Bernard Thierry

Research Director at the Centre National pour la Recherche Scientifique
Département Ecologie, Physiologie & Ethologie
(IPHC ULP CNRS)
23 rue Becquerel
67087 Strasbourg Cedex 2
France

The proximate/ultimate status quo in the biological study of behavior: maintaining it at any cost?

The biological study of behavior was shaped by the divorce between ethology and behavioral ecology twenty years ago. Whereas the heirs of ethology promote a phenomenological study of behaviors, behavioral ecologists focus on their fitness consequences. I argue that both schools share the same blind spot about the link between evolutionary past and the making up of the individual because of their common acceptance of the dichotomy between ultimate and proximate causation. By maintaining a pan-selectionist view of evolution in the study of behavior, the dichotomy hampers exploring how epigenetic processes affect adaptive trade-offs. Giving up the dichotomy would give impetus to research programs that investigate how behavioral traits associate in clusters through development and evolution. It would further a comprehensive view of behavioral phenotypes, making the reunification of behavioral biology an attainable goal.

Jens Krause

Professor of Behavioural Ecology
Institute of Integrative and Comparative Biology
Faculty of biological sciences
University of Leeds

Animal Collective Behaviour

In my talk I would like to introduce the audience to some conceptual ideas for the modelling of animal collective behaviour to understand bird flocking, fish schooling, swarming insects etc. This will be followed by some empirical tests of the models involving both human crowds and fish. The human work touches on some concepts of swarm intelligence. The fish work will showcase a robotic fish that we recently constructed in Leeds. It is a computer-controlled fish that can interact with live fish and become a leader manipulating entire fish shoals. This can be used to gain insights into the basic dynamics of collective behaviours.

Karen McCoy

Chargée de Recherche
Equipe: Structure génétique et adaptations des systèmes symbiotiques
Laboratoire de Génétique et Evolution des Maladies Infectieuses, UMR 2724 CNRS IRD
Centre IRD, 911 avenue Agropolis, 34394 Montpellier FRANCE

Adaptations and constraints in the evolution of ticks and their microparasites

(McCoy, K.D., D. Duneau, F. Kempf & T. Boulinier)

At present, we known little about the characteristics of parasites with the potential to shift and adapt to novel hosts. This host change can have cascading effects on different interacting organisms and be particularly important for species involved in vector-borne disease. Indeed, the adaptation of vector organisms to new hosts can greatly modify the ecology and evolution of both their hosts and the micropathogens they carry. Here, we examined host-associated divergence in the seabird tick, Ixodes uriae, a common ectoparasite found in circumpolar regions of both hemispheres and vector of the Lyme disease bacterium, Borrelia burgdorferi sensu lato. We first tested for host race formation in this ‘generalist’ tick using a population genetic approach and examined the evolution of host-associated divergence events using a combination of nuclear and mitochondrial markers. We then tested the hypothesis that the formation of these races has resulted in an associated divergence in Borrelia sp. circulating in this system using several colonies where different seabird host species breed sympatrically. We discuss these results in relation to the possible importance of cascading host effects in the ecology and epidemiology of tick-borne parasites.

Mark Hewison

CEFS - INRA, BP52627,
31326 Castanet-Tolosan, France
Mark.Hewison arobase toulouse.inra.fr

Reproductive strategies and maternal investment in ungulates

One of the most controversial questions of behavioural ecology concerns how mothers should allocate their reproductive effort between offspring and whether and under what conditions they should favour sons over daughters. Ungulates have been widely used as a model species to study sex-bias in maternal allocation, both pre-natal (in terms of offspring size and sex ratio at birth) and post-natal (in terms of maternal care, notably suckling duration and frequency). In this talk, I will review the information available in the literature and attempt to link inter-specific variation in maternal investment strategy with patterns of sexual dimorphism, variation in reproductive success between the sexes and mating systems among diverse ungulate species. I will illustrate the key points by referring to two contrasting ungulates, the roe deer (Capreolus capreolus) and the red deer (Cervus elaphus), and I will discuss the factors that influence reproductive success in these species with contrasted mating systems (resource defence polygyny and female defence polygyny, respectively).

Vincent Fourcassié

Centre de Recherches sur la Cognition Animale
CNRS UMR 5169, Université Paul Sabatier
118 route de Narbonne, F-31062 Toulouse Cedex 4,
France

Moving in the crowd: the organization of bidirectional traffic on ant foraging trails

(Fourcassié, V. & Dussutour, A.)

In a lot of ant species individuals do not forage solitarily but use pheromone trails to recruit their nestmates to abundant food sources. As recruitment proceeds these trails can rapidly sustain a high volume of bidirectional traffic. In species of ants using mass chemical recruitment the trail pheromone is so attractive that the flow of ants on foraging trails can reach very high values, e.g. up to more than 200 ants/min in army-ants. When long-lasting resources are exploited the passage of thousands of workers on a trail can actually turn it into a physical road that is materialized on the ground and that is sometimes actively maintained and cleared of debris by a specialized group of workers.

The fact that time, rather than energy, is the limiting factor of foraging activities in ants is well documented. To forage efficiently a colony of ants should thus maximize the flow of its foragers (number of ants per unit time) on recruitment trails in order to maximize the rate of resource harvesting from the environment. According to one of the fundamental laws of traffic theory however, the flow on a trail can be maximized for only a small range of the density values of individuals on this trail. Beyond these values traffic congestion occurs and the efficiency of collective foraging begins to decrease. In fact, crowding phenomena slow down the movement of the workers and thus progressively decrease the rate of food return to the nest. This effect is enhanced in ants because, contrary to most animals that move in one single direction during migratory movements, trail traffic in ants involves intermingled flows of outbound and returning foragers so that each head-on encounter induces a delay in the progression of the workers.

In this talk I will review some of the mechanisms used by ants to increase the efficiency of their collective resource harvesting through foraging trails. I will borrow concepts from traffic theory to explain how ants organize their traffic on foraging trails to prevent traffic congestion and to enhance harvesting efficiency. I will show in particular how traffic regulation in ants is based on self-organized processes with simple local interaction rules among individuals being amplified by positive feed-back mechanisms to create large-scale complex traffic structures. The strategies used by different species of ants will be contrasted to illustrate the variety of traffic optimization solutions found in ants facing different biological or physical constraints in their foraging activities.

Martin Giurfa

Research Centre on Animal Cognition, CNRS
Université Paul Sabatier
118 route de Narbonne
31062 Toulouse cedex 9
France
(giurfa arobase cict.fr)

From object recognition to rule learning in honeybees: visual knowledge extracted by a ‘simple’ brain

Visual learning allows acquisition of new environmental information, which in turn allows adaptive responses when viewing experienced events again. This capacity is crucial in contexts such as food search, partner recognition, navigation and defense against potential enemies. It admits different levels of complexity, from simple associative link formation between a visual stimulus (e.g. a specific color) and its outcome (e.g. reward or punishment) to more sophisticated performances such as categorization of objects (e.g. animal vs. non-animal) or apprehending abstract rules applicable to unknown visual objects (e.g. “larger than” or “on top of”). Mastering categories and rules allows, in principle, flexible responses beyond simple forms of learning. Not surprisingly, higher-order forms of visual learning have been mainly studied in vertebrates with larger brains, while simple visual learning has been restricted to animals with small brains such as insects. However, this dichotomy has recently changed, as studies on visual learning in honeybees have yielded surprising results in terms of the sophistication of the tasks that can be achieved. In parallel, the accessibility and small size of the insect brain has allowed to characterize some neural mechanisms of visual learning. Here I present a spectrum of visual learning forms in honeybees, from color and pattern learning, visual attention and top-down image recognition, to category learning and rule extraction. I discuss the necessity and sufficiency of simple associations to account for complex visual learning and benefit from the extensive knowledge on brain organization in insects to discuss neural mechanisms underlying these visual performances.

Étienne Danchin

Groupe d'Écologie Comportementale et Structure des Communautés
Université Paul Sabatier
118 route de Narbonne
31062 Toulouse cedex 9
France

Inclusive Heritability: Behaviour As A Major Vector Of Information Inheritance

Behavioural biologists acknowledge that many behaviours are adaptations produced by selection, but few perceive behaviour as a major vector of information inheritance, and thus of evolution. For instance, students of behaviour often seek genes that code for behavioural variance itself, while ignoring the potential role of additive environmental effects. Genetic information should rather be envisaged as producing the template, largely in the form of learning capacities, on which behaviour can develop and thus vary according to the multiple forms of information obtained during development. In particular, once the genetic template leading to social learning has evolved, the inherited social component of inclusive heritability that can be defined as animal culture may become significant and thus open to evolution. I will provide a taxonomy of biological information, then briefly review the evidence that organisms use non-intentional information in many fitness-affecting decisions and lastly analyse the implications for evolutionary biology. In doing so, I will introduce the concept of 'inclusive heritability' that encompasses any form of information that is transmitted across generations. Inclusive heritability thus quantifies the evolutionary potential of a population. In other words, it is the heredity of differences, the part of variation that is transmitted, whatever the transmission mechanism. One non-genetic component of inclusive heritability is animal culture, the part of inclusive heritability that is transmitted through social learning. I will also provide the first testable definition of culture to help study it. With cultural transmission, behaviour is at the origin of another system of information transmission across generations. I predict that cultural transmission is likely to become a new field in behavioural ecology.

Further reading

Danchin, E., Giraldeau, L.-A. and Wagner, R. H. 2008. An information driven approach to behaviour. In Behavioural Ecology, Danchin, E., Giraldeau, L.-A. and C´zilly, F. (eds), pp. 97-131. Oxford: Oxford University Press.

Danchin, E. and Wagner, R. H. 2008. Cultural evolution. In Behavioural Ecology, Danchin, E., Giraldeau, L.-A. and Cezilly, F. (eds), pp. 693-726. Oxford: Oxford University Press.