of animal deaths. A new interim report commissioned by WWF-Australia suggests that just under 3 billion animals were either directly killed or displaced. Those which were displaced were vulnerable to feral predators such as foxes and cats, or more likely to succumb to starvation. An article in The Guardian about the WWF-Australia report is worth reading – here’s the link.
The actual figure is 2.69 billion individual animals. Think about that for a moment. That’s about equivalent the number of people living in India and China combined. This is the breakdown for the different animal groups that were assessed:
● 143 million mammals
● 2.46 billion reptiles
● 180 million birds
● 51 million frogs
One thing should be immediately apparent: this is not a complete list of the “animals” that have been killed. A lack of data means that fish, turtles and (crucially) invertebrates such as spiders, bees, beetles, and earthworms, were excluded. Those invertebrates live at much higher densities than any of the animal groups that were assessed and indeed are the sole or principle food for many of those species. The number of insects required to support just the insectivorous birds is staggering: globally, birds are estimated to eat 400-500 million tonnes of insects and other arthropods every year.
Even if we were to consider just the larger invertebrates, those bigger than say 0.5 cm in length (which are a minority – most are considerably smaller), then then the true scale of the animal deaths is going to be one or two orders of magnitude higher. Or possibly more. Thirty billion, 300 billion, 3 trillion…? Who knows? It’s impossible to estimate, we just don’t have enough information about those organisms.
The other major component of wildlife that is missing from the report is the plants. I know that studies of plant mortality are being undertaken at the moment and it will be important that this is given the same level of publicity as the assessments of animals.
Writing in the foreword of the report, Dermot O’Gorman the CEO of WWF-Australia pointed out that: “It’s hard to think of another event anywhere in the world in living memory that has killed or displaced that many animals. This ranks as one of the worst wildlife disasters in modern history”.
I disagree. I think it’s THE worst wildlife disaster in terms of the scale of animal losses over such a short period of time. No doubt deforestation and destruction of grasslands in South America, Asia and Africa has killed more animals and plants. But that’s over a timescale of decades to hundreds of years. Australian wildlife was devastated in a matter of months. And no one knows exactly what the 2020-21 fire season will bring. But I think that we can safely predict further impacts on wildlife – and people.
Recently I came across an online game based on a simple cellular automaton modelcalled orb.farm in which you have to design an enclosed ecosystem that supports plant, animal and bacterial life. It’s a little bit addictive and a lot of fun! Reminds me of a more sophisticated form of the Tamagotchi, but without the ridiculous waste of plastic, metal and electronics that inevitably comes with these kids’ crazes.
When I tweeted about this earlier in the week the most excitement was generated by some scientists who actually work in lake ecosystem ecology. They were very impressed! The occasional Easter Eggs that appear also keep you hooked. Helpfully, you can also close down your browser or computer and your ecosystem is still there when you open it up again.
Orb.farm is by Max Bittkerand I hope that he develops it further. I can see it being used for some serious experiments as well as being educational and fun.
Prof. Jeff Ollerton - ecological scientist and author 