ecosystems and global change

Rewinding the Tape of Life

Journal of Ecology Blog

If evolution happened anew, what would the present-day plant world look like?  That is, would the randomized processes that govern evolutionary change tell a different story? And particularly for plants which are sessile organisms, is the starting point of ‘who gets there first’ the most important of all?

Priority effects – the order and timing of species arrival into local communities – can affect ecological community structure and functioning, with profound effects for species persistence and ecological interactions (Chase et al., 2000; van de Voorde et al., 2011). As such, the arrival of different species at different times can dramatically alter the evolutionary tapestry of any given system on ecological time frames, but also in evolutionary time. In particular, the diversification of early arriving species can pre-empt available niche space to prevent the establishment, dominance or diversification of species that arrive later on down the road.

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A closed loop of ideas

This week, I was lucky enough to go to Lausanne, a small Swiss city on Lac Léman, to attend the MELiSSA Workshop. What is MELiSSA? As an ecologist, it is unlikely that you are acquainted with this European Space Agency (ESA) project, which stands for Micro-Ecological Life Support System Alternative. It was created in 1989 (read more on how it began here) and brings together European and Canadian partners from 13 different countries in an attempt to fulfill human needs in outer space via the development of life in closed systems. The main ideas include: recycling waste and carbon dioxide aboard spacecraft by using bacteria; and producing food, water, and oxygen in a regenerative way to keep costs low. Put in their words, it aims “at a total conversion of the organic wastes and CO2 to oxygen, water and food”.


Terrestrial lake eco-loop. Copyright: ESA.


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The future of environmentally-friendly farming?

Our first paper on the agri-environment has just appeared in this month’s issue of PLoS Biology.  This is an important piece for us as it provides a foundation for empirical work being carried out by several group members.

The paper essentially makes three main points.  The first is that we spend a lot more money subsidizing farming than trying to mitigate its environmental impacts.  We’ve tried to plot this out below.  What you can clearly see is that the purple (mitigation expenditure) is nearly invisible relative to what is spent on subsidizing farming (shown in the orange slices).

Financial support to farmers from taxpayers and consumers associated with agricultural policies as a proportion of the total value of agricultural production (VoP) at the farm gate.

The figure now provides what is essentially a map of the ‘perversity‘ of agricultural subsidies – showing where we spend money to do things that are often bad for the environment and costly to the economy.  A first step in reducing conflict between agriculture and the natural environment would be to do away with the subsidies in orange.

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New multi-lake experiment launched

It has been a busy summer for our NERC-funded project RELATED (that stands for Restoring Ecosystems by Linking Aquatic and Terrestrial Ecological Dynamics).  The project aims to test experimentally whether the productivity of aquatic food webs increases with the quantity and quality of terrestrial organic matter deposited in nearshore delta habitats.  It builds on our previous work that showed forests fuel the growth of juvenile fish by subsidizing the base of the aquatic food web.  RELATED will also feature much more work on unlocking the microbial ‘black box’ at the base of the food web as well as better understanding how greenhouse gas emissions might change with surrounding vegetation.  Inland waters are major sources of atmospheric carbon and predicting their responses to future change is of major interest (some great recent work here, here, and here).

Experiment behind the beautiful Living with Lakes Centre

New experiment behind the beautiful Living with Lakes Centre

We’ve now just finished launching the experimental platform behind RELATED.  Over the last 8 weeks, we’ve had a team of 8+ working tirelessly to submerge artificial lake sediments in 3 lakes.  This has involved collecting, mulching, and sifting organic and inorganic materials, mixing these at an industrial scale, and outfitting nearly 300 mesocosms with the appropriate sampling gear.  By replicating our experiment in 3 different lakes, we’ll be able to study terrestrial-aquatic linkages along gradients in eutrophication and climate change – the main drivers of change in the world’s inland waters.  We’ve also had excellent student help from Laurentian University’s School of Architecture work to design and build a network of sampling platforms that will allow us to work without disturbing our sediments.

Artificial sediments with increasing organics from left to right.

Artificial sediments with increasing organics from left to right.

Here’s the main team celebrating the deployment of the experiment in Ramsey Lake:

Explaining the origins of species diversity

The July 2015 issue of New Phytologist has come out and its a doozy!  The entire issue features work on evolutionary plant radiations, drawing together a range of papers that summarize the current state of knowledge about “where, when, why, and how” plant radiations happened.  An editorial by Colin Hughes, Reto Nyffeler Peter Linder outlines the content of what will surely be a landmark issue for years to come!

Many, if not all, of these papers were presented at a symposium organized in Zurich that we attended with our New Zealand collaborators Professors Bill and Daphne Lee in June 2014:

We're somewhere in the crowd

We’re somewhere in the crowd …

For me, this was possibly one of the most intellectually stimulating meetings that I’ve ever attended.  Talks drew major figures in plant ecology, evolution, and systematics and really pushed the boundaries out on ‘diversification’ research.  The field itself is still arguably quite new, with many of the key questions synthesized in a 2008 paper by Peter Linder.  In fact, we have a PhD studentship available to follow-up some of these questions and build on what we talked about at the meeting.

You might have noticed that we even have a contribution in the New Phytologist Special Issue.  Our paper tests the mechanisms by which plant evolutionary radiations emerge and influence ecological dynamics.  We apply more of our expertise in structural equation modelling to focus on 16 species-rich genera in the alpine zone of New Zealand.

Diversity in New Zealand’s alpine.  Celmisia, Chionochloa, Dracophyllum, and Veronica all appear in this photo.

One of the most exciting aspects of our paper is that we’ve tried to reconstruct the niche space that each genus has occupied over the last 20 million years.  This is fairly ambitious and has involved tasks like reconstructing sea surface temperatures through the Cenozoic from isotopic measurements of foraminifera deposited in marine sediment cores, and then using these to estimate past land temperatures.  We’ve also had to consider that the alpine zone has grown immensely over time with uplift of the Southern Alps.  To do so, we collated radiometric dates of rocks and tried to infer their rate of uplift since the Miocene.

Overall, our results suggest that genera that colonized New Zealand earlier encountered more ‘vacant’ environmental space, which promoted species diversification and further occupancy of the environment.  Genera that occupied more environmental space were subsequently more dominant in present-day vegetation plots.  The key message is that time not only explains why diversity arises, but how this diversity influences ecological dynamics.  The Special Issue has many other fabulous papers, so do check it out!

Mutualisms – a little help from friends?

It’s been a while since we’ve last blogged but we’re hoping to pick it up more regularly again over the next few months now that the group is quickly growing.

For now, I thought I’d comment on an interesting study published this month in Applied Vegetation Science by Laura Burkle and Travis Belote.  It links up nicely to work we’re doing on priority effects, which is the idea that species that arrive earlier into a habitat influence the interspecific interactions of later arriving colonists.  Priority effects are hardly surprising. Succession theory long predicted that communities develop along different trajectories depending on the species that are initially present.  But generalizing the direction and strength of priority effects remains challenging.  This is where Sgt. Pepper’s Lonely Hearts Club Band can offer some advice:

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Talking allochthony in Cambridge and Lille

At the start of December, Andrew organized a three-day workshop in Cambridge, bringing over Brian Kielstra, John Gunn, Nikki Craig and Chris Solomon from Canada, Michael Pace, Grace Wilkinson and Stuart Jones from the USA, Jan Karlsson and Martin Breggen from Sweden, and Jon Grey from the UK. The aim was to see how terrestrially-derived organic matter (tOM) contributes to secondary production in aquatic ecosystems, by synthesizing global data collected from 594 observations on C, N and H, in over 10 zooplankton groups from 158 lakes in the northern hemisphere. Ultimately, the group would like to build a model for each consumer by lake. The ten limnologists worked all day (and all night!) but still had time to experience Cambridge, with time spent at the legendary Eagle pub (where great minds meet) and an exquisite dinner at Peterhouse, the University’s oldest college.


A few days later, while Jon, Martin, Jan, Nikki and Stuart traveled home, the rest of the group and I traveled to London to catch the Eurostar to Lille, where we attended the British Ecological Society (BES) and Société Française d’Ecologie (SFE) joint meeting. The meeting was the first of its kind and brought about 1,200 ecologists to the Lille Grand Palais convention center – mainly French and British, but also a lot of attendees from other European countries and the rest of the world.

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