Galls and host occurrences along a forest gradient in Sierra Juárez, Oaxaca, Mexico

This study evaluates the abundance and environmental factors that regulate the regional distribution (hosts and study sites) and specific distribution (microhabitat oviposition) of the galls in the Sierra Juárez, Oaxaca, Mexico. During dry and wet periods, eleven sampling sites, the presence and abundance of galls were examined.. Ecological niche analysis was performed to relate gall niche occurrence/breadths with geographical and climaticgradients at two levels: regional distribution and specific distribution. Oak had the highest number of galls as compared to pines. Among the oaks, the Queráis section recorded twice the amount of galls (9 ±2.14) than the Lobatae section (4.7 ± 2.19). As for the specific distribution level, over 70 % of the galls were located both at the underside of leaves and at primary stem. We believe that abundance and distribution of galls and hosts could be associated with climatic factors. It was found that galls are highly sensitive to climatic and geographical changes. Galls are also attached to specific host structures for their survival. Climatic changes and structural disturbance can generate a crisis of co-extinction.