Biology subjects

Hortal, J.

Publications and source records attributed to Hortal, J..

8 recordsLinked to original sources

bioRxiv2026

Diversity without borders: partitioning continuous spaces using probabilistic equivalent numbers

Equivalent numbers represent biodiversity as the effective number of equally distinct units, typically species, and can be partitioned across scales. In practice, they summarize each unit of biodiversity by a single value and compare units pairwise, misrepresenting units that are better described as distributions and the relationships between several units that share the same space. We introduce an equivalent-number index for assemblages of units represented as probability density functions (PDFs) over a continuous space, estimated as the integral of the pointwise maximum across abundance-weighted PDFs. Resulting equivalent PDF numbers fulfil elementary properties of classical equivalent numbers, and support additive partitioning across any number of nested scales. We illustrate the framework with case studies across three domains: (1) measuring trait diversity considering intraspecific variability in grasslands, (2) partitioning realized bioclimatic niches among clades of Carnivora, and (3) understanding seasonal changes in the partitioning of fish home ranges in geographic space.

ecology↗

bioRxiv2025

Fire shifts the structure and dynamics of woody plant communities in a mediterranean coastal dune ecosystem

Coastal dune ecosystems are dynamic and fragile environments shaped by complex interactions between vegetation and its characteristic abiotic factors. This study investigates the effects of the wildfire that affected the Donana Nacional Park (SW Spain) in 2017 on the composition and structure of woody plant communities in two adjacent Mediterranean coastal dune areas: one affected by fire (Cuesta Maneli) and one unburned (Laguna del Jaral). Using a combination of several analyses (such as non-metric multidimensional scaling (NMDS); Mantel tests; and co-occurrence analyses), we examined how fire influences species distribution, abundance, and their interactions along a coastal-inland gradient. Our results reveal that fire homogenizes woody plant community composition across the coastal-inland gradient, reducing spatial differentiation and increasing overall species abundance in the burned area. Soil characteristics influenced species composition significantly only in the unburned site, suggesting that fire disrupted abiotic filtering processes. Co-occurrence patterns indicate more neutral interactions in the burned area, consistent with reduced competition and increased resource availability post-disturbance. In contrast, the unburned site displayed structured communities with stronger negative co-occurrence at the smaller scales and spatial clustering of species. Spatial pattern analyses showed that positive co-occurrence was more prevalent in the burned area, particularly at smaller spatial scales, indicating potential facilitation effects during early post-fire recovery. These findings highlight how fire reshapes community structure and dynamics after succession. Understanding these processes is critical for effective conservation and management of Mediterranean coastal dune ecosystems facing increasing anthropogenic pressures and climate change-related disturbances.

ecology↗

bioRxiv2024

Impacts of taxonomic change on the Amazonian palm flora

Although taxonomy is an evolving discipline, taxonomic change is rarely accounted for in macroecological studies. By tracking the history of species descriptions and synonymizations of more than 800 names of Amazonian palms, we reveal shifts in species counts across space and time, the factors associated with taxonomic lumping, and the time needed to detect synonyms. The 175 Amazonian palm species known to date are the result of a gradual accumulation of new descriptions and a few distinct revisions events that led to the recognition of approximately 800 heterotypic synonyms. Most of these synonyms were detected after the mid-1990s and caused an 80% decrease in species counts within just three decades. The time to detect synonyms ranged from 3 to 227 years. Species with a large population, widespread distribution, and those described early were more frequently lumped. This suggests undetected synonyms inflate species richness unevenly across taxa and regions. Our study highlights how much taxonomic revisions can affect our understanding of biodiversity. Without them, we risk building our ecological analyses and conservation assessments on shaky ground.

ecology↗

bioRxiv2024

Mobilisation of data from natural history collections can increase the quality and coverage of biodiversity information

AimQuantify potential gains to insect data on the Global Biodiversity Information Facility (GBIF) through further digitisation of natural history collections, assess to what degree this would fill biases in spatial and environmental record coverage, and deepen understanding of environmental bias with regard to climate rarity. LocationAfrotropical realm (mainland only) Time period1814-2022 Major taxa studiedCatharsius Hope, 1837 (Coleoptera: Scarabaeidae) MethodsWe compared inventory completeness of Afrotropical Catharsius GBIF data to a dataset which combined these with records from a recent taxonomic revision. We analysed how this improved dataset reduced regional and environmental bias in the distribution of occurrence records using an approach that identifies well-surveyed spatial units of 100x100km as well as emerging techniques to classify rarity of climates. ResultsThe number of cells for which inventory completeness could be calculated, as well as coverage of climate types by "well-sampled" cells, increased three-fold when using the combined set compared to the GBIF set. Improvements to sampling in Central and Western Africa were particularly striking. Coverage of rare climates was similarly improved, as not a single well-sampled cell from the GBIF data alone occurred in the rarest climate types. Inclusion of further records from natural history collections increased the total number of occurrences, but also filled persisting spatial and environmental data gaps on GBIF. Main conclusionsThese findings support existing literature that suggests data gaps on GBIF are still pervasive, especially for insects and in the tropics and, so, is not yet ready to serve as a standalone data source for all taxa. Biases in spatial coverage of records translate to uneven sampling of environmental conditions, hindering our ability to describe the full breadth of species niches, especially so in climates that occur infrequently. However, we show that natural history collections hold the necessary information to fill many of these gaps, and their further digitisation should be a priority.

zoology↗

bioRxiv2024

Aridity and coexistence with vascular plants determine the dynamics of coastal dune bryophyte communities

The bryophyte communities of Atlantic coastal dunes help stabilising these habitats by promoting nutrient fixation, contributing to soil consolidation and enhancing water retention. Because of climate change and sea level rise, negative impacts on this dune vegetation have already been recorded, including habitat loss, shifts in species distribution and the spread of invasive bryophyte species. Moreover, in this stressful environment, biotic interactions may play a key in shaping plant diversity at these scales. We characterised coastal dune vegetation in 32 sampling sites along a latitudinal aridity gradient across the western Iberian Atlantic. We aimed to assess the potential interactions among moss species and between mosses and vascular plants, and analyse their relationship with abiotic factors to explain the community dynamics of dune bryophytes, and forecast how these communities may respond to climate change. Our results showed that the moss community is mainly influenced by aridity and temperature, with biotic interactions playing a minor, yet significant, role. As aridity increases, moss cover in these dune environments will decrease, and interactions with other plants are unlikely to compensate for this decline, thus in a climate change scenario we expect a decrease in coastal bryophyte community as well as the ecosystem services they provide; simultaneously the spread of the alien moss species Campylopus introflexus, linked to lower aridity, may also slow down. Consequently, the changing climate will shift optimal conditions for moss species to higher latitudes, pushing competition further north

ecology↗

bioRxiv2023

Shaken, not shifted: Genotypic variation tunes how interspecific competition shapes niches

Individual variation in resource use as well as in the response to competitors has been recognized as playing an important role is species interactions. Still, we have as yet little information on whether such responses have a genetic basis as well as on how they affect each other. Here, we tested whether 20 genetically inbred lines of the spider mite Tetranychus evansi vary in their response to a gradient of cadmium concentration within plants as well as in their propensity to reshape niches when facing interspecific competition along this gradient. In absence of interspecific competitors, most lines were negatively affected by cadmium, albeit often in a non-linear fashion. Morevoer, half of the lines exhibited changes in the curvature of the relationship between number of females and cadmium concentration when facing competition with the congeneric T. urticae. Inbred lines also showed a shallower decay in offspring number along the cadmium gradient in presence of interspecific competition. Our findings provide evidence for large, partly genetic, variation in resource use and in the response to interspecific competition in heterogeneous environments. Moreover, we show that genotype responses to interspecific competition is contingent upon their response to an environmental gradient. Together, our results thus emphasize the importance of considering intraspecific variation in responses to interspecific competition, providing novel insights to link intra- and interspecific levels of biodiversity.

ecology↗

bioRxiv2020

Multidimensionality in the thermal niches of dung beetles could limit species' responses to temperature changes

Understanding the consequences of climate change requires understanding how temperature controls species responses across key biological aspects, as well as the coordination of thermal responses across these aspects. We study the role of temperature in determining the species diel, seasonal, and geographical occurrence, using dung beetles as a model system. We found that temperature has relatively low -but not negligible- effects in the three spatiotemporal scales, once accounting for alternative factors. More importantly, the estimated thermal responses were largely incongruent across scales. This shows that species have multidimensional thermal niches, entailing that adjustments to fulfil temperature requirements for one biological aspect, such as seasonal ontogenetic cycles, may result in detrimental effects on other aspects, like diel activity. These trade-offs can expose individuals to inadequate temperatures, reducing populations performance. Paradoxically, the relatively weak effects of temperature we found may have serious consequences for species responses to warming if temperature regulates essential aspects of species biology in divergent ways.

ecology↗

bioRxiv2017

Pleistocene climate change and the formation of regional species pools

This preprint has been reviewed and recommended by Peer Community In Evolutionary Biology (https://doi.org/10.24072/pci.evolbiol.100053). Despite the description of bioregions dates back from the origin of biogeography, the processes originating their associated species pools have been seldom studied. Ancient historical events are thought to play a fundamental role in configuring bioregions, but the effects of more recent events on these regional biotas are largely unknown. We use a network approach to identify regional and sub-regional faunas of European Carabus beetles, and analyse the effects of dispersal barriers, niche similarities and phylogenetic history on their configuration. We identify a transition zone matching the limit of the ice sheets at Last Glacial Maximum. While southern species pools are mostly separated by dispersal barriers, in the north species are mainly sorted by their environmental niches. Strikingly, most phylogenetic structuration of Carabus faunas occurred during the Pleistocene. Our results show how extreme recent historical events -such as Pleistocene climate cooling, rather than just deep-time evolutionary processes, can profoundly modify the composition and structure of geographic species pools.

ecology↗