Ecological profiles of harvestmen (Arachnida, Opiliones) from Vitosha Mountain (Bulgaria): A mixed modelling approach using GAMS

The present study is based on a large-scale sampling program carried out in the area of Vitosha Mountain (Bulgaria). The ecological profiles of the Opiliones inhabiting the investigated area are modelled by a mixed approach, using Generalized Additive Models (GAMs) over a Multiple Correspondeuce Analysis (MCA, performed on the sites by environmental variables matrix) ordination plot. According to the literature data describing the harvestmen species from Vitosha Mountain, the most important factor determining the ecological classification of the Opiliones is the habitat type. The modelled ecological profiles revealed that the elevation contributes the most to the ecological characterization of the Vitosha harvestmen species, followed by the habitat type and moisture regime of the sampling localities. Few harvestmen species demonstrate preferences to the middle- and high-mountain zones, while the majority of harvestmen species are confined exclusively to the low-mountain zone. The different species showed different responses (most of them were linear. not unimodal) towards the environmental variables.