IBRG hosts informal meetings where members of affiliated lab groups in Princeton University's Department of Ecology and Evolutionary Biology give presentations on their current research. These talks are usually about 20-30 minutes long followed by 30 minutes of discussion. We meet during the academic year on Fridays from 3-4pm in Eno Hall 209. All are welcome to attend!

The speaker schedule and mailing list for the 2011-12 academic year are being maintained by Andrew Gallup and Jennifer Schieltz. Please contact Andrew or Jennifer if you are interested in presenting your research or would like to add your name to the group's mailing list.

Archived schedules:
Spring 2011
Fall 2010
Spring 2010

Affiliated labs:
Altmann Lab | Couzin Lab | Hau Lab | Horn Lab | Rubenstein Lab | Wikelski Lab

 
Fall 2011 Schedule
Note: IBRG welcomes presentations given by visitors of our affiliated labs. Guest presenters are indicated by an asterisk (*) in the schedule below.
 
Date Speaker

09/23/11

Gita Gnanadesikan

09/30/11

John Bonner -- professor emeritus
10/07/11 Andrew Hein* - University of Florida 

10/14/11

Qing Cao

10/21/11

Christie Riehl

10/28/11

Stephanie Hauck

11/11/11

Maria Ter-Mikaelian*

11/18/11

Erol Akcay

12/02/11

Peter Molnar

12/09/11

Andrew Berdahl

 
Presentation Abstracts
 

23 September 2011: Gita Gnanadesikan
A New Look at Mammal Migration
Applying a new definition of migration across species and using it to look at motivational and spatial patterns of migration.  

30 September 2011: John Bonner
Behavior in Slime Molds
Despite the apparent simplicity of their multicellular or multinucleate structure, they have remarkably sophisticated behaviors.  

07 October 2011: Andrew Hein
Modeling animal movement: from migration to search behavior
I will discuss some approaches that I am developing to predict and understand patterns of animal movement using biomechanics, biophysics, and search algorithms.

14 October 2011: Qing Cao
Resource Use and Niche Differentiation of Two Sympatric Equids, Przewalski's Horse and Kulan, in Arid Ecosystem
The classic niche theory as the foundation of community ecology, has received much attention since its birth 100 years ago. However, current niche definition as an n-dimensional hypervolume is very conceptual, and has been extremely difficult to measure in practice. Furthermore, natural selection often drives the competing species into occupying different niches, so extant interspecific competition we observe is often small or not existent. Moreover, despite the fact that there are many types of niche differentiations, none of them could guarantee the complete coexistence of the two species. For the reasons above, the niche studies seldom target on large mammals. The anthropological activities have greatly speeded up the extinction rate in nature. Due to their higher dependence on the quantity of resource and space, large mammals are more vulnerable to the changes in their habitat. Thus understanding the degree of the niche differentiation among species is critical to guarantee the persistence of two endangered species, especially if they have similar needs. The reintroduction of Przewalski's horse (Equus ferus przewalskii) to the landscape where a related species - the Kulan (E. hemionus hemionus) lives, provides such an opportunity to look into the process of the niche differentiation, particularly driven by the present competitions between species.

21 October 2011: Christie Riehl
Division of labor and reproduction within cooperatively breeding groups of Greater Anis: hard-working males do not sire more nestlings
Many animals breed in cooperative or communal groups, in which several individuals provide parental care to a shared brood of offspring. However, not all individuals provide the same level of parental care. Parental investment theory, as originally outlined by Robert Trivers, posits that variation in parental care is adaptive, such that group members should adjust their share of parental care according to their share of reproduction in the shared clutch. In this study, I examined the relationship between reproductive success and parental care in the Greater Ani, a communally breeding tropical cuckoo. Groups are typically composed of two or three pairs, which raise their young in a single shared nest. Labor is not equally divided among group members; in fact, one male in each group performs all of the nocturnal incubation and most of the nest defense. Previous researchers have proposed that this male should also sire the majority of chicks in the communal clutch, as predicted by parental investment theory. Contrary to this prediction, I found that reproduction was shared almost equally among males in cooperative groups, with no systematic reproductive advantage accruing to the nocturnally incubating male. In this talk I'll discuss these results and present alternate hypotheses for why variation in parental care may not always reflect current reproductive output.

28 October 2011: Stephanie Hauck
Natural History and Demography of Ndorobo Pastoralists in Northern Kenya
This talk will present some preliminary demographic information on the human and domestic livestock populations of two group ranches in northern Laikipia district, Kenya: Ilmotiok and Tiamamut. These two group ranches contain a mixed hunter-gather/pastoral population that speak a dialect similiar to the Ilsampus clan of the Maasai and have adopted Maasai style livelihoods and culture. The only ethnographic evidence of these groups comes from a study done on the Mukugodo of Dol Dol, a neighboring community (Lee Cronk, Rutgers). I will include data from a population wide census, conducted in 2010 and from a mixed longitudinal sample population of 339 individuals collected approximately monthly from 2008-2011. Some preliminary descriptive statistics of the diet and household characteristics will also be presented.

11 November 2011: Maria Ter-Mikaelian
Vocal behavior of Mongolian gerbils and categorization of calls by the brain
The Mongolian gerbil (Meriones unguiculatus) is a social desert rodent.  In this study, a gerbil colony was allowed to breed freely in a naturalistic habitat over a period of 19 months and was observed for social and vocal behavior.  Adult gerbils were found to vocalize primarily in interactive situations, such as during mating, food disputes, and same-sex aggression.  Calls within an individual behavioral class exhibited substantial variability, but were significantly different from all other classes in one or more acoustic properties.

To determine how calls from different behavioral classes may be processed by the brain, different exemplars of each call type were played to an alert adult gerbil while recording the activity of individual neurons in primary auditory cortex (AI). Responses of individual cortical neurons as well as groups of neurons were analyzed using a clustering algorithm. It was found that while the responses of single neurons reflected variations in the calls’ acoustic features, the pooled responses of multiple AI neurons permitted accurate categorization of calls by behavioral class. 

18 November 2011: Erol Akcay
Evolving group-optimality with and without private information
An ancient debate in evolutionary biology centers on the question of if and when behaviors can evolve that maximize benefits at the group level, but are individually costly. Standard kin selection theory suggests that these behaviors should be confined to clonal groups with perfect relatedness which face no evolutionary conflicts of interests. However, this statement ignores the crucial role that flexible behaviors (such as reciprocity) and the incentives for cooperation they might induce. I will present a general model based on the Price equation that integrates behavioral feedbacks and kin-selection effects. This model shows (i) that relatedness and behavioral responses interact synergistically, (ii) that the scope of group-optimality is much wider than just clonal groups, and (iii) whether evolution leads to group optimality depends critically on the proximate mechanisms that generate the behavioral responses.

In the second part, I will talk about a model of cooperation under private information. The presence of private information frequently creates additional incentives to misrepresent one's information and therefore preclude mutually beneficial outcomes. Hence, stable cooperation to maximize mutual benefit in these situations requires special incentive structures. I will talk our ongoing work to calculate optimal incentive structures in the context of determining reproductive skew within a group, with special emphasis on what the maximum mutual benefit that can be achieved.

02 December 2011: Peter Molnar
An energetic perspective on the ecological impacts of climate change: from polar bears to parasites
One of the biggest challenges in predicting the ecological impacts of climate change relates to the fact that past and predicted environmental conditions often differ substantially from each other, resulting in a lack of data to empirically measure the response of animal populations to future conditions.Here, I explore the use of process-oriented energy budget models to circumvent this problem. Such models explicitly describe the cause-effect relationships linking environmental conditions to ecological response, and can thus be used for prediction without using extrapolation. To illustrate the approach I focus on the Arctic, which is characterized by relatively simple ecosystems and a strong climate signal, making it an ideal model to develop and test predictive models. I first discuss dynamic energy budget models for polar bears, which capture the functional dependence between energy availability and physiological processes to predict survival and reproduction under expected food shortage. Severe nonlinear declines in these demographic parameters are predicted, and existing hypotheses of behavioral adaptation towards terrestrial food sources are rejected on energetic grounds. These so-called ‘supply-side models’ are contrasted with ‘demand-side models’ that capture physiological variables in cases where food limitation is not an issue. The latter approach is applied to arctic nematodes where increased temperatures will result in both faster parasite development and increased mortality. To quantify these contrasting effects and their consequences for parasite prevalence and abundance, I link classical host-parasite models with the ‘Metabolic Theory of Ecology’. I show that parasites with a direct life cycle have an inherent advantage over parasites with an indirect life cycle, although this advantage may be reversed under climate warming due to behavioral thermoregulation of the intermediate hosts and/or an ability of parasites to affect host behavior. These results are illustrated for nematode parasites of muskoxen, predicting nonlinear increases in parasite fitness under future warming.

09 December 2011: Andrew Berdahl
Empirical demonstration of collective gradient tracking
Organisms often locate the resources they nee to survive by following noisy spatial cues such as temperature, chemical concentrations, magnetic fields or light. While there has been some theoretical work showing that animals may benefit from collective navigation when following these cues, empirical studies are nearly absent. To test if collective behavior might improve navigation, we measured the ability of different sized groups of fish to track dynamic light gradients. Our results show that larger groups more effectively track these gradients. From individual trajectories we identified a simple underlying mechanism that drives this results, and which, when put inot a schooling model, replicates our experimental data. As far as we know, this is the first empirical demonstration of navigational benefits from collective behaviour.

 

 
Questions or comments about this webpage? Email Andrew Gallup or Jennifer Schieltz
© 2010 The Trustees of Princeton University

Page last updated 25 May 2011