514 research outputs found

    Tamaño corporal y composición de la fauna ibérica de Scarabaeoidea coprófagos (Insecta, Coleoptera)

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    Body size measurements have been used in a study of the composition of the iberic Scarabaeoidea coprophage fauna. Although the number of iberic species with relatively small body size is much greater, the majority of iberic genera are of a larger average body size. The number of world species of the iberic genera, and the proportion of species present in the Iberian Peninsula, is also a function of average body size. These facts seem to point to rates of speciation, extinction and evolutionary permanence being functions of the body size of the phyletic lines which constitute today's iberic Scarabaeoidea coprophage fauna.Se ha examinado la composición ibérica de 10s Scarabaeoidea coprófagos teniendo en cuenta el tamaño corporal. Aunque el número de especies ibéricas de menor tarnaíío relativo es mucho mayor, la mayoría de 10s géneros ibéricos tienen un tamaño corporal medio superior. El número de especies mundiales de 10s géneros ibéricos y la proporción de especies presentes en la península sobre el total, es también diferente según el tamaño corporal medio. Por todo ello, se estima probable que han debido de existir tasas de especiación, extinción y permanencia evolutiva diferentes, según el tamaño corporal de las líneas filéticas que constituyen la actual fauna ibérica de Scarabaeoidea coprófagos

    More complex distribution models or more representative data?

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    Distribution models for species are increasingly used to summarize species’ geography in conservation analyses. These models use increasingly sophisticated modeling techniques, but often lack detailed examination of the quality of the biological occurrence data on which they are based. I analyze the results of the best comparative study of the performance of different modeling techniques, which used pseudo-absence data selected at random. I provide an example of variation in model accuracy depending on the type of absence information used, showing that good model predictions depend most critically on better biological data

    Comentario bibliográfico

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    Comentario sobre la obra: G. HALFFTER, J. SOBERÓN, P. KOLEFF & A. MELIC (EDS.), 2005. Sobre Diversidad Biológica: El significado de las diversidades alfa, beta y gamma

    A review of the palaeoclimatic inference potential of Iberian Quaternary fossil batrachians

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    Ecological suitability analysis aims to model the potential or probable distribution of species using environmental variables and available species occurrence information as predictors. Most of the European fossil Quaternary amphibians belong to extant species, and being physiologically ectothermic animals, their current ecological niches could become a reliable inference tool to infer past environmental conditions. However, this expectation has never been properly verified. The validity and accuracy of palaeoclimatic inferences based on batrachian species ranges is tested on the Iberian Peninsula, using both palaeofaunistic and Recent distribution data, and an updated database of georeferenced species occurrences is provided. The difficulties of using current geographic information to represent the full spectrum of environmental conditions at which a species occurs are critically examined. A palaeofaunistic review of the role played by historical factors as dispersal limitations for present amphibian species ranges is presented using the available phylogeographical scenarios. Virtual hypothetical taxa can be devised by considering the distributions of several species together and relating their known joint presences with the environmental conditions in these locations. Species distribution models based on these virtual taxa provide the best advisable inferential procedure. For direct raw inferences of the mutual climatic range method, contrary to expectations, the combined taxa sets do not increase their accuracy with the number of species included. This preliminary review shows that Iberian amphibian palaeoclimatic inferences are both valid and reliable enough, a sufficient approximation to complement other techniques. The precision, however, is quite variable among taxa, reflecting the effect of non-climaticPeer reviewe

    Biases in global effects of exotic species on local invertebrates: a systematic review

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    Historical gaps and biases in the literature may have influenced the current knowledge of the impacts of invaders on global biodiversity. We performed a systematic review and compiled the main gaps and biases in the literature and the reported negative, neutral and positive effects of exotic species on local invertebrates worldwide. We analysed the relation of these reported effects to the biogeographical origin of the exotic species, the environmental characteristics of the invaded area, the trophic level of the exotic species and of the invaded local fauna, and the elapsed time after first introduction. We analysed 1276 publications comprising 2984 study cases. From these, 1786 cases included “control” situations (without exotics) and provided quantitative supporting evidence of the effects of exotic species on local invertebrates. The main gaps in the literature included tropical and arid climates, estuaries and marine ecosystems, as well as exotic species coming from Neotropical, Australian, Oriental, Ethiopian and Antarctic regions. Carnivorous and herbivorous species were underreported as exotic species and as impacted invertebrates. The considered variables were mostly unrelated to the reported effects, suggesting that the effects of exotic species on local invertebrates are heterogeneous and not unidirectional. Many impacted invertebrates were assemblages of undefined composition in terms of the native or exotic nature of the invaded organisms. Further avenues to reduce the identified biases in the current knowledge about the effects of exotic species on local invertebrates are also indicatedThe MF’s grant was supported by the Conselho Nacional de Desenvolvimento Cientı´fico e Tecnológico-CNPq (401045/2014-5), program Ciência sem Fronteiras, and by the Universidad de Alcala´. LMB has been supported by the National Institutes for Science and Technology (INCT) in Ecology, Evolution and Biodiversity Conservation (MCTIC/CNPq, 465610/2014-5, FAPEG) and by a CNPq Grant (304314/2014-5

    The species of Scarabaeus Linnaeus (Coleoptera: Scarabaeidae) in Bulgaria and adjacent regions: faunal review and potential distribution

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    We compile the available georeferenced information on Bulgarian Scarabaeus species, including both bibliographic and natural history data to provide basic ecological and biogeographical information as well as maps of climatically favourable areas (potential distributions) for each one of the species. Scarabaeus species in Bulgaria seem to be generally distributed across low altitude areas mainly under warm temperate or Mediterranean conditions, although S. variolosus appears to be the species adapted to the warmest conditions and S. armeniacus inhabits areas of medium altitude. Our results indicate that it is necessary to carry out an extra survey effort in the northern lowlands, away the Stara Planina Mts. in order to validate current climatically suitable territories for some species. However, the recent land use transformations of these lowland areas, together with the general decline of roller dung beetle populations, suggest that this validation may not be possible

    Delimiting the geographical background in species distribution modelling

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    [Aim]: The extent of the study area (geographical background, GB) can strongly affect the results of species distribution models (SDMs), but as yet we lack objective and practicable criteria for delimiting the appropriate GB. We propose an approach to this problem using trend surface analysis (TSA) and provide an assessment of the effects of varying GB extent on the performance of SDMs for four species. [Location]: Mainland Spain. [Methods]: Using data for four well known wild ungulate species and different GBs delimited with a TSA, we assessed the effects of GB extent on the predictive performance of SDMs: specifically on model calibration (Miller's statistic) and discrimination (area under the curve of the receiver operating characteristic plot, AUC; sensitivity and specificity), and on the tendency of the models to predict environmental potential when they are projected beyond their training area. [Results]: In the training area, discrimination significantly increased and calibration decreased as the GB was enlarged. In contrast, as GB was enlarged, both discriminatory power and calibration decreased when assessed in the core area of the species distributions. When models trained using small GBs were projected beyond their training area, they showed a tendency to predict higher environmental potential for the species than those models trained using large GBs. [Main conclusions]: By restricting GB extent using a geographical criterion, model performance in the core area of the species distribution can be significantly improved. Large GBs make models demonstrate high discriminatory power but are barely informative. By delimiting GB using a geographical criterion, the effect of historical events on model parameterization may be reduced. Thus purely environmental models are obtained that, when projected onto a new scenario, depict the potential distribution of the species. We therefore recommend the use of TSA in geographically delimiting the GB for use in SDMs.P.A. and A.J.-V. were supported by the Juan de la Cierva research program awarded by the Ministerio de Ciencia e Innovación – Fondo Social Europeo, and partly by the project CGL2009-11316/BOS – Fondos FEDER. P.A. is in Portugal thanks to a José Castillejo fellowship (2010–11) granted by the Ministerio de Ciencia e Innovación.Peer Reviewe

    RELACIONES ENTRE ESCARABAJOS (COLEOPTERA: SCARABAEIDAE) Y NIDOS DE TUZA (RODENTIA: GEOMYIDAE): IMPLICACIONES BIOLOGICAS Y BIOGEOGRAFICAS

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    The relationship between Onthophagus hippopotamus Haroid and gopher nests (Rodentia: Geomyidae) is confirmad. This relationship is not casual, since this beetle nests with the accumulated excrement of the rodent's burrows. The same relationship has been reportad for another closely related species of Onthophagus (0. coproides Horn) and it is very likely that it atso occurs in other species of the same complex. The existence of a guild of beetles which exploit rodent (and turtie) excrement in the burrows of the latter is aiso confirmad. Here, attention is drawn to the capture of two species of Aphodius along with O. hippopotamus, one of which is more associated with the Onthophagus, and even demonstrates cleptoparasitism on Onthophagus nests. The geographic distribution of Cratogeomys gophers is described, along with its overlap with the distribution of Onthophagus of the hippopotamus complexEn este trabajo se confirman las relaciones entre Onthophagus hippopotamus Haroid y los nidos de tuza (Rodentia: Geomyidae). La relación no puede considerarse como casual, ya que el escarabajo nidifica en base al excremento acumulado en las galerías del roedor. La misma relación había sido señalada para otra especie próxima de Onthophagus {O. coproides Horn). Es muy posible que esta asociación se presente también en otras especies del mismo complejo taxonómico de Onthophagus. Se confirma la existencia de un gremio de escarabajos que explota el excremento de roedores y tortugas dentro de sus galerías. En el trabajo se señala la captura junto con O. hippopotamus de dos especies de Aphodius, una de ellas más asociada con los Onthophagus al punto de que es cleptoparásita de sus nidos. Se discute la distribución de las tuzas del género Cratogeomys y su correlación con la de los Onthophagus del complejo hippopotamu

    Assessing the completeness of bryophyte inventories: an oceanic island as a case study (Terceira, Azorean archipelago)

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    Copyright © Springer Science+Business Media B.V. 2010.How useful, complete or unbiased are comprehensive databases in order to provide reliable estimations of diversity? Using compiled data from bryophytes in Terceira Island (Azores), we specifically aim (1) to describe the register of species over time, (2) to assess the inventory completeness, i.e., the ratio between the observed and the maximum expected species, and (3) to locate the most promising areas for further surveys. First, each new recorded species was plotted against its collecting year, using the number of database-records as a surrogate of survey effort, to get the accumulation curves. These curves were then extrapolated to obtain the theoretical number of existing species according to Clench and exponential models. Spatial and habitat characteristics of the recorded taxa were also explored. Our results show an increasing trend in the rate of recorded species (c. five species per year), as well as a maximum of around a third of the theoretically “real” number of expected species that could yet remain unknown. Nevertheless, predictions of species richness were highly variable depending on the fitting curve used. Survey effort was similar between liverworts and mosses, as were inventory completeness values, but the rate of new recorded species was higher for mosses. Although bryologists visited preferably native habitats, we show that new species citations may also be found in modified habitats (e.g., exotic forests and semi-natural grasslands). We conclude that the analysis of extensive databases is a useful tool in revealing the recording and taxonomic gaps, further showing that bryophyte inventories could still be incomplete in Terceira Island. A strategy on how to improve species’ collections in remote areas is suggested, hoping to contribute to all-inclusive biodiversity studies in the Azores and elsewhere

    The Cynipidae (Hymenoptera) of Comunidad de Madrid: checklist, distributional maps, species richness and conservation status

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    32 páginas, 2 figuras, 1 tabla, 2 apéndices.[ES] Se presenta por primera vez la lista anotada de especies y los mapas de distribución de los Cynipidae de la Comunidad de Madrid. Los datos corresponden a 2189 registros pertenecientes a muestreos y colectas efectuados desde 1982 hasta la actualidad, en 103 localidades de Madrid y en otras 19 cercanas de provincias adyacentes. Se relacionan 107 especies de cinípidos que representan el 73 % del total de especies ibéricas. Cada especie se acompaña de su correspondiente mapa de distribución en la Comunidad de Madrid, reflejando los puntos de las localidades de muestreo en los que ha sido encontrada, junto a su área de distribución potencial en este territorio. Se comentan distintos aspectos sobre la riqueza y distribución de los cinípidos de Madrid: especies de la fauna ibérica ausentes y otras que han de buscarse, especies raras y singulares junto a aquellas áreas de mayor riqueza de especies. El área de mayor riqueza del grupo se sitúa en una franja siguiendo el eje Guadalix-Venturada-Torrelaguna, de terrenos del Cretácico y del Terciario, que presenta también altas cifras de diversidad botánica de los géneros de plantas hospedantes del grupo, especialmente de fagáceas del género Quercus. Algunos enclaves del sureste de Madrid, ricos en especies singulares y raras de cinípidos de la tribu Aylacini, las áreas relictas de Q. petraea del nordeste de Madrid con especies exclusivas asociadas, así como los escasos enclaves remanentes de Quercus suber en la región, también con especies exclusivas de cinípidos asociadas, merecen la máxima protección por lo que respecta a la conservación de los cinípidos.[EN] Acheck list of the Cynipidae from Comunidad de Madrid (Spain) is presented for the first time. The data base contains 2189 records of samplings carried out from 1982 to the present in 103 sites in Madrid and 19 in nearby adjacent provinces. The list of 127 cynipid species from Madrid represents 73% of total Cynipidae species from the Iberian Peninsula. A distribution map in Madrid for each cynipid species is presented, showing the sampling sites where it has been found together with the potential distribution area of the species within the territory. Several aspects on the richness and distribution of the Cynipidae from Madrid are commented: potentially present and absent Iberian species, traindividual and rare species, and areas of high species richness. The area of highest richness for the Cynipidae of Madrid follows a strip of Cretacic and Tertiary soils along the Guadalix-Venturada-Torrelaguna axis, which also shows a high diversity of cynipid host plants, especially Quercus species. Other areas in SE Madrid deserving protection with regard to cynipids are also shown. These areas, some rich in rare and singular Aylacini species, other relictic areas with Quercus petraea in the Northeast and also some small areas with the presence of Quercus suber in parts of the territory of Madrid, deserve maximum protection concerning Cynipid conservation.El trabajo ha sido financiado parcialmente con fondos de los proyectos de la Consejería de Educación de la Comunidad de Madrid, 07M/0080/2002 y GR/AMB/0750/2004 y del Ministerio de Ciencia y Tecnología, proyecto de referencia REN2002- 03518/GLO, concedido a J. L. Nieves-Aldrey.Peer reviewe
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