Browsing by Author "Alfaro, Fernando D."
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- ItemBacterial community structure in a sympagic habitat expanding with global warming: brackish ice brine at 85-90 degrees N(2019) Fernández Gómez, Beatriz; Díez, Beatriz; Polz, Martin F.; Arroyo González, José Ignacio; Alfaro, Fernando D.; Marchandon, Germán; Sanhueza, Cynthia; Farías, Laura; Trefault Carrillo, Nicole Natalie; Marquet, P. A. (Pablo A.); Molina Montenegro, Marco A.; Sylvander, Peter; Snoeijs-Leijonmalm, Pauline
- ItemExclusion of small mammals and lagomorphs invasion interact with human-trampling to drive changes in topsoil microbial community structure and function in semiarid Chile(2018) Alfaro, Fernando D.; Manzano, Marlene; Abades T., Sebastián R.; Trefault Carrillo, Nicole Natalie; De la Iglesia Cabezas, Rodrigo Alonso; Gaxiola Alcantar, Aurora; Marquet, P. A. (Pablo A.); Gutiérrez, Julio R.; Meserve, Peter L.; Kelt, Douglas A.; Belnap, Jayne; Armesto, Juan J.
- ItemHigh-frequency monitoring of hydrological and biogeochemical fluxes in forested catchments of southern Chile(2021) Frene, Cristian; Armesto, Juan J.; Veliz, Freddy; Alfaro, Fernando D.; Weathers, Kathleen C.The variability of rainfall-dependent streamflow at catchment scale modulates many ecosystem processes in wet temperate forests. Runoff in small mountain catchments is characterized by a quick response to rainfall pulses which affects biogeochemical fluxes to all downstream systems. In wet-temperate climates, water erosion is the most important natural factor driving downstream soil and nutrient losses from upland ecosystems. Most hydrochemical studies have focused on water flux measurements at hourly scales, along with weekly or monthly samples for water chemistry. Here, we assessed how water and element flows from broad-leaved, evergreen forested catchments in southwestern South America, are influenced by different successional stages, quantifying runoff, sediment transport and nutrient fluxes during hourly rainfall events of different intensities. Hydrograph comparisons among different successional stages indicated that forested catchments differed in their responses to high intensity rainfall, with greater runoff in areas covered by secondary forests (SF), compared to old-growth forest cover (OG) and dense scrub vegetation (CH). Further, throughfall water was greatly nutrient enriched for all forest types. Suspended sediment loads varied between successional stages. SF catchments exported 455 kg of sediments per ha, followed by OG with 91 kg/ha and CH with 14 kg/ha, corresponding to 11 rainfall events measured from December 2013 to April 2014. Total nitrogen (TN) and phosphorus (TP) concentrations in stream water also varied with rainfall intensity. In seven rainfall events sampled during the study period, CH catchments exported less nutrients (46 kg/ha TN and 7 kg/ha TP) than SF catchments (718 kg/ha TN and 107 kg/ha TP), while OG catchments exported intermediate sediment loads (201 kg/ha TN and 23 kg/ha TP). Further, we found significant effects of successional stage attributes (vegetation structure and soil physical properties) and catchment morphometry on runoff and sediment concentrations, and greater nutrients retention in OG and CH catchments. We conclude that in these southern hemisphere, broad-leaved evergreen temperate forests, hydrological processes are driven by multiple interacting phenomena, including climate, vegetation, soils, topography, and disturbance history.
- ItemInsights into the Gut Microbiome of the South American Leaf-Toed Gecko (Phylodactylus gerropygus) Inhabiting the Core of the Atacama Desert(2024) Rivera, Daniela S.; Beltran, Valentina; Gutierrez-Cortes, Ignacio; Vargas, Constanza; Alfaro, Fernando D.Living in arid environments presents unique challenges to organisms, including limited food and water, extreme temperatures, and UV exposure. Reptiles, such as the South American leaf-toed gecko (Phyllodactylus gerrhopygus), have evolved remarkable adaptations to thrive in such harsh conditions. The gut microbiome plays a critical role in host adaptation and health, yet its composition remains poorly characterized in desert reptiles. This study aimed to characterize the composition and abundance of the gut microbiome in P. gerrhopygus inhabiting the hyperarid Atacama Desert, taking into account potential sex differences. Fecal samples from adult female and male geckos were analyzed by 16S rRNA gene amplicon sequencing. No significant differences in bacterial alpha diversity were observed between the sexes. However, the phylum Bacteroidota was more abundant in females, while males had a higher Firmicutes/Bacteroidota ratio. The core microbiome was dominated by the phyla Bacteroidota, Firmicutes, and Proteobacteria in both sexes. Analysis of bacterial composition revealed 481 amplicon sequence variants (ASVs) shared by female and male geckos. In addition, 108 unique ASVs were exclusive to females, while 244 ASVs were unique to males. Although the overall bacterial composition did not differ significantly between the sexes, certain taxa exhibited higher relative abundances in each sex group. This study provides insight into the taxonomic structure of the gut microbiome in a desert-adapted reptile and highlights potential sex-specific differences. Understanding these microbial communities is critical for elucidating the mechanisms underlying host resilience in Earth's most arid environments, and for informing conservation efforts in the face of ongoing climate change.
- ItemPlant communities on the islands of two Altiplanic Salt Lakes in the Andean region of Bolivia(2016) Coca-Salazar, Alejandro; Villca, Huber; Torrico, Mauricio; Alfaro, Fernando D.
- ItemSociality of Octodontomys gliroides and other octodontid rodents reflects the influence of phylogeny(2014) River, Daniela S.; Abades, Sebastian; Alfaro, Fernando D.; Ebensperger, Luis A.Multiple ecological factors are known to drive variation in social behavior. However, group-living in some species appears to be highly conserved, suggesting a phylogenetic influence. In this study, we evaluated both scenarios using intraspecific and interspecific comparisons across octodontid rodents. We first examined 2 different populations of Andean degu (Octodontomys gliroides), representing 2 extremes of a climate vegetation gradient across the Andes range. We evaluated how ecological variation in terms of abundance and distribution of food resources, predation risk, and burrowing costs predicted interpopulation variation in group size and range-area overlap (2 proxies of sociality). We estimated these measures of sociality from livetrapping and radiotelemetry. We then used phylogenetic methods to determine whether sociality exhibits a phylogenetic signal and reconstructed the ancestral state of sociality across the family Octodontidae. Overall activity of females and males of O. gliroides was greater during nighttime than daytime. Across populations we found significant differences in ecology, including abundance and distribution of food, predation risk, and burrowing costs. However, populations were similar in terms of group size and range-area overlap. The phylogenetic approach revealed a strong and significant phylogenetic signal associated with sociality, where this behavior was present early during the evolution of octodontid rodents. Together, these findings imply that sociality of O. gliroides is not linked to current population differences in ecology.
- ItemSoil bacterial community structure of fog-dependent Tillandsia landbeckii dunes in the Atacama Desert(Springer, 2021) Alfaro, Fernando D.; Manzano, Marlene; Almiray, Cristian; García B., Juan Luis; Osses, Pablo; Río López, Camilo del; Vargas Vásquez, Constanza Giovanna; Latorre H., Claudio; Koch, Marcus A.; Siegmund, Alexander; Abades, SebastianThe interplay between plants and soil drives the structure and function of soil microbial communities. In water-limited environments where vascular plants are often absent and only specialized groups of rootless plants grow, this interaction could be mainly asymmetric, with plants supporting nutrients and resources via litter deposition. In this study, we use observational approaches to evaluate the impact of local distribution of Tillandsia landbeckii across elevation on soil bacterial community structure and composition in the Atacama Fog Desert. Tillandsia landbeckii is a plant without functional roots that develops on meter-scale sand dunes and depends mainly on marine fog that transports resources (water and nutrients) from the Pacific Ocean. Our data show that soil bacterial abundance, richness, and diversity were significantly higher beneath T. landbeckii plants relative to bare soils. However, these differences were not significant across T. landbeckii located at different elevations and with different input of marine fog. On the other hand, bacterial community composition was significantly different with T. landbeckii plants across elevations. Further, samples beneath T. landbeckii and bare soils showed significant differences in bacterial community composition. Around 99% of all operational taxonomic units (OTUs) were recorded exclusively beneath T. landbeckii, and only 1% of OTUs were observed in bare soils. These findings suggest that the presence of T. landbeckii promotes significant increases in bacterial abundance and diversity compared with bare soils, although we fail to demonstrate that local-scale changes in elevation can affect patterns of soil bacterial diversity and abundance beneath T. landbeckii.
- ItemVegetation drives the response of the active fraction of the rhizosphere microbial communities to soil warming in Antarctic vascular plants(2022) Parada-Pozo, Genesis; Bravo, Leon A.; Saez, Patricia L.; Cavieres, Lohengrin A.; Reyes-Diaz, Marjorie; Abades, Sebastian; Alfaro, Fernando D.; De la Iglesia, Rodrigo; Trefault, NicoleIn the Antarctic Peninsula, increases in mean annual temperature are associated with the coverage and population density of the two Antarctic vascular plant species-Deschampsia antarctica and Colobanthus quitensis-potentially modifying critical soil processes. In this study, we characterized the diversity and community composition of active microorganisms inhabiting the vascular plant rhizosphere in two sites with contrasting vegetation cover in King George Island, Western Antarctic Peninsula. We assessed the interplay between soil physicochemical properties and microbial diversity and composition, evaluating the effect of an in situ experimental warming on the microbial communities of the rhizosphere from D. antarctica and C. quitensis. Bacteria and Eukarya showed different responses to warming in both sites, and the effect was more noticeable in microbial eukaryotes from the low vegetation site. Furthermore, important changes were found in the relative abundance of Tepidisphaerales (Bacteria) and Ciliophora (Eukarya) between warming and control treatments. Our results showed that rhizosphere eukaryal communities are more sensitive to in situ warming than bacterial communities. Overall, our results indicate that vegetation drives the response of the active fraction of the microbial communities from the rhizosphere of Antarctic vascular plants to soil warming.