The evolution of ant communities in Madagascar

A main component of the lab's research program investigates and compares the phylogenetic structure of both canopy and leaf litter ant communities across different forest habitat types in Madagascar, in order to infer the environmental and biological processes responsible for these species assemblages. We are particularly interested in whether canopy and leaf litter ant communities differ in phylogenetic diversity, whether they show the imprint of different assembly mechanisms, and whether these patterns deviate between forest types. A first study, comparing a dry and a humid forest habitat, suggested for example that Malagasy ants first adapted to humid habitats and then consecutively to dry forest habitats. This research also showed that niche-related processes were responsible in structuring the humid forest communities, whereas competition may be more prevalent between ants of the dry forest communities. To continue this small-scale study, we are collaborating with Brian Fisher (California Academy of Sciences) on an NSF-funded project to conduct a broad investigation of the evolution of micro-endemism and species diversification of ants in Madagascar on an island-wide scale based on a phylogenomic data set, testing recent hypotheses for abiotic drivers of speciation in Madagascar and inferring the role of biotic factors in community assembly.

Typical rainforest canopy view in Madagascar in the early morning hours.

Phylogenomics of Hymenoptera using
ultraconserved elements

We are involved in several projects that focus on elucidating the evolution and diversification of ants, bees and wasps, including collaborations with the Smithsonian Institution, USDA and Cornell University.  For these phylogenomics projects we mainly use target-enrichment for ultraconserved elements (UCEs). UCEs are a class of markers that have proven to be highly useful for both higher-level and species-level studies. We used UCEs, for example, to reconstruct the evolutionary history of the ant subfamily Formicinae, and to investigate the biogeography of Acropyga ants and their association with trophobiotic, root-feeding mealybugs. In a proof-of-concept study, we have further shown that UCEs can be captured from historical, pinned museum specimens. While age was clearly negatively associated on UCEs locus capture and length, we were able to obtain reasonably good results from specimens up to 120 years old.

Biogeographic evolution of Acropyga ants.

Color pattern evolution in large carpenter bees (Xylocopa)

Large carpenter bees (genus Xylocopa) are a diverse, global clade exhibiting sexual dichromatism in a number of species, with males usually representing the less conspicuous sex (reversed sexual dichromatism). Xylocopa females (and some males) further often carry conspicuous aposematic coloration. Remarkable morphological features that confer a selective advantage to their bearer have often been linked to species diversification. We investigate the evolution of dichromatism and aposematism in Xylocopa, and the hypothesis of an association of these traits with the diversification of Xylocopa, based on a phylogeny of ultraconserved elements (UCEs).

Sexual dichromatism and aposematism in Xylocopa. Top row: females; bottom row: males.

Surveys of (canopy) ant and insect communities

We conduct field surveys for ants to assess species diversity and increase knowledge of species distributions. Our goal is to extend natural history collections by preserving specimens and tissues for subsequent morphological and genomic study. We are particularly interested in the canopy as an understudied habitat with little known insect diversity and use rope-climbing techniques to search and collect arboreal ants nesting in trees.

Past field expeditions have taken us all over Madagascar (including a fair amount of tree-climbing), and also to Myanmar, Mozambique and Uganda.

Tree climbing in Africa