SEEM EVOLUTION | Julia fischer, Göttingen | vendredi 31 mai à 11h30

julia fischerProf. Julia Fischer, Male tolerance and male-male bonds in a multi-level primate society – Insights from wild Guinea baboons
vendredi 31 mai à 11h30
Salle Louis Thaler, UM2, Bat 22, 2e étage
contact : Mike Hochberg


Identifying the factors that drive the evolution of social systems is fundamental for our understanding of the emergence of cooperation and social intelligence, and ultimately human evolution. Members of the genus Papio constitute an important model in this context. To date, two different social organizations have been contrasted: while savannah baboons (Papio anubis, P. cynocephalus, and P. ursinus) live in relatively stable multi-male multi-female groups, hamadryas baboons (P. hamadryas) exhibit a multi-level organization with one-male units as the smallest entities. Notably, West-African Guinea baboons (P. papio)have been barely studied in the wild and their social system has been disputed. Here we report the results of the first systematic study of wild, individually identified Guinea baboons, ranging in the Niokolo-Koba National Park in Senegal. Combining spatial and genetic data, we show that Guinea baboons exhibit a multi-level system consisting of subgroups (“parties”) comprising 3-4 males and several females. Some but not all male members of a given party may be highly related. Specific parties regularly formed a “gang”. Gangs that utilized the same home range as other gangs constituted the “community”. While the social organization of Guinea baboons superficially resembles that of hamadryas baboons, Guinea baboons reveal stronger male-male affiliation, apparently higher female freedom, and more fluid groups. Males spent considerable time in close proximity to each other and engaged frequently in affiliative interactions, indicating a high level of male-male tolerance. Bonding patterns among males were, however, not correlated with genetic relatedness, supporting the view that bonds per se may be adaptive. Playback experiments revealed that males attended most strongly to simulated interactions of their own gang members, while they ignored the simulated presence of males belonging to other gangs in the environment, or strangers. This is in line with their highly tolerant social style. We suggest that Guinea baboons constitute a valuable model for elucidating the emergence of male cooperation and tolerance, and the dynamics of social evolution more generally.

SEEM – Evolution | Vendredi 28 juin 2013 | Alison Duncan | 11h15, salle de réunion du CEFE

Alison©alison duncan0 Duncan, ISEM
Red noise enhances host and parasite persistence in experimental metapopulations
Résu:Environmental fluctuations are important for parasite spread and persistence. However, the impact of the spatial and temporal organisation of environmental fluctuations on host-parasite dynamics is not well understood. Temporal fluctuations can be random but positively autocorrelated, such that the environment is similar to the recent past (red noise), or random and uncorrelated with the past (white noise). We imposed red or white temporal, temperature fluctuations on experimental metapopulations of Paramecium caudatum, experiencing an epidemic of the bacterial parasite Holospora undulata. Metapopulations (2 subpopulations linked by migration) experienced fluctuations between stressful (5ºC) and permissive (23ºC) conditions following red or white temporal sequences. Spatial variation in temperature fluctuations was implemented by exposing subpopulations to the same (synchronous temperatures) or different (asynchronous temperatures) temporal sequences. Red noise, compared to white noise, enhanced parasite persistence. Despite this, red noise coupled with asynchronous temperatures allowed infected host populations to maintain sizes equivalent to uninfected populations. We highlight how patterns of temporal and spatial environmental fluctuations can impact parasite spread and host population abundance. We conclude accurate prediction of parasite epidemics may require realistic models of environmental autocorrelation.
(contact : Samuel Alizon)
SEEM Evolution, Vendredi 28 juin 2013, Ali Duncan, 11h15, salle de réunion du CEFE


SEEM – Ecologie, 24 mai 2013, 10h – Aabir Banerji

banerji AabirAabir Banerji, Institute of Evolutionary Biology and Environmental Studies, University of Zürich, Switzerland The antithesis of indirect defenses and why its short-term optimization may defeat the purpose of biological control

Various means of protection against natural enemies can be obtained via symbiotic or recruited associations with other species. Collectively, these are known as “indirect defenses.” Indirect defenses are widespread and have received much attention within ecology, particularly among practitioners seeking to safeguard crops against herbivorous pests. In contrast, associate-derived means of acquiring, securing, or assimilating prey/hosts – the consumer counterpart of indirect defenses – have been underappreciated and often overlooked. These adaptations are routinely employed by hundreds of terrestrial and aquatic taxa and are often implicitly utilized in applied contexts but have never been recognized as a general phenomenon or assessed in terms of their consequences for long-term population dynamics. I term these adaptations “indirect offenses.” Here I review the mechanisms of indirect offenses using illustrative examples and employ a selection-based model to show why a precise conceptual understanding of indirect offenses may be necessary for preserving the long-term effectiveness of popular biological control agents.

Contact: Olivier Kaltz