Global diversity in light of climate change: the case of ants

Abstract

Aim To use a fine-grained global model of ant diversity to identify the limits of our knowledge of diversity in the context of climate change.Location Global.Methods We applied generalized linear modelling to a global database of local ant assemblages to predict the species density of ants globally. Predictors evaluated included simple climate variables, combined temperature · precipitation variables, biogeographic region, elevation, and interactions between select variables. Areas of the planet identified as beyond the reliable prediction ability of the model were those having climatic conditions more extreme than what was represented in the ant database.Results Temperature was the most important single predictor of ant species density, and a mix of climatic variables, biogeographic region and interactions between climate and region yielded the best overall model. Broadly, geographic patterns of ant diversity match those of other taxa, with high species density in the wet tropics and in some, but not all, parts of the dry tropics. Uncertainty in model predictions appears to derive from the low amount of standardized sampling of ants in Asia, in Africa and in the most extreme (e.g. hottest) climates. Model residuals increase as a function of temperature. This suggests that our understanding of the drivers of ant diversity at high temperatures is incomplete, especially in hot and arid climates. In other words, our ignorance of how ant diversity relates to environment is greatest in those regions where most species occur -hot climates, both wet and dry.Main conclusions Our results have two important implications. First, temperature is necessary, but not sufficient, to explain fully the patterns of ant diversity. Second, our ability to predict ant diversity is weakest exactly where we need to know the most, the warmest regions of a warming world. This includes significant parts of the tropics and some of the most biologically diverse areas in the world.

Morphological structure of ant assemblages in tropical and temperate forests

“…Geographic distributions of ants are affected by a number of environmental characteristics; temperature and precipitation are usually the strongest direct and indirect correlates (Dunn et al 2009, Jenkins et al 2011, Gibb et al 2015a as they possibly affect the amount and distribution of available resources. We therefore tested the hypothesis that aspects of temperature variability and precipitation were important predictors of ant morphological structure.…”

“…Temperature and precipitation are considered drivers of ant species richness patterns at global scale (Dunn et al 2009, Jenkins et al 2011, Gibb et al 2015a) and recent studies also suggest a strong relationship between temperature and ant functional responses (Diamond et al 2012, Stuble et al 2013. Ant functional diversity decreased with reduced temperature in a high elevation gradient (Raymond et al 2013) and climate seasonality played an important role in shaping the occurrence of functional species traits in Mediterranean ant communities (Arnan et al 2014).…”

Assembling an ant community: species functional traits reflect environmental filtering

“…While previous studies have inferred that species distributions are driven by temperature at broader (Jenkins et al 2011;Kaspari et al 2000a, b;Lessard et al 2010) and Wner (Bestelmeyer 1997;Retana and Cerdá 2000;Spiesman and Cumming 2008) geographic scales, or shown that species Table 3 ModiWed fourth-corner analysis of the correlations between species traits and environmental variables for all and common species…”

“…Our work responds to a need for studies on physiological traits, especially thermal tolerance and desiccation resistance, and how they shape ant assemblages in hotter regions (Jenkins et al 2011); developing this understanding is pressing, given that climate models predict the expansion of extreme climate habitats. Climate warming could shift ant assemblage composition in currently moderate environments away from heat-intolerant species and towards heat-tolerant species.…”

Climate change impoverishes and homogenizes ants’ community structure: a long term study

“…In a series of different habitats, Jenkins et al (2011) found that temperature was the most important single predictor of global ant species density. Likewise, Botes et al (2006) showed that temperature explained significant proportions of the variation in species density and abundance in the Northern Cape Floristic Region, South Africa.…”