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CHAINE Alexis

Station d’Ecologie Expérimentale du CNRS

09200 Moulis France 
 
Tel : +33 5 61 04 03 78 
 
Fax : +33 5 61 96 08 51
 
alexis.chaine@ecoex-moulis.cnrs.fr
 
 
Research Axes
 
My interests lie largely in understanding the evolution and dynamics of social groups by integrating knowledge of social interactions, life history strategies, selection, ecology, and population dynamics. Because signals are the basic means of interactions among individuals, much of my work pays special attention to the evolution of signal traits among cooperating and competing individuals. I’ve gravitated towards fairly complex social systems in part because they provide exciting opportunities for novel natural history observations, but also because complexity provides a rich background that affects selection and life history evolution. This complexity, in turn, often produces very dynamic evolutionary pressures leading to a better understanding of how selection operates in natural systems and ultimately how diversity is generated. I use a combination of observational and manipulative methods paired with diagnostic tools (e.g. genetics, theoretical modeling) to understand selection dynamics.
 
Dynamic Sexual Selection on Male Plumage in Lark Buntings
Exaggerated sexual traits are generally thought to arise through consistent selection imposed either by male-male competition or female choice. In complex social systems – as is the case for most social groups – we might expect much more dynamic selection regimes on sexual signals than previously thought. Using lark buntings, Calamospiza melanocorys, as a model system, I have shown that shifts in female preferences or preferences for a number of different qualities could favor the evolution of multiple signals. The study revealed highly dynamic sexual selection on male traits, including reversals in the direction of selection across years due to female mate choice plasticity. Discovering dynamic sexual selection in lark buntings forces us to reconsider some of the most basic assumptions and predictions about sexual selection — including the maintenance of genetic variation under selection and trait exaggeration — and has lead us to begin developing genetic models of trait evolution that incorporate our findings (with S. Alonzo). Because my own experience in modeling is somewhat modest, I have undertaken a collaborative effort with This work is also being extended to a new synthetic framework for understanding the evolutionary causes and consequences of female mate choice plasticity (with B. Lyon and B. Montgomerie).
While female choice causes inconsistent selection leading to weak long term selection in lark buntings, male-male competition exerts consistent selection on a number of male traits across years. Badges of status have been well studied in both breeding and non-breeding birds, but the importance of multiple signals and the temporal stability of dominance badges have been ignored in the literature. I found that one trait, wing patch size, is used in settling long distance disputes whereas another, body color, is important in escalated close range encounters when males are defending territories. My work on male-male competition also provides evidence that multiple badges of status are used in dominance interactions and not just in mate choice. This is a relatively new concept that has only been investigated in one other study to date which was conducted in captivity.
 
The Evolution of ‘Greenbeard’ Signals in Lizards
Social interactions can also generate complexity through alternative life history strategies. The presence of such strategies can lead to very dynamic selection regimes including cyclical stability, drive divergence in life history strategies, and lead to speciation. Alternative strategies are often composed of divergences in fundamental social behaviors including cooperation, aggression, deception, parental care, and sexual display. Cooperation and altruism – where an individual’s actions incur a cost to self but provide a benefit to others – are an enduring challenge to evolutionary theory because they should be invaded by a selfish strategy. In a collaborative project with B. Sinervo, I examined signal based cooperative behaviors in the side-blotched lizard, Uta stansburiana, a species with three alternative strategies. We documented criteria for ‘greenbeard’ altruism – cooperation tied to genic similarity – among unrelated individuals of one morph and determined the genetic basis of this behavior using linkage disequilibrium estimates and a physical genetic map. An unexpected result of our work was the novel finding that social games among males actually stabilize greenbeard behaviors and cooperative strategies fluctuate between altruistic and mutualistic. We have more recently detected similar selection regimes in the European common lizard, Lacerta vivipara, using fitness data, and population genetic modeling.
We have extended these ideas to produce a more general model for mating system evolution that provides the first alternative hypothesis to the ecological mating system framework proposed 30 years ago. With B. Sinervo and D. Miles, I have developed a game theoretic model based on genetic strategies of aggression, sneak, and cooperation linked to male care through genic recognition. This model generated predictions of mating system states as well as the evolutionary transitions from one mating system to another under a wide range of values describing male behaviors. We tested our model predictions with phylogenetic data on rodents and found a striking match to both general and specific model results. In addition, our results provide a new hypothesis for the evolution of genomic imprinting through mating system evolution and may provide an explanation for rodent cycles through alternative male.
 
Information Across Populations and the Evolution of Cooperation
One of the key factors that contributes to many of the rich behaviors and selection dynamics associated with social complexity is social network stability and the movement of individuals. The two major routes to social cooperation are through direct genic altruism or through social reciprocation in stable groups. As such, understanding the evolutionary dynamics of social systems and social networks requires an understanding of dispersal and habitat choice behaviors. I am using a model system, laboratory populations of a ciliate, Tetrahymena thermophila, to experimentally examine the evolutionary balance between cooperation and dispersal, something simply not feasible with larger and longer lived organisms.
We have found kin cooperation in this species which also shows genetic variation in dispersal behavior, but phenotype dependent dispersal reduces the expected trade-off between dispersal and cooperation. Cooperative lines form sedentary individuals and a few long range dispersers to colonize distant patches, but reduce growth rates and increase carrying capacity to improve persistence on a resource long enough to allow colonization of distant patches. Such strategies show a clear integration of life history traits to link within group behaviors and cooperation to dispersal behavior. 
We have also focused on plasticity in dispersal that could generate non-random dispersal and contribute to enhanced social structure or colonization effects. Our evidence suggests that individuals use indirect social information (i.e. immigrants) both to increase dispersal when surrounding patches will provide a benefit (e.g. lower competition, better social environment) and to orient movement. We are now initiating a new set of experiments to examine the links between phenotype dependent dispersal and colonization behaviors. Together, these experiments should help improve our understanding of how social structure can emerge across space when kin compete or cheaters exist.
 
Genes of altruism in humans
This study investigates the genetic basis of altruism in humans. Altruism presents a conundrum to evolutionary biology because an altruistic act by definition entails a fitness cost to the altruist and a fitness benefit to the recipient. With collaborators from the University of Exeter, UK, we have identified the Carnegie Hero Fund, a unique database of demonstrated altruism in humans where criteria for inclusion require a real risk to the life of the altruist. DNA will be isolated from saliva samples of consenting individuals identified from the database to permit a candidate gene approach using genes already found to be implicated in ‘cooperative’ or ‘prosocial’ behaviors in other human studies or in animal models. A secondary goal is to determine if there is evidence for ‘greenbeard’ altruism — genetic resemblance between the altruist and recipient without a direct kinship link.

For more information, check our website : https://altruismgenes.wordpress.com/

 

Collaborators
  • Camille Bonneaud ; University of Exeter, UK
  • Andy Russell ; University of Exeter, UK
  • Bruce Lyon ; Univesity of California, Santa Cruz USA
  • Barry Sinervo ; University of California, Santa Cruz USA
  • Donald Miles ; University of Ohio, Athens USA
  • Nicolas Schtickzelle ; Universite catholique de Louvain, Belgique
  • Stephane Legendre ; ENS Paris
  • Jean Clobert, CNRS USR2936
  • Suzanne Alonzo ; Yale University, USA
 

Honors and Competitions

  • Prix Jeune Chercheur de la Société Française d’Ecologie 2009 
  • Concours CNRS Section 29 : classe 6eme
  • National Evolutionary Synthesis Center (USA) Post-Doctoral Grant Award (2009-2011)
 
Publications
  • Chaine A. and Angeloni A. (2005) Size-dependent mating and gender choice in a simultaneous hermaphrodite, Bulla gouldiana. Behav. Ecol. and Sociobiol. 59 : 58-68.
  • Sinervo B, Chaine A.S., Clobert J., Calsbeek R., Hazard L., Lancaster L., McAdam A., Alonzo S., Corrigan G., and Hochberg M. (2006) Self-recognition, color signals, and cycles of greenbeard mutualism and altruism. Proc. Natl. Acad. Sci. USA 103 : 7372-7377.
  • Sinervo B, Heulin B, Surget-Groba Y, Clobert J, Miles D, Corl A, Chaine AS, Davis A (2007) Models of density-dependent genic selection and a new rock-raper-scissors social system. Am. Nat. 170 : 663-680.
  • Chaine A.S. and Lyon B.E. (2008) Adaptive plasticity in female mate choice dampens sexual selection in male ornaments in the lark bunting. Science 319 : 459-462 (Cover Photo ; coverage in >20 major news shows/papers worldwide and 67 other web sites).
  • Chaine A.S. and Lyon B.E. (2008) Intra-sexual selection on multiple plumage ornaments in the lark bunting. Anim. Behav. 76 : 657-667.
  • Lyon B.E., Chaine A.S., Winkler D.W. (2008) A matter of timing. Science 321 : 1051-1052.
  • Lepetz V., Massot M., Chaine A.S., Clobert J. (2009) Climate warming and evolution of morphotypes in a reptile. Global Change Biology 15 : 454-466.
  • Clobert J., Sinervo B., Danchin, E., Chaine A.S., Ernande B., Socrci G. La plasticité phénotypique. In : Biologie évolutive (Eds : F. Thomas, T. Lefèvre & M. Raymond), De Boeck : 453-490.
  • Chaine A.S. and Lyon B.E. Signal Architecture : temporal variability and individual consistency of multiple sexually selected traits in a passerine bird. Evolution.
  • Schtickzelle N., Fjerdingstad E., Chaine A.S, and Clobert J. (submitted) Dispersal does not hinder cooperative social clusters in a ciliate. BMC Evolutionary Biology.
  • Sinervo B., Chaine A.S., and Miles D. (submitted) Social games and genic selection drives mammalian mating system evolution and speciation. PLOS Biology.
  • Chaine A., Schtickzelle N., Pollard T., Huet M., and Clobert J. Kin cooperation and dispersal in Tetrahymena thermophila. Evolution.