The Impact of Global Warming and Anoxia on Marine Benthic Community Dynamics: an Example from the Toarcian (Early Jurassic)

The Pliensbachian-Toarcian (Early Jurassic) fossil record is an archive of natural data of benthic community response to global warming and marine long-term hypoxia and anoxia. In the early Toarcian mean temperatures increased by the same order of magnitude as that predicted for the near future; laminated, organic-rich, black shales were deposited in many shallow water epicontinental basins; and a biotic crisis occurred in the marine realm, with the extinction of approximately 5% of families and 26% of genera. High-resolution quantitative abundance data of benthic invertebrates were collected from the Cleveland Basin (North Yorkshire, UK), and analysed with multivariate statistical methods to detect how the fauna responded to environmental changes during the early Toarcian. Twelve biofacies were identified. Their changes through time closely resemble the pattern of faunal degradation and recovery observed in modern habitats affected by anoxia. All four successional stages of community structure recorded in modern studies are recognised in the fossil data (i.e. Stage III: climax; II: transitional; I: pioneer; 0: highly disturbed). Two main faunal turnover events occurred: (i) at the onset of anoxia, with the extinction of most benthic species and the survival of a few adapted to thrive in low-oxygen conditions (Stages I to 0) and (ii) in the recovery, when newly evolved species colonized the re-oxygenated soft sediments and the path of recovery did not retrace of pattern of ecological degradation (Stages I to II). The ordination of samples coupled with sedimentological and palaeotemperature proxy data indicate that the onset of anoxia and the extinction horizon coincide with both a rise in temperature and sea level. Our study of how faunal associations co-vary with long and short term sea level and temperature changes has implications for predicting the long-term effects of “dead zones” in modern oceans

THE CULTIVATION OF THE \u201cBIANCHETTO\u201d TRUFFLE: TUBER BORCHII

Tuber borchii Vittad. is an edible truffle with excellent culinary qualities which is eaten either fresh such as in truffled cheese or in cooked dishes such as in sauces or with pasta. Its common name is bianchetto (whitish truffle) to distinguish it from the more expensive Italian white truffle (Tuber magnatum Pico). T. borchii has an high ecological adaptability. Although it is commonly found in littoral calcareous sandy soils with pH 7 to 8 it can also be found in soils with a wide range of textures as well as in sub-acidic soils with pH 6 to 7. It forms ectomycorrhizae with broad leaf trees (oaks, hazel, poplar and linden) and coniferous species as pines and cedar. Its broad ecological requirements mean that T. borchii can be cultivated in areas that are not suited for other highly valued species of truffle such as Tuber magnatum and Tuber melanosporum (the black truffle). T. borchii infected plants can be easily produced using spores but the ease with which it can be pure cultured mean that mycelial inoculation techniques can also be used. These latter techniques were used to perfect an in vitro mycorrhizal synthesis system which has become a model for the study of Ascomycete ectomycorrhizal fungi. In the last ten years T. borchii cultivation has become popular in Italy and it has been successfully introduced to other countries such as New Zealand. The first production occurs 3-6 years after planting and it seems to be advantaged by careful cultural practices including gradual thinning and regular pruning

POPULATION STRUCTURE ANALYSES OF TUBER BORCHII: THE ITALIAN BIANCHETTO TRUFFLE

Objectives: Tuber borchii (Ascomycota, order Pezizales) is an excellent truffle with a significant local market in Italy. Despite the great use of this truffle in scientific experiments, knowledge on its intraspecific variability is scarce. The objective of this work was to investigate the evolutionary forces shaping genetic variability in this ascomycetes with a classical phylogenetic approach and a stochastic models (Kingman, 2000) to study the gene flow, migration and mutation rate. Material and Methods : To handle these goals, analyses were carried out using 61 samples from 11 different Provinces of Italy trying to have, as far as possible, an heterogeneity in growing conditions, habitats and hosts. Samples were identified considering anatomo-morphological characters (Zambonelli et al,. 2000). On the other side, DNA was extracted and four loci markers (ITS, IGS, β-tubulin and PKC) were screened to look for polymorphisms. Phylogenetic analyses of the sequence data were performed with maximum parsimony and maximum likelihood with PAUP (Swofford, 2003) and data were combined with MrBAYES software (Huelsenbeck and Ronquist, 2001) to have more realistic information. Approximation of the evolutionary history of populations was facilitated by use of the SNAP Workbench (Price and Carbone, 2005). Results : Genetic data showed the presence of two different haplotypes named 1 and 2, which were difficultly resolved by morphological analyses. The haplotypes are descended from a common ancestral population at some time in the past and have since diverged with a very low level of gene flow with a weak asymmetrical migration from haplotype 1 to haplotype 2. Moreover the oldest mutations are found in the haplotype 2. Conclusion : These results may allow us to formulate an early hypothesis on the natural processes of evolution of Italian T. borchii populations, in fact the two major phylogenetic groups observed may represent a species partition where haplotype 1 and 2, could be in the beginning of a speciation event or represent cryptic species