Grants and current projects

2017: Heisenberg Program: DFG Grants BR 2930/3-1 and BR 2930/5-1

The phasmatodean tree of life: resolving evolutionary patterns of diversity and disparity in a mesodiverse insect lineage

Stick and leaf insects, or Phasmatodea, are a mesodiverse lineage of large terrestrial herbivores that exhibit extreme forms of masquerade crypsis, imitating twigs and leaves to deceive visually hunting predators. Phasmatodea comprises ~3000 extant species and stands out as one of the last remaining insect orders for which a robust higher-level phylogenetic hypothesis is lacking, and we have only rudimentary understanding of the basal phylogeny for these insects. Yet, phasmatodeans serve as a model system to address important questions in evolutionary biology, such as speciation, evolution of asexuality, loss and regain of morphological traits, and clade diversification or, more precisely, repeated adaptive radiations in geographic isolation. New research suggests that the extant diversity is the result of a surprisingly recent rapid radiation and that geographical distribution rather than traditional taxonomic grouping and morphological similarity reflects the evolutionary relationships among stick and leaf insects. An extensive temporally calibrated phylogenetic analysis based on a combination of transcriptomic and Sanger sequence data selected for maximum phylogenetic coverage from >600 taxa (~20% of the known species diversity) is supposed to reliably resolve the relationships among stick and leaf insects. The obtained tree will provide an evolutionary framework for (i) tracing the global historical biogeography of phasmatodeans, (ii) assessing rates of speciation and extinction, and (iii) reconstructing ancestral character states and transformations of crucial traits that have an effect on diversification rates. These traits comprise flight capability and the presence of associated structures, such as ocelli and wind-sensitive hairs, body size and form, and the capacity for asexual reproduction. A plethora of mostly undescribed fossil specimens will be incorporated in the study, serving as calibration points for the phylogeny and also allowing comparison of quantitative morphometric and discrete anatomical traits between extinct and extant forms. The project is designed to significantly advance our understanding of adaptive clade diversification across space and time in this largely neglected group of insects.

2016: NSF (Nation Science Foundation) grant with Prof. Dr. Michael F. Whiting and Dr. James A. Robertson (Brigham Young University, Utah, USA) Award #1557114

Investigating a cross-kingdom convergence: The phylogeny of stick insects and the evolution of masquerade crypsis (Insecta: Phasmatodea)

Stick and leaf insects are large, tropical herbivores with an incredible ability to mimic twigs, bark, and leaves. Despite being important players in tropical ecosystems, stick insect diversity and evolution is the least understood of any large insect group. Many stick insects rely on ants to help disperse their eggs, but little is known about how this complex interaction evolved. The project will result in a greater understanding of stick insect evolution and the first, comprehensive understanding of species diversity. Because stick insects are common and diverse in the tropics, this research will provide critical baseline data for ongoing tropical conservation efforts. Four undergraduate students will gain training in all aspects of the scientific process using stick insects as a focal group. An interactive museum exhibit targeted to K-12 students will present the evolution of stick insect camouflage, ant associations, and the role these insects play in the natural world. The exhibit will also focus on conservation issues in the tropics, using the Lord Howe Stick Insect as an example of species rescue and recovery.

The project will reconstruct a robust phylogeny for stick insects based on DNA sequence data, document the parallel evolution of the different stick insect body types, investigate shifts from crypsis to aposematism, and determine whether these shifts are correlated with other life history traits and species radiations. The project will decipher the evolution of stick insect oviposition techniques, determine how many times egg dispersal via ants has evolved, investigate correlates of adult dispersal ability and reliance on ant-mediated egg dispersal, and study the temporal and geographic overlap of particular plant and phasmid species. It will also provide the baseline data to understand a fascinating cross-kingdom convergence on reliance on ant-mediated egg dispersal in both stick insects and angiosperms. This project will provide the scaffolding for future taxonomic work, revisionary systematics, and studies into the evolution of their unique forms.

DFG Grant BR 2930/2-1

Biodiversity and evolution of Malagasy stick insects: Ancient lineages or recent adaptive radiation? - BR 2930/2-1

Madagascar is one of our planet's leading biodiversity hotspots exhibiting an extraordinarily distinct and diverse, but also severely endangered biota. Many elements of its fauna are poorly documented and remain largely unexplored. For example, the evolutionary history of the Malagasy stick insects (order Phasmatodea) is entirely obscure. Stick insects are large terrestrial arthropods with limited dispersal abilities, forming at least four distinct taxonomic groups on Madagascar, i.e., endemic families and subfamilies with completely unresolved phylogenetic affinities in respect to continental lineages. An extensive multigene phylogenetic analysis and molecular clock approach is supposed to infer whether (i) the Malagasy phas-matodean fauna can be explained by vicariance biogeography (forming relics of the Gond-wana fragmentation), (ii) if it is the product of a single post-Gondwanan colonization, or (iii) the result of multiple recent oceanic dispersal events. This project is also designed to investi-gate the adaptive clade diversifications and microendemism of phasmatodeans on Mada-gascar. By using Bayesian reconstruction methods in combination with quantitative mor-phometric and discrete anatomical characters the project is aimed to significantly advance our understanding of the phylogeography and evolution of distinct ecomorphs of stick insects on islands, e.g., ground-dwellers and canopy-dwellers, flying and flightless forms.