The present and likely past climatic distribution of the termite Microhodotermes viator in relation to the distribution of heuweltjies

Abstract

There is disagreement about the role of the termite Microhodotermes viator in heuweltjie formation. The attribution to faunal genesis is based on overlapping distributions of the fauna and mounds. We investigated this overlap and the degree to which present and past environmental factors explain distributions. We used georeferenced locations of M. viator and heuweltjies to construct Maxent species distribution models against climate, edaphic and topographic characteristics. We also used climate-hindcasts to retrodict past distributions to Holocene and Last Glacial Maximum (LGM) conditions. The distribution of heuweltjies is largely a sub-set (49% by area) of the distribution of M. viator. Our analysis indicated that M. viator distribution in the LGM and Holocene was similar to current. Models of heuweltjies distribution based on LGM climate associated heuweltjies with summer aridity and predicted the majority of the current distribution of the heuweltjies with high accuracy (AUC = 0.92), but failed to predict the eastern extent of the range. Heuweltjies in the east have previously been identified as bush clumps and may thus be currently forming, providing an extant model for the process of formation. We conclude that partial distribution overlaps do not imply causation of heuweltjies by M. viator.