Origine, Structure et Evolution de la Biodiversité
UMR 7205 MNHN/CNRS
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LEGENDRE Frédéric
Associate Professor - Muséum national d’Histoire naturelle - Equipe Phylevo
Département Systématique et Evolution - CP50
45 rue Buffon 75005 Paris, France
Tel : (+33) 1 4079 8126
Fax : (+33) 1 4079 5679
Email : legendre@mnhn.fr
My research deals with the evolution of behavior in insects. I reconstruct phylogenies before using them as a historical reference to test evolutionary hypotheses. Following this phylogenetic approach, I mainly investigate the evolution of social behavior in termites and cockroaches (Insecta : Dictyoptera).
I am also the curator of Isoptera (termites), Embioptera, Ephemeroptera, Plecoptera, Psocoptera, Trichoptera and Zoraptera in Paris Museum
RESEARCH INTERESTS
Given its paradoxical dimension with regard to natural selection, social behavior has long been of central interest in biology. Indeed, in the “Origin of species”, Darwin already mentioned how sterile castes of insect societies were a “special difficulty, which at first appeared to [him] insuperable”.
Living in a group brings diverse advantages and constraints to individuals. If advantages exceed drawbacks, natural selection can readily explain group living origin. Few exaggerated forms of social behavior like altruism, however, seem hardly interpretable in the only light of natural selection. Thus, social behavior evolution still remains a tremendous challenge, which is taken up using different approaches : ethology, population genetics, phylogeny, genomics…
My work aims at studying the evolution of social behavior in a phylogenetic framework.
1. Social evolution and evolutionary trends
Social behavior evolution has always been seen as a progressive, irreversible and complexity-increasing path, with eusociality as the ultimate step. Even though some exceptions to this linear trend have been shown, ‘laws’ of specialization and of irreversibility are still closely tied to the evolution of social behavior.
Classification of social categories illustrates these evolutionary trends, each category being a more complex step than the previous one. Complexity increase with the acquisition of one or several key features, which would make individuals better adapted to their environment and thus would be selectively advantageous.
These evolutionary trends can be tested in a phylogenetic framework : Comparing expected patterns under a null hypothesis (e.g., evolution is linear) with the observed patterns enable us to evaluate how adequate to social evolution of our model organisms this hypothesis is.
2. Evolutionary forces and modalities of social evolution
In social behavior classification, a switch from one category to another is associated with the acquisition of at least one key feature. The acquisition of such key features has been explained mostly in a functional context. In other words, key features are seen as adaptations.
This scenario overemphasizes the importance of ecological pressures in social behavior evolution to the detriment of other pressures. Yet, alternatives and complements to natural selection (e.g., phylogenetic inertia) may play a significant role in social evolution.
Phylogenetic analyses and behavioral observations can help to highlight the relative importance of these different forces.
3. Phylogenetic analysis of behavior
Studying the evolution of behavior in a phylogenetic framework requires the availability of phylogenetic hypotheses. Consequently, the first step of most of my research projects is to build a phylogenetic hypothesis using molecules and/or morphology. Non-traditional characters like behavioral ones are also integrated in phylogenetic matrices. Such process allows a better definition of behaviors observed and also a more thorough investigation of social behavior evolution hypotheses. But it might also require adapting or developing methodology to reach an adequate phylogenetic framework.
Therefore, building new tools for the phylogenetic analysis of behavior is part of my research projects.
PUBLICATIONS
Legendre, F., Marting, P.R. and Cocroft, R.B. (2012) Competitive masking of vibrational signals during mate searching in a treehopper. Animal Behaviour 83 : 361-368
Grandcolas, P., Nattier, R., Legendre, F. and Pellens, R. (2011) Mapping extrinsic traits such as extinction risks or modelled bioclimatic niches on phylogenies : does it make sense at all ? Cladistics 27 : 181-185
Legendre, F., Robillard, T., Song, H., Whiting, M. F. and Desutter-Grandcolas (2010). One hundred years of instability in Ensiferan relationships. Systematic Entomology 35 : 475-488
Legendre, F., Robillard, T., Desutter-Grandcolas, L., Whiting, M.F. and Grandcolas, P. (2008). Phylogenetic analysis of non-stereotyped behavioral sequences with a successive event-pairing method. Biological Journal of the Linnean Society 94 : 853-867
Legendre, F. (2008). Cockroaches : Ecology, Behavior, and Natural History (by Bell, W. J., Roth, L. M. et Nalepa, C. A.) Book Review. The Quarterly Review of Biology 83 : 222
Legendre, F., Whiting, M. F., Bordereau, C., Cancello, E. M., Evans, T. and Grandcolas, P. (2008). The phylogeny of termites (Dictyoptera : Isoptera) based on mitochondrial and nuclear genes : implications for the evolution of the worker and pseudergate castes, and foraging behaviors. Molecular Phylogenetics and Evolution 48 : 615-627
Legendre, F., Pellens, R. and Grandcolas, P. (2008). A comparison of behavioral interactions in solitary and presocial Zetoborinae cockroaches (Blattaria, Blaberidae). Journal of Insect Behavior 21 : 351-365
Desutter-Grandcolas, L., Legendre, F., Grandcolas, P., Robillard, T. and Murienne, J. (2007). Distinguishing between convergence and parallelism is central to comparative biology : a reply to Williams and Ebach. Cladistics 23 : 90-94
Pellens, R., D’Haese, C. A., Bellés, X., Piulachs, M-D., Legendre, F., Wheeler, W. and Grandcolas, P. (2007). The evolutionary transition from subsocial to eusocial behavior in Dictyoptera : phylogenetic evidence for modification of the "shift-in-dependent-care" hypothesis with a new subsocial cockroach. Molecular Phylogenetics and Evolution 43 : 616-626
Pellens, R., Legendre, F. and Grandcolas, P. (2007). Phylogenetic analysis of social behavior evolution in [Zetoborinae + Blaberinae + Gyninae + Diplopterinae] cockroaches : an update with the study of endemic radiations from the Atlantic forest. Studies in Neotropical Fauna 42 : 25-31
Robillard, T., Legendre, F., Desutter-Grandcolas, L. and Grandcolas, P. (2006). Phylogenetic analysis and alignment of behavioral sequences by direct optimization. Cladistics 22 : 602-633
Desutter-Grandcolas, L., Legendre, F., Grandcolas, P., Robillard, T. and Murienne, J. (2005). Convergence and parallelism : is a new life ahead of old concepts ? Cladistics 21:51-61
Murienne, J., Grandcolas, P., Piulachs, M. D., Bellés, X., D’Haese, C., Legendre, F., Pellens, R. and Guilbert, E. (2005). Evolution on a shaky piece of Gondwana : is local endemism recent in New Caledonia ? Cladistics 21 : 2-7
Grandcolas, P., Legendre, F., Park, Y. C., Bellés, X., Murienne, J. and Pellens, R. The genus Cryptocercus in East Asia : distribution and new species (Insecta, Dictyoptera, Blattaria, Polyphagidae). Zoosystema 27 : 725-732
Grandcolas, P., Guilbert, E., Robillard, T., D’Haese, C. A., Murienne, J. and Legendre, F. (2004). Mapping characters on a tree with or without the outgroups. Cladistics 20 : 579-582
TEACHING & STUDENTS
Graduate students
- Sandra Goutte (September 2010 - ) : Adaptations to noisy torrent environments in frogs : combining morphological, eco-ethological and phylogenetic approaches - co-direction with Alain Dubois (HDR)
Regular classes :
- Phylogenetic analysis of behavioral sequences (Doctoral school of MNHN)
- Information sources in phylogenetics : behavioral data (Master of UPMC - Paris VI)
- Phylogenetic tests of evolutionary hypotheses (Master of UPMC - Paris VI)
- Probabilistic phylogenetic inference (Master of UPMC - Paris VI)
- Phylogenetic reconstruction : why and how ? (Formation of High School teachers)
Ponctual interventions :
- Non-traditional characters in phylogenetics (Doctoral school of MNHN)
- Classification of living things (Guest lecture in Paul Eluard Middle School, Montreuil)
FIELDTRIPS
New-Caledonia 2010. Rapid Assessment Program (Conservation International) on Mount Panié. In charge of Orthopteroïd Insects.
Indonesia 2010. Study of cockroach communities with emphasis on Perisphaerus sp. (Blaberidae : Perisphaeriinae).
Singapore 2009. Collecting cockroaches with a special emphasis on the subsocial species Perisphaerus flexicollis (Blaberidae : Perisphaeriinae).
Perisphaerus flexicollis exhibits subsocial behaviours like nymph-guarding by females. Also, first instar nymphs probably feed upon nourishment produced by the mother.
United States 2008. Field observations and collecting of Tylopelta gibbera (Hemiptera : Membracidae) in Missouri.
Like other treehoppers studied so far, Tylopelta americana communicates through vibrations transmitted via its host plant (Desmodium sp.)
I investigated male localisation behaviour of a mating partner and male-male competition in such behaviour.
French Guyana 2006. Study of cockroach communities on Kaw Mountain.
Thanatophyllum akinetum is a solitary Zetoborinae living in the litter, whereas Paradicta rotunda is a gregarious Blaberinae living in treeholes.
