Person:
Sánchez Jiménez, Abel

First Name

Abel

Last Name

Sánchez Jiménez

URI

https://hdl.handle.net/20.500.14352/74359

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Biológicas

Department

Biodiversidad, Ecología y Evolución

Area

Matemática Aplicada

Identifiers

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Search Results

Now showing 1 - 8 of 8

Project number: 63
Diseño e implementación de la metodología Flipped Classroom en la asignatura de “Estadística aplicada a la Biología”. Uso de dispositivos móviles para la evaluación del alumnado
(2020) Juan Llamas, María del Carmen; Murciano Cespedosa, Antonio; Sánchez Jiménez, Abel; Villacorta Atienza, José Antonio
Static internal representation of dynamic situations reveals time compaction in human cognition
(Journal of Advanced Research, 2020) Villacorta-Atienza, José Antonio; Calvo Tapia, Carlos; Díez-Hermano, Sergio; Sánchez Jiménez, Abel; Lobov, Sergei; Krilova, Nadia; Murciano Cespedosa, Antonio; López-Tolsa, Gabriela E.; Pellón, Ricardo; Makarov Slizneva, Valeriy
Introduction: The human brain has evolved under the constraint of survival in complex dynamic situations. It makes fast and reliable decisions based on internal representations of the environment. Whereas neural mechanisms involved in the internal representation of space are becoming known, entire spatiotemporal cognition remains a challenge. Growing experimental evidence suggests that brain mechanisms devoted to spatial cognition may also participate in spatiotemporal information processing. Objectives: The time compaction hypothesis postulates that the brain represents both static and dynamic situations as purely static maps. Such an internal reduction of the external complexity allows humans to process time-changing situations in real-time efficiently. According to time compaction, there may be a deep inner similarity between the representation of conventional static and dynamic visual stimuli. Here, we test the hypothesis and report the first experimental evidence of time compaction in humans. Methods: We engaged human subjects in a discrimination-learning task consisting in the classification of static and dynamic visual stimuli. When there was a hidden correspondence between static and dynamic stimuli due to time compaction, the learning performance was expected to be modulated. We studied such a modulation experimentally and by a computational model. Results: The collected data validated the predicted learning modulation and confirmed that time compaction is a salient cognitive strategy adopted by the human brain to process time-changing situations. Mathematical modelling supported the finding. We also revealed that men are more prone to exploit time compaction in accordance with the context of the hypothesis as a cognitive basis for survival. Conclusions: The static internal representation of dynamic situations is a human cognitive mechanism involved in decision-making and strategy planning to cope with time-changing environments. The finding opens a new venue to understand how humans efficiently interact with our dynamic world and thrive in nature.
Complexity of river ciliate communities at a national park highlights the need for microbial conservation
(Aquatic Conservation: Marine and Freshwater Ecosystems, 2018) Quintela Alonso, Pablo; Pérez‐Uz, Blanca; Sánchez Jiménez, Abel; Murciano Cespedosa, Antonio; Centeno, Juan D.; García-Rodríguez, Manuel; Montero, Esperanza; Muñoz Araújo, Benito; Olmedo Salinas, Cristina; Refoyo Román, Pablo; Velasco González, Ismael; Martín Cereceda, María Mercedes
1.Microorganisms play pivotal roles in aquatic ecosystems. Free‐living protists are the main components of the eukaryotic microbial communities at the base of freshwater ecosystems. Ciliate grazing channels a large proportion of organic matter into multicellular organisms. Surprisingly, ciliates and other microorganisms are neglected in global conservation schemes. 2. Interstitial ciliates were sampled in three sites of varying human pressure on the River Manzanares (La Pedriza National Park, Spain). Abundances of trophic groups and species were adjusted to a generalized linear model (GLM Poisson regression). 3.Ciliate communities were rich in species (74 morphotypes) and although traditional microscopy retrieved a high number of species that appeared only once or in low numbers, rarefaction analyses estimated much larger species richness. These results illustrate that rarefaction assays are a useful first step for exploring the extent of the ciliate cryptic diversity in freshwater ecosystems. 4.Benthic ciliate communities changed significantly, both spatially and at a short temporal scale. The fluctuating nature of the community was manifested by the presence of many ephemeral species at the same river site, revealing a complex and transient community structure. No significant short‐term changes were observed in the physical–chemical properties. Therefore, even slight differences in the abiotic variables may cause rapid shifts of ciliate species. 5.Overall, human pressure had an effect on the interstitial (or benthic) ciliates that resulted in a reduction of species richness and their abundance.
Influencia de la temperatura sobre la asimetría de pilancones en ambiente granítico. Aplicación de un modelo de regresión lineal
(Boletín de la Sociedad Geológica Mexicana, 2017) García Rodríguez, Manuel; Sánchez Jiménez, Abel; Murciano Cespedosa, Antonio; Pérez Uz, María Blanca; Martín Cereceda, María Mercedes
Las pilas representan un tipo de forma presente en casi todos los ambientes climáticos. El trabajo estudia el papel de los ciclos térmicos como un agente importante del modelado y asimetría que presentan las paredes de las pilas en un clima Mediterrá- neo templado - frío. El estudio se ha realizado en el macizo granítico de la Pedriza de Manzanares, zona protegida de gran valor ambiental, incluida en el Parque Nacional de la Sierra de Guadarrama (Madrid, España). El análisis de la variabilidad térmica mediante modelos de regresión perió- dica múltiple, pone de manifiesto la influencia de los ciclos diario y anual en función de las orientaciones norte y sur de las paredes de las pilas. Un modelo matemático de regresión lineal muestra cómo la variabilidad térmica diaria influye en la alteración de las paredes de las pilas, generando superficies planas o de concavidad más o menos pronunciada. El trabajo también establece relaciones entre el grado de alteración de las diferentes partes de las pilas, con la presencia de líquenes y dureza relativa de la roca. Los resultados avalan la hipótesis de relación causal entre la variabilidad térmica y alteración de las paredes de las pilas según su orientación norte o sur.
Rain-Fed Granite Rock Basins Accumulate a High Diversity of Dormant Microbial Eukaryotes
(Microbial Ecology, 2019) Velasco González, Ismael; Sánchez Jiménez, Abel; Singer, David; Murciano Cespedosa, Antonio; Díez-Hermano, Sergio; Lara, Enrique; Martín-Cereceda, Mercedes
Rain fed granite rock basins are ancient geological landforms of worldwide distribution and structural simplicity. They support habitats that can switch quickly from terrestrial to aquatic along the year. Diversity of animals and plants, and the connexion between communities in different basins have been widely explored in these habitats, but hardly any research has been carried out on microorganisms. The aim of this study is to provide the first insights on the diversity of eukaryotic microbial communities from these environments. Due to the ephemeral nature of these aquatic environments, we predict that the granitic basins should host a high proportion of dormant microeukaryotes. Based on an environmental DNA diversity survey, we reveal diverse communities with representatives of all major eukaryotic taxonomic supergroups, mainly composed of a diverse pool of low abundance OTUs. Basin communities were very distinctive, with alpha and beta diversity patterns non-related to basin size or spatial distance respectively. Dissimilarity between basins was mainly characterised by turnover of OTUs. The strong microbial eukaryotic heterogeneity observed among the basins may be explained by a complex combination of deterministic factors (diverging environment in the basins), spatial constraints, and randomness including founder effects. Most interestingly, communities contain organisms that cannot coexist at the same time because of incompatible metabolic requirements, thus suggesting the existence of a pool of dormant organisms whose activity varies along with the changing environment. These organisms accumulate in the pools, which turns granitic rock into high biodiversity microbial islands whose conservation and study deserve further attention.
Germination fitness of two temperate epiphytic ferns shifts under increasing temperatures and forest fragmentation
(PLoS ONE, 2018) Gabriel Y Galán Moris, José María; Murciano Cespedosa, Antonio; Sirvent, Laure; Sánchez Jiménez, Abel; Watkins, James E.
Ferns are an important component of ecosystems around the world. Studies of the impacts that global changes may have on ferns are scarce, yet emerging studies indicate that some species may be particularly sensitive to climate change. The lack of research in this subject is much more aggravated in the case of epiphytes, and especially those that live under temperate climates. A mathematical model was developed for two temperate epiphytic ferns in order to predict potential impacts on spore germination kinetics, in response to different scenarios of global change, coming from increasing temperature and forest fragmentation. Our results show that an increasing temperature will have a negative impact over the populations of these temperate epiphytic ferns. Under unfragmented forests the germination percentage was comparatively less influenced than in fragmented patches. This study highlight that, in the long term, populations of the studied epiphytic temperate ferns may decline due to climate change. Overall, epiphytic fern communities will suffer changes in diversity, richness and dominance. Our study draws attention to the role of ferns in epiphytic communities of temperate forests, emphasizing the importance of considering these plants in any conservation strategy, specifically forest conservation. From a methodological point of view, the model we propose could be easily used to dynamically monitor the status of ecosystems, allowing the quick prediction of possible future scenarios, which is a crucial issue in biodiversity conservation decision-making.
Data from: Germination fitness of two temperate epiphytic ferns shifts under increasing temperatures and forest fragmentation
(2018) Gabriel y Galán, Jose María; Murciano Cespedosa, Antonio; Sirvent, Laure; Sánchez Jiménez, Abel; Watkins, James E.
Ferns are an important component of ecosystems around the world. Studies of the impacts that global changes may have on ferns are scarce, yet emerging studies indicate that some species may be particularly sensitive to climate change. The lack of research in this subject is much more aggravated in the case of epiphytes, and especially those that live under temperate climates. A mathematical model was developed for two temperate epiphytic ferns in order to predict potential impacts on spore germination kinetics, in response to different scenarios of global change, coming from increasing temperature and forest fragmentation. Our results show that an increasing temperature will have a negative impact over the populations of these temperate epiphytic ferns. Under unfragmented forests the germination percentage was comparatively less influenced than in fragmented patches. This study highlight that, in the long term, populations of the studied epiphytic temperate ferns may decline due to climate change. Overall, epiphytic fern communities will suffer changes in diversity, richness and dominance. Our study draws attention to the role of ferns in epiphytic communities of temperate forests, emphasizing the importance of considering these plants in any conservation strategy. Derived from our results, it seems that it would be more practical to focus attention to forest conservation. From a methodological point of view, the model we propose could be easily used to dynamically monitor the status of ecosystems, allowing the quick prediction of possible future scenarios, which is a crucial issue in biodiversity conservation decision-making.
Diversity of DNA Sequences from Pathogenic and Potentially Pathogenic Eukaryotic Microorganisms in Protected Granite Mountain Rocks
(Diversity, 2023) Murciano Cespedosa, Antonio; Pérez Uz, María Blanca; Williams, Richard Alexander John; Sánchez Jiménez, Abel; Martín Cereceda, María Mercedes; Velasco-González, Ismael; Lara, Enrique; Singer, David; de Cos-Gandoy, Amaya; García-Rodríguez, Manuel
Rain-fed mountain granite rock basins are temporary habitats conditioned by a fluctuating environment and the unpredictability of precipitation or flooding rates. These small highland freshwater habitats remain largely unexplored at the microbial level. The aim of this work is to report the presence in these habitats of genetic sequences of microbial eukaryotes that are pathogens and potential pathogens of humans, wildlife, cattle, crops as well as of other microorganisms. We sequenced the hypervariable region v4 of the 18S rDNA gene from environmental DNA of sediments taken from 21 rock basins in a National Park in Spain. More than a fifth (21%) of the eukaryotic Operational Taxonomic Units (OTUs) found are ascribed to pathogenic (within 11 Phyla) and potential pathogenic (within 1 phylum, the Chytridiomycota) microorganisms. Some OTUs retrieved are of agro-economic and public health importance (e.g., Pythium spp., Lagenidium spp., Candida spp. and Vermamoeba vermiformis). In 86% of the basins, the most abundant OTUs were affiliated to Chytridiomycota, a broad fungal group including saprozoic and parasitic taxa. Two OTUs affiliated to chytrids were significantly correlated with high concentrations of heavy metals. The high proportion of chytrid-like microbial sequences found emphasises the role of these freshwater habitats for adding knowledge regarding the ecological trade-offs of the still rather unknown Chytridiomycota. Our results show that rain-fed rock basins may be model habitats for the study and surveillance of microbial community dynamics and genetics of (mainly opportunistic) microbial pathogens.