Researchers: Dr. Thomas Lecocq
The meeting between mates is one of the most important steps for the reproduction. The individuals localize, recognize, and select their sexual partners through the courtship behavior that involves reproductive traits (e.g. feathers, mating call or chemical secretions). The reproductive traits have a key role in the pre-mating recognition and in the maintenance of reproductive isolation. The evolution of reproductive traits is shaped (i) by intraspecific interactions to maximize encounter rates among conspecific mates (sexual selection), and (ii) by interspecific interactions to maintain isolation barriers and decrease the likelihood of hybridization events among syntopic sister species, and to minimize eavesdropping by potential predators. Beyond these selective pressures, eco-climatic constraints can also affect the evolution of reproductive traits.
Geographic variation in reproductive traits has been observed in several species such as moths, flies, bees, and birds. The geographic variation could be driven by changes in intraspecific selection, interspecific interactions or local adaptation to eco-climatic constraints across the species area. However, the evolution of sexual recognition signals in geographic framework has received far less attention to date. Now, divergences in reproductive traits act as an important force in promoting pre-zygotic isolation and speciation. This places a premium to understand the processes that lead to this geographic variation.
Our research aims to investigate (i) processes and geographic configuration that lead to geographic differentiation of reproductive traits and (ii) consequences of this differentiation on speciation. We broach this topic through bumblebee species and one of their reproductive traits (the male marking secretions). We use (i) phylogenetic and phylogeographic approaches and (ii) environmental niche modelling methods along with (iii) comparative analyses of the differentiation patterns and natural variation of male marking secretions on specimens from populations across the species distribution.
Researchers: Dr. Thomas Lecocq, Nicolas Brasero, Maxence Gérard
The current bumblebee decline leads to inbreeding in populations that fosters a loss of allelic diversity and diploid male production. As diploid males are viable and their offspring is sterile, bumblebee populations can quickly fall in a vortex of extinction. We investigate for the first time a potential pre-mating mechanism through a major chemical reproductive trait (male cephalic labial gland secretion; CLGS) that could prevent monandrous virgin queens to mate with diploid males.
See also used of reproductive trait differentiation in taxonomy and in biological conservation
Divergences, diversity and variability in genetic and chemical reproductive traits of male (MMS) in B. lapidarius. A: Interpolation maps of genetic distance. B: Interpolation maps of nucleotide diversity. C: Interpolation maps of MMS distance. D: Interpolation maps of MMS variability.
Scenario of the recent history of B. lapidarius. Approximate location of European refugia and isolated East Turkish populations. The light grey area: range of East Turkish populations. The red area: approximate location of the South Italian refuge. The purple area: approximate location of the refuge of the Balkan region. The green area: approximate location of the refuge of Central-Eastern Europe. The orange area with question mark: the putative Iberian refuge. Arrows are postglacial movements after the Last Ice Age.
Chromatograms of three Bombus individuals and homologies between compounds.