Alternative mating tactics in the alpine newt Triturus alpestris alpestris

Sexual behaviors in dyadic encounters in the alpine newt, Triturus alpestris alpestris, is described to test whether male behavior is influenced by external cues, that is, female responsiveness. Depending on this factor, a male exhibits one of the two following tactics during the sperm transfer phase. The male either waits for a positive response from the female before initiating sperm transfer ("waiting" tactic), or creeps and deposits a spermatophore in front of a nonresponsive female ("luring" tactic). The sperm transfer success rates of these tactics are 31% and 6%, respectively,and encounter success rates, 64% and 8%, respectively. The success of the second tactic is linked to behaviors that lure the female, notably quiver and distal lure. The same individual can exhibit both tactics, and neither body size nor condition appears to influence the tactic a male exhibits. These tactics can be interpreted as the result of a conditional strategy, that is, a strategy that allows an individual to incorporate information about its ability to obtain fitness through alternative tactics and then express the tactic that maximizes its fitness. More particularly, these tactics are examples of a side-payment strategy, that is, a strategy that allows individuals to achieve small gains by capitalizing on passing opportunities

Enluminures médiévales. Chef-d'oeuvre de la Bibliothèque nationale de France et de la British Library, 700-1200.

Traduction de l’anglais pour l’édition française du catalogue publié pour l’achèvement du projet Polonsky : France et Angleterre : Manuscrits médiévaux entre 700 et 1200 (BnF, British Library)

Data from: Facultative paedomorphosis as a mechanism promoting intraspecific niche differentiation

Organisms with complex life cycles are characterized by a metamorphosis that allows for a major habitat shift and the exploitation of alternative resources. However, metamorphosis can be bypassed in some species through a process called paedomorphosis, resulting in the retention of larval traits at the adult stage and is considered important at both micro- and macroevolutionary scales. In facultatively paedomorphic populations of newts, some individuals retain gills and a fully aquatic life at the adult stage (paedomorphs), while others undergo complete metamorphosis (metamorphs), allowing for a terrestrial life-stage. Because facultative paedomorphosis affects trophic structures and feeding mechanism of newts, one hypothesis is that it may be maintained as a trophic polymorphism, with the advantage to lessen intraspecific competition during the shared aquatic life-stage. Here, we tested this hypothesis combining stomach content data with stable isotope techniques, using carbon and nitrogen stable isotopes, in facultatively paedomorphic alpine newts (Ichthyosaura alpestris). Both stomach content and stable isotope analyses showed that paedomorphs had smaller trophic niches and were more reliant on pelagic resources, while metamorphs relied more on littoral resources, corresponding to a polyphenism along the littoral-pelagic axis and the extension of the population’s trophic niche to otherwise ‘underused’ pelagic resources by paedomorphs. Interestingly, stable isotopes revealed that the trophic polyphenism was less marked in males than in females and potentially linked to sexual activity. Although paedomorphosis and metamorphosis are primarily seen as results of trade-offs between the advantages of using aquatic versus terrestrial habitats, this study provides evidence that additional forces, such as intraspecific trophic niche differences between morphs and trophic niche expansion, may play an important role in the persistence of this dimorphism in heterogeneous environments. Moreover, the different patterns found in males and females show the importance of considering sex to understand the evolutionary ecology of trophic polymorphisms

Effetti dell’endosulfan sugli Anfibi: uno studio morfologico e comportamentale

Dottorato di Ricerca in Biologia Animale, XIV Ciclo a.a. 2010-2011The declining amphibian population is a global phenomenon in conservation biology that has attracted the attention of many scientists (Russell et al., 1995; Stallard, 2001; Sparling e Fellers, 2009). As for the majority of recent reductions in Earth biodiversity, the amphibian decline can also be attributed to direct human impact on the environment such as the use of pesticides and other chemical pollutants. Therefore, understanding the impacts of agrochemicals on amphibians is a challenging proposition. Amphibians are sensitive to the action of pollutants and they are considered excellent bioindicators of the environmental quality due to their biological, ecological and anatomical characteristics. For these reasons, amphibians are broadly used as typical targets in evaluating the effects of chemicals on aquatic and agricultural ecosystems (Schuytema e Nebeker, 1996; Pollet e Bendell-Young, 2000; Venturino et al., 2003; Bernabò et al., 2008). Decreased species richness, reduced populations, and high deformity incidences have been reported in agroecosystems, which might be linked to the extensive use of pesticides (Berrill et al., 1994, 1997; Bonin et al., 1997; Knutson et al., 2002; Davidson, 2004; Bridges et al., 2004; Relyea, 2005). As outlined by Boone et al. (2005) there is a lack of data for many commonly used pesticides with regard to their effects on amphibians. We chose endosulfan, an organochlorine globally used on a wide variety of crops and other sectors. The environmental persistence and toxicity of endosulfan forced several national authorities to ban it and to propose its inclusion as a persistent organic pollutant in the Stockholm convention (Kelly et al., 2007; EPA, 2010). Endosulfan reaches aquatic systems through direct application, as well as spray drift and runoff from agricultural areas (Leonard et al., 1999, 2000, 2001; Broomhall, 2002; Jergentz et al., 2004) and levels in nature pose a risk to aquatic ecosystems. The last EPA (2010) report on endosulfan, highlights the need for further work to consider amphibians as model species. Previous studies on the effects of endosulfan on amphibians showed detrimental effects on survival, growth, development and metamorphosis, and even caused deformity, severe changes in gill morphology and behavioural alterations (Bernabò et al., 2008; Brunelli et al., 2009, 2010; Jones et al., 2009; Shenoy et al., 2009). Therefore, we proposed to assess the effects of chronic exposure to ecologically relevant concentrations of endosulfan on two anuran species during larval development. In particular, we focused attention on the morphological endpoint evaluating the effects on Bufo bufo skin, to validate the hypothesis of our research group using a morphological approach in a toxicological study. Recently we demonstrated that environmentally relevant endosulfan concentrations (0.1, 0.05 and 0.01 mg/L) may affect Bufo bufo gills morphology and ultrastructure (Brunelli et al., 2010). On this basis we proposed completing the study on endosulfan toxicity in Bufo bufo tadpoles evaluating the effects of the same sublethal concentrations on skin. In fact, the thin and permeable skin of amphibians directly interacts with all environmental constituents, including toxicants. Moreover there is a gap in literature on endosulfan effects on this target organ. We also analyzed the effects of endosulfan on Rana dalmatina tadpoles. Firstly, we examined the short-term toxicity of endosulfan determining the LC50 value and after this preliminary analysis we conducted a classical toxicological study evaluating the effects of sublethal concentrations of endosulfan (0.005, 0.01 and 0.05 mg/L) on survival, growth, development, metamorphosis, deformities presence in Rana dalmatina tadpoles and, in collaboration with the University of Liege we applied new tools for evaluating behavioural patterns. For the first time we used video-tracking analyses to test the quantitative effect of endosulfan on the locomotion. We exposed Bufo bufo tadpoles from Gosner stage 25 until stage 42 to a chronic static renewal system according to the experimental design and conditions of our previous studies (according to Brunelli et al., 2010). and the epidermis was removed after 96 h, 14 and 20 days and analyzed by Trasmission Electron Microscopy (TEM). Exposure to endosulfan caused a general defensive response by mucous secretion and the appearance of large secretory vescicles in Bufo bufo larval epidermis. The exposure to all concentrations, already after 96 h, caused an increase of intercellular spaces, alteration of the cell-cells interactions, cellular degeneration, in particular of the typical larval bufonidae cells (Riesenzellens). The epidermal-dermal junctions and the figures of Eberth in the basal layer, were completely lost at the end of exposure. Our results were successful in showing that environmentally relevant concentrations of endosulfan negatively affected the epidermis of Bufo bufo tadpoles after long-term exposure, resulting in ultrastructure modification in the treated animals compared to controls and that epidermal damage was strongly correlated with exposure time. These results are consistent with our previous findings (Bernabò et al., 2008; Brunelli et al., 2010) concerning the morphological alteration pattern of the gill epithelium during long term exposure. We confirmed that the morphological approach is an useful tool in evaluating the effects of environmental contamination at sublethal levels in sensitive organisms like amphibians, and we supported the role of amphibian skin as a good biomarker following pesticide exposure. Rana dalmatina tadpoles were exposed to several nominal concentrations of endosulfan to assess the sensitivity of the species by estimating the LC50 value at 96 h in a static exposure system. We found that the nominal 96 h LC50 value was 0.074 mg/L. After this preliminary analysis, Rana dalmatina tadpoles were exposed to sublethal concentrations of endosulfan (0.005, 0.01, 0.05 mg/L) in a chronic static renewal system from Gosner stage 25 for the entire course of larval development. Mortality, larval growth (mass), body length, development, time to metamorphosis and deformities presence were monitored regularly over the entire course of larval development. The behaviour (swimming activity) was recorded after 7, 14, 21 and 28 days of exposure and analyzed by a video-tracking software Ehovision 7 XT (Noldus Information Technology, The Netherlands). We analyzed behavioural traits such as: distance moved, velocity, immobility and space use. Our results showed that long-term exposure to environmentally relavant concentrations of endosulfan impaired survival, larval growth, development, metamorphosis, swimming activity and caused severe morphological alteration in tadpoles exposed to 0.01 and 0.05 mg endosulfan/L (medium and high concentrations). With regards to the inhibition of metamorphosis in the highest concentrations, this has a profound implication in the light of amphibian decline. Instead, the lowest concentration of endosulfan (0.005 mg/L) did not cause any significant effects on growth, development and on swimming activity, although we have observed a slightly significant reduction in survival without decreasing the success of metamorphosis. In natural environments, increased incidences of deformities, a reduced larval growth could increase susceptibility to predation (Rohr et al., 2003), delay metamorphosis or result in metamorphosis at a smaller size having negative effects on future fitness, growth and overwinter survival (Brodie and Formanowicz, 1983; Semlitsch et al., 1988; Smith, 1987; Boone and Semlitsch, 2002; Altwegg and Reyer, 2003; Boone and James, 2003). We used video-tracking analyses for the first time to test the quantitative effects of a pesticide on the behaviour of amphibians. And we observed that behavioural effects occurred from 7 days of exposure and tadpoles exposed to the medium and high concentrations of endosulfan exhibited several anomalies in swimming activity such as: shorter distance moved, slower speed, swirling, resting and different space use. Our findings are in agreement with the previous studies of our research group on endosulfan effects on Bufo bufo (Brunelli et al., 2009) and, with the use of video-tracking analysis, we had advantages over standard visual methods. In fact we precisely quantified swimming activity anomalies. We demonstrated that quantitative ecotoxicology is thus a valuable tool to assess conservation concerns when other techniques cannot detect detrimental effects. Our study thus confirms and extends the results of previous studies on the toxicity of this organochlorine pesticide in showing its possible role in amphibian decline.Università della Calabri

Stomach contents and morphological measurements of newts

Contains stomach contents (as numerical abundance), total ingested dry mass, snout-vent length and body mass of each newt

Stable isotopes composition of newts

Contains carbon and nitrogen stable isotope composition of each newt

Superconductivity at 1 K in Y-Au-Si quasicrystal approximants

We report the structural and physical properties of two Y-Au-Si (YAS) compounds, Y14.1Au69.2Si16.7 and Y15.4Au68.6Si16.1, which are 1/1 approximant crystals of a Tsai-type quasicrystal without intrinsic magnetic moments. The compounds differ by the presence of either a tetrahedron (Au,Si)4 or a single Y atom at the center of their characteristic structural building unit consisting of concentric polyhedral shells. Both compounds exhibit bulk superconductivity, which seems to be of a conventional type-II BCS type. The compound with Y atoms at the cluster center has a slightly higher transition temperature with a sharper step in the specific heat than the compound with tetrahedral units. We discuss the occurrence of this superconducting state in the light of the specific structural and physical properties of these quasicrystal approximants

Nonequilibrium dynamical behavior in noncoplanar magnets with chiral spin texture

We observe nonequilibrium dynamical magnetic behavior in the magnetically ordered phase of a Tsai-type Tb-Au-Si quasicrystal approximant system. The magnetic texture in the ordered phase is found to exhibit scalar spin chirality (SSC) order, inferring that SSC is the order parameter of the present magnetic system. We further find that the introduction of “pseudo-Tsai” clusters, associated with additional Tb atoms in the structure, induces spin-glass dynamics. We discuss the observed dynamical magnetic behavior in the Tb-Au-Si systems, considering the effect of the pseudo-Tsai clusters on the magnetic configuration and local spin chirality

Evolutionary ecology of facultative paedomorphosis in newts and salamanders

Facultative paedomorphosis is an environmentally induced polymorphism that results in the coexistence of mature, gilled, and fully aquatic paedomorphic adults and transformed, terrestrial, metamorphic adults in the same population. This polymorphism has been of interest to scientists for decades because it occurs in a large number of caudate amphibian taxa as well as in a large diversity of habitats. Numerous experimental and observational studies have been conducted to explain the proximate and ultimate factors affecting these heterochronic variants in natural populations. The production of each alternative phenotype is based on a genotype x environment interaction and research suggests that differences in the environment can produce paedomorphs through several ontogenetic pathways. No single advantage accounts for the maintenance of this polymorphism. Rather, the interplay of different costs and benefits explains the success of the polyphenism across variable environments. Facultative paedomorphosis allows individuals to cope with habitat variation, to take advantage of environmental heterogeneity in the presence of open inches, and to increase their fitness. This process is expected to constitute a first step towards speciation events, and is also an example of biodiversity at the intraspecific level. The facultative paedomorphosis system is thus ripe for future studies encompassing ecology, evolution, behaviour, endocrinology, physiology, and conservation biology. Few other systems have been broad enough to provide varied research opportunities on topics as diverse as phenotypic plasticity, speciation, mating behaviour, and hormonal regulation of morphology. Further research on facultative paedomorphosis will provide needed insight into these and other important questions facing biologists

Atomic-Scale Tuning of Tsai-Type Clusters in RE-Au-Si Systems (RE = Gd, Tb, Ho)

Tsai-type quasicrystals and approximants are distinguished by a cluster unit made up of four concentric polyhedral shells that surround a tetrahedron at the center. Here we show that for Tsai-type 1/1 approximants in the RE-Au-Si systems (RE = Gd, Tb, Ho) the central tetrahedron of the Tsai clusters can be systematically replaced by a single RE atom. The modified cluster is herein termed a "pseudo-Tsai cluster" and represents, in contrast to the conventional Tsai cluster, a structural motif without internal symmetry breaking. For each system, single-phase samples of both pseudo-Tsai and Tsai-type 1/1 approximants were independently prepared as millimeter-sized, faceted, single crystals using the self-flux synthesis method. The full replacement of tetrahedral moieties by RE atoms in the pseudo-Tsai 1/1 approximants was ascertained by a combination of single-crystal and powder diffraction studies, as well as energy dispersive X-ray spectroscopy (EDX) analyses with a scanning electron microscope (SEM). Differential scanning calorimetry (DSC) studies revealed distinctly higher decomposition temperatures, by 5-35 K, for the pseudo-Tsai phases. Furthermore, the magnetic properties of pseudo-Tsai phases are profoundly and consistently different from the Tsai counterparts. The onset temperatures of magnetic ordering (T-mag) are lowered in the pseudo-Tsai phases by similar to 30% from 24 to 17 K, 11.5 to 8 K, and 5 to 3.5 K in the Gd-Au-Si, Tb-Au-Si, and Ho-Au-Si systems, respectively. In addition, the Tb-Au-Si and Ho-Au-Si systems exhibit some qualitative changes in their magnetic ordering, indicating decisive changes in the magnetic state/structure by a moment-bearing atom at the cluster center