On the misidentification of species: sampling error in primates and other mammals using geometric morphometrics in more than 4,000 individuals

An accurate classification is the basis for research in biology. Morphometrics and morphospecies play an important role in modern taxonomy, with geometric morphometrics increasingly applied as a favourite analytical tool. Yet, really large samples are seldom available for modern species and even less common in palaeontology, where morphospecies are often identified, described and compared using just one or a very few specimens. The impact of sampling error and how large a sample must be to mitigate the inaccuracy are important questions for morphometrics and taxonomy. Using more than 4000 crania of adult mammals and taxa representing each of the four placental superorders, we assess the impacts of sampling error on estimates of species means, variances and covariances in Procrustes shape data using resampling experiments. In each group of closely related species (mostly congeneric), we found that a species can be identified fairly accurately even when means are based on relatively small samples, although errors are frequent with fewer specimens and primates more prone to inaccuracies. A precise reconstruction of similarity relationships, in contrast, sometimes requires very large samples (> 100), but this varies widely depending on the study group. Medium-sized samples are necessary to accurately estimate standard errors of mean shapes or intraspecific variance covariance structure, but in this case minimum sample sizes are broadly similar across all groups (≈ 20-50 individuals). Overall, thus, the minimum sample sized required for a study varies across taxa and depends on what is being assessed, but about 25-40 specimens (for each sex, if a species is sexually dimorphic) may be on average an adequate and attainable minimum sample size for estimating the most commonly used shape parameters. As expected, the best predictor of the effects of sampling error is the ratio of between- to within-species variation: the larger the ratio, the smaller the sample size needed to obtain the same level of accuracy. Even though ours is the largest study to date of the uncertainties in estimates of means, variances and covariances in geometric morphometrics, and despite its generally high congruence with previous analyses, we feel it would be premature to generalize. Clearly, there is no a priori answer for what minimum sample size is required for a particular study and no universal recipe to control for sampling error. Exploratory analyses using resampling experiments are thus desirable, easy to perform and yield powerful preliminary clues about the effect of sampling on parameter estimates in comparative studies of morphospecies, and in a variety of other morphometric applications in biology and medicine. Morphospecies descriptions are indeed a small piece of provisional evidence in a much more complex evolutionary puzzle. However, they are crucial in palaeontology, and provide important complimentary evidence in modern integrative taxonomy. Thus, if taxonomy provides the bricks for accurate research in biology, understanding the robustness of these bricks is the first fundamental step to build scientific knowledge on sound, stable and long-lasting foundations

Red coral extinction risk enhanced by ocean acidification

The red coral Corallium rubrum is a habitat-forming species with a prominent and structural role in mesophotic habitats, which sustains biodiversity hotspots. This precious coral is threatened by both over-exploitation and temperature driven mass mortality events. We report here that biocalcification, growth rates and polyps’ (feeding) activity of Corallium rubrum are significantly reduced at pCO2 scenarios predicted for the end of this century (0.2 pH decrease). Since C. rubrum is a long-living species (.200 years), our results suggest that ocean acidification predicted for 2100 will significantly increases the risk of extinction of present populations. Given the functional role of these corals in the mesophotic zone, we predict that ocean acidification might have cascading effects on the functioning of these habitats worldwid

Nested interactions between chemosynthetic lucinid bivalves and seagrass promote ecosystem functioning in contaminated sediments

In seagrass sediments, lucinid bivalves and their chemoautotrophic bacterial symbionts consume H2S, relying indirectly on the plant productivity for the presence of the reduced chemical. Additionally, the role of lucinid bivalves in N provisioning to the plant (through N2 fixation by the symbionts) was hypothesized. Thus, lucinids may contribute to sediment detoxification and plant fitness. Seagrasses are subject to ever-increasing human pressure in coastal environments. Here, disentangling nested interactions between chemosynthetic lucinid bivalves and seagrass exposed to pollution may help to understand seagrass ecosystem dynamics and to develop successful seagrass restoration programs that consider the roles of animal-microbe symbioses. We evaluated the capacity of lucinid bivalves (Loripes orbiculatus) to promote nutrient cycling and seagrass (Cymodocea nodosa) growth during a 6-week mesocosm experiment. A fully crossed design was used to test for the effect of sediment contamination (metals, nutrients, and hydrocarbons) on plant and bivalve (alone or interacting) fitness, assessed by mortality, growth, and photosynthetic efficiency, and for the effect of their nested interaction on sediment biogeochemistry. Plants performed better in the contaminated sediment, where a larger pool of dissolved nitrogen combined with the presence of other trace elements allowed for an improved photosynthetic efficiency. In fact, pore water nitrogen accumulated during the experiment in the controls, while it was consumed in the contaminated sediment. This trend was accentuated when lucinids were present. Concurrently, the interaction between clams and plants benefitted both organisms and promoted plant growth irrespective of the sediment type. In particular, the interaction with lucinid clams resulted in higher aboveground biomass of C. nodosa in terms of leaf growth, leaf surface, and leaf biomass. Our results consolidate the notion that nested interactions involving animal-microbe associations promote ecosystem functioning, and potentially help designing unconventional seagrass restoration strategies that exploit chemosynthetic symbioses.Versión del edito

Budget of Primary Production and Dinitrogen Fixation in a Highly Seasonal Red Sea Coral Reef

Biological dinitrogen (N2) fixation (diazotrophy, BNF) relieves marine primary producers of nitrogen (N) limitation in a large part of the world oceans. N concentrations are particularly low in tropical regions where coral reefs are located, and N is therefore a key limiting nutrient for these productive ecosystems. In this context, the importance of diazotrophy for reef productivity is still not resolved, with studies up to now lacking organismal and seasonal resolution. Here, we present a budget of gross primary production (GPP) and BNF for a highly seasonal Red Sea fringing reef, based on ecophysiological and benthic cover measurements combined with geospatial analyses. Benthic GPP varied from 215 to 262 mmol C m−2 reef d−1, with hard corals making the largest contribution (41–76%). Diazotrophy was omnipresent in space and time, and benthic BNF varied from 0.16 to 0.92 mmol N m−2 reef d−1. Planktonic GPP and BNF rates were respectively approximately 60- and 20-fold lower than those of the benthos, emphasizing the importance of the benthic compartment in reef biogeochemical cycling. BNF showed higher sensitivity to seasonality than GPP, implying greater climatic control on reef BNF. Up to about 20% of net reef primary production could be supported by BNF during summer, suggesting a strong biogeochemical coupling between diazotrophy and the reef carbon cycle

Food-induced Emotional Resonance Improves Emotion Recognition

The effect of food substances on emotional states has been widely investigated, showing, for example, that eating chocolate is able to reduce negative mood. Here, for the first time, we have shown that the consumption of specific food substances is not only able to induce particular emotional states, but more importantly, to facilitate recognition of corresponding emotional facial expressions in others. Participants were asked to perform an emotion recognition task before and after eating either a piece of chocolate or a small amount of fish sauce – which we expected to induce happiness or disgust, respectively. Our results showed that being in a specific emotional state improves recognition of the corresponding emotional facial expression. Indeed, eating chocolate improved recognition of happy faces, while disgusted expressions were more readily recognized after eating fish sauce. In line with the embodied account of emotion understanding, we suggest that people are better at inferring the emotional state of others when their own emotional state resonates with the observed one

Production properties of K*(892) vector mesons and their spin alignment as measured in the NOMAD experiment

First measurements of K*(892) mesons production properties and their spin alignment in nu_mu charged current (CC) and neutral current (NC) interactions are presented. The analysis of the full data sample of the NOMAD experiment is performed in different kinematic regions. For K*+ and K*- mesons produced in nu_mu CC interactions and decaying into K0 pi+/- we have found the following yields per event: (2.6 +/- 0.2 (stat.) +/- 0.2 (syst.))% and (1.6 +/- 0.1 (stat.) +/- 0.1 (syst.))% respectively, while for the K*+ and K*- mesons produced in nu NC interactions the corresponding yields per event are: (2.5 +/- 0.3 (stat.) +/- 0.3 (syst.))% and (1.0 +/- 0.3 (stat.) +/- 0.2 (syst.))%. The results obtained for the rho00 parameter, 0.40 +/- 0.06 (stat) +/- 0.03 (syst) and 0.28 +/- 0.07 (stat) +/- 0.03 (syst) for K*+ and K*- produced in nu_mu CC interactions, are compared to theoretical predictions tuned on LEP measurements in e+e- annihilation at the Z0 pole. For K*+ mesons produced in nu NC interactions the measured rho00 parameter is 0.66 +/- 0.10 (stat) +/- 0.05 (syst).Comment: 20 p

Final NOMAD results on nu_mu->nu_tau and nu_e->nu_tau oscillations including a new search for nu_tau appearance using hadronic tau decays

Results from the nu_tau appearance search in a neutrino beam using the full NOMAD data sample are reported. A new analysis unifies all the hadronic tau decays, significantly improving the overall sensitivity of the experiment to oscillations. The "blind analysis" of all topologies yields no evidence for an oscillation signal. In the two-family oscillation scenario, this sets a 90% C.L. allowed region in the sin^2(2theta)-Delta m^2 plane which includes sin^2(2theta)<3.3 x 10^{-4} at large Delta m^2 and Delta m^2 < 0.7 eV^2/c^4 at sin^2(2theta)=1. The corresponding contour in the nu_e->nu_tau oscillation hypothesis results in sin^2(2theta)<1.5 x 10^{-2} at large Delta m^2 and Delta m^2 < 5.9 eV^2/c^4 at sin^2(2theta)=1. We also derive limits on effective couplings of the tau lepton to nu_mu or nu_e.Comment: 46 pages, 16 figures, Latex, to appear on Nucl. Phys.

Inclusive production of ρ0(770),f0(980)\rho^{0}(770), f_0(980) and f2(1270)f_2(1270) mesons in νμ\nu_{\mu} charged current interactions

The inclusive production of the meson resonances $\rho^{0}(770)$, $f_0(980)$ and $f_2(1270)$ in neutrino-nucleus charged current interactions has been studied with the NOMAD detector exposed to the wide band neutrino beam generated by 450 GeV protons at the CERN SPS. For the first time the $f_{0}(980)$ meson is observed in neutrino interactions. The statistical significance of its observation is 6 standard deviations. The presence of $f_{2}(1270)$ in neutrino interactions is reliably established. The average multiplicity of these three resonances is measured as a function of several kinematic variables. The experimental results are compared to the multiplicities obtained from a simulation based on the Lund model. In addition, the average multiplicity of $\rho^{0}(770)$ in antineutrino - nucleus interactions is measured.Comment: 23 pages, 14 figures, 8 tables. To appear in Nucl. Phys.

Search for the exotic Θ+\Theta^+ resonance in the NOMAD experiment

A search for exotic Theta baryon via Theta -> proton +Ks decay mode in the NOMAD muon neutrino DIS data is reported. The special background generation procedure was developed. The proton identification criteria are tuned to maximize the sensitivity to the Theta signal as a function of xF which allows to study the Theta production mechanism. We do not observe any evidence for the Theta state in the NOMAD data. We provide an upper limit on Theta production rate at 90% CL as 2.13 per 1000 of neutrino interactions.Comment: Accepted to European Physics Journal

Search for nu(mu)-->nu(e) Oscillations in the NOMAD Experiment

We present the results of a search for nu(mu)-->nu(e) oscillations in the NOMAD experiment at CERN. The experiment looked for the appearance of nu(e) in a predominantly nu(mu) wide-band neutrino beam at the CERN SPS. No evidence for oscillations was found. The 90% confidence limits obtained are delta m^2 < 0.4 eV^2 for maximal mixing and sin^2(2theta) < 1.4x10^{-3} for large delta m^2. This result excludes the LSND allowed region of oscillation parameters with delta m^2 > 10 eV^2.Comment: 19 pages, 8 figures. Submitted to Phys. Lett.