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Communication Dans Un Congrès Année : 2017

Disentangling phylogenetic from climatic signal in Cinnamomum leaf traits : implications in paleoclimatic studies

Résumé

The relationship between leaf physiognomy and climate has been studied for more than a century. Various methods have been developed by paleobotanists to use leaf physiognomy as a terrestrial paleoclimatic proxy. In the physiognomic taxon-free approach, climate reconstruction methods are based on the underlying assumption of an adaptive convergence of leaf traits in all plant families, under the same climatic constraints. In the past decades, several studies have enlightened the relative importance of phylogenetic signal in the distribution of leaf traits. Therefore, further work is needed to assess the impact of evolutionary history on leaf traits distributions. We started our investigations using a taxon-based approach on the genus Cinnamomum Schaeff. (Lauraceae). Fossil leaves of Cinnamomum are quite abundant in the Cenozoic fossil record of Europe. However, studies on its fossil and extant variability towards phylogeny and climate through geologic times are scarce. Thus the aims of this study are (1) to evaluate the potential phylogenetic signal (PS) in leaf traits in extant Cinnamomum, (2) to measure PS impact on physiognomy-climate relationship and (3) to assess if there are any trait convergences due to climate. Quantitave and qualitative leaf traits of 30 species were extracted using worldwide-distributed herbarium specimens and traditional morphometrics. The sampling included 260 specimens distributed in 30 species, with one leaf considered per specimen. In order to test the phylogenetic signal, we calculated Blomberg’s K for each trait. Preliminary analyses show that most of the variability observed in Cinnamomum leaf physiognomy does not seem to be highly influenced by the phylogeny of the genus. Indeed, we observed low K values, indicating that the leaf physiognomy of Cinnamomum might comprise convergent traits linked to environmental variables. However, further work is needed on additional characters, especially on the apex and the venation pattern. Statistical analyses of the variability of Cinnamomum towards climate should allow us to verify this hypothesis (work in progress). Finally, the analysis of fossil specimens in order to derive paleoclimatic variables should testify the usefulness of isolated fossil leaves of Cinnamomum in paleoclimatic reconstruction.
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Dates et versions

hal-03618426 , version 1 (24-03-2022)

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  • HAL Id : hal-03618426 , version 1

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Mélanie Tanrattana, Dario De Franceschi, Anais A Boura. Disentangling phylogenetic from climatic signal in Cinnamomum leaf traits : implications in paleoclimatic studies. Congrès Agora Paleobotanica, Jul 2017, Montpellier, France. ⟨hal-03618426⟩
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