Sprecher
Beschreibung
Out of the seed plants of the Mesozoic, the order Ginkgoales stands out due to a combination of several factors. Not only were they present from the beginning of Triassic until the K/Pg mass extinction, but their geographic range was also global with remains having been found on all continents (including Antarctica). Perhaps most importantly, however, a single species -Gingko biloba- has weathered the tides of extinction, enduring into the present and providing us with a unique opportunity to witness a fraction of the diversity that the order once had. Yet, this lone survivor creates additional challenges to our understanding of the evolution of the group. The morphological variability of the leaves of this single species is considerable, and often exceeds the variability used to distinguish between different extinct species.
In order to gain insight on how much of the diversity in the fossil record may be a result of intraspecific variability, we tried to quantify the variability present within the extant species to then compare it with what observed within single fossil localities and species. To achieve this, we measured the shape over 500 leaves from living Ginkgo trees from around the globe using topologic data analysis, TDA, a mathematical process that comprehensively quantifies the characteristics of the shape, making it possible to infer evolutionary/genetic distances between two individual specimen by there topologic similarity. This represents the first step to generate a large database of leaf shape including fossil Ginkgoales from across their temporal and spatial distribution.