Tag: ecology

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Global Lakes Observatory Network Meeting

During unseasonably warm, dry and bright weather in mid-October,the Global Lakes Observatory Network (GLEON) held its annual meeting in Mulranny, Co. Mayo.

The meeting was organised by TCD alumni Elvira de Eyto, Eleanor Jennings and Valerie McCarthy, along with their GLEON, Marine Institute and Dundalk IT colleagues. GLEON represents a network of scientists working on lakes with high frequency physico-chemical observations obtained from buoys deployed with sensors. It is a grassroots network of limnologists, ecologists, information technology experts, and engineers who have a common goal of building a scalable, persistent network of lake ecological observatories.

Unlike more traditional conference formats, where attendees sit and listen to research presentations, GLEON members are grouped together to discuss their areas of interest, identify potential for collaborations and to make the decisions that will inform the future path of the GLEON network. Although the program was very full, the open, collaborative and discursive approach ensured the meeting was highly enjoyable.

The current membership of this global organisation currently stands at 351, attendance at the Mulranny meeting at more than 100 and as the photo shows, there was also a strong showing of TCD students and staff, past and present.

Author

Caroline Wynne: c.wynne[at]epa.ie

Photo credit

Caroline Wynne

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The selfish huddle

As it is December now and the frost is creeping in I thought I’d talk about one of the all time favourite winter animals: the penguin! These happy footed, tuxedoed up cartoon-esque waddlers are among the most charismatic and endearing of creatures. They are favourites in films, books, documentaries, toys and of course a must on Christmas cards. Tales of their romantic dances, lifelong partnerships and working together to get through the winter have long been a part of the ‘nicer side’ of wildlife television and research. But are these loveable, laughable poster birds of cooperation and cuteness really all that genuine? Recent research would suggest not…

It has long been observed that emperor penguins form mass huddles to help prevent heat loss while they incubate their eggs amid Arctic storms. Anybody who has watched March of the Penguins can’t help but feel for the poor mites as they shuffle about with ice crystals covering their faces! Morgan Freeman also gives a heart warming narrative of their struggles during this time and how they “take turns” to be at the centre of these huddles so nobody is left at the edges long enough to freeze entirely. Nice thought, but it seems not quite the reality. A paper published in Plos one last week looked at the mathematics of the famous penguin huddles. What they found was that the shape and movement of these huddles over time was most accurately (although not perfectly) described by individual penguins setting out to minimize their own heat loss, rather than generously taking turns.  Penguins at the edges seek to move toward the centre while those in the centre have neither the space nor inclination to move anywhere so remain stationary. The result is a dynamic huddle that actually achieves pretty uniform heat loss from the huddle. So in this case being selfish can benefit the group.

This is not the first account of penguins acting in a less than Disney-like fashion: they have been observed stealing pebbles from neighbours’ nests and waiting to see whether other, more hungry, souls fare okay in orca/seal infested waters before jumping in themselves. There are stories too of them pushing their fellows off ice floats in to swelling seas to check for leopard seals but these are largely dispelled by researchers as misconceptions of the unfortunate results of the hustle and bustle of clumsy penguins perched on cliff edges!

I’m sorry to shatter any illusions of a wholly philanthropist snuggly-for-the-sake-of-it penguin but it is another nice example of how we humans often choose to perceive interactions in the animal world based on our own ideas of moral obligation: we like to see penguins cuddling in the cold to say “see what we can face when we work together?” Don’t worry though, I am sure that none of these findings will do much to shake the penguins off of their happy-go-lucky, cuddly pedestals and they will still be a key player in the Christmas festivities and focus points of many a blockbuster documentary to come. After all, who can resist that waddle!?

Author

Deirdre McClean: mccleadm[at]tcd.ie

Photo credit

www.funnycutepics.com

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A Waxwing winter you say?

The Bohemian Waxwing Bombycilla garrulus might not be a bird you are too familiar with, but this winter might change all that, for it seems we’re heading for a Waxwing winter. Don’t worry; Waxwings are not giant, flesh-eating birds. They are, in fact, a small and very beautiful passerine species that migrate to our lands to feast on fruiting bushes and trees.

The breeding range of the Bohemian Waxwing extends across most of northern Europe, Asia and western North America, and our nearest breeding populations are to be found in northern Sweden and Finland. These exotic-looking birds visit us each winter in small numbers but some years, known as irruption years, when the resources available at their breeding grounds are not enough to meet the demands of the population, there are huge migratory influxes into Ireland and Britain. One such cause of these irruption years is a failure of the berry crop and this is said to have happened across Scandinavia this year.

These birds typically arrive on the north and east coasts and make their way inland as they gorge on our rowan, hawthorn, rose hip and cotoneaster berries. Waxings tend to frequent urban areas as rowan and other trees line many of our gardens, streets and car parks (so next time you’re out shopping stop, listen and have a wee look around). I’ve heard from numerous people this year that the berry crop in Ireland has been very poor and this could spell bad news for the Waxwings. On top of this, we receive huge influxes of winter thrushes such as Redwing, Fieldfare and continental Blackbirds which are also berry fans, making for stiff competition.

So what then for the Waxwings? It seems likely they will keep pushing further west and south in search of more food – some have already shown up in Kerry, Cornwall and the Isles of Scilly! It will be exciting to see reports next year from monitoring programmes such as BirdTrack as to how far south, and in what numbers, the Waxwings were forced to migrate in search of food. You can take part in reporting them too. It will also be very interesting to see how their populations fare over the winter, especially if it’s a severe one. Let’s hope they fare well.

Author

Sean Kelly: kellys17[at]tcd.ie

Photo credit

wikimedia commons

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Cod, correlation and causation

so help you Cod

 at the Guardian reports on a battle between science and politics which is worth highlighting. The Atlantic cod fisheries in the Atlantic collapsed during the 90s due to overfishing. They have yet to recover. The Atlantic cod is an apex predator and its decline effected a trophic cascade, which modified the original food web, perhaps irrevocably.

The Canadian government is holding the grey seal responsible for this. They argue that the seals, which are growing in number, are preventing the recovery of the stocks and are planning to kill 70,000 of them next year.

This has vexed a group of marine biologists at Dalhousie University so much that they wrote an open letter arguing that cod are rarely preyed upon by the seals. Instead, the cod’s main predators are other, larger fishes. And in actual fact, the seal preferentially feeds on these fishes. So any reduction in seal numbers will produce the opposite result to the one intended, seals will be killed, the predatory fish population will increase, and the cod population will decline even further.

Correlation does not imply causation. But perhaps, the view of the Canadian government is that of Winston Churchill who once remarked, scientists should be on tap, not on top.  It will be interesting to see how this one plays out.

Author

Adam Kane: kanead[at]tcd.ie

Photo credit

wikimedia commons

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Biodiversity in Our Lives

It’s worthwhile highlighting the recent success of the “Biodiversity in Our Lives” campaign which has generated some notable publicity this week in Science. PhD students here at Trinity College decided to impress upon the public some facts about biodiversity and how it can impact our lives, often in surprising ways. To do this they decided to create a series of beermats which have succinct descriptions of these impacts. Pubs around Dublin have received a second round of the beermats and to coincide with this many of the students are giving pop up pub talks.

Author

Adam Kane: kanead[at]tcd.ie

Photo credit

Biodiversity in Our Lives

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“Toxic” nectar and pollen in an invasive plant species

For the longest time floral nectar was considered to be made of two components: simple sugars (such as sucrose, fructose and/or glucose) and water.  Research carried out in the past two decades however has repeatedly shown this paradigm to be incorrect.  As analytical techniques such as high resolution GC-MS and HPLC have become commonplace, the composition of floral nectar of hundreds of plant species has been investigated in detail. The findings of this research have revealed that floral nectar has a lot of components other than sugars; amino acids, lipids, proteins, and vitamins have been detected at low concentrations.  One surprising class of constituents of floral nectar has been found in plant species belonging to over 21 different families; plant secondary metabolites.  It is strange to see these secondary metabolites- compounds such as alkaloids, terpenes, and phenolics- in floral nectar because we normally associate them with defence of plants against herbivores.  They are often repellent to insect visitors and can potentially cause floral nectar to be unappealing to flower-visitors.  The paradoxical phenomenon has many potential adaptive and non-adaptive hypotheses (see Adler 2000 for an excellent review) and it’s a subject about which there has been some really exciting literature published lately.

At NERD club one of our discussions focused around this topic of “toxic nectar”.  I study the toxins found in the floral nectar of Rhododendron ponticum, a group of compounds called grayanotoxins.  R. ponticum is invasive in Ireland and I am particularly interested in the effects of these toxins on native Irish insects that may use this mass flowering resource in early spring.  Our discussion ranged from thinking about work done in other systems in which plant toxins might play an important role to considering trophic accumulation and mechanisms by which organisms deal with ingestion of toxins. I enjoyed the meeting immensely and it made me reflect upon how useful it is to discuss your research with as many people as possible.  The varying opinions and perspectives that colleagues form different departments can bring to the discussion are both insightful and inspirational.  We get so involved in our own research it is refreshing to hear these different perspectives, so thanks to everyone who could come along!

Author

Erin Jo Tiedeken: tiedekee[at]tcd.ie

Photo credit

Erin Jo Tiedeken

 

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Thinking small to think big

Charles Darwin Bacteria (Serratia marcescens), Nutrient Agar, Petri Dish

The concept of using bacteria and other microbes to test some of the big questions is creeping more and more into the world of ecology and evolution. Evolutionary biologists have been coming around to this idea for many years now (see Lenski’s experiment for a wonderful example of this) but the concept is still hard for most ecologists, particularly empirical ones to swallow. This is primarily a function of the microbial systems being thought of as ‘too simplistic’ and ‘unrealistic’ to apply to real world populations. In a review in 2009 Angus Buckling and colleagues very elegantly address the above charges and some of the other most frequently raised arguments against using bacterial microcosms.  My argument (and his!) essentially comes down to two things:

1. Ecologists are supposed to be devising models and experiments to understand the dynamics of real world populations and the consequences of anthropogenic impacts on the organisms that inhabit the planet and yet they are largely ignoring the biggest Kingdom of organisms-Bacteria!

2. While nobody is suggesting that what happens in a 200ml microcosm tube will perfectly mimic or predict the exact response of a 200acre coral reef, why can they not be used as models to help test some of the theories or predictions that might equally affect larger systems?

Microbial systems have very similar dynamics to most other empirical food webs, in particular aquatic ones with highly size-structured predator-prey interactions, social cooperation and complex community networks. The importance of bacteria and microbes in the environment and their role in disease is undeniable and widely recognised meaning that individually bacteria are some of the most well studied organisms out their in terms of their genetic information and growth patterns. This can be used to the advantage of ecologists and evolutionary biologists by isolating strains of particular interest and culturing them very easily in laboratory conditions over short time periods to yield potentially very powerful results when viewed at the population or community scale.

One of the big problems in the field of ecology is linking empirical and theoretical study results; they frequently disagree due to the time scales, interactions and networks involved. The problem is basically that, however good the theoretical model, it cannot encompass all of the complexities of a natural system, and, similarly, while the empirical studies are more difficult to rebuke for their lack of realism or complexity, it is often impossible to disentangle the many different interactions taking place to get to the root of the question. What is therefore needed is a means to bridge this gap and provide logistically feasible model systems for testing more generalized ecological and evolutionary theory. I think the microbial systems might be a partial solution to this problem, as well as being fascinating for their own sake they can really aid in the developing and testing the drivers and disentangling the complex interactions in ecological and evolutionary processes. What they lack in size they certainly make up for in potential!

Author

Deirdre McClean: mccleadm[at]tcd.ie

Photo credit

Zachary Copfer: http://sciencetothepowerofart.com/

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“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!). Continue reading ““See you later, pollinator””

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Sulawesi field report

A Lemon-bellied White-eye Zosterops chloris with nesting material in its bill, Tomia Island

July and August of this year saw members of the Behavioural and Evolutionary Ecology research group embark on another field season studying the birds of tropical south-east Sulawesi, Indonesia. Principal investigators Dr. Nicola Marples and Dr. Dave Kelly were joined this year by PhD student Seán Kelly, as well as a number of undergraduates from the university. This year’s expedition, carried out in collaboration with Operation Wallacea, consisted of two teams: the mist netting team, led by Dr. Marples and Dr. Kelly, and the behavioural team led by Seán Kelly.

The netting team trapped birds using mist nets at various locations on Buton island, mainland south-east Sulawesi and Wangi-wangi island (of the Wakatobi archipelago). While small passerines such as white-eyes, sunbirds and flowerpeckers were the target species, individuals from a total of 35 species were caught. The season proved to be a great success with over 300 birds trapped and processed. Data on plumage, morphology, age, sex and breeding condition were collected from each bird, which was colour-ringed and released unharmed. A small number of body feathers were also plucked from each bird for later genetic and stable isotope analyses.

The behavioural team spent the season on various islands of the Wakatobi archipelago collecting detailed behavioural ecology data on the white-eye, sunbird and flowerpecker species present. This included information on their diets, competitors, preferred habitats, social habits, courtship and breeding, as well as their foraging and flocking behaviours. Data collection took place in the early morning and evening, walking 1 km transects through scrub, farmland or forest edge habitats. This resulted in some fantastic insights into the behaviour and ecology of these poorly studied species.

From analysis of the plumage, morphometric and genetic data we have found a number of significant differences between bird populations on the Wakatobi archipelago and mainland Sulawesi, as well as between populations within the Wakatobi. It is hoped that the behavioural data gathered this season will help us to understand the selective pressures driving this divergence, giving us further insight into the evolution of this region’s fascinating avifauna.

Author

Seán Kelly: kellys17[at]tcd.ie

Photo credit
Seán Kelly
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What did what to what? Finding causality in chaos.

A new paper has been published in Science by George Sugihara and colleagues, which is an immediate contender for the most insightful paper I’ve ever read. In the paper they outline a new method, which they dub ‘Convergent Cross Mapping’ (CCM), for detecting causality between variables using time series data. Not only does CCM allow for the detection of causality but also its directionality. The method takes us well beyond the previous confines of Granger causality (which requires the assumption that systems are linear, or are showing linear behaviour near an equilibrium), and allows us to tease out causality in systems that show non-linearity and chaos. As examples of possible applications of their method the authors address two classic causality problems:

Predator-prey dynamics of Didinium and Paramecium. The authors show that there is bidirectional causality in this classic predator-prey system, but that top-down control is stronger than bottom up control (i.e. Didinium has a larger effect on the Paramecium population than vice-versa).

Dynamics of Pacific sardines and anchovies. There has been a long-standing debate about the cause of alternating dominance between sardines and anchovies in the Pacific. Some arguing that competition between the species is the driver, while others claim the pattern is caused by differing responses to temperature. The authors weigh in on this debate by showing that, while sardine and anchovy abundance is negatively correlated, this is a mirage as there is no causation in either direction. The authors also unambiguously show that sea surface temperature does causally affect the abundance of both species, indicating that climate is the main driver.

I think this method will be absolutely invaluable to future studies, and for me has already proved its worth from the results the authors present. The videos below are from the supplementary information of the paper and explain the method simply using beautiful illustrations.

watch?v=7ucgQE3SO0o

watch?v=NrFdIz-D2yM

watch?v=rs3gYeZeJcw

Author

Luke McNally: mcnall[at]tcd.ie

Photocredit

Wikimedia commons