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RESUMEN Las garzas que se reproducen en colonias presentan requerimientos ecológicos similares e intensifican sus relaciones interespecíficas. Sin embargo, estas especies pueden coexistir al segregarse temporal y espacialmente. Se estimó el número de nidos de ocho especies de garzas (Ardea alba, Egretta thula, E. caerulea, E. tricolor, E. rufescens, Bubulcus ibis, Nycticorax nycticorax y Cochlearius cochlearius) durante la temporada reproductiva marzo a agosto de 2018 en Isla Pájaros, Laguna Mar Muerto, Oaxaca-Chiapas, México. Así mismo, se estimaron las abundancias de las parejas reproductoras, el patrón temporal y espacial de reproducción por especie, y se describió el sitio de anidación. Se contaron nidos en 96 parcelas y se midieron ocho variables ambientales. Se registraron 1018 nidos, donde B. ibis presentó el mayor número de parejas reproductoras (299), seguida por E. tricolor (213) y E. thula (142). Las especies menos abundantes fueron C. cochlearius (35) y E. caerulea (33). La distribución de los nidos en la isla varió espacial y temporalmente entre parcelas al igual que la composición de especies y la abundancia de nidos por parcela (P < 0,001). Se registró una distribución vertical en la construcción de los nidos de al menos tres especies, mientras que las cuatro garcitas de similar tamaño (E. thula, E. caerulea, E. tricolor y B. ibis) anidaron juntas en las partes intermedias. Se registraron agrupaciones entre las especies y características de la vegetación. Los patrones de distribución espacial y temporal de estas especies permiten entender el uso de un recurso común durante la reproducción. ABSTRACT Herons that breed in colonies have similar ecological requirements and intensify their interspecific relationships. However, these species can coexist by segregating temporally and spatially. In this study, the number of nests from eight species of herons (Ardea alba, Egretta thula, E. caerulea, E. tricolor, E. rufescens, Bubulcus ibis, Nycticorax nycticorax, and Cochlearius cochlearius) was estimated during the breeding season from March to August 2018 in Isla Pájaros, Mar Muerto Lagoon, Oaxaca-Chiapas, Mexico. Likewise, the number of breeding pairs, the temporal, and the spatial pattern of reproduction by species were estimated, and the nest sites were described. Nest were counted in 96 plots and eight environmental variables were measured. A total of 1018 nests were recorded, with B. ibis having the highest number of breeding pairs (299), followed by E. tricolor (213) and E. thula (142). The least abundant species were C. cochlearius (35) and E. caerulea (33). Nest distribution on the island was heterogeneous and varied spatial and temporally among plots as did species composition and nest abundance per plot (P < 0.001). A vertical distribution in the nest construction of at least three species was recorded on the island, while the four egrets of similar size (Egretta thula, E. caerulea, E. tricolor, and Bubulcus ibis) nested together in middle parts of the mangrove. Clusters among species and vegetation characteristics were recorded. The spatial and temporal distribution patterns of these species allow us to understand the use of a common resource during reproduction.

Both earthworms and terrestrial isopods have been used to evaluate the quality of contaminated soil by NPs. However, most experiments have been conducted in the laboratory and under greenhouse conditions. Besides, little is known of Fe accumulation in earthworms from iron NPs (Fe NPs) under natural conditions. Therefore, the objective of this research was to evaluate the effect of manufactured NPs on the accumulation of Fe in macroinvertebrates from forest soil. Our results revealed that earthworms consume low amounts of Fe in a concentration of 1000 mg Fe NPs kg−1 of dry soil, with a behavior constant over time. Besides, we observed that earthworms could not detect Fe at low concentrations (1 or 10 mg Fe NPs kg−1), so they do not limit soil consumption, which translates into high amounts of Fe in their bodies. By contrast, the content of Fe in organisms is inversely proportional to increasing concentrations in the soil (R2 = -0.41, p < 0.05). Therefore, although studies are needed, in addition to considering environmental factors and the physicochemical properties of the soil, endogenous worms in the evaluated area could, under natural conditions, be useful to inform us of contamination of NP manufactured from Faith. Besides, for future research, a novel methodology should be considered to demonstrate more realistic avoidance behavior under field conditions., Agricultural Science; Agricultural Soil Science; Environmental Science; Soil Science; Environmental Impact Assessment; Environmental Pollution; Environmental Toxicology; soil pollution; Nanoparticles earthworm's avoidance; nanotoxicology; Iron oxides; Clitellata; Soil organisms; Eisenia fetida; nanoremediation

Guarianthe skinneri (Bateman) Dressler & W.E. Higgins, is a native orchid from Mexico, considered as threatened species in the NOM-ECOL-059-SEMARNAT-2010, mainly due to the disappearance of its natural habitat and illegal collection during the flowering season. The aim of this research was to induce in vitro callogenesis using different types of explants and phytoregulators, in order to establish a mass production technique as a contribution to the conservation of this species. We evaluated leaf and pseudobulb pith explants growing in semi-solid medium MS, adding BAP, 2, 4-D, Kin, the combination of BAP/2 and 4-D/Kin/Sad and a control without any type of plant growth regulators. Statistical analysis showed that pseudobulb pith explants are more suitable for in vitro callus induction in comparison to leaf explants, because of a lower percentage of contamination (18.8% in pith and 73.2% in leaves). Likewise, the pseudobulb pith explants showed increased callus formation (10.8%) in comparison to leaf explants (7.6%). Regarding the phytoregulators employed, BAP promoted increased callus formation (17%) compared to other phytoregulators (7-10%). This is the first report of the use of pseudobulb pith as an explant for callus induction in G. skinneri. Resumen: Guarianthe skinneri (Bateman) Dressler & W.E.Higgins, es una especie de orquídea nativa de México catalogada como amenazada por NOM-ECOL-059-SEMARNAT-2010, sobre todo por la desaparición de su hábitat natural y las colectas ilegales durante su floración. El objetivo del trabajo fue inducir la callogénesis in vitro en explantes de Guarianthe skinneri mediante reguladores del crecimiento vegetal, con la finalidad de iniciar investigaciones orientadas al establecimiento de una estrategia de propagación in vitro, mediante embriogénesis somática u organogénesis indirecta, con la cual pudiera eventualmente producirse plantas que puedan satisfacer la demanda local de esta planta sin alterar las poblaciones silvestres y con ello contribuir a su conservación. Se utilizaron explantes de hoja y médula de pseudobulbo en medio semisólido MS con los fitorreguladores BAP, 2,4-D, Kin, la interacción de BAP/2,4-D/Kin/Sad y un testigo sin hormonas vegetales. El análisis estadístico mostró que los explantes de médula son más aptos para la introducción in vitro en comparación a los de hoja, debido a que presentan menores porcentajes de contaminación (18.8% en médulas y 73.2% en hojas). Así mismo, los explantes de médula indujeron mayor formación de callo (10.8%) en comparación con los de hoja (7.6%). La BAP propició mayor formación de callo (17%) en comparación con los otros fitorreguladores (7-10%). Este es el primer reporte que propone el uso de médula de pseudobulbo como explante para la inducción callogénica de G. skinneri.

Guarianthe skinneri (Bateman) Dressler and W.E. Higgins, is a native orchid from Mexico, considered as threatened species in the NOM-ECOL-059-SEMARNAT-2010, mainly due to the disappearance of its natural habitat and illegal collection during the flowering season. The aim of this research was to induce in vitro callogenesis using different types of explants and phytoregulators, in order to establish a mass production technique as a contribution to the conservation of this species. We evaluated leaf and pseudobulb pith explants growing in semi-solid medium MS, adding BAP, 2, 4-D, Kin, the combination of BAP/2 and 4-D/Kin/Sad and a control without any type of plant growth regulators. Statistical analysis showed that pseudobulb pith explants are more suitable for in vitro callus induction in comparison to leaf explants, because of a lower percentage of contamination (18.8% in pith and 73.2% in leaves). Likewise, the pseudobulb pith explants showed increased callus formation (10.8%) in comparison to leaf explants (7.6%). Regarding the phytoregulators employed, BAP promoted increased callus formation (17%) compared to other phytoregulators (7-10%). This is the first report of the use of pseudobulb pith as an explant for callus induction in G. skinneri. Guarianthe skinneri (Bateman) Dressler and W.E. Higgins., is a native orchid from Mexico, considered as threatened species by NOM-ECOL-059-SEMARNAT-2010, mainly due to the disappearance of its natural habitat and the illegal collection during its flowering season. The aim of this research was to induce in vitro callogenesis from different type of explants, using phytoregulators, in order to look for a massive production technique to contribute to its conservation. We evaluated the leaf and pseudobulb marrow explants growing in semi-solid medium MS adding BAP, 2, 4-D, Kin, the interaction of BAP/2, 4-D/Kin/Sad and a control without any type of plant growth regulators. Statistical analysis showed the pseudobulb marrow explants are more suitable for in vitro introduction in comparison to leaf explants, since they perform a lower percentage of contamination (18.8% in marrow and 73.2% in leaves). Likewise, the pseudobulb marrow explants increased callus formation (10.8%) in comparison to leaf explants (7.6%). Regarding the phytoregulators employed, BAP have allowed to increased callus formation (17%) compared to other phytoregulators (7-10%). This is the first report, which proposes the use of pseudobulb marrow as explant for callus induction in G. skinneri.

Se define un proceso-U como una colección de estadísticas-U, con índices una familia de núcleos simétricos.