Sprecher
Beschreibung
During the Devonian, the two largest groups of euphyllophytes, the lignophytes and the ferns s.l., converged independently toward similar stele shapes (i.e., the architecture of primary vascular tissues). Throughout this period, stelar architecure in these groups evolved from ancestors with simple protosteles into a range of diversity that includes most of the stele types present in modern plants, as well as unique stele shapes not seen in modern tracheophytes. This early and broad diversification, the extant and extinct diversity of stelar architecture, as well as the architectural convergence observed across phylogenetically distant lineages, inspire questions about the potential selective advantage of different stele types. However, despite decades of research on this subject, the adaptive value of stele morphology is still debated. The two prevailing hypotheses propose either (1) that stele architecture is adaptive and has evolved under selection towards increased drought resistance, or (2) that stele shapes are non-adaptive byproducts - evolutionary spandrels - of developmental integration. We focus on the initial results of a project aimed at testing which of the two hypotheses best explains the evolution and diversity of stele shapes by developing a model capable of reproducing the entire range of stele diversity observed across vascular plants. In subsequent steps we plan to simulate the evolutionary trajectory of stele shape in the absence of selective pressures and under selection driven by drought resistance. The results of simulations will be compared against the diversity of Devonian stelar architectures and their distribution across known phylogenetic relationships of Devonian groups.