Assistant Professor in Biology / Maître de Conférences en Biologie
Université Pierre et Marie Curie
Laboratoire Écologie & Évolution UMR 7625
Équipe Évolution des Sociétés Animales
7, quai St Bernard
Bâtiment A, 7ème étage, Case 237
75252 PARIS CEDEX 05
Tel. +33 (0) 1 44 27 26 94 | Fax. +33 (0) 1
44 27 35 16
E-mail : mathieu.molet(+@)snv.jussieu.fr
The evolution of biodiversity relies on the production and selection of new phenotypes. I study these mechanisms in the context of animal societies, using ants as a model. Ants consist of 13000 species that occupy a variety of ecological niches throughout the world. One important reason for this success is their morphological caste system associated with efficient division of labour. Indeed, in addition to the two ancestral castes (winged queens and wingless workers), many ant species have evolved novel castes such as wingless queens and soldiers. Wingless queens are a response to selective pressures against long range dispersal and solitary colony foundation, while soldiers allow for better colony defense, food storage and/or foraging. The evolutionary and developmental processes that led to this diversity are poorly known. I study them with an integrative approach that focuses on morphological, physiological, behavioural and developmental variables. My model species are mostly from Madagascar (Cerapachys, Mystrium, Odontomachus) but also from Africa (Cataglyphis, Platythyrea) Australia (Rhytidoponera), Asia (Gesomyrmex) and Europe (Temnothorax).
Diversity of castes and life-cycles
The life cycle of ant colonies is mostly known from species with winged queens. Studying this in species with wingless queens reveals unexpected diversity. Wingless queens do not found colonies alone but with the help of nestmate workers (dependent colony foundation = fission). Accordingly they mate near their nest after attracting males using pheromones. We have found that, depending on species, colonies contain either one big queen with large ovaries specialized for egg-laying, or numerous small queens with relatively small ovaries that can either mate and lay eggs or function as helpers. This entails original division of labour, conflicts for reproduction, dynamics of colony emigration and genetic structures.
Small wingless queens (red) and workers (black) of Mystrium ‘red’.
© Alex Wild
Mechanisms for generating novelty
We compare novel castes (wingless queens and soldiers) to conspecific or congeneric winged queens and wingless workers in order to assess the evolutionary link between these phenotypes and test the hypothesis that novel castes are mosaics of ancestral castes. We use two approaches: morphometry (assessing growth rules and describing morphological modules) and evo-devo (assessing gene expression in imaginal wing discs of larvae).
Imaginal discs of Mystrium oberthueri wingless queen larva (DAPI).
© Mathieu Molet
Role of developmental anomalies in evolution
Ant colonies produce rare anomalies called intercastes that are morphologically very variable but look intermediate between winged queens and wingless workers. We study the morphology, behaviour and physiology of intercastes in order to assess the costs and benefits that they bring to colonies. We compare them to novel castes. We developed and evolutionary scenario that involves genetic accommodation and buffering properties of colonial life to connect these anomalies to regularly produced novel castes. We also explore the diversity of intercastes produced artificially following hormone applications.
(Top) Colony of Mystrium rogeri with a queen surrounded by workers and a few intercastes.
(Bottom) Magnification of an intercaste: notice the tiny wing buds.
© Sylvain Londe
Environmental pressures and evolution of colonial reproductive strategy
The replacement of winged queens by wingless queens or reproductive workers is tightly linked with selection against long-range dispersal by flight and independent colony foundation. We study why and how colonies alter their reproductive strategy in response to environmental changes.
Rhytidoponera ants adapt colonial reproduction to environmental gradients.
© Alex Wild
For general public / Vulgarisation en français :
Molet M. & Peeters C. 2010
Molet M. 2009
Assistan Professor in Biology, Laboratoire Ecologie & Evolution, Université Pierre et Marie Curie, Paris, France.
Post-Doctoral Research Assistant
Bee Sensory and Behavioural Ecology Laboratory, Queen Mary University, London, UK.
“Application of the Bumblebee foraging pheromone for commercial greenhouse pollination”, with Lars Chittka.
PhD in Ecology
Laboratoire Ecologie & Evolution, Université Pierre et Marie Curie, Paris, France
“From independent colony foundation to fission: evolution of colonial reproductive strategies in ants”, with Christian Peeters.
Licence and Master in Biology and Ecology
Ecole Normale Supérieure Ulm / Université Pierre et Marie Curie, Paris, France.
The anomalous ants database project
Equipe Evolution des Sociétés Animales
Laboratoire Ecologie & Evolution UMR 7625 (FR)
Université Pierre et Marie Curie (EN)
Bee Sensory and Behavioural Ecology Laboratory, Queen Mary University, London (EN)
2011-2013 Sylvain Londe
UNDEGRADUATE & GRADUATE Students
2006-2007 Isabelle Follin
2006-2007 Allan Debelle
2008-2009 Morgane Guérin
2008-2009 Ayano Kawamoto
2008-2009 Thibaut Viscard
2009-2010 Sébastien Guidici
2009-2010 Diane Bouchet
2009-2010 Delphine Vilaysack
2009-2010 Melkior Cotonnec
2009-2010 Messika Revel
2009-2010 Battle Karimi
2010-2011 Frédéric Fyon
2010-2011 James Chester
2011-2012 Julian Donald
2011-2012 Vincent Maicher
2011-2012 Hélène Albert
2011-2012 Pauline Pierret
2011-2012 Juliette Auvinet