Heat shock proteins expression during thermal risk exposure in the temperate xerothermic ant Formica cinerea

The abiotic conditions of the desert habitat fluctuate in a circadian rhythm of hot days and cold nights. Species living in desert habitats evolved many adaptations to increase their chances of survival. However, abiotic conditions in xerothermic habitats of a temperate climate are much different. Diurnal fluctuations are not as strong, but animals have to cope with seasonal changes and hibernate during the winter, which may potentially influence their adaptations to critical temperature conditions. We attempted to assess heat resistance adaptations using the example of a widely distributed xerothermic ant Formica cinerea. Using Real-Time PCR, we measured the expression of three heat shock protein genes (Hsp60, Hsp75, Hsp90) and assessed the adaptations of F. cinerea to enable foraging in risk prone conditions. The analysis of gene expression using the Generalized Linear Model surprisingly indicated that there was no significant effect of temperature when comparing workers from the control (23ºC) with workers foraging on the surface of hot sand (47-54ºC). As a next step we tried to estimate the threshold of a thermal resistance with the use of thermal chambers. Expression of all Hsps genes increase compare to the control group, expression of Hsp60 and Hsp90 continued up to 45ºC

Differential impact of two dominant Formica ant species (Hymenoptera, Formicidae) on subordinates in temperate Europe

Competition is one of the basic mechanisms shaping ant assemblages. Dominant territorial species are known to restrictively influence the traits of subordinates in various ways. However, there could be differences in the effects of dominants due to differences in their colony structure, lifestyle and also behaviour. We tested this hypothesis in natural circumstances in an area where a Formica exsecta Nyl. supercolony neighbours a strong population of the European slave-maker F. sanguinea Latr. For the purpose of our study three different sites were selected: one dominated by F. exsecta, a neighbouring site dominated by F. sanguinea, and a third site where both species co-occurred. We analyzed the structure of subordinate ant communities based on nest counts, and by recording the activity of ants at baits. Based on our findings the structure of ant communities differed significantly among the three sites. The F. exsecta site was characterized by the lowest nest density of subordinates, especially in the case of aggressive species as Lasius platythorax Seifert. At baits even the simple presence of the dominant limited the abundance and occurrence of subordinates. In contrast, no such negative effect could be revealed at the F. sanguinea site. The community of the mixed site showed intermediate features in many respects. Generally, the supercolonial F. exsecta had a bigger influence on the ant community than the slave-making F. sanguinea. On the other hand, our findings revealed a slight protective role of the territorial F. exsecta for potential slave species to F. sanguinea. The current study underlines the importance of differences between dominant ant species in shaping differentially ant communities even within the same restricted area