INTECOL day 1: A day full of ecosystems #INT13

Note: These are some thoughts from the first day of INTECOL. –Sorry for the abruptness and lack of polish on these entries, there were many talks and I have little time for a proper composition.

*acronyms: BEF = Biodiversity and Ecosystem Function; GBIF = Global Biodiversity Information Facility

It is clear to me that INTECOL is the premiere ecological meeting. There are delegates from countries all over the world from 67 countries , with especially strong European contingents. The next INTECOL meeting will be in Beijing in 2017. This is a special INTECOL as this is the 100th anniversary of the British Ecological Society. The opening talk by Sandra Diaz was held in an immense auditorium at the ExCeL centre, with a couple of thousand in attendance.

Morning plenary:

Sandra Diaz: functional traits are at the core for understanding changes in biodiversity and how species contribute to ecosystem function. Theophrastus, Greek philosophers, created first functional groups. Looks at key traits for tens of thousands of species, only possible through TRY data base. Most variation explained by size ( height, seeds, etc.), second was leaf economy ( leaf N, Leaf area, etc). These traits define plant functional design. Densities low on the fringes of this trait space -physical challenges, and many of these species use human help for success (crops and weeds). Two dense areas in the trait space -big slow growing trees, and small species. Effect and response traits are important for linking environmental change to ecosystem services. These traits can be linked or decoupled, and could change management options.

Linking trait dispersion and values to ecosystem function is a new area, and so few studies. We just don't know enough to understand how functional diversity links to environmental change and ecosystem services.

 Sandra Diaz giving her plenary lecture

Tree of life in ecosystems symposium:

Lisa Donovan: how selective pressures influence evolution of biogeochemical cycling. Traits appear evolutionary labile, and reported on a common garden experiment to find genetic differences controlling traits. Nitrogen has phylogenetic signal but few differences between close relatives. Major differentiation within species and especially for different agricultural lines.

Erika Edwards: Need to move down to small scale to truly understand the evolution of traits that affect ecosystem function. She looks at the genus Viburnum. Need to think about whole organism traits. E.g., branching and growth pattern. This originates from tropics and reinvaded temperate regions repeatedly, and a mix of different and similar strategies emerged. growth patterns highly conserved, but leaf spectrum traits were not. Flowering time seems linked to carbon economy traits.

Amy Zanne: Evolution and biogeography of leaf and stem traits. Angiosperms originated in the tropics and understory woody species and spread everywhere and all types of morphologies. Most species are woody and not exposed to freezing, and lineages move back and forth in climate species but less so with growth form. lineages shift growth form first, followed by climate changes.

Cornwell. Evolution of decomposition. Differences in decomposition rates among different phylogenetic lineages. Did plant life go from fast cycling world to slow one during evolution. Experiment in common garden for decomposition rates. basal angiosperms (magnolias) has lower decomposition than eudicots, which has fast decomposition rates.

Afternoon plenary:

Joel Cohen. Taylor's law after half a century. Taylor's law has been verified but we don't understand it. Taylor's law states that the variance of a population is positively related to the mean population size. Further mean population size is correlated with body size. He showed that tree data supports a body size-variance relationship. Does it apply to food webs? Data from aquatic systems show this pattern across species. Why do we care about Taylor's law? Used for understanding fluctuations in epidemiology, conservation of endangered species and management of forestry resources. Can see the same variance-mean relationships in nonbiological data -computer data packets, weather data and stock market trades. No underlaying theory to explains these. Previous attempts, such as affects of competition, do not seem to affect pattern.

Biodiversity & Ecosystem function session:

Enrique Chaneton. Movement of large herbivores around the world, introduction of cattle versus reintroducing native extirpated herbivores. Little is know how these large herbivores influence forests. Multiple pathways of effect from changing plant composition and waste excretion, affects decomposition. Within an Argentinean park, sites on lake islands do not have introduced herbivores and compared to nearby mainland sites. Herbivores reduce vegetation cover by sixty percent. Trees and shrubs were particularly affected. Distinct composition shifts. Litter layer was substantially different. In dry sites, higher decomposition in ungrazed sites. Volcanic eruption during research 'sometimes shit happens' killed many of the cattle.

Carsten Meyer. Examined the completeness of species point data inventories. Looked at GBIF records and compare to known distribution maps. GBIF records are highly biased to North America, Europe and Australia. Species rich areas are almost absent from GBIF records. Not adequate for research or conservation. Funding, accessibility and human safety all at play for biases. These factors seem to differ among taxonomy, interestingly. Countries that under report are large emerging economies (china, India, Brazil, Russia) which could finance these efforts but for some reason do not.

Julia Koricheva. Tree species richness and genetic diversity on leaf miners. What is the relative importance of these two effects. Two experiments, one manipulating tree richness -up to five species, and another with up to eight clones of silver birch. Silver birch was in both experiments, so was the focus of leaf miner surveys. Tree richness affects miner richness, but not abundance. More leaf miner species with higher tree richness in first year, but not second. For genetic diversity, miner richness also increased with number of clones. Looked at effect sizes of two experiments and genetic diversity appeared to have a stronger effect on leaf miner richness.

Tommaso Jucker. Complementarity in functional groups enhances wood production. He noticed that there were eighty talks on BEF at INTECOL. Four species combinations two pines and two oaks. Biomass increased with richness, but looked at more detail, growth over the past ten years from wood cores. Both pines grew much better in mixture, but oaks only increase growth when other oak is present. Tree that benefit the most are small trees. For pines, wet year showed largest increase in growth, most room for complementarity.

Eric Allen. Direct and indirect effects of landuse on multifunctionality. Landuse intensity changes functions, it increases biomass but reduces bird diversity, flower cover, increases pathogens, etc. Used path analysis to compare landuse and biodiveristy as well as environmental variables. from this analysis, plant richness seems negatively correlated with multifunctionality. looked at groups of functions (e.g., production, soils, cultural). some plots shows strong indirect effects of richness for some functions.

Siobhan Vye. Responses to multiple stressor change. Examined stressors in coastal systems. Looked at how an invasive species affected community response to stress by experimentally combining species in mesocosms and manipulated nutrient enrichment and temperature. Invader increases productivity. The presence of the invader determined how the stressor influenced community functions.

Sebastian Meyer. BEF changes over time. A number of studies show that BEF experiments increase in strength over time. Examined how functions change over time using Jena experiment. How many different functions show changes over time? Over half of functions are influenced by diversity generally. He regressed the richness-function slopes across time, and about one third of functions showed increasing diversity effects over time. What are the mehanisms? The stronger relationships are driven by a combination of changes in high diversity treatments and changes in low diversity treatments.

Everything you ever wanted to know about peer review, but were afraid to ask

The thing about peer review is that there isn't much of an education process. Maybe you've published a paper or two and experienced the process as an author, and then you're asked to start reviewing for other authors. It's a bit like the telephone game - you mimic the reviews you received, maybe noting what you liked and avoiding what you didn't like. But that's often all you have to go on, and when you're just beginning a little advice might come in handy. To that end, the British Ecological Society has just published a pretty useful Peer Review 101 text. This should be required reading for new reviewers.

http://www.britishecologicalsociety.org/wp-content/uploads/Publ_Peer-Review-Booklet.pdf

#esa2013 What ESA tells us about where ecology is going

The annual ESA meeting functions in a lot of different ways. There are the obvious: the sharing of ideas and work, the discovery of new ideas, methods or sources of inspiration, networking and job finding, social reunions. But it also functions as a kind of report on the state of the field (and that's not even considering sessions meant to explicitly do this, like the panel “Conversations on the Future of Ecology”). The topics and methods presented say a lot about what ideas and methods are timeless, what is trendy, and over many meetings, where ecology appears to be going. If you go to enough ESAs, you are participating in a longitudinal study of ecology (or at least your subfield).

I went to my first ESA five years ago in Albuquerque, NM. One of the things that struck me was that there were two Community Assembly and Neutral Theory sessions and many talks in those focused on tests of neutral theory, particularly looking at species abundance distributions (SADs) and various iterations of neutral models. There are usually still one to two sessions called Community Assembly and Neutral Theory, but five years later, I don't think I saw a single talk that looked at SADs for evidence of neutral theory (and only one or two talks that were named to explicitly include neutral theory). Instead, the concept first introduced by Hubbell has morphed from "neutral theory" in to something slightly more general, designated "neutral dynamics". This gets used in a lot of ways – most precisely, neutral dynamics are in the spirit of neutral theory, suggesting that population demographic rates are similar, allowing long-term co-occurrence. Sometimes this is cited with reference to equalizing fitness effects in a Chessonian framework, where similarity in fitnesses prevents exclusion despite overlap in species niches. But it also seemed to get used in a default sort of way, as the explanation for why niche differences between species weren't discovered by a study, or else "neutral" was used interchangeably with "stochastic". In any case, the pattern appeared to be a move from highly specialized and precisely defined usage of the term, to broader incorporation of the concept that had suddenly acquired several, often less precisely defined meanings. Instead of being the central focus of a few specialized talks, neutrality was commonly invoked as a minor theme or explanation in many more talks. It is not what I expected, but its continuing usage suggests that neutrality has developed a life of its own.

Other topics similarly seem to have taken on separate lives from their initial application; even over the short time I've been attending ESA. For example, sessions focused on simple applications of ecophylogenetics methods (overdispersion, clustering, using different systems) were relatively common 3-4 years ago, while there wasn't a single contributed session specifically named for phylogenetics this year. There was however many sessions in which phylogenetic work formed the backbone of talks that were about broader questions, including in the "Evolution, Biodiversity, and Ecosystem Function" session and the “Coexistence of Closest Relatives: Synthesis of Ecological and Evolutionary Perspectives”. In the best case scenarios, it seems like even over-hyped approaches may be used with more nuance in time, as people recognize what information these methods can and cannot provide.

Sometimes it did seem that there is a lag between when critiques of certain methods or ideas are expressed and when they actually get incorporated into research. I could be wrong, but it seems this is most common where the research is focused on particular study systems or species, and methodology may be driven more by precedent in the literature and criticisms may take longer to infiltrate (since they aren’t the main focus of the work anyways). And unfortunately, the topics and sessions which appear to be timeless are those on human-related applications (restoration, climate change, invasion). Those pressures are sadly unchanging.

*The great thing to do would be map out changes in keyword frequency over the ESAs that have archived programs. Unfortunately, I don’t have the time/motivation.

#esa2013 Day 5: Survival mode

The final day crowd is usually a little worse for wear. 

(Adapted from phdcomics.com)

#esa2013 Day4: Sisters getting along, and our variable world

The talks I saw today were uniformly good and a number were excellent. At least half of them focused on the many implications for ecology of nature's innate variability. It appears that community ecologists have decided that now is the time to start considering the fact that the environment is not stationary, which was long a default assumption in most theoretical and empirical work. Many of the talks I saw reflected this changing approach. The other half were part of a symposium organized by Sharon Strauss that looked at coexistence among sister species. This topic, combining as it did large-scale evolutionary and biogeographic processes with local competitive interactions made for a broad range of talks and some interesting attempts to reconcile different methodologies and scales.

Our variable world

Many of the past studies on environmental variability and coexistence involve desert winter annuals. Desert winter annuals are limited by available water, and the yearly rains vary greatly in the amount and timing of onset. The hypothesis is that variable germination (via prolonged dormancy in seedbanks) may allow desert winter annuals to reduce the variance in their fitness between years. Alejandra Martinez-Berdeja presented some tidy hypothesis testing using biogeographical gradients: if variable germination is an adaptive response to variable precipitation, she hypothesized that differences in germination variability might be expected where precipitation is more or less predictable. Looking at the three North American deserts, she predicted that variable germination would be greater where rainfall was more variable (bi-seasonal) compared to winter rainfall deserts. She measured the involucres (dispersal structures determining seed release) on collected seeds and found that indeed they were larger in more variable rainfall deserts, producing greater variability in seed release. Further, in winter rainfall deserts, variability in the size of involucres was correlated with variability in rainfall at a site, again suggesting a link between germination variability and rainfall variability. Her next step will hopefully be to expand the tests look at the effect of autocorrelation in rainfall likelihood on bet-hedging, since this should increase selection for bet-hedging type adaptations.

David Vasseur gave a great talk showing how extreme environmental conditions--which we are seeing as part of the changes in mean and variance of the climate--could have particularly detrimental effects on population growth rates. Species have temperature performance curves that reflect the relationship between their fitness and the temperatures they experience. Vasseur showed that in the tropics, species tend to have much narrower temperature ranges over which they can grow and survive than species in the temperature regions, and experts agree that these narrower curves give tropical species less ability to deal with increasing temperatures. But variability is rarely considered in this equation. When variability is present, long-term species fitnesses will be subject to Jensen's inequality (nonlinear averaging) mean that shape of these performance curves is additionally important: that in some situations (concave curves) variability is particularly detrimental, and in some situations (convex curves) it may have a beneficial effect. Vasseur then used models to show that as temperature variation increases, it is increasingly likely that its effect will be negative, and high variation will produce high extinction rates. In fact, on average Vasseur predicted that temperature variation would have negative effects, a concerning conclusion.

Sisters getting along

This organized symposium was advertised as: “Whether closest relatives coexist reflects the often opposing effects of limiting similarity, mode of speciation, reproductive isolation, niche conservatism, competition and facilitation, which may be strongest in sister taxa; using new phylogenies, niche models, and experimental approaches, we explore coexistence in closest relatives in both plants and animals.” It was an interesting and useful idea – sister species (species who are each other’s most recent relative) are an important tool to understand how evolution, biogeography, and ecological interactions determine coexistence. The content of the symposium provided a number of example systems, methods, and approaches that suggested this was an important but still far from cohesive area of work. Mark McPeek spoke about the damselfly work he has done over the last many years, which shows that sister species are sympatric and ecologically identical, co-occurring happily through neutral dynamics. In contrast, Richard Glor talked about his work with Hispaniola anoles, where biogeography is an explanation for radiations, close relatives use different microhabitats and rarely compete locally and traits are divergent among close relatives. Looking at California plant species, Brian Anacker’s talk suggested something in between these extremes. A broad survey showed that 80% of sister pairs were sympatric, range overlap was modest but not uncommon, but asymmetry in range size was high. Ecological differences between sister species were not particularly clear in the handful of traits he examined, not even for reproductive traits. Sister species can and do co-occur, although not in large portions of their ranges. Having established the current state of knowledge, hopefully the symposium will stimulate greater focus on the construct of sister species as a way of understanding coexistence at multiple scales.

Finally, not being willing to miss another talk with the word “derby” in the title, I attended Daniel Atwater’s talk, “Is competition among plants like a boxing match or a demolition derby? Why competitor suppression may not matter in plant communities”. Atwater argued that there were two ways to win at plant competition – be good at suppressing your competitors, or be good at tolerating them. When in competition with a single individual, being a strong suppressor should be favoured, but in competition with multiple species, tolerance may be a better strategy. That’s because resources spent on suppressing one competitor may also benefit any other species involved in the competition. In such cases, tolerance of your competitors may provide the greatest benefit. (Apparently this scenario is like a successful (but frowned upon) strategy (sandbagging) in a demolition derby). Atwater used experimental data from blue bunch grass grown in competition with spotted knapweed to parameterize a model in which he found the optimum strategy in single versus multi-species competitions. The model agreed with his hypothesis that tolerating competitors is favoured when multiple species are competing. Although I am not clear on whether competitive strategies are easily classified as tolerant vs suppressing it was an interesting talk, and left me thinking about new questions.

ESA 2013 Day 3: Bolkerisms

All the best quotes that I caught today were undeniably from Ben Bolker, who also gave an interesting talk.

"The hallmark of great theoretical ecology is that it is obvious in hindsight. When you explain it to someone, they say well, of course."

In relation to a philosophical issue: "That's a beer question, not a coffee question".

To explain the reason he and his coauthors chose to build a model to explore the question, Bolker showed a Dilbert cartoon illustrating the truism "When all you have is a hammer, everything looks like a nail".

Only one full day left to go, and it looks like it will be a good one!

ESA 2013, day 3: Like a kid in a candy store.

Sometimes there are moments in my career where feel truly fortunate. Today I was fortunate enough to be a speaker in a session on evolution, biodiversity and ecosystem function. The other talks in this session were outstanding, full of amazing insights into how historical evolutionary dynamics affect modern-day ecological patterns. The presentations were followed by a fantastic panel discussion stimulated by thoughtful questions from the audience. The talks covered a range of topics from including species interactions in models of evolutionary change to using traits to understand coexistence to trying to find patterns when close relatives do not coexist.

The first talk from Luke Harmon on finding phylogenetic signatures on species interactions was incredible. He is an entertaining speaker and included references to his kids finding leaf cutter ants.  He show us how one could fit phylogenetic models that include coevolution. The negative effects of coevolution should affect trait evolution and one should see this signature in variance-covariance matrices. Random evolutionary change generates covariance between species. Stabilizing selection will remove this covariance, while with competition there should be negative covariances apparent. From models we see an interesting signature where older species are able to diverge and fill niche space (thus diverging rapidly) while later species are constrained in their evolution (thus remaining similar). Older species can contribute more to ecosystem function because of historical competitive effects.

Next was Nathan Kraft talking about how traits can potential shed light on fitness and niche differences in coexisting species. In a plant experiment with focal species grown alone and at different densities with competitors, he showed that very few pairs met the conditions for coexistence. For those that do appear to be able to coexist, no traits were associated with fitness difference, but several traits appeared to be associated with fitness differences. Multivariate analyses  showed that an assortment of five traits collectively appeared to be associated with niche differences. Some of these traits appeared to also explain fitness differences, revealing the complexity in assigning traits to specific ecological effects.

In Jeannine Cavender-Bares’ talk, she examined how evolutionary transitions in seed dormancy helped explain modern day ecological patterns in the Fabaceae family (the pea and bean family). The Fabaceae includes species that have dormant and non-dormant  seeds. Dormancy should be favored in certain environments (e.g., less predictable and poor environments). Large seeds are much less likely to be dormant, as well as those occurring at lower latitudes. Historical transitions in dormancy seemed to be correlated with changes in temperature lineages experienced.

Finally, Sharon Strauss critically examine dhow to separate history form ecology. We need to be cognizant of scale effects, where larger scale observations will include more close relatives than we usually see at local scales. Communities contain ‘ghosts’ of past competition and assembly. If species originate allopatrically (in separate places), then we expect that close relatives should not coexist, which can skew our inference about how ecological differences have evolved. Within habitats we seldom see closely related species coexisting . She gave a number of great Californian examples of species appearing to co-occur at large scales but not locally. For example, Limnanthes plants occur in the same region but species never co-occur in the same vernal pool.

These talks represent the collective excitement about the fact that we are entering a new synthesis in ecology. Evolution is required to understand ecological patters and ecological interactions are need for understanding evolutionary change. These talks exhibited where the forefront of this synthesis is, and it was a great afternoon of talks.

ESA Day 2: The problem with statistics...

These are just my favourite quotes from talks on day two of ESA:

(All from great, but anonymous, speakers)

After showing the results of a spatial statistics test: "...But still I was worried because that would be using statistics to prove something and that feels wrong."

On being asked how the speaker quantified earthworm abundance: "I used a non-invasive electroshock technique".
(I'm sure this is normal procedure, it just sounds hilarious to the uninformed).

ESA day 2: The shampoo salesman and new questions.

Day two started off on a high note with Bernhard Schmid's talk on evolution in biodiversity-ecosystem function (BEF) experiments. He is one of the originators of the Jena biodiveristy experiment, for years they have been maintaining plant species in monocultures and in polycultures to assess how much more ecosystem function is produced by multi-species assemblages over single species monocultures. However, it occurred to Schmid that species in these two contexts face different pressures, which may have resulted in evolutionary changes. In monocultures, species face high intraspecific densities and thus competition is severe, as is negative indirect effects like pathogen sharing and herbivory rates. Within polycultures, intrraspecific interactions may involve niche differences, with opportunities for character divergence to further stabilize coexistence. He reported on an experiment that took seeds and cuttings from monoculture and polyculture populations and grew then in monoculture or polyculture. He showed that individuals originating from monoculture did better in monoculture and species originating from polyculture did better in polyculture. The implications are fascinating. If the rate of evolutionary change in performance are equivalent between monocultures and polycultures, the BEF relationships should remain constant. However, if the rates of change are greater for polyculture populations the BEF relationship should get stronger over time. Conversely, BEF relationships should became weaker if higher evolutionary change in monoculture. 

It was hard to top this talk, but there were several other impressive talks as well. Jacob Vander Laan used a country-wide dataset on aquatic insect diversity across the USA and showed that at larger scales, beta-diversity decreases with connectivity, but is seemingly unaffected by environmental heterogeneity.

Restoration is community assembly with management goals and Emily Grman gave an interesting talk on assessing the success of prairie restoration by accounting for management activities, landscape, historical and local abiotic factors. She showed that management activities were the most important, with species-rich sowings result in rich communities, even though many of the species are not those in the sown mixture. Sowing a high diversity of grasses did not increase diversity, but high diversity of forbes did. Other factors like landscape influences and local factors were not important.

Will Pearse examined plant diversity patterns and homogenization across six large urban centres. He showed that there has been little taxonomic homogenization, but substantial phylogenetic and moderate functional trait homogenization. Beyond the interesting questions about how urban centres may cause biotic homogenization is the new tools that Pearse created for these analyses, and that are available online. As a self described 'shampoo salesman', he created a general tool called Phylogenerator that creates a pipeline that makes estimating trees form sequence data more efficient -definitely a tool that ecologists should be using. He further created a way to quantify complex leaf shapes and has a tool available for that, called Stalkless.

All in all , this was a good day, one that has stimulated new questions and approaches. These talks got me thinking about some of my data and experiments and how I can extend them to new questions. 

ESA 2013 Day 1: Temporal variation, roller derby, and topics in between

With day 1 over, ESA 2013 was off to an excellent start. Minneapolis seems like a very friendly place, and I enjoyed perhaps the most chatty bus ride I've ever experienced. As always, I failed to determine the best point on the trade off plot between cherry-picking certain talks based on topic, speaker and friends, and staying put in a session with an interesting topic. Nonetheless I managed to see some really good talks.

Among them, I saw Lauren Shoemaker in the Theoretical Ecology section, who illustrated how to model the four metacommunity paradigms (I.e. species sorting, mass effects, neutral, and patch dynamics) with the Chessonian framework of equalizing and stabilizing forces. She illustrated how both deterministic and stochastic models could replicate dynamics from the four paradigms. This suggests that rather than the usual description of the neutral paradigm as stochastic and the mass effect and species sorting paradigms as niche-based and therefore deterministic, the terms niche and deterministic and neutral and stochastic should not be synonymous. Rather, in the Chessonian framework, fitness differences drive neutral-type dynamics and spatial niches structure the species sorting and mass effects paradigms. More importantly, the results show how the paradigms are just a few sets of points on the much broader set of parameter values that could describe metacommunity dynamics.

It must be funny for Peter Chesson to follow up a talk in which his name is used as an adjective. After the talk on the Chessonian framework, he spoke about the fact that environment is fluid and non-stationary, yet models of communities have almost always treated it as being at equilibrium. Since it is not, ideally models of community dynamics would begin to incorporate environmental variation, and ask questions more relevant to non-equilibrium systems. For example: when is long-term persistence expected, given this non-stationarity and can communities in a non-stationary system still be stable? He showed that including environmental fluidity into models doesn't mean that communities are necessarily unstable, for example, when spatial and temporal trends of environmental variation match, communities may be stationary.

In another of many good talks about temporal variation (seemingly a popular topic of late), Colin Kremer showed that altering the basic characteristics of abiotic temporal variation (amplitude, means, periodicity) changed the amount of diversity present as communities evolved over time. Temporal variation isn't a simple concept anymore than spatial variability is - it has different characteristics with different effects on ecological dynamics and needs to be considered in greater depth.

My biggest disappointment was that I had a time conflict and couldn't attend a talk titled "Significant changes in the skin microbiome mediated by the sport of roller derby".  No doubt I would have learned a lot.