Examinando por Autor "Hidalgo, Pamela"

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    Assessing the food web structure of the mesozooplankton community in the highly variable coastal upwelling system of the southeast Pacific
    (Elsevier, 2025) Cabrera-Nunez, Susana; Fernandez-Urruzola, Igor; Bode, Antonio; Hernandez-Trujillo, Sergio; Hidalgo, Pamela; Escribano, Ruben
    Zooplankton are a key component in the food web of highly productive coastal upwelling systems linking primary producers to higher trophic levels. However, the complex taxonomy, wide size spectrum, and diverse trophic behaviors of zooplankton make it challenging to characterize their food web structure. This study proposes a Trophic Behavior Index (TBI) to assess the trophic structure of zooplankton and test the hypothesis that key biological attributes such as body size, diel vertical migration (DVM) behavior and trophic interactions, rather than environmental factors, primarily shape the food web dynamics of mesozooplankton communities. To this end, we analyzed depth-stratified daytime and nighttime samples of mesozooplankton collected from the upper 900 m at three oceanographically contrasting stations in the Southeast Pacific upwelling system. Vertical gradients in temperature, chlorophyll-a and dissolved oxygen were examined in relation to zooplankton abundance and composition, their DVM behavior, biomass size spectra and trophic position. The proposed TBI was constructed from zooplankton body size assessed by automated image analysis, DVM amplitude and trophic position of taxonomic groups derived from nitrogen stable isotope composition. This index was then compared across environmental conditions, allowing the classification of mesozooplankton into four major trophic functional groups: low predators (primary consumers), moderate predators, strong predators and top predators (very strong predators). Variability in oceanographic conditions influenced the zooplankton community composition and size spectrum; however, our findings suggest that zooplankton body size, DVM behavior and trophic position are the primary determinants of trophic structure. This is reflected in the relative abundance of functional groups, with strong and very strong predators prevailing in offshore areas, whereas the coastal zone was dominated by primary consumers and moderate predators. Overall, our findings support the TBI as a robust community descriptor of zooplankton trophic structure across highly variable oceanographic settings.
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    Environmental Stability Drives and Maintains the Global Patterns of Phylogenetic Endemism in the Marine Realm
    (Wiley, 2025) Rivera, Reinaldo; Gonzalez, Carolina E; Hidalgo, Pamela; Urbina, Mauricio A; Escribano, Ruben
    Aim: Endemism is a critical aspect of biological diversity, yet the mechanisms driving it remain unclear. The leading hypoth-esis posits that prolonged environmental stability fosters speciation and reduces extinction rates, promoting endemism. Whileterrestrial studies exist, marine environments remain underexplored. This study analysed the global distribution and drivers ofphylogenetic endemism in two marine taxa: Calanidae copepods and Blenniidae fish.Location: Global.Time Period: From the Last Glacial Maximum (LGM, past 24,000 years) to the current period.Taxa: Calanidae copepods and Blenniidae fish.Methods: We assessed taxonomic and phylogenetic diversity, endemism and areas of paleo- and neo-endemism usingCategorical Analysis of Neo- and Paleo-Endemism and Piecewise Structural Equation Modelling to evaluate the influence ofpresent-day and historical environmental variables.Results: Results showed consistent diversity patterns and significant endemism hotspots, with Calanidae in the SouthernHemisphere and Blenniidae in the Northern Hemisphere. Tropical regions, particularly the Indonesian-Australian Archipelago(IAA), exhibited high species richness and endemism for both groups. Paleo- endemism was observed in the Pacific for Calanidaeand the IAA for Blenniidae, suggesting that these areas are either relict diversity centres or diversification hubs.Main Conclusions: The Mediterranean and Caribbean Seas emerged as biodiversity cradles for Calanidae and Blenniidae re-spectively. Phylogenetic endemism is driven by both historical and contemporary factors, with centres of endemism emergingin regions where past environmental fluctuations have been moderate (hypothesis 1) and where cold, productive ocean currentsfoster the development of endemic areas (hypothesis 2). These findings underscore the importance of historical stability in oceantemperatures in shaping phylogenetic endemism, indicating that long-term environmental stability sustains marine endemism