Artículos científicos

URI permanente para esta colecciónhttp://10.0.96.45:4000/handle/11056/14821

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A New Hybrid of Serpocaulon (Polypodiaceae) from Costa Rica
(Bio One Research Evolved, 2013) Rojas Alvarado, Alexander; Chaves-Fallas, José Miguel
A new hybrid Serpocaulon 3 sessilipinnum A. Rojas & J.M. Chaves is described. The new taxon has characters intermediate between S. fraxinifolium (Jacq.) A.R. Sm. and S. ptilorhizon (Christ) A.R. Sm., which are related mainly with leaf size, rhizome scales, shape and division of blade, shape and width of pinnae, number of areolae and sori series, and shape and color of spores
Áreas protegidas de Costa Rica: Fragmentación, tamaño y forma
(Instituto Centroamericano para la investigación en biología y conservación, 2011-10) Sandoval Hernández, Iván; Castillo Chinchilla, Maikol
La reducción en el tamaño del hábitat y la fragmentación ha sido considerada como una de las principales causas de extinción de las especies. Como una estrategia para disminuir el efecto de los procesos de fragmentación en Costa Rica se crearon Áreas Protegidas (AP), como una medida de mitigación a procesos de fragmentación que sufrió el país. Se realizó un análisis de la base de datos de áreas protegidas del Atlas Digital de Costa Rica y se calculó el tamaño (Ha), perímetro, área, la medida del vecino más cercano y los índices de Forma Euclidiana de las AP de Costa Rica. Encontramos que las AP de Costa Rica presentan tamaños variables (1331 Ha en Reservas Naturales Absolutas, hasta 621039 Ha en Parques Nacionales). El índice de forma MSI, varió desde 1 en áreas con formas geométricas (Reservas Naturales Absolutas), hasta a 20 (Reservas indígenas con conformas más complejas). La dimensión fractal presentó valores bajos (1.18 a 1.28), lo cual indica que las áreas protegidas de Costa Rica tienden a las formas geométricas y no fractales. El índice perimetral varió de 3 a 33, lo cual indica que las áreas protegidas tienen formas compactas, con una alta exposición a los efectos de la matriz. La distancia general entre las AP es de 17161 metros. Con excepción de algunos parques nacionales, pocas áreas protegidas presentan tamaños grandes, los cuales se requieren para el mantenimiento de procesos naturales y dinámicos en paisajes con algún grado de fragmentación.
Assessment of methods for predicting eukaryotic promoter sequences
(IEEE, 2023) Jiménez Oviedo, Byron; Arroyo Hernández, Jorge; Solano-González, Stefany
Identifying promoters is challenging due to their short sequences, low conservation, and complex regulation. Historically, this was done through slow and expensive experimental methods. Efficient pattern recognition and statistical approaches have revolutionized this process, offering a faster and more cost-effective solution. Accurate promoter identification is vital for experimental biologists and biotech applications, enabling precise gene expression regulation. This document evaluates traditional machine learning methods (SVM, MLP, LDA, PSFN and denseNet) for promoter recognition, confirming their suitability. Our methodology consisted of using a partition of 80 to 20 percent for data training and analysis, respectively. The former was used to optimize the parameters at a k-fold with k = 10 by cross-validation; after optimization, the parameters were used to analyze the 20 percent of data. The F1 metric score is a positive predictive value that calculates the precision and sensitivity. Therefore, our findings align with [2] as the F1 metric score was above 85% in SVM and both PSFN methods, affirming them as the most reliable options for promoter prediction. The objective was to find a method that accurately validates the prediction of promoters and non-promoters by a comparison of methods. To achieve this, we incorporated sequences from humans, which are validated with these characteristics, to apply this workflow to sequences from other organisms in the future.
Beta diversity and oligarchic dominance in the tropical forests of Southern Costa Rica
(Blackwell Publishing Ltd, 2019-03) Morera-Beita, Albert; Sánchez, Damián; Wanek, Wolfgang; Hofhansl, Florian; Werner, Huber; Chacón-Madrigal, Eduardo; Montero Muñoz, Jorge L.; Silla, Fernando
Recent studies have reported a consistent pattern of strong dominance of a small subset of tree species in neotropical forests. These species have been called “hyperdominant” at large geographical scales and “oligarchs” at regional-landscape scales when being abundant and frequent. Forest community assembly is shaped by environmental factors and stochastic processes, but so far the contribution of oligarchic species to the variation of community composition (i.e., beta diversity) remains poorly known. To that end, we established 20.1-ha plots, that is, five sites with four forest types (ridge, slope and ravine primary forest, and secondary forest) per site, in humid lowland tropical forests of southwestern Costa Rica to (a) investigate how community composition responds to differences in topography, successional stage, and distance among plots for different groups of species (all, oligarch, common and rare/ very rare species) and (b) identify oligarch species characterizing changes in community composition among forest types. From a total of 485 species of trees, lianas and palms recorded in this study only 27 species (i.e., 6%) were nominated as oligarch species. Oligarch species accounted for 37% of all recorded individuals and were present in at least half of the plots. Plant community composition significantly differed among forest types, thus contributing to beta diversity at the landscape scale. Oligarch species was the component best explained by geographical and topographic variables, allowing a confident characterization of the beta diversity among tropical lowland forest stands
Biological treatments affect the chemical composition of coffee pulp
(Elsevier, 2003-02-16) Ulloa Rojas, Juan B.; Verreth, J.A.; Amato, S.; Huisman, E.A.
Biological treatments were applied to fresh coffee pulp (CoP) to improve its nutritive value for monogastric animals by reducing its content of cellulose and antinutritional factors (ANFs) such as total phenols, tannins and caffeine. Treatments were: (1) ensiling with 0, 50 and 100 g kg 1 molasses for 2 and 3 months, (2) aerobic decomposition for 0, 7, 14, 21, 28, 35 and 42 days, (3) aerobic bacterial inoculation (Bacillus sp.) for 0, 7, 14, 21 and 28 days. Ensiled CoP (E-CoP) showed higher fat and ash contents than oven dried-CoP (OD-CoP; P < 0:05). Similarly, true protein values tended to increase. The cellulose and total phenols levels of E-CoP were lower than OD-CoP (P < 0:05). The E-CoP tannins levels tended to be lower than OD-CoP whereas caffeine levels remained unaffected. Improvement in the nutritional quality of E-CoP was associated with higher fat and protein contents and reduction of cellulose, total phenols and tannins. The aerobic decomposition treatment improved the nutritional quality of CoP by increasing true protein and fat contents. In addition, total phenols, tannins, caffeine and cellulose contents were reduced by an increase in treatment time (P < 0:05). Bacterial treatment increased the protein content of CoP after 21 days (from 137 to 392 g kg 1) and decreased it after 28 days. Cellulose, total phenols, tannins and caffeine contents reduced with an increase in time of bacterial degradation. Bacterial treatment improved the CoP quality by increasing protein content and reducing cellulose and ANFs, es pecially after 21 days of treatment. Both the aerobic decomposition (after 21–28 days) and the aerobic bacterial degradation of CoP (after 21 days) appeared more suitable to improve the nutritional quality of CoP than the ensiling. 2003 Elsevier Science Ltd. All rights reserved
Biotransformation and oxidative stress responses in fish (Astyanax aeneus) inhabiting a Caribbean estuary contaminated with pesticide residues from agricultural runoff
(Springer (Alemania), 2023) Mena, Freylan; Vargas, Seiling; Guevara-Mora, Meyer; Vargas-Hernández , José Mauro ; Ruepert, Clemens
The estuarine ecosystem of Madre de Dios Lagoon (MDL), in the Caribbean Coast of Costa Rica, is exposed to contamination with pesticide residues coming from the upstream agricultural areas. Biomarkers can provide a better indication of the fitness of biota in real mixture exposure scenarios than traditional lethal dose toxicity measurements. Here, we measured biomarkers of biotransformation, oxidative stress, and neurotoxicity on Astyanax aeneus, an abundant fish species in MDL. Glutathione S-transferase activity (GST), catalase activity (CAT), lipid peroxidation (LPO), and cholinesterase activity (ChE) were measured in fish collected during seven sampling campaigns, carried out between 2016 and 2018. Pesticide residues were analyzed in surface water samples collected every time fish were sampled. Residues of 25 pesticides, including fungicides, insecticides, and herbicides, were detected. The biomarkers measured in A. aeneus varied along the sampling moments, with biotransformation and oxidative stress signals showing a coupled response throughout the assessment. Furthermore, significant correlations were established between three biomarkers (GST, LPO, and CAT) and individual pesticides, as well as between GST and LPO with groups of pesticides with shared biocide action. Among pesticides, insecticide residues had a major influence on the responses observed in fish. This work demonstrates the chronic exposure to pesticide residues in MDL and how such exposure is related to physiological responses in fish that can affect their health and potentially, the trophic networks. This early warning information should be considered to improve the protection of estuarine ecosystems in the tropics.
Body mass explains digestive traits in small vespertilionid bats
(Springer Science and Business Media Deutschland GmbH, 2021-02-11) Cabrera Campos, Iván; Carballo Morales, Jorge; Saldaña-Vázquez, Romeo A.; Villalobos Brenes, Federico; Araya Berdon, Jorge
Bats are unique among mammals in that they have evolved the capacity to fly. This has generated strong selective pressure on the morphology and function of their digestive system. Given that in bats intestinal length and nominal surface-area are proportional to body mass, this trait importantly relates to explaining some of their digestive characteristics. We described the relationship between digestive traits and body mass of four species of bats of the family Vespertilionidae living in a montane ecosystem in central Mexico. We calculated food transit time, apparent dry matter digestibility, and defecation rate in feeding trials under captive conditions. We also: (1) built a model of the relationship between digestive traits and body mass to determine if this association was consistent within the members of the family Vespertilionidae, and (2) mapped these traits along the phylogeny to explore how digestive characteristics may have evolved. In our feeding trials, body mass was positively related to transit time and negatively related to apparent dry matter digestibility. The model predicted accurately the transit time in bats with body mass < 20 g. The phylogenetic approach suggested that over the evolutionary history of the family, transit time decreased as digestibility increased. Because of the results obtained here, it is likely that for most bats of the family Vespertilionidae, adaptations in digestive traits to process food have followed evolutionary changes in their body mass. We discuss these findings in a physiological and ecological context.
Bovine spongiform encephalopathy risk management in Latin America: Costa Rica as a representative country for risk management and policy
(Inderscience Enterprises Ltd., 2010) Wilson, Margaret A.; Herrera-Ulloa, Angel; Krewski, Daniel; Tyshenko, Michael
Costa Rica is a representative Latin American country with significant regional cattle production for its size. The country experienced an exceedingly low challenge for bovine spongiform encephalopathy (BSE) as evidenced by no direct meat and bone meal imports from the UK, few imported cattle, no specified risk materials imports from high risk countries, and cattle that are entirely grass-fed. In addition, there is little domestic feed recycling or potential for amplification and the country has further improved its tracing of imported cattle. Risk management to control both internal and external BSE risk factors has been implemented in Costa Rica, and it has negligible risk for domestic BSE. Costa Rica has complied with World Organisation for Animal Health (OIE) surveillance standards. To date Costa Rica has not reported any cases of either BSE or variant Creutzfeldt-Jakob disease (vCJD).
Caracterización del paisaje y análisis del límite oeste del Parque Nacional Carara, Costa Rica: implicaciones para la conservación de la biodiversidad
(Museo Nacional de Costa Rica, 2012) Quesada-Acuña, Sergio Gabriel; Valdelomar, Valerie; Arrieta Ch, Cristina; Ruíz Morales, Gustavo; Matarrita Herrera, Miguel Angel; Araya G., José Fabio; Sandoval Hernández, Iván
It is unknown if the current size and shape of protected areas (PA) in Costa Rica favors retention of viable populations of wildlife. The western border of Carara National Park (CNP) and its surroundings were characterized at a landscape level in order to consider their implications for biodiversity conservation. 54 400 hectares of Costa Rican Central Paciic tree cover were analyzed (1997, 2000, 2005) to calculate the size of the PAs, mean shape index, mean patch fractal dimension and edge density. Aside from that, we performed eight habitat evaluations on the western border of the CNP (“costanera-sur” highway) to assess tree composition, regeneration, litter, horizontal obstruction, and canopy cover. It was determined that the PAs were between 36 and 5 242 hectares long. We observed that the tree cover increased from 21 231,8 hectares in 1997 to 29 006,9 hectares in 2000, and decreased to 26 933,4 hectares in 2005. We found out that most of the tree cover (2005) belongs to CNP and ZP Cerros de Turrubares, but both of them present high values of edge density and mean shape index, suggesting that they are susceptible to alteration and fragmentation. The four evaluated points have a similar successional stage. In order to maintain the potential of CNP as an area for biodiversity conservation, we recommend reducing the maximum speed limit in the region adjacent to the park. It is also important to establish frequent monitoring of the tree cover and promote reforestation programs to create corridors that stop the area’s fragmentation and facilitate biodiversity conservation.
Caracterización hidrogeoquímica de los acuíferos volcánicos Bar va y Colima en el Valle Central de Costa Rica
(Instituto Mexicano de Tecnología del Agua, Tecnología y ciencias del agua, 2016) Madrigal-Solís, Helga; Fonseca-Sánchez, Alicia; Reynolds-Vargas, Jenny
La composición química del agua subterránea está determinada por procesos antropogénicos y por interacciones con el material geológico que conforma el acuífero. El presente estudio describe la caracterización hidrogeoquímica de los acuíferos volcánicos Barva y Colima, en el Valle Central de Costa Rica, con el fin de ampliar el conocimiento acerca de las interacciones entre ambos acuíferos y determinar si hay alguna evolución desde las zonas altas hasta las más bajas del acuífero Barva. Se realizaron de 1 a 9 campañas de muestreo en 51 sitios entre los años 2002 y 2004, y se analizaron los nitratos e iones mayoritarios. Las aguas del Barva y Colima se clasificaron como del tipo bicarbonatada mixta, con excepción de un sitio. Se encontró un aumento de bicarbonatos, cloruros, calcio, magnesio, sodio y potasio desde las partes altas hasta las partes bajas del acuífero Barva, probablemente por procesos de disolución natural de las rocas y lixiviación de iones provenientes de actividades antropogénicas. En el caso de los nitratos, se encontró una mediana de 0.2 mg/l de NO3 -N en el sector de mayor altitud, mientras que en las partes de altitud mediana y baja, las medianas aumentaron a 3.6 y 5.3 mg/l, respectivamente. Sin embargo, el sector al suroeste de la zona de estudio presentó un aumento únicamente en bicarbonatos y sodio con respecto a la zona de menor altitud del acuífero Barva y, por el contrario, se encontraron concentraciones relativamente bajas de nitratos, con una mediana de 1.1 mg/l de NO3 -N. En comparación con el acuífero Barva, el Colima presentó concentraciones más bajas de nitratos en sitios sobreyacidos por el acuífero Barva, por lo que se concluye que los nitratos provenientes de fuentes antrópicas son diluidos en este acuífero antes de su posible percolación hacia el Colima. Se recomienda mantener programas de monitoreo permanentes para evaluar posibles aumentos en las concentraciones de nitratos en ambos acuífero
Cloning, purification and characterization of nigrelysin, a novel actinoporin from the sea anemone Anthopleura nigrescens
(Elsevier B.V., 2019) Alvarado Mesén, Javier; Solano-Campos, Frank; Canet, Liem; Pedrera, Lohans; Hervis, Yadira P.; Soto, Carmen; Borbon Alpizar, Henry; Lanio, María Eliana; Lomonte, Bruno; Valle, Aisel; Alvarez, Carlos
Actinoporins constitute a unique class of pore-forming toxins found in sea anemones that being secreted as soluble monomers are able to bind and permeabilize membranes leading to cell death. The interest in these proteins has risen due to their high cytotoxicity that can be properly used to design immunotoxins against tumor cells and antigen-releasing systems to cell cytosol. In this work we describe a novel actinoporin produced by Anthopleura nigrescens, an anemone found in the Central American Pacific Ocean. Here we report the amino acid sequence of an actinoporin as deduced from cDNA obtained from total body RNA. The synthetic DNA sequence encoding for one cytolysin variant was expressed in BL21 Star (DE3) Escherichia coli and the protein purified by chromatography on CM Sephadex C-25 with more than 97% homogeneity as verified by MS-MS and HPLC analyses. This actinoporin comprises 179 amino acid residues, consistent with its observed isotope-averaged molecular mass of 19 661 Da. The toxin lacks Cys and readily permeabilizes erythrocytes, as well as L1210 cells. CD spectroscopy revealed that its secondary structure is dominated by beta structure (58.5%) with 5.5% of a-helix, and 35% of random structure. Moreover, binding experiments to lipidic monolayers and to liposomes, as well as per meabilization studies in vesicles, revealed that the affinity of this toxin for sphingomyelin-containing membranes is quite similar to sticholysin II (StII). Comparison by spectroscopic techniques and modeling the three-dimensional structure of nigrelysin (Ng) showed a high homology with StII but several differences were also detectable. Taken together, these results reinforce the notion that Ng is a novel member of the actinoporin pore-forming toxin (PFT) family with a HA as high as that of StII, the most potent actinoporin so far described, but with peculiar structural characteristics contributing to expand the understanding of the structure-function relationship in this protein family.
Comparison of amino acid profiles of feeds and fish as a quicic metiiod for selection of feed ingredients: a case study for Colossoma mactopomum (Cuvier)
(John Wiley & Sons, 1996) van der Meer', M B; Verdegem, M C J
The amino acid profile of Colossoma macropomum was determined. Indispensable amino acid levels were sim ilar to those reported in other fish species. Suitability of local. Costa Rican, ingredients as protein sources for C. macropomum was evaluated based on their pro tein content and indispensable amino acid profile. It was calculated that, in a standard diet (40% protein, 25% fish meal), blood meal, soya meal, poultry by products, meat and bone meal, and meat meal can substitute more than 80% of the fish meal. More than 40% of the fish meal can be substituted by shrimp meal, pigeon pea, cotton meal, peanut oU cake, cow pea, corn gluten and water hyacinth. As differences between amino acid profiles between fish species seem to be small, promising alternative ingredients for C. macropomum might be equally interesting for formulation of feeds for other species. Soya meal is thecurrently used ingredient with the highest potential to substitute fish meal completely. Further research is needed to determine if the use of alternative ingredients is limited by constraints such as decreased feed digesti bility, presence of anti-nutritional factors, additional production and processing costs.
Cooling, cryoprotectant and hypersaline sensitivity of penaeid shrimp embryos and nauplius larvae
(Elsevier, 2001-10-23) Alfaro-Montoya, Jorge; Komen, J.; Huisman, E.A.
The sensitivity of embryos of the penaeid shrimp, Trachypenaeus byrdi, to cooling, cryoprotec tant exposure dimethyl sulfoxide : DMSO, sucrose, methanol and glycerol , and hypersaline Ž . treatment was assessed in order to gain basic knowledge for cryopreservation procedures. In addition, cooling and DMSO exposure was evaluated in Penaeus stylirostris and T. byrdi nauplii. Morulae and advanced embryos setae development stage showed tolerance to cooling at 10 Ž . 8C, but were very sensitive to 08C exposure. Methanol exposure at 128C up to 2 M, was non-toxic for advanced embryos. DMSO toxicity was intermediate; no statistical decrease in survival Ž . P)0.05 was measured at 0.5 M. Sucrose and glycerol were toxic to both embryo stages over 0.25 and 0.5 M, respectively. Morulae were more resistant to hypersaline treatment at 55 ppt than advanced embryos. Nauplii showed a better tolerance to cooling and DMSO exposure than embryos. These findings are being applied to develop a cryogenic protocol for penaeid embryos. q 2001 Elsevier Science B.V. All rights reserved.
Cultivation potential of Vanilla crop wild relatives in two contrasting land use systems
(Elsevier (Países Bajos), 2023-09) Watteyn, Charlotte; Reubens, Bert; Azofeifa Bolaños, José Bernal; Solano-Campos, Frank; Pérez Silva, Araceli; Karremans, Adam; Muys, Bart
Vanilla is an important cash crop for many smallholder farmers around the tropics, and a highly appreciated spice used in a wide range of products. The crop species Vanilla planifolia is, however, facing a number of threats that are jeopardizing a stable vanilla supply. The neotropical realm holds at least 37 fragrant Vanilla species besides V. planifolia. These so-called Vanilla crop wild relatives (CWRs) possibly possess interesting traits for crop improvement and market diversification, but received meager attention so far. The aim of our study was therefore to provide insights into the cultivation potential of four Vanilla CWRs (Vanilla hartii, V. odorata, V. pompona and V. trigonocarpa) naturally growing within our study region in southern Costa Rica, by comparing their plant performance and aromatic profiles with V. planifolia and a commercially used hybrid, and this in two types of land use systems where vanilla could possibly be introduced. As such, we established six field sites in secondary forests (SF), adding economic value to these often undervalued ecosystems, and six in existing cacao plantations (CP), diversifying monocrop agrosystems. First, we measured plant survival, vitality and growth over a period of two years, and compared these plant performance traits among Vanilla species and land use systems using (generalized) additive mixed models. The models also enabled us to observe possible effects of additionally measured, site-specific environmental variables on vanilla plant performance. Second, we evaluated the aromatic potential of Vanilla CWR pods using high-performance liquid chromatography. We found that the hybrid had the highest overall plant vitality and growth, and this in both CPs and SFs, while V. planifolia was characterized by a rather low vitality, but high growth rates, and clearly performed inferior in SFs. The CWRs had a good overall vitality, and this in the two land use systems, but were characterized by lower growth rates compared to the hybrid and V. planifolia. The aromatic profiles of the Vanilla CWR pods indicated potential for market diversification, with V. odorata highly resembling the profile of the commercially used species. The other CWRs had varied profiles, with especially V. hartii containing high anisyl contents interesting for niche markets. Based on our assessment of Vanilla CWR plant performance and aromatic profiles, we see potential for their integration within the two studied land use systems. Corresponding planting designs should, however, take into account species-specific light intensity preferences, monitor chemical properties and the presence of growth-promoting and disease-suppressive soil microbiota, and incorporate vanilla tutor and shade trees with optimal functional traits. We developed a possible vanilla cultivation design that could be implemented for further evaluation in terms of production feasibility.
Development and Deterioration of Spermatophores in Pond-Reared Penaeus vannamei
(World aquaculture society, 1993) Alfaro, Jorge; Lozano, Xenia
Spermatophore deterioration in pond-reared Penaeus vannamei was studied, and spermatophore quality was evaluated and improved. Sperm production of males collected from grow-out ponds was increased by two techniques: eyestalk ablation using a fresh frozen maturation diet (13% body weight); and laboratory culture using a diet of the formulated feed Nicovita Plus (3% body weight/ d) and frozen squid (2%). Findings are complementary to previous reports that eyestalk ablation improves quality of spermatophores in young (25.7 g) males. The timing of eyestalk ablation for activation of the endocrine mechanism, leading to improved spermatophore quality was also ex plored. After eyestalk ablation, performed between postmolt and intermolt stages, 26 g males required a minimum of three spermatophore regenerations or 42 d to significantly increase sper matophore size and sperm count. On the other hand, the laboratory culture (2.5 mo) technique improved the quality of spermatophores in successive regenerations for non-ablated males. In the present study, subadult P. vannamei produced spermatophores which, if not transferred or manually ejaculated, gradually deteriorated (successive stages are described), while a new compound sper matophore was being synthesized.
Dietary resource overlap among three species of frugivorous bat in Costa Rica
(Cambridge University Press, 2019-05-03) Maynard, Lauren; Ananda, Ariana; Sides, Maria Fernanda; Burk, Hannah; Whitehead, Susan
The maintenance of biodiversity in tropical forests is thought to be dependent on fine-scale mechanisms of niche partitioning that allow species to coexist. This study examined whether three species of short-tailed fruit bat that co-occur at a lowland tropical forest site in Costa Rica (Carollia castanea, C. perspicillata, C. sowelli) avoid inter- and intraspecific competition through dietary specialization on species in the genus Piper. First, dietary composition was examined using faecal samples (N = 210), which yielded three main findings: (1) bat species and sexes vary in overall reliance on fruits of Piper, with a higher percentage of seeds of Piper detected in the diets of C. castanea (98.2%) and females (91.5%); (2) adults and juveniles partition species of Piper by habitat, with a lower percentage of mid- to late-successional species of Piper detected in adults (20.8%); and (3) overall, there is a strong dietary overlap among and within the three species of Carollia. Second, controlled choice experiments were conducted with individual bats (N = 123) to examine preferences for different species of Piper. These results indicated few differences in Piper preference based on bat species, sex, age class or reproductive status, suggesting preference is not the primary mechanism shaping the observed differences in dietary composition. Overall, the dietary composition and preference similarities suggest there is strong competition both among and within the three species of Carollia for food resources.
Disadvantages of living in a populous neighborhood for sit-andwait predators: Competition for space reduces pit-trap size in antlion larvae
(Blackwell Publishing Ltd, 2020-11-01) Farji-Brener, Alejandro Gustavo; Juncosa Polzella, Agostina Silvia; Madrigal-Tejada, Daniela; Centeno-Alvarado, Diego; Hernández-Soto, Mariana; Soto-Huaira, Mayori; Gutiérrez-Cruz, Sebastián
The study of how trap design responds to biotic and abiotic conditions can help to understand the selective forces affecting the foraging of trap-building organisms. We experimentally tested whether pit design can be modified by intraspecific competition for space in larvae of Myrmeleon crudelis, a common sit-and-wait predator that digs conical pit traps in the soil to capture walking arthropods. In a tropical forest in Costa Rica, we measured pit dimensions, larval body size, and the level of competition (i.e., density of neighboring traps) in 40 antlion larvae. These larvae were then taken to the laboratory and allowed to build new traps in individual containers. We measured within-individual changes in the size of traps in the field and in the laboratory, and related these to the level of competition experienced in the field. Larvae with relatively high levels of competition in the field showed a greater increase in the size of their pits in the laboratory. This change was independent of larval size. Larvae with none or few neighbors in the field showed little change in their pit sizes, whereas those with higher competition levels increased their diameter and depth up to 1,400% and 1,000%, respectively. Our results demonstrate that, at least in high-density aggregations, pit design is restricted by competition in addition to the constraints imposed by body size. This work suggests that biotic interactions can play a role in the design of extended phenotypes in sit-and-wait predators that live in dense aggregations
Dolphin sympatric ecology in a tropical fjord: habitat partitioning by bathymetry and topography as a strategy to coexist
(Cambridge University Press, 2007) Oviedo Correa, Lenin Enrique
Sympatric species need to avoid pervasive competition to counter its suppressor effects. Dietary divergence and habitat partitioning are strategies for coexistence. Golfo Dulce is a tropical fjord located in the southern Pacific waters of Costa Rica. This embayment is characterized by the mixture of neritic and oceanic-like features. Sympatric populations of spotted and bottlenose dolphins share this particular marine ecosystem. To analyse the means of coexistence among both dolphin populations, an approach using the marginality and specialization indices of ecological niche factor analysis was used to establish separation between realized niches of both species. Habitat partitioning is sustained by difference in habitat use; bathymetry and topography separated both species’ ecological niches. Dietary divergence could not be concluded because of lack of accurate dietary information. Nevertheless, it is likely to be separated by consumption of demersal prey by Tursiops truncatus, and pelagic prey by Stenella attenuata, accordingly with the differences in habitat use. Golfo Dulce could be perceived as an area of conservation importance: a geographical unit considered to contain special conservation values for both dolphin species.
Downward but stable trend in the abundance of arribada olive ridley sea turtles (Lepidochelys olivccea) at Nancite Beach, Costa Rica (1971-2007)
(Chelonian Research Foundation, 2009) Fonseca, Luis G.; Murillo, Grettel A.; Guadamúz, Lenín; Spínola, Romeo M.; Valverde, Roldán A.
Although the olive ridley sea turtle (Lepidochelys olivacea) is the most abundant sea turtle in the world, the species has exhibited a significant decrease in the size of arribadas at Nancite Beach, Costa Rica, since its discovery in 1970. In the present study, we compiled data on number of nesting females per arribada from previous authors for the period 1971–1997 and collected new data using a total count methodology and a strip transect method for the arribadas during 1999–2007. We used generalized additive models to assess the trend of arribada size for the period 1971–2007. Our data indicate a significant reduction of 42%, 84%, and 90% in the number of nesting females per arribada in the periods 1971–1984, 1971–1992, and 1971–2007, respectively. Although we could not determine the specific reasons for this attrition we speculate that this decline may be driven by embryo-associated mortality due to a poor nest microenvironment in this beach. Our data confirm that the Nancite arribada population has undergone a significant decrease over the past 36 years but that the population currently appears to be at a stable low point. In addition, our data show that hatchling production may be increasing at this beach, which suggests the possibility that this population may recover over a few decades. The significant attrition observed in this study underscores the ephemeral nature of arribada populations in general and the need for the continued monitoring of the Nancite population.
Ecoregions occupied are more related to diet diversity than body mass in Artibeina bats
(BioOne Digital Library, 2022-02-14) Saldaña-Vázquez, Romeo A.; Villalobos Brenes, Federico; Hernández-Montero, Jesús Rafael; Ferreyra García, Daniel; MOLINA-RODRÍGUEZ, JOSÉ P.
Abstract. Understanding the factors that explain animals' diet diversity is important to comprehend niche partitioning, co-existence, biotic interactions, and the vulnerability of species populations to habitat transformation. Species body mass and their geographical range are positively related to the diversity of food items they consume and consequently with their potential ecological niche occupied. However, the relative weight of these factors to explain diet diversity in mammals is poorly known. Using Artibeina frugivorous bats as a biological model, we evaluate the importance of body mass and ecoregions occupied to explain the diet diversity of these bats. We analyzed our data using phylogenetic correlations and Bayesian statistics techniques. Our results show a stronger phylogenetic correlation between bats' diet diversity with the number of ecoregions they occupied than with their body mass. These results suggest Neotropical frugivorous bats that occupy different habitats had a major possibility to have a higher diet diversity. In addition, these results are related with the 'bottom-up' diet diversity hypothesis that postulates that diet diversity in frugivorous bats is related to ecosystem plant diversity.

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