Symbioses are intimate and durable associations between organisms of different species, among which are the commensal, mutualist and parasite type relationships. The laboratory is interested in the various adaptations shown by symbiotic organisms as well as in the mechanisms that ensure the transgenerational longevity of symbioses.


Phylogeny and coevolution


Living on or in another metazoan often leads to profound morphological, physiological and behavioral changes in symbiotic organisms. To study the adaptations developed by symbiotic organisms, we analyze the evolutionary history of model symbiocosms. The "crinoid-myzostomid" and "echinoderm-carapid fish" pairs are among our preferred models. Their evolutionary history is traced using modern phylogenetic inference methods based on morphological and molecular (DNA) data. These methods allow us to analyze the interactions that have existed between taxa associated for several million years and to determine what were their respective influences on parameters such as their morphology and their behavior.


Parasitism and disease

Diseases are alterations of the “health state” of an organism that can sometimes be induced by parasites. They can alter the morphology, physiology or behavior of hosts. The laboratory pays particular attention to the diseases developed by certain parasites. In this, we are interested in diseases that appear in emerging aquacultures such as Skin Ulceration Diseases of sea cucumbers, Bald Sea Urchin Diseases of Sea Urchins or Epiphytic Filamentous Diseases of Algae. The etiology of the diseases is analyzed and solutions are proposed to aquaculturists to limit their extension.

In the marine environment, symbiotic organisms have developed over time a set of sensory mechanisms that allow them to meet their hosts. Among the sensory signals, the chemical signals are probably the oldest and most ubiquitous. With respect to host-symbiotic interactions, chemical signals are generally called allelomones (chemical signals between heterospecific individuals). More particularly, the terms "kairomone" and "allomone" are used in the case of signals beneficial to the recipient and transmitter species, respectively. Although it has long been recognized that marine symbiotic organisms take advantage of allelomones to recognize their hosts, the molecular identification of these chemical signals has remained very sketchy. The laboratory is interested in the chemical signals emitted by echinoderms (sea urchins, sea stars, sea cucumbers, crinoids and brittle stars) involved in the installation and durability of symbiotic associations.

Olfactory recognition and chemical ecology