Wissenschaftskolloquium

20.01.
The macroevolution of ant mandibles in a 3D morphology context
M. Sc. Julian Katzke, Karlsruhe Institute of Technology & Okinawa Institute of Science and Technology

Ants are a terrestrially dominant animal group, much of their success owing to the highly derived, eusocial, and ground-living workers that have evolved from solitary, winged ancestors. One of the most striking aspects of the diversity that underlies the worker phenotype is the extraordinary variety of mandibles, both in morphology and in ecological function. I will present results on patterns in macroevolution and t morphological diversification from a dataset based on X-ray tomography representing more than 600 mandible shapes. A common central phenotype, a “ground plan”, has been established in ant evolution and is retained across major extant clades. From this core phenotype, ant lineages repeatedly explore aberrant shapes in the peripheral regions of morphological space and increase overall disparity. This morphological expansion is primarily driven by predatory lineages. Another source of disparity lies within worker caste polymorphism, where the evolution of major workers allows shape exploration, presumably because they can be specialized while the colony maintains performance across all worker tasks. As ant mandibles are quantitatively distinct in shape compared to other Hymenoptera and extinct stem ant lineages, and ant mandible morphology is characterized by modified joints, I further outline a framework combining mandible form and motion to test the adaptive significance of the ground plan. This diversification of a potential key innovation underlies one of the great evolutionary success stories, with a general conservatism towards a ground plan superseded by functional demands enabled by division of labor or by weaponizing the mandibles for predatory use. In this, I further intend to give a macroscopic view of the use of large amounts of 3D – biodiversity phenomics – data highlighting what is in store for the Antscan database of soon over 3000 Synchrotron micro-CT scans of ants.

As usual, we will also broadcast via zoom for those who can not join in person: https://zoom.us/j/94510498226

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