The goal of our group is understand the principles governing the evolution of animal societies and the ecological and evolutionary consequences of social life. To study these questions we combine disciplines of animal behaviour, ecology, evolutionary genetics and genomics. Our current interests include:
Ageing in social insects
There is tremendous variation in life span between castes in ants, with queens living over 500 times longer than males and 50 times longer than sterile workers. The fact that individuals of these different castes share the same genome and exhibit such enormous variation in lifespan allows us to ask fundamental questions about the evolution of lifespan with respect to the expression of several groups of genes implicated in the ageing process. We investigate the mechanisms that underlie the deterioration of an individual's body as well as the control of these processes at the molecular level. This will allow us to gain further insight into the physiology of ageing as well as shed light on its evolution.
Experimental tests of kin selection
The development of kin selection theory has been one of the major breakthroughs in evolutionary biology. However, kin selection has rarely been tested experimentally although such tests would not only permit validation of the Hamiltonian hypothesis of indirect gene transmission but also provide evidence for Darwin's concept of evolution by natural selection as a whole. We have worked on sex allocation in ants of the genus Formica, showing kin-selected worker manipulation of the secondary sex ratio.
In collaboration with Prof. Dario Floreano at the EPFL we are investigating the role of relatedness (genetic similarity), levels of selection, and group size on the evolution of collective actions, communication and division of labour in artificial ant colonies. We are using colonies of artificial ants implemented as small mobile robots with simple vision and communication abilities. Selection experiments are done with the help of genetic algorithms.
Genetic, ecological and molecular bases for variation in social systems
The number of queens within a social insect colony is an important trait in social evolution. Queen number can be highly variable both between and within species, and we are interested in how and why transitions in social structure occur. In collaboration with Dr. Kenneth Ross (University of Georgia), we have identified a gene (Gp-9) influencing social behaviour in the fire ant Solenopsis invicta. We are currently quantifying the genetic variability of this gene as well as other closely linked genes using a genomic approach. We are also interested in the evolution and consequences of unicoloniality in the Argentine ant. This species has invaded the Mediterranean coast about 80 years ago and there is no aggression between workers from Spain, France and Italy.
Division of labour in insect societies
Division of labour in social insect societies underpins their ecological success. The allocation of workers to various tasks critically affects colony efficiency and fitness, but little is known about the underlying principles because it has been impossible to track large numbers of individuals continuously. We have developed a system based on fiducial identification labels and video tracking to follow all individuals in a colony for extended periods. We will use this to investigate thoroughly how environmental factors, social interactions and individual experiences affect the behavioural trajectories of workers. We will manipulate colonies of Camponotus fellah and track changes in task allocation and in the social network of the colony. We will also test the assumption that division of labour increases the efficiency of individuals when they perform specialised tasks.
Causes and consequences of genetic caste determination
Extraordinary cases of genetic determination of reproductive caste have been found in several ants, including harvester ants and fire ants. In these systems, two separate genetic groups must interbreed to produce workers, but produce new reproductive queens only from within-group matings. Using various molecular genetic markers, we are investigating the evolutionary origins of this phenomenon, which appears to be derived from past interspecific hybridisation events, as well as its consequences for the biology of the species.
The fire ant genome
In collaboration with other colleagues we are currently sequencing the fire ant genome. This will be an important step to address many questions related to social behaviour and aging.
Queen specialization in multiple-queen colonies of social insects
Colonies of social insects produce both sterile workers and fertile new queens and males. Many ant species present multiple-queen colonies. In these colonies, either each queen contributes equally to each caste or there may be a queen specialization. Our aim is to investigate the mechanisms underlying such a specialization in order to go deeper into the understanding of the organization and ecological success of multiple-queen species of social insects.