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 Sinead Morris and Simon Leblanc. 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 2014 schedule

Date and time Speaker
Ricardo Martinez-Garcia
Ariana Strandburg-Peshkin
Adam Wolf
George Constable
Anieke van Leeuwen
No lab tea: Fall break
David Borenstein
Open!
Open!
No lab tea: Thanksgiving
Matt Lutz
Open!
Open!

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

Optimizing the search for resources sharing information: the Mongolian gazelle. Ricardo Martinez-Garcia

Communication among individuals frequently leads to group formation, which often has clear direct benefits such as reducing individual vulnerability to predators. Such strategies may, however, also have important incidental benefits. For example, an individual that has found a good foraging patch might try to attract conspecifics to reduce its risk of predation, but also provides its conspecifics with information on the location of good forage, thus increasing the foraging efficiency of those responding to the call.

In this presentation we will investigate the relationship between communication and search efficiency in a biological context by proposing a model of searchers with long-range pairwise interaction. After a general study of the properties of the model, we will go deeper into an application to the particular case of acoustic communication among Mongolian gazelle, for which data are available, searching for good habitat areas. Our results point out that the search is optimal (i.e. the mean first hitting time among searchers is minimum) at intermediate scales of communication, showing that both an excess and a lack of information may worsen it.

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Mechanisms of decision-making and collective movement in wild baboons Ariana Strandburg-Peshkin

Animal groups are often characterized by complex social structures in which individuals exhibit sophisticated use of social information. A major determinant of fitness relates to how animals in such groups make collective decisions, such as where to move to seek appropriate habitat, to forage, and to avoid predators. Baboons have been a model system for studying social living for decades, and as a result their social structure is well-characterized. Yet, due to methodological constraints, little is known about how coordinated collective movement is achieved in these, and other similarly complex, societies. When opinions conflict between group members, it remains unclear whether individuals use simple heuristics, or if they follow more complex rules based on whom they are interacting with. To reveal the underlying fine-grained structure of leadership and social decision-making in a wild baboon troop, we deployed high-resolution GPS collars on almost all adult members of the troop. By analyzing how individuals moved in relation to one another we identified and analyzed a large number of both successful, and failed, movement initiation attempts. We found that decision-making in these groups contained elements of both distributed (self-organized) control, and differential influence according to individuals’ identity. Specifically, when one option was clearly preferred by a large majority, individuals followed the majority. In contrast, when competing options were similarly-supported, specific individuals had disproportionately high influence on the decisions of followers. By studying the fine-scale movement during such decision-making events, we further found that consensus decisions are made only when the difference in directions proposed by of individuals or subgroups exceeds a critical angle, whereas individuals resolve small differences by choosing an average direction. This highlights the importance of considering explicitly the geometry of decision-making in animal groups and demonstrates how different mechanisms of leadership can operate in the same system depending on the level of spatial and numerical conflict.

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Title TBA Adam Wolf

Abstract TBA

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Title TBA George Constable

Abstract TBA

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Title TBA Anieke van Leeuwen

Abstract TBA

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Type VI Secretion as a Defensive Strategy David Borenstein

Type VI secretion (T6S) is a cell-to-cell microbial weapon that is homologous to a phage delivery system. Genes for T6S are widespread in nature, and experimental evidence links it to both host-pathogen and intermicrobial interactions. What advantages does T6S offer in the context of bacterial interspecies competition? To explore this question, we used our novel modeling language (http://www.ecoprogramming.org) to develop a computational model of a growing microbial community in which individual cells can attack and kill cells of different species, but not of their own species. In simulations pairing two otherwise identical T6S+ species against one another, we find that the majority species benefits greatly from high attack rates. However, when T6S+ invaders attack a T6S- resident population, T6S attack provides only a marginal benefit to the attackers. In addition, an arbitrarily small growth advantage can allow T6S- individuals to dominate in competition with T6S+ individuals. Finally, given a sufficiently large resident T6S- population with a growth rate advantage, T6S+ invasion never succeeds in displacing the resident T6S- population. We conclude that T6S can be an effective defense against invasion, but offers limited benefit to an invader.

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Title TBA Matt Lutz

Abstract TBA

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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