A Systematic Review of Global Drivers of Ant Elevational Diversity

Abstract

Ant diversity shows a variety of patterns across elevational gradients, though the patterns and drivers have not been evaluated comprehensively. In this systematic review and reanalysis, we use published data on ant elevational diversity to detail the observed patterns and to test the predictions and interactions of four major diversity hypotheses: thermal energy, the mid-domain effect, area, and the elevational climate model. Of sixty-seven published datasets from the literature, only those with standardized, comprehensive sampling were used. Datasets included both local and regional ant diversity and spanned 80° in latitude across six biogeographical provinces. We used a combination of simulations, linear regressions, and non-parametric statistics to test multiple quantitative predictions of each hypothesis. We used an environmentally and geometrically constrained model as well as multiple regression to test their interactions. Ant diversity showed three distinct patterns across elevations: most common were hump-shaped mid-elevation peaks in diversity, followed by low-elevation plateaus and monotonic decreases in the number of ant species. The elevational climate model, which proposes that temperature and precipitation jointly drive diversity, and area were partially supported as independent drivers. Thermal energy and the mid-domain effect were not supported as primary drivers of ant diversity globally. The interaction models supported the influence of multiple drivers, though not a consistent set. In contrast to many vertebrate taxa, global ant elevational diversity patterns appear more complex, with the best environmental model contingent on precipitation levels. Differences in ecology and natural history among taxa may be crucial to the processes influencing broad-scale diversity patterns.

Ground-Dwelling and Vegetation Ant Fauna in Southern Brazilian Grasslands

“…Since the geographic area in Pampa is larger and the sampled sites were spatially further apart, there is indeed more heterogeneity of associated habitat conditions (e.g. soil types, vegetation physiognomies, plant richness; Streck et al, 2008;Ferreira et al, unpublished data) and thus a higher probability of finding a richer associated ant community in the Pampa. Ant fauna composition was also singular between these grassland regions (sharing only 43% of the total richness), and community structure based on dominant species also shifts regarding number of dominant species and their identity.…”

The truncated bell: an enigmatic but pervasive elevational diversity pattern in Middle American ants

“…Several taxa or functional groups have emerged as frequent subjects of diversity studies. Among insects, ants are commonly studied because they are a dominant component of ecosystems, they are diverse, and species-level identification is increasingly possible (Wilson and Hölldobler 2005, Szewczyk and McCain 2016, Tiede et al 2017). Here we report diversity patterns of leaf-litter ants in wet forests of the Middle American corridor.…”

“…A general approach has been to apply linear models, with richness as the response variable, and multiple predictor variables (temperature, precipitation, area, mid-domain effect). Szewczyk and McCain (2016) reviewed 20 studies of ant diversity on elevational gradients. The most common pattern was an asymmetrical mid-elevation peak in diversity, with the peak below the midpoint of the gradient.…”

Spatial distribution of butterfly (Lepidoptera: Papilionoidea) along altitudinal gradients at Gunung Ledang National Park, Johor, Malaysia

“…Even though the butterfly fauna in this study is also lower than those recorded from higher mountains in Borneo such as Gunung Mulu National Park (276 species) [12] and Kinabalu National Park (625 species) [11], the species accumulation curves (Fig. 7) especially for elevations of 400 m and 800 m still exponentially increased, which suggested that there was an expectation to discover more species at each of these elevations with intensive samplings (more individuals sampled, more sampling time and larger size of study areas) [6]. In fact, more than half of the species found in this study were singletons and doubletons.…”