Historical and phylogenetic constraints on the incidence of entire leaf margins: insights from a new South American model

Abstract

AimThe relationship between the proportion of species with an entire leaf margin (pE) and mean annual temperature (MAT) is one of the most powerful tools for estimating palaeotemperatures. However, phylogenetic and phytogeographic constraints on this relationship have remained unexplored. Here we investigate the pE-MAT relationship for modern floristic assemblages from southern South American forests, assess its conformity to other models and test for the existence of historical constraints on pE-MAT models. Location South America.Methods We used samples from 30 sites located in Chile between 32°and 44°S to test for a pE-MAT relationship and compared it with four regional models. We assessed the reliability of these models for predicting MAT from instrumental records in eight modern temperate-forest localities in Chile. Additionally, palaeotemperatures for Cenozoic fossil floras were estimated. To assess historical constraints in pE, we measured the phylogenetic signal in leaf margin type and the association between leaf margin and phytogeographic affiliation, defined by the distribution of genera. ResultsWe found a significant pE-MAT relationship for Chilean forest species that differed from Australia and Northern Hemisphere models, but not from tropical South America (TSA). Temperatures for southern South American localities predicted from the new regional model -combining Chilean and TSA datasetswere more accurate than those from previous models. We also showed that leaf margin type has a strong phylogenetic signal, which was further confirmed by the highly significant effect of phytogeographic element on leaf margin type. Main conclusionsDifferences between the Chilean and other regional models are explained by historical legacy, as Chilean leaf margin types are strongly affected by phylogenetic closeness and phytogeographic elements. We highlight that leaf margin analyses should be conducted within the context of a flora with a shared history. Thus, we propose a new model for South America to estimate palaeotemperatures for regional fossil floras.

Evidence for an Early-Middle Miocene age of the Navidad Formation (central Chile): Paleontological, paleoclimatic and tectonic implications

“…Towards the end of the Eocene, this Subtropical Gondwana Paleoflora of southern South America was replaced by Mixed Paleoflora, which in turn gave way to Subtropical Neogene Paleoflora indicating hot, humid conditions during the Early-Middle Miocene (Hinojosa andVillagrán, 1997, 2005). Maximum continental temperatures were reached between 17-15 Ma, as indicated by fossil leaves and pollen of Miocene deposits in Chile and Argentina (Hinojosa, 2005;Hinojosa et al, 2011). After the Middle Miocene Climatic Optimum, pollen records suggest a marked decrease in temperature attributed to glaciation in West Antarctica and the beginning of uplift in the Andes (Zachos et al, 2001).…”

“…Belonging to the Subtropical Neogene Flora ('Pololos paleoflora' in figure 3), this suggests mean temperatures of 21-24ºC and a mean annual rainfall of 44-91 cm. There was thus a gradual increase in temperature and aridification between 16-12 Ma, which can be attributed to accelerated uplift in the Andes that prevented the spill-over of humid air from the east Hinojosa et al, 2011). Finally, pollen with affinity to modern Araucaria angustifolia (Bertol) and Araucaria araucana (Koch) occur together in both the lower and upper units, but these species are presently separated by the Arid Diagonal.…”

Planície Aluvionar Do Rio Mogi-Guaçu, Sp, Brasil – As Relações Ambientais Entre O Ambiente Aquatico E a Análise Climática Baseada Em Assembléias De Folhas

“…A Eq. 5 é a mais precisa para o calculo da temperatura (Tabela 4, Figura 7), como também fora comprovado por outros autores (Hinojosa et al 2011;Fanton, 2013) que as aplicaram para florestas tropicais e austrais da América do Sul. Os conjuntos de amostras provenientes dos diques marginais de rio e associadas ao Cerrado na área estudada refletem melhor a temperatura quando utilizadas as equações baseadas no LMA.…”

Variation of leaf margin serration in Populus nigra of industrial dumps

“…Степень изрезанности края листа ископаемых растений широко используется для реконструкции континентальных палеотемператур (Wolfe, 1971;Dolph, 1979;Wolfe, 1993;Wilf, 1997;Royer, Wilf, 2006;Adams et al, 2008;Royer et al, 2009;Hinojosa et al, 2011;Royer et al, 2012).…”