Intraspecific functional traits and stable isotope signatures of ground-dwelling ants across an elevational gradient

Abstract

● Ant morphological traits (dry mass, head length, body size and leg length) increased with elevation.

● Ant δ¹³C increased with elevation, whereas δ¹⁵N did not.

● Ant δ¹³C values correlated positively with soil C:N ratio.

Understanding the responses of species to changing climates is becoming increasingly urgent. Investigating the effects of climate change on the functional traits of species at the intraspecific level is particularly important. We used elevation gradients as proxies for climate change to explore the intraspecific responses of two ground-dwelling ant species, Ectomomyrmex javanus and Odontoponera transversa, from 100 to 700 m.a.s.l. within a subtropical evergreen broadleaf forest. Our study addressed the specific relationships among environmental factors, trait variations, and trophic levels. Key functional traits such as dry mass, head length, body size, and leg length exhibited a general increase with elevation. Using stable isotope signatures (δ¹³C and δ¹⁵N), we quantified shifts in diets and trophic positions along the elevation gradients. Notably, our data revealed a significant elevation-related increase in Ant δ¹³C, whereas δ¹⁵N exhibited no such correlation. Moreover, Ant δ¹³C values of E. javanus demonstrated a negative correlation with mean annual temperature (MAT), and the δ¹³C values of both species correlated positively with soil C:N ratio. Having revealed that the individual traits and δ¹³C signatures of ground-dwelling ants exhibit significant negative correlations with temperature, our findings suggest that climate warming has the potential to cause intraspecific variation in the functional traits and diets of ground-dwelling ants and possibly other insect species.

Graphical abstract

Keywords

altitude / ant / climate change / stable isotope / trophic position

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