Shall we kill all our bees?

1024px-Bee_covered_in_pollenKill all the bees!!”, the modest proposal of Prof. Paul Sutton from University of South Australia is a provocative attempt to convince economic rationalists to finally start counting what really counts.

If all the bees were to go extinct we will have to replace them by, for example, hand-pollinating our crops. That means employment, economic growth in terms of GDP and tax revenues: very good for the Economy.

Now, the fact that not many economists will actually support this policy does not change the fact that if all the bees are going to be gone then GDP would actually rise, jobs would actually be created as well as tax revenues.

This is a market failure too big to be ignored! We need to “abandon magical thinking about free markets and invisible hands … and develop appropriate worldviews that are broader than the narrow economic worldview we are currently trapped in”. The services provided by healthy ecosystems should be considered too big to fail, just like the big banks.

Environmental scientists have lost an argument with economic rationalists. The evaluation of ecosystem services strives to use a common language between environmental sciences and economics.

Economists are the primary advisors of governments. We need environmental scientists with the same decisional power to face future challenges deriving from our current model of infinite growth on a finite planet.

Author

Luca Coscieme, coscieml[at]tcd.ie

Photo credit

Wikimedia commons

Seminar series highlights: Phil Stevenson

hoenybee

As mentioned previously on the blog, Andrew Jackson and I started a new module this year called “Research Comprehension”. The module revolves around our Evolutionary Biology and Ecology seminar series and the continuous assessment for the module is in the form of blog posts discussing these seminars. We posted a selection of these earlier in the term, but now that the students have had their final degree marks we wanted to post the blogs with the best marks. This means there are more blog posts for some seminars than for others, though we’ve avoided reposting anything we’ve posted previously. We hope you enjoy reading them, and of course congratulations to all the students of the class of 2014! – Natalie

Here’s articles from Maura Judge and Chris Parsisson inspired by Professor Phil Stevenson‘s seminar, “Pollinator fidelity in coffee and citrus: is it all just sex and drugs?”

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An unlikely love story

Maura Judge

This is the story of a certain love affair, commonly known as floral constancy. The story involves pollinators and flowers. Floral constancy is the tendency of a pollinator to remain faithful to and exclusively visit a certain flower species or morphospecies. Whilst remaining faithful, the pollinator bypasses other available flower species that could potentially be more rewarding.

So what are the drivers of this phenomenon? For the plant species, the benefits are more obvious as pollinators that are flower faithful are more likely to transfer pollen to other flowers of the same species and hence, flower constancy favors flower pollination. Furthermore, flower constancy prevents the loss of pollen during interspecific flights and prevents pollinators from clogging stigmas with the pollen of other flower species. Hence, the reasons for the evolution of floral constancy in plants are obvious.

However, what could be the benefits for a pollinator? To ignore other flowers that could potentially provide more nectar than their preferred type contradicts the optimal foraging theory. Nonetheless, floral constancy has been observed in honeybees (Apis mellifera), bumblebees (Bombus terrestris) and butterflies (Thymelicus flavus). Drivers of floral constancy are rewards associated with cues such as flower shape, colour or scent. For example, honeybees have been found not to attempt to feed on other available flowers that exhibit an alternative colour to their preferred flower type. One hypothesis for the evolution of floral constancy in pollinators is that insects can only identify and handle one flower type or species at a time due to their limited memory capacity.

There are three other hypotheses for the evolution of floral constancy in pollinators. The first is the learning investment hypothesis which refers to the ability of a pollinator to learn a motor skill to obtain nectar from a certain species of flower. Learning these motor skills requires a substantial investment of energy and switching to other flower species could be energetically costly and hence, inefficient and non-adaptive. Furthermore, feeding from one particular plant species increases the insect’s efficiency to obtain nectar from it. The second hypothesis is the costly information hypothesis which states that pollinators stay faithful to one plant species because they know that they obtain a reliable reward from it, i.e. nectar. Hence, the pollinator does attempt to feed on other plant species because it cannot predict the amount of nectar in other flowers and could essentially waste foraging time and energy on flowers that contain possibly less or even no nectar. The third alternate hypothesis is the resource partitioning hypothesis. It states that, in social foragers, flower constancy could benefit the entire colony as if individual foragers specialize on specific flower species, foragers avoid competing with one another. Thus floral constancy would increase foraging efficiency.

In addition, Prof. Stevenson and his colleagues have found evidence for another hypothesis in which toxins such as caffeine are the drivers of floral constancy in pollinators. Evidence for this came from bees being found to be more likely to forage on the same plant species if it contained caffeine and less likely to confuse it with similar signals from other plant species. They have found evidence of plant defence compounds enhancing the memory of reward in pollinators. Honeybees rewarded with caffeine, which occurs naturally in coffee and citrus plant species, were three times as likely to remember a learned floral scent as honeybees rewarded with sucrose alone. Thus, this proposed hypothesis ties the little understood phenomenon of floral constancy in with the little understood ecological role of plant defence compounds occurring in floral nectar.

Admittedly, this love affair is not as rosemantic (pun intended) as Romeo and Juliet’s. However, it is very intriguing nonetheless and the mechanisms behind it are still very uncertain. Exciting new evidence underlying the mechanisms involved is being found by Stevenson and his collaborators and it seems likely that it is not solely Britney Spears who finds toxicity attractive.

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The deviousness of flowers

Chris Parsisson

It should have come as no surprise to us that flowers act as drug pushers to get their evil way. Phil Stevenson of The University of Greenwich and Kew gave a short talk about the loyalty of pollinators to nectar producers.

Flowers have many devious tricks and will stop at nothing to reach their ultimate reproductive goals.  A world before flowers must have been a drab place with wind pollination being the order of the day and clouds of pollen wafting across the countryside in a desperate bid to land on a female plant part and perpetuate the gene line of the parent. No colourful flowers, no enticing perfume, no sweet honey. Just a hay fever sufferer’s nightmare. No wonder some plants formed a partnership with pollinators to streamline the operation.

And what a partnership it was! Insects often took on the role of pollinators and tied their fortunes to the plants’ success as plants tied themselves to the pollinators. Flowers evolved colours and scents to attract insects then often refined their flowers for special partners. Bees and wasps became preeminent in pollination and became dependent on supplies of nectar and pollen for their living. Always lured in by the flowers their co-evolution made both mutually dependent. The beauty of flowers and scents led to human intervention and flowers were developed with multiple petals and constant flowering periods but these developments often led to sterile flowers or loss of scents the need for human pollination. Isn’t it always the way? But who is keeping score? The millions of cultivated roses grown around the world must outnumber the wild roses in hedgerows so again the inclusive fitness of the roses, originally chosen for a brighter or extra petal, was assured. We too were seduced by the flowers into serving their nefarious schemes.

We discovered in recent decades that the colour we see on a flower is not the same as that seen by many pollinators. Bees see more in the ultra violet range and the patterns they perceive on many flowers lead directly to nectaries or to the stamens for a dusting of pollen or to shed some onto the stigma in this joint effort. No wonder many cultivated flowers with their multiple petals, lack of scent and vibrant colours are inaccessible to many bees, the landing instructions are lost and the nectaries have often been sacrificed for more petals. Best leave the cultivated flowers for the humans, enthralled by the flowers’ guile.

We know that some orchids lure male bees in with the promise of quick uncomplicated sex. Like a seaport pimp enticing a sailor down an alley with promises of beautiful girls nearby, the orchid entices him in and delivers nothing. The female bee is really another co-evolved flower and the male gets nothing for his trouble. The orchid delivers its pollen onto the bee’s back and off he goes looking for another flower. The floral equivalent of robbing the sailor and sending him staggering off into the night.

Now, it seems, we find that flowers are demanding loyalty of bees by slipping them drugs without their knowledge. Small amounts of caffeine are included with the nectar at a level thought to be below the taste consciousness of the bee but enough to make it remember the hit it got and return for more. This occurs in many coffee species and also in citrus species. It makes evolutionary sense. All flowering plants are competing with every neighbouring flower. If they weren’t and there were enough pollinators to go around all flowers would be simple in form and give out a minimum amount of nectar. That’s why flower form evolved so dramatically. The cunning flowers need an extra edge to ensure that bees come back to them as long as their flower lasts. Many flowers need a pollinator to visit more than once: to take away pollen to another flower and to bring in pollen. Often the female stigma ripens at a different time to the male anthers to prevent self-fertilisation so multiple visits may be ensured by making a bee remember the little lift it got at a particular plant.

Pollination is a serious business as 65% of crops are insect pollinated. Concerns about sudden hive collapse of honey bees and losses of pollinators are real. Even the managed bees are not enough for all pollination needs so wild pollinators must be carefully watched. Large monocultures may be detrimental to bees as tests have shown that levels of amino acids in some nectar may be harmful if eaten in excess.

Many leads could follow this research as a way to best serve the pollinators but, rest assured, those devious flowers will be still full of tricks.

Image: Wikicommons

Big is better!

INTECOLlogo

Reflections on geeking it up at Intecol 2013 by Jane Stout

Having not been to a 2000+ delegate, multi-session, international conference for several years, I was a bit nervous in the run up to INTECOL2013 “Into the next 100 years: advancing ecology and making it count” – would it be possible to see all the talks, read all the posters and meet all the people I planned to? (Answer: no). Would I remember everyone and would anyone remember me from past meetings? (Answer: some yes, some no – thank goodness for name tags). Could I follow in the footsteps of Katie Taylor, the last girl from Bray to take the stage at the London ExCeL Arena, and take the Olympic gold? (Answer: no; note to self: must try harder). But I needn’t have worried – INTECOL 2013 was excellent: it was well organised, the quality of the science was top-notch, the sun shone, and the whole thing was very inspiring and humbling.

First off, there were some excellent plenaries. Georgina Mace’s talk on “Looking forwards not backwards: Biodiversity conservation in the 21st century” was particularly lucid and inspiring, even though one of the things that I remember best was when she did look backwards, at what she termed the four “ages of conservation”: 1. Nature for itself (all about protected areas, species, populations), 2. Nature despite people (all about the terrible things humans have done to nature – threats and drivers – I think this was more or less when I started my BSc), 3. Nature for people (ecosystem function, ecosystem services) and 4. People and nature (about changes and dynamics, involving more socioeconomics etc.). She highlighted that conservation focus has moved fast but the science has not necessarily kept up. And that extremes not averages may matter more in the future.

Bill Sutherland’s plenary on “How do we improve decision making?” was also really good – he talked about how (not) to make decisions and stressed that good scientific evidence was not only fundamental, but needed to be effectively communicated in order to be taken into account.  He also highlighted some research into so-called “experts” which was fascinating (see Bergman et al. 2011). The panel discussion following Bill’s talk was really good, especially as it was effectively and humorously chaired by Professor Sue Hartley (Director – York Environmental Sustainability Institute). Having Bob May describe his position as the first Chief Scientist to the UK government was really interesting – and made me realise how great it would be if we had a similar position here in Ireland.

David Tilman managed to pull a plenary talk out of the bag at <48hrs notice, which was not only impressive in itself, but also an excellent talk. He described some of the findings from the Cedar Creek biodiversity plots which show the importance of biodiversity (“I knew biodiversity was going to be important, what I hadn’t realised was just how important”) and talked about how it wasn’t necessary to trade biodiversity off against food production – we just all need to eat less meat. He suggested that we all to invite friends round and cook vegetarian food (try this veg curry!).

Aside from the plenaries, there were heaps of really interesting talks. There were so many good titles that there wasn’t a hope of seeing everything that I wanted to. The thing that amazed me was how many pollination related talks there were. The last time I went to a conference like this there was maybe half a dozen pollinator talks. At this meeting there were at least 44 oral presentations with something to do with pollination or bees in the title. Hardly surprising given all the media hype associated with bee decline, but great to see how this field has grown in the past 10 years.

I was fortunate enough to speak in the symposium “Threats to an ecosystem service: evaluating multifactorial pressures on insect pollinators”, which included a really excellent introduction by Claire Kremen, who described, among other things, almond pollination in the US – millions of honeybee colonies are shipped into California from all over the country to pollinate almonds because there are no wild bees left in the orchards. One of the things she’s working on is introducing native wild plants in hedgerows into the landscape – made me realise how lucky we are here in Ireland with our complex landscapes full of hedgerows. Many of the other speakers in this session were talking about work they have done as a result of the Pollinator Initiative funding in the UK. There’s some excellent work going on there. The symposium was followed by a social event which apparently was sort of like speed dating but with “experts” moving around the room speaking to different people (who were mostly equally, if not more, expert themselves). Not sure whether it really worked, but there was a glass of wine in it for everyone (and no dating involved thankfully).

I saw some really nice presentations by current PhD students – some of my favourites were Alistair Campbell from Lancaster talking about enhancing beneficial insect communities and their services in cider apple orchards by planting flower strips; Gita Benadi from Wurzburg talking about her work on phenological synchrony between plants and pollinators and implications of shifts in either taxa with climate change; and Katherine Orford from Bristol talking about her work on how grassland management affects pollinator community diversity, function and biomass. Keep an eye out for their papers…

I didn’t manage to get to the BES birthday party, which was apparently great fun, but there were some great social interactions (shame about the beer – this part of London is so new there aren’t any decent pubs). We did take the cable car from the Excel Arena to the O2 Arena aka Millennium Dome and then a boat up the River Thames which was cool. And the sun shone! Happy geeky nerdy sunny ecology days…


Author:

Jane Stout: stoutj[at]tcd.ie

@JaneCStout

Image source:

intecol2013.org 

What I did this summer: Tortured some bees

Bumble-bee_on_Rhododendron

Among the multiple pressures currently driving decline in bee populations, little attention has been given to naturally occurring toxins in plant nectar.  We carried out research this summer on invasive Rhododendron ponticum, a plant that contains neurotoxins in its floral nectar.  We found this toxin to be lethal to honeybees, but apparently benign to the plant’s main pollinators, bumblebees.  Differential responses by bee species to toxins and other pressures means we need to consider bee decline on a species by species basis.

It is well documented that bee populations worldwide are in trouble, and we’ve written about this on the blog before.  From peer reviewed scientific literature to the August 2013 issue of Time magazine, everyone is talking about declines in bee populations.  Bees are important pollinators and contribute to the pollination of 75% of our crop species, which translates to 35% overall global crop production.  The downfall of wild and domestic pollinators could pose serious risks for food security and ecosystem function.

Most people agree that the decline of bees can’t be attributed to one specific cause.  Instead, multiple pressures such as habitat loss (including loss of forage plants, as well as nesting, mating and overwintering sites for wild bees), and exposure to new diseases and parasites are probably all contributing.  One of the suspected drivers of bee decline that has received a lot of media coverage lately is exposure to synthetic pesticides, especially neonicotinoids, which end up contaminating the nectar and pollen of bee-pollinated crops.  Surprisingly though, pesticides aren’t the only potentially harmful chemicals bees are exposed to in their food.  They also have to cope with natural plant toxins in nectar and pollen.  Plants often produce toxic secondary compounds, such as alkaloids, terpenes, and phenolics, to defend against herbivorous insects, like aphids and caterpillars.  We humans tend to use many of these chemicals for our own purposes- for example, nicotine (found in nicotiana plants) and caffeine (in citrus and coffee plants).  But plant nectar is generally thought to function as a reward for pollinating insects like honeybees.  Why then do we find these deterrent chemicals in floral nectar?  And how are they impacting honeybees and wild bees?  This is a large part of my PhD project, see this old blog post for more detail.

Researchers in the lab of Dr. Jane Stout at Trinity College Dublin are studying drivers of bee decline, and a current project focusses on a plant that contains toxins in its nectar, Rhododendron ponticumRhododendron is an ecologically damaging invasive plant in Ireland and Great Britain, famous for the problems it has caused in forest ecosystems in places such as Killarney National Park.  This plant grows in moist, acidic soil, and often takes over the understory and edges of forests, shading out other floral resources.  The work done at Trinity (in collaboration with Dr. Phil Stevenson at Greenwich University and Dr. Geraldine Wright at Newcastle University) has found that Rhododendron contains a class of toxic chemicals known as grayanotoxins (GTX) in its nectar and pollen.  These chemicals are neurotoxins, which block the sodium channels of insects and cause neurological symptoms, like paralysis.  To certain insects, this toxin can be lethal.

I am doing a PhD with Dr. Stout and one of my studies is investigating how GTX from Rhododendron nectar affects Irish bees.  Together with undergraduate Zoology students Tara English and Sharon Matthews, I’ve performed assays using honeybees, bumblebees, and solitary bees.  We fed the bees sugar solutions that are designed to mimic floral nectar, but bees in one treatment are fed solutions containing the toxin and their survival and behavior is compared to control groups, fed solutions containing no chemicals.  Surprisingly, the consequences of ingesting GTX from Rhododendron were very different depending on which species of bee was being tested.

Bumblebees can be seen feeding on Rhododendron every May and June in Ireland, and so, as you would expect, they have no apparent negative reaction to consumption of GTX: there was no impact on survival or behavior.  Solitary bees are more rarely found feeding on Rhododendron.  In the lab, no differences in survival were detected in one species of Andrena, but these bees showed behavioral changes.  Bees flipped on their backs and twitched for hours after eating solutions containing GTX.  They eventually recovered, but one can imagine that this behavioral response could make them easy targets for predators like birds, and prevent them from foraging and provisioning their nests in their usual way.

Lastly, and most dramatically, were the effects on honeybees.  Honeybees showed an almost immediate neurological response to consuming solutions containing nectar-relevant concentrations of GTX: within fifteen to twenty minutes, the bees began twitching and lost antennal function.  Some unrolled their proboscis and couldn’t role the tongue-like structure back in, while others regurgitated the liquid as soon as possible.  Regardless of their symptoms, within three to six hours, bees fed the GTX solution were dead.

Even though the effect of GTX on honeybee survival is dramatic, compared to the other pressures on the industry, Rhododendron is probably not a huge problem for honeybees.  Field surveys by the TCD researchers show that honeybees are not found foraging on Rhododendron in Ireland, even when hives are kept in the middle of a forest invaded by the plant.  Honeybees have a remarkable ability to communicate which are the best plants to collect nectar and pollen from, and it’s likely that they quickly learn to avoid this toxic plant.  Still, Rhododendron is likely preventing the growth of other plants that might provide forage resources for honeybees, to some extent changing the landscape in an unfavorable way for this species.  But our work, in combination with previous work from the Stout laboratory, shows honeybees do not represent the entire ecological story.  A study carried out in 2006 and 2007 by Anke Dietzsch showed that the number of bumblebee colonies of two species was higher in areas invaded by Rhododendron when compared to uninvaded control sites in both years.  Rhododendron provides a huge amount of nectar and pollen early in spring that this group of bees can take full advantage of.  So is Rhododendron good for bees or bad for bees?  Turns out it depends what bee species you’re talking about.

The species-specific response to the toxin in Rhododendron nectar is surprising, and emphasizes that not all bees are the same.  It’s easy to group these insects into one category, but the impacts of chemicals and other pressures could be very different for each species.  It also emphasizes that honeybees are facing many challenges in our changing landscape.  Some of these challenges, like habitat change from invasive species and exposure to chemicals, can interact to make the picture even more complicated.  Pollinators, including honeybees, need all the help we can provide.

Work on the toxic nectar of Rhododendron ponticum is funded by Science Foundation Ireland, with additional support from the U.S. National Science Foundation, Irish Research Council’s EMBARK Postgraduate Scholarship Scheme, and the Wellcome Trust.


 Author:

Erin Jo Tiedeken: tiedekee[at]tcd.ie

@EJTiedeken

Photo source:

Wikicommons

 

School of Natural Sciences Postgraduate Symposium: Part 2/4

Phoenicopterus_roseus_(Walvis_bay)

On the 15th and 16th April we had one of my favourite events at Trinity College Dublin: the annual School of Natural Sciences Postgraduate Symposium. Over the course of two days many of our PhD students presented their work to the School. We also had two amazing plenary talks from Dr Nick Isaac (CEH) and Professor Jennifer McElwain (UCD). For those of you who are interested in exactly what we work on here at EcoEvo@TCD, here are the abstracts from the PhD student presentations. Check out the TCD website for more details!

 

Danielle McLaughlin: BMP signalling disruption in the foregut of the Adriamycin mouse model of Oesophageal Atresia/Tracheo-Oesophageal fistula.

1/3500 neonates are born annually with Oesophageal Atresia/Tracheo-Oesophageal Fistula(OA/TOF), a birth defect of unknown cause, where the oesophagus fails to properly form and connect with the stomach. Despite corrective surgery, afflicted children have long-term health problems. Oesophagus and trachea arise from embryonic foregut. We use an animal model with OA/TOF-like foregut malformations, the Adriamycin Mouse Model(AMM), to investigate the developmental origins of these malformations. An important embryonic organising structure, the notochord, is abnormal in shape, position and molecular characteristics in AMM embryos. Current work focuses on Bone Morphogenic Protein signalling, analysing downstream events and showing very specific disturbances in AMM notochord and foregut.

Donna Hawthorne: What role did fire play in the Irish uplands, from the early Holocene to the present day, and how should fire be best managed in the future?

Significant changes in global and regional climate as well as changes in vegetation, land use, agriculture and policy, have promoted an increase in fires in the Irish landscape, especially in upland areas. Past climatic oscillations have been studied at 10 sites throughout Ireland in an attempt to understand the current climatic changes which may mirror future patterns in climate. This coupled with the palaeo-reconstructed landscape character and fire regime at each of these upland sites, will seek to develop a model of risk assessment and management for future fire in the Irish landscape. The data span from the early Holocene to the present day, drawing on charcoal and pollen data, radiocarbon dating, and mineral and chemical data from lacustrine sediments, as well as the historical record from a number of sites in Killarney National Park. This work presents the first chronological comparison of regional fire activity across various locations throughout Ireland, and provides a base line level of data which can be drawn on in future scenarios when fire frequency is expected to increase. This work is in its second year of a four year PhD programme and preliminary results will be presented.

Eileen Diskin: The f word. *Highly commended*

Antibiotic resistant bacteria are bacteria that can survive exposure to the antibiotics designed to render them harmless. You’ve probably heard them mentioned in the news; MRSA is frequently cited as an example of the threat they pose to human health. In this presentation, I will give an overview of my research on environmental reservoirs of antibiotic resistance. In sharing a selection of my results, I will address several questions: What does my approach have to offer? What challenges have I overcome in my research, and what opportunities have arisen as a result? I will conclude by considering what the next steps are, both in my project specifically and in this research area more generally.

Anurati Saha: The influence of mechanical forces for the definition of articular cartilage.

Articular cartilage covers the terminal ends of bones at synovial joints.  It allows pain-free movement with injury or degeneration leading to diseases such as osteoarthritis Current treatment is whole joint replacement but stem cell regenerative therapies would offer a more sustainable solution.  Previous research in the lab has shown that appropriate mechanical stimulation from movement of the embryo is required for normal joint formation; joints fuse when movement is absent. My project aims to increase our knowledge of mechanical regulation of joint development in a number of respects and to explore application of such findings to achieve stable differentiation of cartilage for alternative regenerative therapies.

Erin Jo Tiedeken [@EJTiedeken]: The buff-tailed bumblebee Bombus terrestris has poor acuity for the detection of toxins in nectar. *Highly commended*

Bees feed exclusively on nectar and pollen to obtain carbohydrates and proteins necessary for survival.  Paradoxically, these plant products often contain toxic secondary compounds usually associated with defence against herbivores.  Although these compounds commonly occur at low concentrations they may still have significant effects on pollinator behaviour and health. The aim of this study was to determine whether a generalist bumblebee, Bombus terrestris, can detect naturally-occurring concentrations of potentially toxic compounds in floral nectar. We found the detection thresholds for five plant compounds: quinine, caffeine, nicotine, amygdalin, and grayanotoxin, all of which are found in the nectar of plants pollinated by Bombus species.  In paired choice experiments, individuals were offered both a sucrose solution and a sucrose solution containing a putative ‘toxin’. The detection threshold was determined when bees significantly preferred the sucrose solution to the solution containing the secondary compound.  The detection threshold depended on the compound, but in all cases was above the naturally-occurring concentration range found in floral nectar.  The inability of bumblebees, an important group of pollinators, to detect toxins in floral nectar suggests this plant trait may be maintained in plant populations if it confers any benefit to the plant.

Lindsay Hislop: Does nutrient enrichment moderate the effect of water level fluctuations on littoral communities?

Freshwater abstraction from lakes in order to support a growing human population is rapidly becoming a major global stress on lacustrine ecosystems. The consequent amplification of water level fluctuations disproportionately impacts lake littoral zones, which contain the majority of their biological diversity. However, remarkably little is known about the impacts of amplified water level fluctuations on littoral assemblages and less still is known about how they interact with nutrient enrichment, one of the most pervasive and important of human disturbances on the biosphere. To address this, an experiment was established in large outdoor mesocosms and the effects of water level fluctuations and nutrient enrichment, both separately and together were quantified.

School of Natural Sciences Postgraduate Symposium: Part 1/4

Postgraduate students from Trinity College Dublin's School of Natural Sciences
Postgraduate students from Trinity College Dublin’s School of Natural Sciences

On the 15th and 16th April we had one of my favourite events at Trinity College Dublin: the annual School of Natural Sciences Postgraduate Symposium. Over the course of two days many of our PhD students presented their work to the School. We also had two amazing plenary talks from Dr Nick Isaac (CEH) and Professor Jennifer McElwain (UCD). For those of you who are interested in exactly what we work on here at EcoEvo@TCD, here are the abstracts from the PhD student presentations. Check out the TCD website for more details!

 

Rebecca Rolfe [@rolfera]: Identification of mechanosensitive genes during skeletal development: alteration of genes associated with cell signalling pathways.

Mechanical stimulation is important for correct formation of the skeleton. Mutant mouse embryos that develop with no skeletal muscle have altered mechanical stimulation resulting in specific defects in ossification and joint formation. We tested the hypothesis that mechanical stimuli influence the regulation of genes important in skeletal development by analysing the transcriptome of muscle-less and control skeletal tissue. We found 1,132 independent genes are differentially expressed with significant enrichment of genes associated with development and differentiation and cytoskeletal architecture. In particular, multiple components of the Wnt signalling pathway are affected. Further analysis will examine the mechanisms by which mechanical stimulation influences gene expression and differentiation, findings that are relevant to controlling differentiation in stem cell based regenerative therapies.

Adam Kane [@P1zPalu]: Scrounging Scavengers: Vultures acquire information on carcass location from scavenging eagles.

Vultures have an ecological role as obligate scavengers. In addition to being unable to kill prey for themselves we suggest that they are dependent on other species to locate food. Our analyses of bird arrival times at carcasses show that vultures join a carcass after discovery by raptors more often than expected by chance. We develop a game-theoretic model showing that such an interspecific producer-scrounger game is evolutionary stable when vultures are dominant to raptors in agonistic interactions over food. This hierarchy was confirmed at the carcass. Vulture populations are declining so our findings have implications for the conservation of the group.

Sarah Hearne [@SarahVHearne]: Intrinsic and extrinsic factors shape global marine diversity.

Intensifying anthropogenic pressures on ecosystems on a global scale have lead to an increased focus on the relationships between biodiversity and stability. Many studies of biodiversity have focussed on changes in diversity measures over relatively short timescales. However, there are also long-term changes in biodiversity which have been revealed through the fossil record. My project is examining global marine invertebrate diversity throughout the Phanerozoic Period (540my to present) to determine the causes of the cycles of extinction and origination over this time period. Using a new technique, convergent cross mapping, it has been shown that extinction and origination are both driven by diversity and each other, while extinction is also causally affected by temperature and origination by sea level.

Aoife O’Rourke: Spring foraging resources and the behaviour of pollinating insects IN grey dune ecosystems.

Grey dunes are a priority habitat under the EU Habitat Directive. They often contain creeping willow (Salix repens L., Salicaceae), which is suggested to be an important early season resource for bees and other obligate flower visitors. However, there is a paucity of empirical evidence to support this claim. We examine the springtime activity of obligate flower visitors in the grey dune ecosystem in relation to nectar sugar concentration and composition, relative abundance (%) of essential amino acids in pollen, and the abundance of floral units of S. repens and co-flowering plants in the environment. We also investigate the effect of S. repens presence on the abundance and species richness of solitary bees, bumblebees and hoverflies. Insect focal observation, pan-trapping and chemical analyses techniques were used to explore our research questions. Results will be presented and discussed in the context of managing habitat to increase resource availability for pollinators during spring.

Deirdre McClean [@deirdremcclean1]: The world in a bottle: Investigating stability and social transactions in microbial communities. *Best talk 1/2*

Understanding how perturbations affect the long term stability and dynamics of different systems has been a core challenge for ecological research. Identifying the mechanisms by which communities respond to and recover from different perturbations is of vital importance for assessing the impacts of anthropogenic pressures on the environment. Long term, multi-generational field studies are typically impractical, costly and confounded by a host of other ecological variables that need to be accounted for. Logistically feasible model systems are therefore needed in order to test more generalized ecological and evolutionary theory. Here we use experimental microcosms to examine the interactions among food web structure, habitat modification and social interactions in order to determine how these might moderate the effects of perturbations on stability.

Brian McGuinness: Escallonia spp. fungal pathogens. Sadly Brian missed the symposium but we still have his abstract…

A fungal disease affecting plants from the genus Escallonia has become a significant problem for both the nursery industry and for gardeners who use it as an ornamental boundary hedging. Development of lesions generally starts on older leaves throughout the plant usually causing some degree of defoliation ranging from mild to severe and sometimes resulting in plant death. We show how susceptibility of Escallonia to leaf spot disease varies across species and infra-specific taxa by in-situ assessment. No 100% genetic match currently exists for the organism causing the leaf spotting which is the same organism affecting plants in the U.K. Next steps include generating a full taxonomic description based on morphology and conducting next generation sequencing to identify any population differences that may exist.

“See you later, pollinator”

Scientific conferences can be a great way of meeting people, getting and sharing new ideas, and networking with people from, often, all over the world. And they can be good fun too! On October 25th-28th several people in the School travelled to Norway for the annual conference held by the Scandinavian Association for Pollination Ecologists (SCAPE). This meeting is held for ecologists working with pollination, plant reproductive biology and other related fields and it attracts a small but expert crowd from Scandinavia, Europe, and sometimes even further afield (this year there were attendees from Brazil and Israel!).

PhD and MSc students are particularly encouraged to present their work and it is an amicable place to give a conference presentation or poster.  In the past the friendly nature did not detract from the quality of the research or of the feedback that’s received, and this year was no exception.  It was particularly exciting to hear a talk by Amots Dafni, who literally wrote THE book on pollination ecology.  He was discussing work his lab carried out which surprisingly did not support an old hypothesis: that floral heat rewards attract males bees to overnight inside flowers.  We also heard about communities of bacteria on plant organs, the effects herbivores can have on the volatile (smell) profiles that attract pollinators, the potential positive effects of bees that “rob” nectar, and a really interesting talk about when pollination limits the yield of crops.

For a conference that sounds so specialized it was amazing to hear the range of topics people were working on. There was also a field trip around the beautiful surroundings of the island of Skjaerhalden where the conference was held, and a Norweigan style party! SCAPE is an example of how a balance of work and play make for a creative and inspiring mix, and where the facilitation of open, non-competitive discussions can lead to a greater understanding of the topics presented, and also sow the seeds for exciting collaborative endeavours. And the catchphrase for the weekend… “see you later, pollinator”!

Author

Erin Jo Tiedeken: tiedekee[at]tcd.ie

Photo credit

Erin Jo Tiedeken