Ecological Niche Modelling Approaches: Challenges and Applications in Vector-Borne Diseases

Abstract

Vector-borne diseases (VBDs) pose a major threat to human and animal health, with more than 80% of the global population being at risk of acquiring at least one major VBD. Being profoundly affected by the ongoing climate change and anthropogenic disturbances, modelling approaches become an essential tool to assess and compare multiple scenarios (past, present and future), and further the geographic risk of transmission of VBDs. Ecological niche modelling (ENM) is rapidly becoming the gold-standard method for this task. The purpose of this overview is to provide an insight of the use of ENM to assess the geographic risk of transmission of VBDs. We have summarised some fundamental concepts and common approaches to ENM of VBDS, and then focused with a critical view on a number of crucial issues which are often disregarded when modelling the niches of VBDs. Furthermore, we have briefly presented what we consider the most relevant uses of ENM when dealing with VBDs. Niche modelling of VBDs is far from being simple, and there is still a long way to improve. Therefore, this overview is expected to be a useful benchmark for niche modelling of VBDs in future research.

Keywords: climate change; ecological niche models; global change; mosquito-borne diseases; neglected tropical diseases; species distribution models; tick-borne diseases.

Figure 1

Representation of the Hutchinson’s duality between the geographical and environmental spaces occupied by Hyalomma marginatum tick, the main vector of the Crimea-Congo virus [48] (occurrence records were downloaded from the VectorMap data portal [http://www.vectormap.si.edu], accessed on 24 February 2023, and https://doi.org/10.5061/dryad.2h3f2, accessed on 24 February 2023). Worldwide (a) and detailed (b) geographical distribution of the H. marginatum tick (red dots); (c) distribution in the environmental space (as defined by mean annual temperature and annual precipitation) of the environmental combinations available worldwide (grey dots, 100,000 random locations chosen worldwide), and the environmental space occupied by the H. marginatum tick (red dots, 475 non-duplicated georeferenced records).

Figure 2

Representation of the environmental spaces available in (a) continental Spain (yellow dots), and in (b) the Canary Islands (light green dots) as defined by mean annual temperature and annual precipitation. The blue dots represent the environmental space occupied by the Hyalomma marginatum tick as restricted to the boundaries of continental Spain (77 non-duplicated occurrence records), whereas the red dots represent the environmental space occupied by its global occurrences (475 non-duplicated occurrence records). (a) A niche model of the H. marginatum tick, based solely on the occurrences in continental Spain (blue dots), will truncate the lower limit of the species’ thermal tolerance. Most of these boundary-restricted occurrences (blue dots) have been recorded in areas with mean annual temperatures superior to 13 °C (blue dashed line), while the species withstands mean annual temperatures as lower as 6 °C (red dots, red dashed line). Thus, a projected distribution based on this truncated niche model will underestimate those environments available in Spain with mean annual temperatures between 6 °C and 13 °C (between red and blue dashed lines). (b) A similar situation will occur if this same truncated niche model should be transferred to the Canary Islands to identify areas suitable for the establishment of H. marginatum populations. Such a model will fail to predict those areas in Canary Islands presenting mean annual temperatures between 6 °C and 13 °C (between red and blue dashed lines).