The continuous increase in urbanization has been perceived as a major threat for biodiversity, particularly within tropical regions. Urban areas, however, may still provide opportunities for conservation. In this study focused on Macao (China), one of the most densely populated regions on Earth, we used a comprehensive approach, targeting all the vertical strata inhabited by ants, to document the diversity of both native and exotic species, and to produce an updated checklist. We then compared these results with 112 studies on urban ants to illustrate the dual roles of cities in sustaining ant diversity and supporting the spread of exotic species. Our study provides the first assessment on the vertical distribution of urban ant communities, allowing the detection of 55 new records in Macao, for a total of 155 ant species (11.5% being exotic); one of the highest species counts reported for a city globally. Overall, our results contrast with the dominant paradigm that urban landscapes have limited conservation value but supports the hypothesis that cities act as gateways for exotic species. Ultimately, we argue for a more comprehensive understanding of ants within cities around the world to understand native and exotic patterns of diversity.

Critical Thermal maximum (CT_max) is often used to characterize the upper thermal limits of organisms and represents a key trait for evaluating the fitness of ectotherms. The lack of standardization in CT_max assays has, however, introduced methodological problems in its measurement, which can lead to questionable estimates of species’ upper thermal limits. Focusing on ants, which are model organisms for research on thermal ecology, we aim to obtain a reliable ramping rate that will yield the most rigorous measures of CT_max for the most species. After identifying three commonly used ramping rates (i.e., 0.2, 0.5 and 1.0°C min^-1) in the literature, we experimentally determine their effects on the CT_max values of 27 species measured using dynamic assays. Next, we use static assays to evaluate the accuracy of these values in function of the time of exposure. Finally, we use field observations of species’ foraging activities across a wide range of ground temperatures to identify the most biologically relevant CT_max values and to develop a standardized method. Our results demonstrate that the use of a 1°C min^-1 ramping rate in dynamic assays yields the most reliable CT_max values for comparing ant species’ upper thermal limits, which are further validated in static assays and field observations. We further illustrate how methodological biases in physiological trait measurements can affect subsequent analyses and conclusions on community comparisons between strata and habitats, and the detection of phylogenetic signal (Pagel’s λ and Bloomberg’s K). Overall, our study presents a methodological framework for identifying a reliable and standardized ramping rate to measure CT_max in ants, which can be applied to other ectotherms. Particular attention should be given to CT_max values obtained with less suitable ramping rates, and the potential biases they may introduce to trait-based research on global warming and habitat conversion, as well as inferences about phylogenetic conservatism.

Despite its small size, Hong Kong hosts a surprising level of ant diversity. Through faunal studies on arthropods conducted in Hong Kong over recent years, a new record and species of the genus Ponera have been discovered, which are introduced here. Poneraguangxiensis Zhou, 2001 is reported for the first time from Hong Kong, and Poneratudigongsp. nov. is here described as a new species, easily distinguishable from other Ponera species and unique within the genus for its four mandibular teeth.

The Taiwanese species of the ant genus Technomyrmex are revised with recently collected material. Five species are recognised, three in the T. albipes species group and two in the T. bicolor species group, including one new species, T. formosensis sp. nov., and two newly recorded species. The occurrence of T. albipes, previous records of which were based on misidentifications, is confirmed for the first time in Taiwan. The structure of genitalia is compared between winged and wingless males of T. brunneus.

The assumption that differences in species' traits reflect their different niches has long influenced how ecologists infer processes from assemblage patterns. For instance, many assess the importance of environmental filtering versus classical limiting-similarity competition in driving biological invasions by examining whether invaders’ traits are similar or dissimilar to those of residents, respectively. However, mounting evidence suggests that hierarchical differences between species' trait values can distinguish their competitive abilities (e.g. for the same resource) instead of their niches. Whether such trait-mediated hierarchical competition explains invasions and structures assemblages is less explored. We integrate morphological, dietary, physiological and behavioural trait analyses to test whether environmental filtering, limiting-similarity competition or hierarchical competition explain invasions by fire ants on ant assemblages. We detect both competition mechanisms; invasion success is not only explained by limiting similarity in body size and thermal tolerance (presumably allowing the invader to exploit different niches from residents), but also by the invader's superior position in trait hierarchies reflecting competition for common trophic resources. We find that the two mechanisms generate complex assemblage-level functional diversity patterns—overdispersion in some traits, clustering in others—suggesting their effects are likely missed by analyses restricted to a few traits and composite trait diversity measures.

Under global warming, animal species show shrinking body size responses, cascading deep changes in community structure and ecosystem functions. Although the exact physiological mechanisms behind this phenomenon remain unsolved, smaller individuals may benefit from warming climate more than larger ones. Heat‐coma, a physiological state with severe consequences on locomotion ability, is often considered as an “ecological death” scenario under which individuals are unable to escape and exposed to predation, further heat injury, and other hazards. Species are expected to increasingly encounter heat‐coma temperature thresholds under warming climate, and body size may be an important trait for thermoregulation in particular for ectotherms. The relationship between heat‐coma and shrinking body size remains, however, unclear. Yet, recovery after short‐term heat‐coma is possible, but little is known about its importance in thermal adaptation and how organismal size correlates with post heat‐coma recovery. Here, using ants as a model system, we firstly examined the fate of heat‐comatose individuals under field conditions to quantify the ecological benefits of post heat‐coma recovery. Then, we quantified ants' recovery ability after heat‐coma using a dynamic thermal assay in the laboratory and asked if thermal resilience varies between species with different body mass. Our results confirm that heat‐coma represents an inherent ecological death where individuals failed to recover from coma suffer strong predation pressure. Additionally, following phylogenetic signals inclusion, organisms with small mass were more likely to recover, supporting the temperature‐size rule in thermal adaptation and recent studies showing a decrease in body size composition of ectotherm community under warmer climatic conditions. Body size as a fundamental trait in ecology thus affects ectotherm survival under thermal stress, which may drive species body size adaptations and community composition under future warming scenarios.