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 (20 minutes of presentation and 10 minutes of questions) and are scheduled generally on Wednesdays at 12:30 pm. All talks this semester will be held in Eno 209 unless stated otherwise.

This semester, talk schedules and email lists will be maintained by Elise Myers and Kaia Tombak. Please contact one of us to have your name added to the labtea email list so that you can receive reminders about upcoming meetings.

Fall 2015 schedule

Date and time Speaker
Marco Visser
Matthieu Barbier
Joanna Bryson
Daniel Cooney
Anieke van Leeuwen
Helene Muller-Landau
Karla Kvaternik
Colin T. Kremer
Chris Kempes
Lisa McManus
Ariana Strandberg-Peshkin
Dane Klinger
Emily Klein
George Hagstrom

Note: Priority is given to graduate students. A symbol next to the speaker's name means that approval is pending for a week and graduate students can still claim the slot.

Titles and abstracts

Lianas Affect Population Growth Rates of Tropical Trees Marco Visser

Lianas are increasing across the Neotropics and dramatically reduce the growth, survival, and fecundity of their host trees. Whether lianas affect tree species population growth rates differentially remains unknown. In this talk, I show how we used integral projection models to integrate liana effects across the life-cycle into total effects on population growth rates for 33 tropical tree species from Panama. Liana infestation decreased tree growth, survival and reproduction. Fast-growing tree species exhibited stronger declines in survival than did slow-growing species. Heavy liana infestation involving more than half of the host’s canopy reduced population growth rates by 1.9% per year. The reduction was greatest among fast-growing species, which showed much higher sensitivity to liana infestation. Lianas have strong differential effects on tree species populations, and thus ongoing increases in liana abundance are likely to alter tree species composition in Neotropical forests.

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How to reverse-engineer your social system in 7 easy steps Matthieu Barbier

Societies are among the most salient examples of adapted systems with a hierarchy of goals - in biological terms, multiple selection levels operating simultaneously - from individual preferences to institutional efficiency and so forth. Much theoretical effort has focused on optimal or evolutionary responses to a single level of selection, or simple conflicts between the smallest level (individual wants) and the largest (collective good). Far less has been done to understand how and when multiple intermediate levels can develop and interact. I suggest that the clearest language for this problem is not agent or population dynamics, but a non-dynamical form of system modelling that looks more like (reverse) engineering. Interestingly, this approach is also far more compatible with the questions and data of qualitative social science, and may offer a way of making those more easily testable. What it lacks is a consistent formal framework applicable to natural systems, which I have tried to develop in a restricted setting.

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Costly punishment as a strategy for optimising public goods investment Joanna Bryson

[With the goal of] account[ing] for the variation by global region in antisocial punishment (ASP-sanctioning those contributing more than the sanctioner in public goods games (as described by Herrmann, Thöni & Gächter (2008)), [we] examined strategies expressed by Herrmann et al's subjects. We also looked at the impact of having a group member invest all (Cooperator) or none (Freerider) of their allotment in the PG. We created evolutionary ABM exploring the coherence of our hypotheses. In Herrmann et al's data, rates of ASP vary more than those of altruistic punishment (AP). Variation across subject pools in the proportion of Cooperators is much greater than in the proportion of Defectors. We found no significant correlation between AP and the proportion of Cooperators, AP and Freeriders, and ASP and Freeriders, but a strong anticorrelation between ASP and the proportion of Cooperators (r = −0.62, p < 0.01). Many more individuals employed both AP and ASP than ASP exclusively. Exclusive AP and complete abstention from punishment were widely-used strategies. When an individual is punished, they are less likely to invest the same amount in the PG in the next round. ASP results in random variation, whereas AP results in increased public goods investment (PGI). Our models show that when PGI is subject to selection in regularly varying contexts, populations form with peaks of similar PGI strategies across a range of values extending both above and below optimal PGI levels. We believe that overall levels of PGI are generated by populations composed of multiple strategies, including over and under investment (cf. Maclean et al 2010). Shifting between strategies as a result of individual experience may allow agile tracking of changing economic landscapes. Punishment may be a social mechanism accelerating such tracking. We are currently studying its impact with further simulations.

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The Moran Process and Evolution in Finite Populations Daniel Cooney

This talk will provide an introduction to the frequency-dependent Moran process as a model for stochastic evolution in finite populations. In particular, we will focus on the relationship between payoffs in underlying evolutionary games and the mapping between individuals' payoffs and their reproductive fitnesses in the Moran process. We will discuss the traditional linear fitness version of the Moran process, as well as the newer exponential fitness mapping and it's particularly nice properties. After outlining the standard tools for analysis of the Moran process, we will make use of these tools to explore the roles of assortment and kin selection in the evolution of cooperation.

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Social-ecological dynamics in exploited marine systems Anieke van Leeuwen

Over-harvesting of marine resources has resulted in a multitude of fish population collapses in recent decades. In order to better understand the processes underlying these collapses and to assess the potential for population recovery, fisheries management is moving away from both single-species stock assessments and total-allowable catch quota. Management approaches increasingly focus on the intricate dynamics in entire ecosystems as well as on the social dynamics of the fisheries. I will present an approach to couple ecological dynamics in simplified food web modules of exploited fish species with the social dynamics in the fisheries harvesting from the food web.

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Testing for Directional Change in Carbon Budgets of Tropical Forests Using Forest Plot Data Helene Muller-Landau


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Strategic MABs and Social Foraging Models Karla Kvaternik


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Changing Climate and Evolving Marine Ecosystems Colin T. Kremer


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Title Chris Kempes


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Exploring Regime Shifts in the Coral Triangle Lisa McManus


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Social and Environmental Influences on Movement in Wild Baboons Ariana Strandberg-Peshkin


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Title Dane Klinger


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Title Emily Klein


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Title George Hagstrom


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Links to previous schedules

  1. Fall 2000
  2. Spring 2001
  3. Fall 2001
  4. Spring 2002
  5. Fall 2002
  6. Spring 2003
  7. Fall 2003
  8. Spring 2004
  9. Fall 2004
  10. Spring 2005
  11. Fall 2005
  12. Spring 2007
  13. Fall 2007
  14. Spring 2008
  15. Fall 2008
  16. Spring 2009
  17. Fall 2009
  18. Spring 2010
  19. Fall 2010
  20. Spring 2011
  21. Fall 2011
  22. Spring 2012
  23. Fall 2012
  24. Spring 2013
  25. Fall 2013
  26. Spring 2014
  27. Fall 2014
  28. Spring 2015