# Thermal tolerance and heritability in dune-dwelling ants reveal bioindicator potential for climate vulnerability in coastal ecosystems

## TL;DR

This study explores how dune-dwelling ants respond to thermal stress, identifying one species as a potential indicator of climate vulnerability in coastal ecosystems.

## Contribution

The study introduces a novel integration of thermal tolerance metrics and heritability estimates to assess bioindicator potential in coastal ant species.

## Key findings

- M. simplex has significantly lower thermal tolerance compared to diurnal relatives.
- Colony identity explains a large portion of thermal tolerance variance in M. simplex.
- M. simplex is suggested as a bioindicator of thermal vulnerability due to limited resilience.

## Abstract

Climate change is expected to intensify thermal stress in coastal ecosystems, threatening biodiversity and ecosystem functioning. In this study, we investigate species-specific and colony-level variation in thermal tolerance among three psammophilous ant species (Mycetophylax spp.) inhabiting Brazilian coastal dunes. Using critical thermal limits (CTmin and CTmax), linear mixed-effects models, and heritability estimates, we assessed the role of diel activity rhythms and genetic structure in shaping thermal performance. Results revealed that M. simplex, a nocturnal and substrate-specialized species, exhibited significantly lower CTmin and CTmax values compared to diurnal congeners, and that colony identity explained a substantial portion of variance (H² = 0.53 for CTmin, H² = 0.39 for CTmax). These findings suggest limited thermal resilience and evolutionary constraints in M. simplex, reinforcing its potential as a bioindicator of thermal vulnerability. Given projected warming and habitat disturbance in southeastern Brazil, we highlight the importance of integrating functional traits and genetic metrics into environmental monitoring and conservation planning.

The online version contains supplementary material available at 10.1007/s00484-025-03081-5.