TY - JOUR T1 - Resilience of plant-insect interactions in an oak lineage through Quaternary climate change JF - Paleobiology Y1 - 2015 A1 - Su, Tao A1 - Adams, Jonathan M. A1 - Wappler, Torsten A1 - Huang, Yong-Jiang A1 - Jacques, Frédéric M. B. A1 - Liu, Yu-Sheng A1 - Zhou, Zhe-Kun SP - 174 EP - 186 AB -

Plant-insect interactions are vital for structuring terrestrial ecosystems. It is still unclear how climate change in geological time might have shaped plant-insect interactions leading to modern ecosystems. We investigated the effect of Quaternary climate change on plant-insect interactions by observing insect herbivory on leaves of an evergreen sclerophyllous oak lineage (Quercus section Heterobalanus, HET) from a late Pliocene flora and eight living forests in southwestern China. Among the modern HET populations investigated, the damage diversity tends to be higher in warmer and wetter climates. Even though the climate of the fossil flora was warmer and wetter than modern sample sites, the damage diversity is lower in the fossil flora than in modern HET populations. Eleven out of 18 damage types in modern HET populations are observed in the fossil flora. All damage types in the fossil flora, except for one distinctive gall type, are found in modern HET populations. These results indicate that Quaternary climate change did not cause extensive extinction of insect herbivores in HET forests. The accumulation of a more diverse herbivore fauna over time supports the view of plant species as evolutionary “islands” for colonization and turnover of insect species.

VL - 41 ER - TY - JOUR T1 - A new positive relationship between pCO2 and stomatal frequency in Quercus guyavifolia (Fagaceae): a potential proxy for palaeo-CO2 levels JF - Annals of Botany Y1 - 2015 A1 - Hu, Jin-Jin A1 - Xing, Yao-Wu A1 - Turkington, Roy A1 - Jacques, Frédéric M. B. A1 - Su, Tao A1 - Huang, Yong-Jiang A1 - Zhou, Zhe-Kun SP - 777 EP - 788 AB -

Background and Aims The inverse relationship between atmospheric CO2 partial pressure (pCO2) and stomatal frequency in many species of plants has been widely used to estimate palaeoatmospheric CO2 (palaeo-CO2) levels; however, the results obtained have been quite variable. This study attempts to find a potential new proxy for palaeo-CO2 levels by analysing stomatal frequency in Quercus guyavifolia (Q. guajavifolia, Fagaceae), an extant dominant species of sclerophyllous forests in the Himalayas with abundant fossil relatives.Methods Stomatal frequency was analysed for extant samples of Q. guyavifolia collected from17 field sites at altitudes ranging between 2493 and 4497 m. Herbarium specimens collected between 1926 and 2011 were also examined. Correlations of pCO2–stomatal frequency were determined using samples from both sources, and these were then applied to Q. preguyavaefolia fossils in order to estimate palaeo-CO2 concentrations for two late-Pliocene floras in south-western China.Key Results In contrast to the negative correlations detected for most other species that have been studied, a positive correlation between pCO2 and stomatal frequency was determined in Q. guyavifolia sampled from both extant field collections and historical herbarium specimens. Palaeo-CO2 concentrations were estimated to be approx. 180–240 ppm in the late Pliocene, which is consistent with most other previous estimates.Conclusions A new positive relationship between pCO2 and stomatal frequency in Q. guyavifolia is presented, which can be applied to the fossils closely related to this species that are widely distributed in the late-Cenozoic strata in order to estimate palaeo-CO2 concentrations. The results show that it is valid to use a positive relationship to estimate palaeo-CO2 concentrations, and the study adds to the variety of stomatal density/index relationships that available for estimating pCO2. The physiological mechanisms underlying this positive response are unclear, however, and require further research.

VL - 115 ER -