Does sediment composition sort kinorhynch communities?. An ecomorphological approach through geometric morphometrics

Ecomorphology studies the relationship between organisms’ morphology and environment features. To better understand whether the shape of the body and the appendages involved in the movement is correlated to sediment composition in meiofaunal organisms, we study the evolved morphological adaptations to environment in selected taxa of the phylum Kinorhyncha: the allomalorhagid families Dracoderidae and Pycnophyidae, and the cyclorhagid genus Echinoderes. The selected taxa include the most diverse groups of Kinorhyncha worldwide, representing the 75.5% of the total phylum diversity. Widened, plump bodies and lateral terminal spines may be adaptive for species living in coarse, more heterogeneous sediments, as they could maintain a more powerful musculature to actively displace the sediment grains applying a greater force. Conversely, slender, vermiform bodies and lateral terminal spines would represent an adaptation of species inhabiting fne, more homogeneous sediments where there would not be much need to exert a high force to displace the sediment particles, and a more vermiform shape would even favour the burrowing of the animal through the smaller interstices. The studied kinorhynch taxa would also be adapted to the higher velocity of the sea-water and the intense erosion and transportation of heterogeneous sediments by possessing more robust bodies, avoiding getting laid of substratum under these conditions. These fndings provide evolutionary evidence that body shape in the studied kinorhynch groups is adapted to environment

Integración de impactos ecológicos causados por plantas exóticas invasoras: propuesta metodológica

Tanto en España como en Europa existen demasiadas plantas exóticas invasoras para poder afrontar la gestión de todas ellas, por lo que es necesario priorizar las más nocivas. Sin embargo, ello requiere disponer de medidas cuantitativas, sistemáticas y comparables de su impacto. La información disponible es desigual en cuanto a los criterios y variables para medir impactos y por tanto difícil de integrar. Proponemos el siguiente método para integrar medidas de impactos procedentes de distintos estudios: 1) Búsqueda de casos de estudio, 2) cálculo de tamaños del efecto; 3) clasificación de los casos por nivel de organización, 4) integración de los tamaños del efecto para cada especie y nivel de impacto con técnicas de meta-análisis, y 5) estima de un índice de fiabilidad (basado en el número de casos) y otro de consistencia (basado en la heterogeneidad entre casos). Aplicamos este método para estimar los impactos en España de tres árboles invasores (Ailanthus altissima, Robinia pseudoacacia y Ulmus pumila). Encontramos 50 casos para A. altissima, 39 para R. pseudoacacia y 15 para U. pumila. Los impactos en el nivel de ecosistema (fertilidad) fueron los más estudiados, mientras que los de comunidad e individuo están menos documentados. Robinia pseudoacacia tiende a incrementar la fertilidad, mientras que A. altissima no altera esta propiedad. La metodología propuesta tiene la ventaja de permitir estimar el impacto con datos de estudios diversos, pero su aplicación está limitada por la disponibilidad de casos de estudio

Do cryptic species of earthworms affect soil arthropods differently? The case of the Carpetania elisae complex in the center of the Iberian Peninsula

In recent years, it has been discovered that the endemic earthworm Carpetania elisae (formerly Hormogaster elisae) consists of a complex of at least six cryptic species. Studying the relationships between these new cryptic species and other soil animal communities may be important to understand their functional role in the soil, and eventually to detect possible differences that may help in the delimitation of these species. We have studied the effects of two of these cryptic species (species I from El Molar [Ce1] and species II from El Tomillar [Ce2]) on soil microarthropod communities. Several laboratory experiments were performed with both cryptic species, in the soils of both localities inhabited by these earthworm species, to determine their effects on soil microarthropod communities. Both earthworm species grew quite well throughout the experiment in their original soil, but while Ce1 grew up well when cultivated in the opposite soil from El Tomillar, Ce2 cultivated in the soil from El Molar survived but did not grow. Ce1 from El Molar showed a clear negative effect on microarthropods from El Molar and El Tomillar, whereas Ce2 from El Tomillar had a clear negative effect on soil microarthropods from its original soil but not on the ones from the opposite soil of El Molar. This paper demonstrates differences of both cryptic species on their effects on soil community, which suggest that they may play different roles in the soil system. Several mechanisms likely involved on the effect of earthworms on soil arthropods are discussed, being the competition for organic matter the most probable one in the case of these endogeic earthworms

Geostatistical and multivariate analysis of the horizontal distribution of an earthworm community in El Molar (Madrid, Spain)

The earthworm community in El Molar (Madrid) is studied, and its distribution patterns and relation with some soil factors are described by using geostatistic and multivariate tools. Six species were found, Hormogaster elisae, Allolobophora rosea and Allolobophora caliginosa being the three most abundant ones. These speciesexhibited a clumped distribution. The most dominant species, H. elisae, was distributed in patches of an average size of 45m in spring and more than 100m inautumn. A. rosea was aggregated in patches of an average size of 22m and A. caliginosa formed patches of an average size of 38 m. There seemed to be a positive correlation between the abundance of H. elisae and the percentage of total and coarse sands, as well as a negative correlation with clay, nitrogen, carbon and coarse loams contents, opposite to what was observed for A. rosea

Unearthing the historical biogeography of Mediterranean earthworms (Annelida:Hormogastridae)

Aim: The genetic diversity and distribution of earthworm species in the Mediterranean Basin has been influenced by their low vagility, as well as by the basin’s complex geological and climatic history. Within this context, our objective was to evaluate the evolutionary history of hormogastrid earthworms by exploring their phylogeny, reconstructing ancestral areas and identifying potential vicariance and dispersal events. Location: Western Mediterranean region, encompassing the geographical range of the family Hormogastridae (four genera, 30 species and subspecies). Methods: We sampled the easternmost area of the hormogastrid range and integrated 606 new sequences with all the molecular data available from previous studies on the westernmost area. Mitochondrial and nuclear markers were amplified and sequenced, and the hormogastrid phylogeny (using Bayesian and likelihood methods) and networks were investigated. Ancestral-area reconstructions were implemented in rasp. Results: Ancestral-area reconstructions provided similar results for alternative phylogenetic hypotheses, placing the origin of Hormogastridae between southern France and the north-eastern Iberian Peninsula, and highlighting north–central Sardinia as a key ancestral area for diversification of eastern Hormogastridae (Hormogaster redii and H. samnitica). Multiple vicariance and dispersal events were detected, indicating a complex evolutionary history. Sardinian populations of H. samnitica and H. redii were not monophyletic but were related to populations from other areas, suggesting that Sardinia is a more complex biogeographical region than anticipated. Our results identified a phylogenetic relationship between the southern Sardinian fauna and that of Sicily, as well as relationships between the fauna of north-eastern Sardinia and those of the Italian Peninsula and the Tuscan Archipelago. Main conclusions: Our results suggest a complex evolutionary history for hormogastrid earthworms, showing the possibility of many dispersal and vicariance events and multiple faunal interchanges between land-masses, which may reflect the biogeographical complexity of the Mediterranean Basin

Horizontal Distribution of an Earthworm Community at El Molar, Madrid (Spain)

The earthworm community in El Molar (Madrid) is studied, and its distribution patterns and relation with some soil factors are described by using geostatistic and multivariate tools. Six species were found, Hormogaster elisae, Allolobophora rosea and Allolobophora caliginosa being the three most abundant ones. These speciesexhibited a clumped distribution. The most dominant species, H. elisae, was distributed in patches of an average size of 45m in spring and more than 100m inautumn. A. rosea was aggregated in patches of an average size of 22m and A. caliginosa formed patches of an average size of 38 m. There seemed to be a positive correlation between the abundance of H. elisae and the percentage of total and coarse sands, as well as a negative correlation with clay, nitrogen, carbon and coarse loams contents, opposite to what was observed for A. rosea

Endocrine disruptors in soil: effects of bisphenol A on gene expression of the earthworm Eisenia fetida

Xenobiotics such as bisphenol A (BPA), are present in biosolids, which are applied as organic fertilizers in agricultural fields. Their effects on soil life have been poorly assessed, and this is particularly important in the case of earthworms, which represent the main animal biomass in this medium. In the present work we study the impacts of BPA on gene expression of Eisenia fetida, a widely used ecotoxicological model. Chronic soil tests and acute contact tests were performed, and gene expression was analyzed in total tissue and in masculine reproductive organs of the earthworms. The genes studied in this research played a role in endocrine pathways, detoxification mechanisms, stress response, epigenetics, and genotoxicity. Most of the genes were identified for the first time, providing potentially useful biomarkers for future assessments. For chronic exposures, no changes were detected in whole-body tissue; however, masculine reproductive organs showed changes in the expression of genes related to endocrine function (EcR, MAPR, AdipoR), epigenetic mechanisms (DNMTs), genotoxicity (PARP1), and stress responses (HSC70 4). For acute exposures, the expression of one epigenetic-related gene was altered for both whole-body tissues and male reproductive organs (Piwi2). Further changes were detected for whole-body tissues involved in detoxification (Metallothionein), stress (HSC70 4), and genotoxicity (PARP1) mechanisms. Acute exposure effects were also tested in whole-body tissues of juveniles, showing changes in the expression of Metallothionein and Piwi2. The molecular changes found in the analyzed earthworms indicate that exposure to BPA may have negative implications in their populations. Particularly interesting are the alterations related to epigenetic mechanisms, which suggest that future generations may be impacted. This study is the first to evaluate the molecular effects of BPA on soil organisms, and further assays will be necessary to better characterize the true environmental repercussions. Capsule: Levels of gene expression in total-body tissues and masculine reproductive organs were analyzed in earthworms after exposure to bisphenol A and we observed associated changes in detoxification, endocrine, epigenetic, genotoxic and stress pathways

Bisphenol A in artificial soil: Effects on growth, reproduction and immunity in earthworms

The application of biosolids in agricultural fields is increasing annually. They contain not only nutrients but also xenobiotics, such as Bisphenol A (BPA). These compounds are not regulated in the use of biosolids in agriculture, which highlights the need to assess their effects on soil life, of which earthworms are most abundant of the animal representatives. In this study the effect of BPA on life-history parameters, such as mortality, growth and reproduction, and on immunity, is evaluated for Dendrobaena veneta and Eisenia fetida. Sublethal concentrations were evaluated by a modified OECD artificial soil test. Decline in growth with increasing concentration of BPA was detected during the first two weeks and the opposite effect for the next two, although these differences were only significant at the highest concentration. Reproduction traits were only significantly different for E. fetida, for which the number of juveniles decreased at higher concentrations, thus showing different sensitivity in both species. By using a contact test, the potentially harmful effect of direct contact with BPA was shown to be much higher than in soil (resembling natural) conditions. Finally, results indicate that BPA may not affect the immune system of these animals, at least in terms of coelomocyte viability

Is Hormogaster elisae (Oligochaeta, Hormogastridae) a predator of mites and springtails?

El texto completo del documento ha sido retirado con fecha 25-11-2009 por petición de la autoraDepto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEpu

Soil functionality at the roadside: Zooming in on a microarthropod community in an anthropogenic soil

Earth movements for road construction give rise to nutrient-poor anthrosols. Early onset of soil processes in these environments has been reported on the basis of plant cover establishment. Evidences of full soil functionality, however, would reveal the emergence of a self-sustainable ecosystem on these manmade substrates. The aims of the present study involved (1) assessing soil functionality on six-year-old road embankments by means of the QBS index, based on microarthropod communities (2) elucidating soil properties responsible for the composition of soil microartrhopod communities, and (3) exploring the practical implications of soil quality for road embankment management. Road embankments were functional with QBS values comparable to those found in natural systems (>100). Soil quality in these environments depended on soil organic carbon dynamics. Among the 36 arthropod groups found, Acari and Collembola dominated the soil community. Variation in microarthropod community composition was best explained by higher abundances of Brachypilina (Oribatida, Acari) and Symphypleona (Collembola). These trends in soil community structure were intimately linked to soil organic carbon content, clay content and humidity. Given its relevance, the acknowledgment of the early functionality attained by these roadside anthrosols should lead to the revision of current protocols for roadslope monitoring and management