Microgeographic variation in early fitness traits of Pinus sylvestris from contrasting soils

Premise

The possibility of fine-scale intraspecific adaptive divergence under gene flow is established by theoretical models and has been confirmed empirically in tree populations distributed along steep altitudinal clines or across extreme edaphic discontinuities. However, the possibility of microgeographic adaptive divergence due to less severe but more frequent kinds of soil variation is unclear.

Methods

In this study, we looked for evidence of local adaptation to calcareous versus siliceous soil types in two nearby Mediterranean Pinus sylvestris populations connected via pollen flow. Using a greenhouse experiment, we tested for variation in early (up to three years of age) seedling performance among open-pollinated maternal families originating from each edaphic provenance when experimentally grown on both types of natural local substrate.

Results

Although seedlings were clearly affected by the edaphic environment, exhibiting lower and slower emergence as well as higher mortality on the calcareous than in the siliceous substrate, neither the performance on each substrate nor the plasticity among substrates varied significantly with seedling edaphic provenance.

Conclusions

We found no evidence of local adaptation to a non-extreme edaphic discontinuity over a small spatial scale, at least during early stages of seedling establishment. Future studies on microgeographic soil-driven adaptation should consider long-term experiments to minimize maternal effects and allow a potentially delayed expression of edaphic adaptive divergence.     

Polysaccharides of Calcareous Algae and Their Effect on the Calcification Process

The composition and structure of polysaccharides from several groups of calcareous algae (including calcareous cyanobacteria), which differ in the calcification mode (extracellular, cell wall, or intracellular), are reviewed. Two families of marine algae, Corallinaceae (Rhodophyta) and Coccolithophoraceae (Prymnesiophyta = Haptophyta), are considered in detail; they exhibit the cell wall and intracellular calcification modes, respectively, and synthesize unusual polysaccharides that seem to directly participate in the calcification process.     

Evolution of the coccolith genus Lotharingius during the Late Pliensbachian-Early Toarcian interval in Asturias (N Spain). Consequences of the Early Toarcian environmental perturbations

The evolution of the coccolith genus Lotharingius was investigated in 18 samples from the West Rodiles section (Asturias, Northern Spain), Upper Pliensbachian-Lower Toarcian in age. In each sample, the length and width of the coccolith and of its central area were measured on 150 specimens of Lotharingius. A total of 2700 specimens were measured, and 10,800 measurements were obtained. Based on the results of the morphometric analysis, the stratigraphic ranges, the abundance patterns and the light microscope observations, the aims of this work are to determine whether the specimens analysed correspond to different species, to distinct ecophenotypes or to an anagenetic lineage of morphotypes of a single species with overlapping stratigraphic ranges, and to test the influence of the paleoenvironmental perturbations during the Early Toarcian on the studied genus. Three species of Lotharingius were distinguished: L. hauffii, L. sigillatus and L. crucicentralis. Based on central area size and structure, two morphotypes (A and B) of L. hauffii were differentiated. All the parameters measured show a great overlap between the morphotypes and species. An increase in both coccolith and central area size and a development of more complex central area structures were observed through the studied section. L. hauffii is the smallest form, followed by L. sigillatus, and finally L. crucicentralis is the largest species and has the most complex central area structure. A clear decrease in size or “dwarfing” of the species was observed in the samples corresponding to the Early Toarcian environmental perturbations. L. crucicentralis was not identified in these samples. We hypothesize that the changes in size and abundance of the Lotharingius species could be related to the unfavourable palaeoenvironmental conditions for the biomineralization of their coccoliths.     

Changes in calcareous nannofossil assemblages during the Mid-Pleistocene Revolution

The distribution of calcareous nannofossils are quantitatively analysed in high-resolution deep-sea core samples from North Atlantic DSDP Site 607 and Eastern Mediterranean ODP Site 967, between marine oxygen isotope stage (MIS) 35 and 15, in order to observe the response of calcareous nannofossils to the Mid-Pleistocene Revolution (MPR). Nannofossil abundance patterns show major variations through MIS 25–22 and distinct higher amplitude changes from MIS 21 upward, sometime clearly correlatable to glacial–interglacial cycles. High amplitude, short-term, fluctuations of small placoliths and F. profunda characterize the interval through MIS 24 to 22/21, suggesting strong instability in nutricline dynamics and surface water productivity. Principal Component Analysis and Shannon–Weaver indices (diversity and dominance) highlight significant shifts, mainly related to variations in the characteristics of surface waters. In both sites a minimum in diversity is recorded at MIS 22/21, corresponding to a maximum in the dominance of Reticulofenestra spp. at Site 607 and of Pseudoemiliania lacunosa at Site 967. Above MIS 21 the increase in abundance of various taxa (C. leptoporus, Umbilicosphaera spp., Syracosphaera spp., Rhabdosphaera spp., Oolithotus spp.) and a general increase in diversity are related to a distinct trend toward more stable and oligotrophic surface waters in contrast to the higher productivity and less stratified surface waters of the Early Pleistocene.     

Calcareous nannofossil biostratigraphy (Upper Bajocian-Lower Bathonian) of the Ravin du Bès section (Bas Auran, Subalpine Basin, SE France): Evolutionary trends of Watznaueria barnesiae and new findings of “Rucinolithus” morphotypes

A biostratigraphic study based on calcareous nannofossils was performed on the Ravin du Bès section (Bas Auran area, SE France). Semi-quantitative estimates of total nannofossil and single species abundances showed that calcareous nannofloras are rare to common and their preservation is poor to moderate. The following biohorizons were identified and calibrated to ammonite biozonation: the first occurrence (FO) of Watznaueria aff. W. communis, the FO of Pseudoconus enigma; the FO of “Rucinolithus”; the last occurrence (LO) of Carinolithus magharensis; the FO of Stephanolithion speciosum octum and the FO of Watznaueria barnesiae. These results confirm that calcareous nannofossils are good biostratigraphic markers for the Bajocian/Bathonian boundary interval. Moreover, the occurrence of P. enigma allows a direct calibration between Tethyan and Boreal nannofossil events and biozones. Morphometric analyses were performed on the W. communis-W. barnesiae group in order to quantify changes between the two taxa. The intermediate form W. aff. W. communis has been identified; it comprises coccoliths very similar to W. communis, but with central area length ≤ 0.9 μm. This study allowed the detailed reconstruction of the evolutionary trends from W. communis to W. barnesiae: the intermediate taxon W. aff. W. communis appears abruptly in the latest Bajocian and persists after the FO of W. barnesiae in the earliest Bathonian. Our results support the model of punctuated equilibrium rather than a phyletic gradualism. The finding of “Rucinolithus” morphotypes, very similar to the Cretaceous taxa R. terebrodentarius and R. terebrodentarius youngii, is intriguing. They might represent nannoliths strongly affected by a recurrent “Lazarus effect” or be diagenetic artifacts or of bacterial bioprecipitation.     

OOCARDIUM STRATUM A RARE (?) DESMID (CHLOROPHYCEAE)1

The monotypic desmid, Oocardium stratum Nägeli is reported from calcareous stream. Because, of its unusual habitat, it is easily overlooked and is probably more common in occurrence than is reported.     

The role of complement in hydatid disease: In vitro studies

Kassis A. I. and Tanner C. E. 1976. The role of complement in hydatid disease: in vitro studies. International Journal for Parasitology6: 25–35. Fresh sera from normal humans, guinea pigs, sheep, cotton rats, B10.D2/n Sn mice or infected cotton rats lyse viable protoscoleces of Echinococcus granulosus and E. multilocularis in vitro. This protoscolecidal activity can be abolished by heating at 56°C, EDTA or incubating with cobra venom factor, suggesting that complement proteins participate in this lytic process. Crude unfiltered hydatid fluid, as well as complement-lysed dead protoscoleces, are anticomplementary in vitro and, as such, probably protect viable protoscoleces in vivo against the action of complement. This anticomplementary activity was found to be associated with the calcareous corpuscles. A hypothesis is presented which relates these in vitro findings to the development of the parasite in vivo. It is suggested that the use of formalin during surgery to kill the parasite should be replaced by fresh serum.     

Fertility changes in surface waters during the Aalenian (mid-Jurassic) of the Western Tethys as revealed by calcareous nannofossils and carbon-cycle perturbations

In Aalenian times, the South Iberian Palaeomargin was part of the westernmost Tethys Ocean. The Median Subbetic palaeogeographic domain of the Betic Cordillera was a relatively deep trough in the South Iberian Palaeomargin during the Early Jurassic–Late Cretaceous interval, where mainly pelagic and hemipelagic limestones and marls were deposited. A semiquantitative study of nannofossil assemblages was performed in sediments from the upper Toarcian–lowest Bajocian from two Median Subbetic sections (Agua Larga and Cerro de Mahoma). Nannofossil assemblages are composed mainly of cosmopolitan and Tethyan taxa. The NJ8a, NJ8b and NJ9 Zones as well as other useful biohorizons (FOs of Triscutum tiziense and Carinolithus magharensis and LO of Similiscutum finchii) were identified and directly correlated to ammonite zones. The analysis of the relative abundances of some common to abundant taxa including Biscutum, Carinolithus superbus, Crepidolithus crassus, Lotharingius, Schizosphaerella and Watznaueria display noticeable fluctuations that can be correlated between the two sections. The comparison of these fluctuations with the δ¹³C_carb curves and the interpretation of the palaeoecologic significance of some of these taxa provided an outline of the palaeoceanographic trophic regime throughout the interval studied. During the latest Toarcian–Early Aalenian, the high proportions of oligotrophic Schizosphaerella, moderately high proportions of C. crassus and low proportions of eutrophic Biscutum, correlate with low to moderate values in the δ¹³C_carb curves. Radiolarians display low abundance throughout this interval. This is interpreted as an interval where mesotrophic to oligotrophic and stable conditions occurred in surface waters. The Middle Aalenian, characterized by high proportions of Schizosphaerella and C. crassus and low proportions of Biscutum, correlates with low values in the δ¹³C_carb curves, and was interpreted to correspond to an episode when stable oligotrophic conditions occurred in surface waters. Radiolarians moderately increased throughout this interval. Finally, the Late Aalenian–earliest Bajocian interval, with lower proportions of Schizosphaerella and C. crassus, and higher proportions of Biscutum, also correlates with a significant positive excursion in the δ¹³C_carb curve, suggesting a shift from oligo- to eutrophic conditions in surface waters. This change in productivity is also revealed by a conspicuous increase in radiolarian abundance, at the same time as a quasi-complete replacement of Early Jurassic radiolarian fauna took place. The analysis of faunal-flora turnovers reveals a causal link between the global carbon-cycle and the pelagic response. This noticeable faunal-flora change throughout the Late Aalenian–Bajocian can be interpreted as a major biological response to the drastic modification in the western Tethys palaeogeography as consequence of the Atlantic opening, which in turn caused a new pattern in the oceanic circulation.