Theoretical Ecology Lab Tea




The Theoretical Ecology Lab Teas are informal meetings where members of affiliated lab groups give talks on their current research and receive feedback from their audience.  The talks are 30 minutes and are scheduled generally on Wednesdays at 12:30 pm in Eno Hall 209.

Talk schedules and email lists are maintained by Albert Kao, Caroline Farrior, and Eili Klein. Please contact, or to have your name added to the labtea email list so that you can receive reminders about upcoming lab teas.



Spring 2011

Wednesday February 2nd at 12:30pm Albert Kao
Wednesday February 9th at 1:00pm Chris Bauch and Madhur Anand
Wednesday February 16th at 12:30pm Matthew Aardema, Jenny Ouyang, and Allison Shaw
Wednesday February 23rd at 12:30pm (Guyot 100) Christina Faust
Wednesday March 2nd at 12:30pm (Eno 209) Miguel Fortuna
Wednesday March 9th at 12:30pm Roger Kouyos
Wednesday March 16th Spring Break -- no lab tea
Wednesday March 23rd at 12:30pm Ricky Der
Thursday March 31st at 12:30pm (Guyot 100) Jeanne Denoyer
Wednesday April 6th at 12:30pm Juan Bonachela
Wednesday April 13th at 12:30pm Ray Dybzinski
Wednesday April 20th at 12:30pm Shaopeng Wang
Wednesday April 27th at 12:30pm Carla Staver
Wednesday May 4th at 12:30pm Carey Nadell
Tuesday August 2nd at 10:00am Adam Lampert

Titles and abstracts

Wednesday February 2nd at 12:30pm

Consensus Decision-Making in Animal Groups
Albert Kao
Obligatory schooling species often must decide between discrete choices, such as which food patch to visit. There exists theory in the social science literature about the optimal way to combine individuals' opinions and information about the quality of the food patches to maximize the groups' probability of choosing the correct patch. However, it is not clear whether an animal group following simple and local interaction rules can effectively pool information in this way. I will present simulation results that show that not only can simple swarms closely match the optimal strategy given the right parameter values, but that a simple, biologically realistic learning rule allows a swarm to quickly learn these optimal parameter values.

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Wednesday February 9th at 1:00pm

"Human-environment Systems in Epidemiology"
Chris Bauch
Vaccination programs generate herd immunity, which protects unvaccinated individuals. This creates the possibility of dynamic feedback loops between individual vaccinating behaviour and disease dynamics: increased vaccine coverage depresses disease prevalence, which thus reduces the incentive for further vaccination. This can be seen as a class of human-environment interactions, where herd immunity serves as the environmental context for human decisions. I will give an overview of recent work in mathematical modelling of this interaction.

"Global Ecological Change in Forests"
Madhur Anand
Global forests have reduced in coverage dramatically over the past several millenia due to various causes. But, since just a few millenia, at least in some places in the world, forests have been expanding. Similarly over the past few centuries forests have declined worldwide and yet some regions have seen a "forest transition" with increasing forests with increasing population size, industrialization and urbanisation, contrary to what might be expected. I present some recent related empirical studies and suggest directions for future modelling work.

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Wednesday February 16th at 12:30pm

"Optimal seasonal reproduction in birds and butterflies"
Matthew Aardema, Jenny Ouyang, and Allison Shaw
Many organisms exhibit seasonal variation in life history traits such as number of reproductive bouts. In some butterfly populations, individuals will have a single generation per year, whereas in other populations individuals will undergo two generations in one year. Similarly, in some bird populations, individuals vary across populations in the number of clutches they lay within a given season. The variation in strategy for both cases seems to be related to season length (a function of latitude and temperature). We have written a simple analytic model to predict the optimal number of times individuals should breed in a given season, for both birds and butterflies. In the simplest case, we find that individuals in an environment with 'short' seasons should always have one reproductive bout per year whereas individuals in an environment with 'long' seasons should always have two reproductive bouts per year. Additionally, we explore what happens if we add environmental stochasticity to the model, and how the results differ for a scenario with overlapping generations (birds) versus non-overlapping generations (butterflies).

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Wednesday February 23rd at 12:30pm (Guyot 100)

"Sustainable Development Hotspots: How to Spend Aid Dollars to Achieve Environmentally Sustainable Development in Afghanistan and Pakistan"
Christina Faust
Recent large increases in aid dollars to Afghanistan and Pakistan demonstrate US interest for national security but also generate potential for sustainable development planning in the region. Utilizing natural disaster data, climate change models, underlying socioeconomic indicators of populations, and reports of conflict, we identify several development hotspots where low-risk investments could support strong economic growth. We then compare our findings with current distribution of development aid. Although the focus of this paper is on Afganistan and Pakistan, the methodology and framework can be adapted to other regions and alternative objectives for development dollars.

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Wednesday March 2nd at 12:30pm (Eno 209)

Evolution of a Modular Software Network
Miguel Fortuna
I will present some ideas and thoughts about the evolution of modularity in a complex software network with the aim of shedding light on the study of networks of ecological interactions between species. This is an ongoing work in collaboration with Juan A. Bonachela and Simon A. Levin.

Debian GNU/Linux operating system provides a unique opportunity to study simultaneously the evolutionary and ecological processes determining the structure of ecological networks of interacting species as food webs. In the two systems, both processes occur at different time-scales. In the evolutionary time-scale, speciation and extinction can be translated into the appearance and disappearance of software programs (packages hereafter) from one version to the following one. In the ecological time-scale, colonization and local extinction, i.e. community assembly, would be equivalent to the package installation process in a local computer. Dependencies and conflicts between packages mimic predator-prey interactions and competitive exclusion relationships, respectively. Due to them, only a subset of the available packages can be installed in a computer, as only a subset of the species pool can coexist in a local ecological community. Last, there is an interplay between macroevolution and community assembly, because the interactions introduced by the new species (packages) alter the dynamic of the colonization/extinction (installation) in a local community (computer).

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Wednesday March 9th at 12:30pm

Different diseases call for different treatment: modeling the influence of pathogen biology on treatment strategies to contain resistance
Roger Kouyos
Hospital-acquired infections contribute substantially to global morbidity and mortality. The rise of resistance together with the shortage of new broad-spectrum antibiotics lead to the question of how available drugs can be optimally used to minimize disease burden. This question has been answered differently depending on the infectious disease. Mathematical models are useful for pointing out factors leading to diverging treatment recommendations as well as for guiding resource-intensive clinical studies. We analyze three strategies for coordinating empirical usage of two drugs in a hospital ward: population wide combination therapy, random assignment to different drugs (Mixing) and rotating first-line therapy (Cycling). We find that the long-term population-wide benefit is expected to depend mainly on three clinically relevant and accessible factors: the prevalence of resistance among incoming patients, the relative transmissibility of resistant pathogens as well as the pathogen turnover rate. Specifically, combination therapy is expected to be the superior strategy unless the community prevalence of doubly resistant strains is high and the doubly resistant pathogens are very easily transmitted. This benefit of combination therapy is particularly pronounced in the small and therefore highly stochastic patient populations characteristic of hospital wards. Cycling may reduce inappropriate treatment if the cycling period is optimized. However, the benefit when employing a period adapted to the turnover rate is always lower than the loss when the cycling period is too long. Taken together, we find that depending on the biological and clinical specifics of the pathogen and on the clinical setting each of the three strategies can be optimal. However, despite this variability, combination therapy is for most settings optimal from the point of view of minimizing resistance.

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Wednesday March 23rd at 12:30pm

Towards Mathematical Models of Cultural Dissemination
Ricky Der
The enormous success of mathematical descriptions of biological evolution begs the question of whether similar concepts could be used to quantify the evolution of cultural objects, for instance the techniques of the fine arts. In this talk we consider ways of approaching such modeling, with a focus on the evolution of musical forms, making analogies and drawing from methods in population genetics, stochastic processes on graphs, and the theory of language evolution. Both the possible insights that could be gained, as well as the new difficulties in constructing such a theory will be evaluated.

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Thursday March 31st at 12:30pm (Guyot 100)

Leaf size scaling of plant trait relationships
Jeanne Denoyer
Leaf traits such as maximum photosynthetic rate (A), nitrogen content (N), respiration rate (Rd), and phosphorus content (P) are of fundamental importance across a range of scientific disciplines. Although they may be expressed using per-leaf-area normalizations, per-leaf-mass normalizations are often preferred because they tend to show much stronger inter-trait relationships. Here, we develop a simple method that partitions, in an unbiased way, trait data from a large global database into area- and mass- based components. We describe the most comprehensive examination to date of leaf size scaling of physiological traits and its impact on the structure of trait relationships in order to reconcile discrepancies between per-unit-area and per-unit-mass patterns. Consistent with the idea that leaves are constructed to perform area-based light interception and gas exchange, we find that A and P are almost entirely area-based, whereas N and Rd are largely, but not entirely, area-based. We go on to show that apparently strong mass-based relationships are largely due to normalization-induced correlations that do not reflect the underlying biological relationships between the traits. We introduce statistical tools to remove leaf size scaling effects and present a cursory analysis of the size-independent leaf economics spectrum. These analyses will greatly improve the effectiveness and accuracy of the use of plant trait relationships in important applications ranging from predicting agricultural yields to the response of the biosphere to global change.

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Wednesday April 6th at 12:30pm

Juan Bonachela

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Wednesday April 13th at 12:30pm

Caroline Farrior

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Wednesday April 20th at 12:30pm

Ray Dybzinski

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Wednesday April 27th at 12:30pm

Carla Staver

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Wednesday May 4th at 12:30pm

Carey Nadell

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Tuesday August 2nd at 10:00am

Colonization-competition tradeoff promotes species packing
Adam Lampert
Many species are subject to a metabolic tradeoff between quick reproduction and better resource utilization (colonization-competition tradeoff). Quicker reproducers (colonizers) are advantageous when resource is abundant, whereas better resource competitors are advantageous when resource is limiting. It is well understood that this tradeoff may lead to a coexistence of many species, each of which is characterized by its colonization ability q, provided that the resource is spatially extended and is subject to fluctuations. However, it is unknown how evolution shapes the abundance of species as a function of q. In this talk, I will show that the colonization-competition tradeoff inherently leads to “species packing” in which several values of q are widespread and exhibited by many species, while values in between these packs are relatively rare. Such patterns were indeed observed in body-size distributions of multi-cellular organisms.

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Links to previous schedules

    Fall 2000    Spring 2001
    Fall 2001    Spring 2002
    Fall 2002    Spring 2003
    Fall 2003    Spring 2004
    Fall 2004    Spring 2005
    Fall 2005    Spring 2007
    Fall 2007    Spring 2008
    Fall 2008    Spring 2009
    Fall 2009    Spring 2010
    Fall 2010   

Last update: July 31, 2011
Eili Klein