Areas of endemism of the orchids of Megamexico: Hotspots of biotic interactions with pollinators

Abstract

Ecological interactions and evolutionary processes in areas of endemism remain little studied despite the fact that identifying the patterns of functional signatures in areas of endemism could reveal important information regarding community assembly and functioning. Here, we investigated whether areas of endemism of the orchids of Megamexico are hotspots of biotic interactions by comparing the orchid–pollinator interactions with those of adjacent areas. Patterns of functional signatures and phylogenetic signal were estimated, using pollination syndromes as a proxy for functional attributes. Phylogenetic signal was estimated by coding pollinator groups for every orchid recorded. Metrics of the interaction networks and the phylogenetic signal were compared with those obtained from adjacent areas. Our results indicate that areas of endemism show higher significant differences in the phylogenetic signal compared with adjacent areas. This can be explained by the many distantly related orchid lineages sharing attributes related to pollination. Network size and robustness differed statistically between the areas of endemism and the adjacent areas. The same configuration of modules in interaction networks was found in the areas of endemism; however, remarkably, the composition of species in large genera differed in these areas. Areas of endemism harbor more orchid lineages that closely interact with many groups of insects. The southerly areas of endemism in Chiapas and Central America are prominent, with the most significant phylogenetic signal and networks metrics. Results indicate that areas of endemism for the orchids of Megamexico represent hotspots of biotic interactions. Strategies for conservation must take this biotic interaction into account.