Authors:J. Gallardo-Cruz, J. Meave, E. Pérez-García and J. Hernández-Stefanoni
The importance of space as an ecological factor is an emerging paradigm in community ecology, particularly as a driving force of biodiversity patterns. We analysed β-diversity linked to spatial structure in four communities (tropical dry forest, savanna, xerophytic vegetation, subdeciduous forest) that occur in a tropical complex landscape of southern Mexico. The landscape was described through an object-oriented classification of a Quickbird satellite image. The classification revealed a highly heterogeneous spatial arrangement of the four communities. Global (landscape-level) β-diversity was 0.12 (mean Sørensen index), a value smaller than those observed for the individual communities (0.20–0.41). By using multivariate classic and partial Mantel tests, and Mantel correlograms based on two distance classes, we analysed β-diversity spatial variation related to landscape configuration. The Mantel statistic values for the four communities combined were negative and very similar both for the classic Mantel (rM = −0.23) and the partial Mantel test (rM = −0.19). Correlograms proved significant spatial autocorrelation across most of the analysed distance classes, except in the case of riparian subdeciduous forest. Tropical dry forest and savanna occupy large, highly connected areas in the landscape. Correlograms for these two communities showed decreasing trends, starting at positive, significant autocorrelation values at short distances. The loss of floristic autocorrelation beyond a 5000 m distance for the tropical dry forest may reflect spatially autocorrelated dispersal, and thus a dispersal-limited community. Xerophytic vegetation displayed a distinctly different correlogram, with a wavy shape showing an alternation of positive and negative values, in agreement with the insular configuration of this community in the landscape. We suggest that the routinely incorporation of a spatial approach in community ecology research will help in furthering our understanding of the elusive issues of species turnover across space.
Authors:F.A. Rodríguez-Zaragoza, M. Ortiz, F. Berrios, L. Campos, A. de Jesús-Navarrete, J. Castro-Pérez, A. Hernández-Flores, M. García-Rivas, F. Fonseca-Peralta and E. Gallegos-Aguilar
Banco Chinchorro is the largest reef in the Mexican Caribbean. Historically, spiny lobster, queen conch and over 20 other reef species have been exploited here. Multispecies intervention management from an ecosystem perspective has been developed in this area; however, an assessment of the effects of such practices on ecosystem health is required. Five quantitative trophic models were constructed using Ecopath with Ecosim. The results show that, in terms of biomass, benthic autotrophs are the dominant group in all communities. Ecosystem Network Analysis indices showed that Cueva de Tiburones was the most mature, developed, complex and healthy subsystem, but, El Colorado and La Baliza were the subsystems most resistant to disturbances. The fisheries mainly concentrate on primary (La Baliza and Cueva de Tiburones sites) and secondary consumers (La Caldera, Chancay, and El Colorado). The greatest propagation of direct and indirect effects, estimated by Mixed Trophic Impacts and Ecosim simulations, were generated by the benthic autotrophs, small benthic epifauna, benthic-pelagic carnivorous fish and benthic carnivorous fish, among others. In contrast, the System Recovery Time showed different patterns among subsystems, indicating several compartments that reduce resilience. Considering the structure, dynamics, trophic functioning and ecosystem health of Banco Chinchorro, its ecological heterogeneity highlights the need for the design of a specific (by subsystem) management strategy, particularly because different species or functional groups present greater sensitivity to human interventions in each community.
Authors:Guilherme Borges, Ricardo Orozco, Corina Benjet, Kalina I. Martínez Martínez, Eunice Vargas Contreras, Ana Lucia Jiménez Pérez, Alvaro Julio Peláez Cedrés, Praxedis Cristina Hernández Uribe, María Anabell Covarrubias Díaz Couder, Raúl A. Gutierrez-Garcia, Guillermo E. Quevedo Chavez, Yesica Albor, Enrique Mendez, Maria Elena Medina-Mora, Philippe Mortier and Hans-Juergen Rumpf
Background and aims
DSM-5 includes Internet gaming disorder (IGD) as a condition for further study. While online and offline gaming may produce undesired negative effects on players, we know little about the nosology of IGD and its prevalence, especially in countries with emerging economies.
A self-administered survey has been employed to estimate prevalence of DSM-5 IGD and study the structure and performance of an instrument in Spanish to measure DSM-5 IGD among 7,022 first-year students in 5 Mexican universities that participated in the University Project for Healthy Students (PUERTAS), part of the World Health Organization’s World Mental Health International College Student Initiative.
The scale for IGD showed unidimensionality with factor loadings between 0.694 and 0.838 and a Cronbach’s α = .816. Items derived from gaming and from substance disorders symptoms mixed together. We found a 12-month prevalence of IGD of 5.2% in the total sample; prevalence was different for males (10.2%) and females (1.2%), but similar for ages 18–19 years (5.0%) and age 20+ (5.8%) years. Among gamers, the prevalence was 8.6%. Students with IGD were more likely to report lifetime psychological or medical treatment [OR = 1.8 (1.4–2.4)] and any severe role impairment [OR = 2.4 (1.7–3.3)]. Adding any severe role impairment to the diagnostic criteria decreased the 12-month prevalence of IGD to 0.7%.
Discussion and conclusions
Prevalence of DSM-5 IGD and the performance of diagnostic criteria in this Mexican sample were within the bounds of what is reported elsewhere. Importantly, about one in every seven students with IGD showed levels of impairment that would qualify them for treatment under DSM-5.