Geographic body size variation in ectotherms: effects of seasonality on an anuran from the southern temperate forest

Indexación: Web of Science; Scopus.Background: Body size variation has played a central role in biogeographical research, however, most studies have aimed to describe trends rather than search for underlying mechanisms. In order to provide a more comprehensive understanding of the causes of intra-specific body size variation in ectotherms, we evaluated eight hypotheses proposed in the literature to account for geographical body size variation using the Darwin's frog (Rhinoderma darwinii), an anuran species widely distributed in the temperate forests of South America. Each of the evaluated hypotheses predicted a specific relationship between body size and environmental variables. The level of support for each of these hypotheses was assessed using an information-theoretic approach and based on data from 1015 adult frogs obtained from 14 sites across the entire distributional range of the species. Results: There was strong evidence favouring a single model comprising temperature seasonality as the predictor variable. Larger body sizes were found in areas of greater seasonality, giving support to the "starvation resistance" hypothesis. Considering the known role of temperature on ectothermic metabolism, however, we formulated a new, non-exclusive hypothesis, termed "hibernation hypothesis": greater seasonality is expected to drive larger body size, since metabolic rate is reduced further and longer during colder, longer winters, leading to decreased energy depletion during hibernation, improved survival and increased longevity (and hence growth). Supporting this, a higher post-hibernation body condition in animals from areas of greater seasonality was found. Conclusions: Despite largely recognized effects of temperature on metabolic rate in ectotherms, its importance in determining body size in a gradient of seasonality has been largely overlooked so far. Based on our results, we present and discuss an alternative mechanism, the "hibernation hypothesis", underlying geographical body size variation, which can be helpful to improve our understanding of biogeographical patterns in ectotherms.https://frontiersinzoology.biomedcentral.com/articles/10.1186/s12983-015-0132-

Trophic ecology of the Endangered Darwin's frog inferred by stable isotopes

Indexación: Scopus.Acknowledgements. We thank Dr. Mauricio González-Chang for his contribution to invertebrate identification and Sally Wren for the revision of an earlier version of the manuscript. We are also extremely grateful to Tomás Elgueta Alvarez for providing Video S1. B.E.M.B. has a fellowship awarded by Universidad Andres Bello. This research project was approved by the Bioethics Committee at the Universi-dad Andres Bello, Chile (N°13/2015), and by permits N°5666/2013, N°230/2015, and N°212/2016 of the Chilean Agriculture and Livestock Service, and N°026/2013 and N°11/2015 IX of the Chilean National Forestry Corporation. This study was funded by the Dirección General de Investi-gación y Doctorados, Universidad Andres Bello, through grant N°DI-53-11/R and national funds through FONDE CYT N°11140902 and 1181758 (to C.S.A.).Darwin's frogs Rhinoderma spp. are the only known mouth-brooding frogs on Earth. The southern Darwin's frog, R. darwinii, is found in the temperate forests of southern South America, is listed as Endangered and could be the only extant representative of this genus. Based on stomach contents, invertebrate prey availability and stable isotope analysis, we determined for the first time trophic ecological parameters for this species. Our results showed that R. darwinii is a generalist sit-and-wait predator and a secondary consumer, with a trophic position of 2.9. Carbon and nitrogen isotope composition indicated that herbivore invertebrates are their main prey, detected in 68.1% of their assimilated food. The most consumed prey included mosquitoes, flies, crickets, grasshoppers and ants. Detritivore and carnivore invertebrates were also ingested, but in lower proportions. Our results contribute to a better understanding of the feeding habits of this fully terrestrial amphibian and provide the first insight into their role linking low forest trophic positions with intermediate predators. We provide valuable biological information for in situ and ex situ conservation which can be used when developing habitat protection, reintroduction and captive breeding programmes. As revealed here, stable isotope analysis is a valuable tool to study the trophic ecology of highly endangered and cryptic species. © The authors 2018.https://www.int-res.com/abstracts/esr/v36/p269-278

The Hurwitz Map and Harmonic Wave Functions for Integer and Half-Integer Angular Momentum

Harmonic wave functions for integer and half-integer angular momentum are given in terms of the Euler angles $(\phi,\theta,\psi)$ that define a rotation in $SO(3)$, and the Euclidean norm $r$ in ${\Bbb R}^3$, keeping the usual meaning of the spherical coordinates $(r,\phi,\theta)$. They form a Hilbert (super)-space decomposed in the form \Cal H=\Cal H_0\oplus\Cal H_1. Following a classical work by Schwinger, $2$-dimensional harmonic oscillators are used to produce raising and lowering operators that change the total angular momentum eigenvalue of the wave functions in half units. The nature of the representation space \Cal H is approached from the double covering group homomorphism $SU(2)\to SO(3)$ and the topology involved is taken care of by using the Hurwitz map $H:{\Bbb R}^4\to{\Bbb R}^3$. It is shown how to reconsider $H$ as a 2-to-1 group map, $G_0={\Bbb R}^+\times SU(2)\to {\Bbb R}^+\times SO(3)$, translating into an assignment $(z_1,z_2)\mapsto (r,\phi,\theta,\psi)$ in terms of two complex variables $(z_1,z_2)$, under the appropriate identification of ${\Bbb R}^4$ with ${\Bbb C}^2$. It is shown how the Lie algebra of $G_0$ is coupled with the two Heisenberg Lie algebras of the $2$-dimensional (Schwigner's) harmonic oscillators generated by the operators $\{z_1,z_2,\bar{z}_1,\bar{z}_2\}$ and their adjoints. The whole set of operators close either into a $9$-dimensional Lie algebra or into an $8$-dimensional Lie superalgebra. The wave functions in \Cal H can also be written in terms polynomials in the complex coordinates $(z_1,z_2)$ and their complex conjugates $(\bar{z}_1,\bar{z}_2)$ and the representations are explicitly constructed via highest weight (or lowest weight) vector representations for $G_0$.Comment: 19 pages, 1 diagra

On quadratic Hom-Lie algebras with equivariant twist maps and their relationship with quadratic Lie algebras

Hom-Lie algebras having non-invertible and equivariant twist maps are studied. Central extensions of Hom-Lie algebras having these properties are obtained and shown how the same properties are preserved. Conditions are given so that the produced central extension has an invariant metric with respect to its Hom-Lie product making its twist map self-adjoint when the original Hom-Lie algebra has such a metric. This work is focused on algebras with these properties and we call them quadratic Hom-Lie algebras. It is shown how a quadratic Hom-Lie algebra gives rise to a quadratic Lie algebra and that the Lie algebra associated to the given Hom-Lie central extension is a Lie algebra central extension of it. It is also shown that if the 2-cocycle associated to the central extension is not a coboundary, there exists a non-abelian and non-associative algebra, the commutator of whose product is precisely the Hom-Lie product of the Hom-Lie central extension. Moreover, the algebra whose commutator realizes this Hom-Lie product is shown to be simple if the associated Lie algebra is nilpotent. Non-trivial examples are provided

Análisis del perfil motivacional de diversos grupos de atletas y su repercusión en el nivel de satisfacción deportiva

The purpose of this study was to identify the motivation among different athletics groups and see the influence motivational profile of satisfaction feel them. The sample was composed of 51 subjects from schools and sport clubs in Murcia. The sample was classificated according to gender, age, frequency of practice, possession of federal license and type training. As instruments were used three test; BREQ-2 for self-determination, TEOSQ, for motivacional orientation and SSI, for satisfaction level. All them, adapted to the context athletic.The results showed more satisfaction level and less bore level in subjects with high task orientation and intrinsic motivation/self-determined, and greater motivation to achieve (ego and task). The ideal profile were younger women, federated, which train them frequently and always accompanied. The age was the most influential factor. These results could be studied by the coaches in order to they keep in mind the variables that can be modified such as training methodology to achieve greater satisfaction and of this form, a better adherence and competitive results. It would be wise to consider athletes from an early stage was facing the enjoyment of athletics for the future, not to reduce their level of satisfaction and motivation, increasing the possibility of sport dropout.El objetivo del presente estudio, es analizar la motivación que experimentan diversos grupos de atletas y como esta, influye en sunivel de satisfacción con el deporte. Se utilizó una muestra de 51 sujetos provenientes de escuelas y clubes de la Región de Murcia,siendo clasificada la muestra en función del género, edad, frecuencia de práctica, posesión de licencia federativa y tipo de entrenamiento. Como instrumentos se utilizaron el cuestionario BREQ-2 para la autodeterminación, TEOSQ, para la orientación motivacional y SSI para el nivel de satisfacción, todos ellos adaptados al contexto atlético. Los resultados mostraron mayor satisfacción y menor aburrimiento en los sujetos con alta orientación a la tarea y motivación intrínseca-autodeterminada, así como mayor motivación hacia el logro (ego y tarea). El perfil ideal fueron las mujeres más jóvenes, federadas, que realizan una práctica frecuente y siempre acompañadas, siendo la edad el factor más influyente. Estos resultados, podrían servir a los entrenadores para tener en cuenta qué variables pueden modificar tales como la metodología de entrenamiento, para lograr una mayor satisfacción y con ello, una mayor adherencia y resultados competitivos. Sería conveniente formar atletas desde las primeras etapas con orientación hacía el disfrute del atletismo para que de cara al futuro, no se reduzca su nivel de satisfacción y motivación y con ello, la posibilidad de abandono deportivo

Cryptic disease-induced mortality may cause host extinction in an apparently stable host- parasite system

The decline of wildlife populations due to emerging infectious disease often shows a common pattern: the parasite invades a naive host population, producing epidemic disease and a population decline, sometimes with extirpation. Some susceptible host populations can survive the epidemic phase and persist with endemic parasitic infection. Understanding host–parasite dynamics leading to persistence of the system is imperative to adequately inform conservation practice. Here we combine field data, statistical and mathematical modelling to explore the dynamics of the apparently stable Rhinoderma darwinii–Batrachochytrium dendrobatidis (Bd) system. Our results indicate that Bd-induced population extirpation may occur even in the absence of epidemics and where parasite prevalence is relatively low. These empirical findings are consistent with previous theoretical predictions showing that highly pathogenic parasites are able to regulate host populations even at extremely low prevalence, highlighting that disease threats should be investigated as a cause of population declines even in the absence of an overt increase in mortality