No abstract

The specific heat of toluene in glass and crystal states, has been measured both at low temperatures down to 1.8 K (using the thermal relaxation method) and in a wide temperature range up to the liquid state (using a quasiadiabatic continuous method). Our measurements therefore extend earlier published data to much lower temperatures, thereby allowing to explore the low-temperature "glassy anomalies" in the case of toluene. Surprisingly, no indication of the existence of tunneling states is found, at least within the temperature range studied. At moderate temperatures, our data either for the glass or for the crystal show good agreement with those found in the literature. Also, we have been able to prepare bulk samples of toluene glass by only doping with 2% mol ethanol instead of with higher impurity doses used by other authors.

Grotta Mora Cavorso (Jenne, Latium), a complex karstic system in Central Italy, has returned one of the most precious Prehistoric palaeontological and anthropological heritage. Through the analysis of pollen spectra and charcoals from cave stratigraphic levels (Late Pleistocene final phases—Holocene), the overall vegetation trend of the site was pointed out. Although taphonomy and palynology of cave deposits are complex, pollen assemblage represents a reliable source for inferring past vegetation; indeed, climatic, environmental, and cultural interactions determine fossil pollen record. Site formation processes and postdepositional bias should be generally considered in the analysis of stratigraphic sequences used to define paleoenvironmental conditions. The sediment deposits from Grotta Mora Cavorso showed a vegetation pattern point in out a progressive increase in woody plants from lower levels upward. Palynological investigations highlighted a changing environment predominantly characterized by cooler and perhaps more humid conditions than today, with plant subalpine and marsh communities nearby the cave. The ecological requirements of the identified plant taxa supplied useful indications to reconstruct ancient and modern environments of the Simbruini Mounts and the Upper Aniene River valley. This scenario, in accordance with previous faunistic and carpological findings and palynological analyses from Latium, provided a further perspective on the vegetation history, biodiversity, and climate of an important crossroads between the Adriatic and the Tyrrhenian coasts.

Several species of the Gypsophila genus are endemic to the Iberian Peninsula, including gypsophytes of particular ecological, evolutionary and biochemical interest, and taxa that have undergone both sympatric and allopatric genetic differentiation. The niche shift among these taxa has been assessed using ecological niche modelling and ordination techniques, adopting a niche overlap approach to compare the similarity and equivalency of the ecological niches. We used the Maximum Entropy method to study the potential distribution of these taxa in different eras: the Last Glacial Maximum (LGM), the Mid Holocene and the current conditions. We present evidence of niche shift during the speciation of G. bermejoi, with a strong niche overlap between the parental taxa (G. struthium subsp. struthium and G. tomentosa), yet both overlap much more weakly with the hybrid species. This phenomenon may be explained by genetic and epigenetic interactions, and it has been described in other species. We also studied the sister subspecies G. struthium subsp. struthium and G. struthium subsp. hispanica, with mostly allopatric distributions and with the Iberian System mountain range acting as a geographical barrier. The Iberian System and other mountain ranges may have favored differences in the climatic conditions on either side of the mountain range, which is consistent with an incipient process of bioclimatic ecological speciation. These results seem to indicate that niche shift can occur over very different timespans. In the case of G. bermejoi, speciation may have produced significant niche shifting in one or two generations due to its alloploid nature. By contrast, G. struthium subsp. struthium and G. struthium subsp. hispanica seem to have undergone a more gradual process of allopatric genetic differentiation driven by bioclimatic factors. Both these processes are relatively recent and they will have been strongly influenced by the climate change at the end of LGM.