Trait-mediated competition drives an ant invasion and alters functional diversity.

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.

Diversity pattern of insects from Macao based on an updated species checklist after 25 years.

Background: Insects represent one of the most diverse groups in the organism world with extremely rich species and morphological diversity, playing important roles in natural and city ecosystems. Regional compilation of insect species lists helps to clarify the richness of insect species in a region, enhances our understanding the structure and function of a local ecosystem and promotes the protection and development of insect resources. Moreover, it also serves as a valuable reference for cities with small area, large population and high urbanisation like Macao. Macao (Macau) Special Administrative Region (SAR) is situated at the Pearl River Delta on the southeast coast of mainland China. With urban development accelerating at great rate in a quite restricted area, Macao still has rich fauna, within which the insect diversity is surprisingly high. New information: In this study, we systematically sorted out major references items of manuals or handbooks, monographs, articles, dissertations, official websites and other publicly available information sources about the insects recorded in Macao and, thus, generated a checklist of 15 orders, 166 families, 868 genera, 1,339 species and 118 subspecies. During this process, the preliminarily summarised list was re-examined to eliminate synonyms and invalid species, based on many more extensive literature reviews. Besides, spelling errors of scientific names, authors and years were corrected. Meanwhile, the catalogue revealed a different composition pattern of species diversity between orders from those of the world and China. Even based on the most conservative estimates, the number of insect species in Macao should not be lower than 3,340 species, which hints at the necessity of deeper investigations with adequate collecting in the future to achieve more comprehensive recognition and understanding of Macao's insect biodiversity.

The role of body mass in limiting post heat-coma recovery ability in terrestrial ectotherms.

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.

Testing the reliability and ecological implications of ramping rates in the measurement of Critical Thermal maximum.

Critical Thermal maximum (CTmax) 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 CTmax 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 CTmax 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 CTmax 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 CTmax 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 CTmax 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 CTmax in ants, which can be applied to other ectotherms. Particular attention should be given to CTmax 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.

A new subterranean species and an updated checklist of Strumigenys (Hymenoptera, Formicidae) from Macao SAR, China, with a key to species of the Greater Bay Area.

In the past few decades, sampling of leaf litter with Winkler extractors revealed how abundant and ubiquitous ants from the genus Strumigenys are. It is now known that this genus has the third greatest number of species within the Formicidae family. However, very few subterranean species are known, which may be due to the current under-sampling of the soil stratum. Here, a holistic sampling approach, including the use of subterranean traps, was employed in Macao SAR, China. Subterranean traps allowed the collection of a new cryptic ant species: Strumigenys subterranea Brassard, Leong & Guénard, sp. nov. Moreover, extensive sampling of the leaf litter in secondary forests provided four new species records for the genus. The list of Macanese Strumigenys is here updated, elevating the known diversity in Macao to nine species. Furthermore, to facilitate further research on ants of the Guangdong-Hong Kong-Macao Greater Bay Area, a key to the 29 Strumigenys species known from the region is provided. Lastly, recommendations for sampling methods to assess ant biodiversity underground are discussed. In conclusion, this study highlights the importance of using extensive sampling methods, and suggests that relatively small patches of secondary forests within cities can hold a surprisingly high diversity as well as some undescribed species.

A new species and new record of the cryptobiotic ant genus Ponera Latreille, 1804 (Hymenoptera, Formicidae) from Hong Kong.

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. Ponera guangxiensis Zhou, 2001 is reported for the first time from Hong Kong, and Ponera tudigong sp. nov. is here described as a new species, easily distinguishable from other Ponera species and unique within the genus for its four mandibular teeth.

Taxonomic revision of the genus Ponera Latreille, 1804 (Hymenoptera: Formicidae) of Taiwan and Japan, with a key to East Asian species.

Ponera is a widespread genus of litter and soil ants. The highest diversity of the genus is found in Asia, with Taiwan and Japan being two of the most species-rich regions. Here, we systematically review the taxonomy of the 16 Taiwanese and Japanese Ponera species, two of which are new species from Taiwan: Ponera terayamai sp. n. and P. wui sp. n. A new key for Ponera species of East Asia is presented.

Taiwanese species of the ant genus Technomyrmex (Formicidae: Dolichoderinae).

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.