Repeated surveying over 6 years reveals that fine-scale habitat variables are key to tropical mountain ant assemblage composition and functional diversity

Temperature-driven homogenization of an ant community over 60 years in a montane ecosystem

Identifying the mechanisms underlying the changes in the distribution of species is critical to accurately predict how species have responded and will respond to climate change. Here, we take advantage of a late-1950s study on ant assemblages in a canyon near Boulder, Colorado, USA, to understand how and why species distributions have changed over a 60-year period. Community composition changed over 60 years with increasing compositional similarity among ant assemblages. Community composition differed significantly between the periods, with aspect and tree cover influencing composition. Species that foraged in broader temperature ranges became more widespread over the 60-year period. Our work highlights that shifts in community composition and biotic homogenization can occur even in undisturbed areas without strong habitat degradation. We also show the power of pairing historical and contemporary data and encourage more mechanistic studies to predict species changes under climate change.

Diversity of Trichoderma species associated with soil in the Zoige alpine wetland of Southwest China

The ecology of soil fungi is poorly understood, and recent comprehensive reports on Trichoderma are unavailable for any region, including the Zoige alpine wetland ecological region in China. One hundred soil samples were collected from different soil types and soil layers in Zoige alpine wetland ecological regions. Using the traditional suspension plating method, 80 Trichoderma strains were chosen to analyze species diversity. After a preliminary classification of morphological characteristics and the genes glyceraldehyde-3-phosphate dehydrogenase (gpd), 57 representative strains were selected and eventually identified as seven species via phylogenetic analyses of multilocus sequences based on the genes transcription elongation factor 1 alpha (tef1), encoding RNA polymerase II subunit B (rpb2) and ATP citrate lyase (acl1). Among them, T. harzianum was the dominant species isolated from five soil layers and four soil types, and had the highest isolation frequency (23%) in this zone, while T. polysporum and T. pyramidale were rare species, with isolation frequencies of less than 1%. Our detailed morphological observation and molecular phylogenetic analyses support the recognition of Trichoderma zoigense was described for the first time as a new species, while T. atrobrunneum as a new record for China was found. Our results will be used as a reference for a greater understanding of soil microbial resources, ecological rehabilitation and reconstructions in the Zoige alpine wetland.

Plant shade enhances thermoregulation of internal environments in Trinervitermes trinervoides mounds

Microhabitats may be crucial in buffering organisms from temperature extremes, particularly given increases in maximum temperature associated with global climate change. For example, thermoregulation in termite mounds is influenced by prevailing ambient conditions, and plant canopies may reduce external temperatures, in turn lowering internal temperatures. This buffering may be crucial during heat waves. Whether this happens, and to what extent, remains equivocal, however. We tracked internal temperatures in eight inhabited and six uninhabited Trinervitermes trinervoides mounds, half of each group of which were shaded by vegetation. T. trinervoides seek to maintain internal mound temperatures at c. 20 °C in winter and c. 30 °C in summer. Temperatures were logged for 72 h in winter, and again in summer. Internal temperatures of uninhabited mounds mirrored those of external temperatures, with temperatures varying by c. 15 °C, although shading was associated with some buffering of internal temperatures. Internal temperatures within inhabited mounds were far less variable, varying by c. 6 °C over the course of our study. In summer, exposed inhabited mounds maintained temperatures c. 29.5 °C, whilst shaded inhabited mounds were c. 27.5 °C. In winter, mean internal temperatures of exposed and shaded inhabited mounds were very similar, at 21.8 and 22.0 °C, respectively. Internal mound temperature varied significantly with external (ambient) temperature, mound activity, temperature, shading, and to a small extent, mound volume. The buffering effect of shade was evident in summer (c. 2 °C) but not in winter, suggesting that the benefit of such temperature modulation may be most important when ambient temperatures reach heat extremes, e.g. during heat waves.