Gaju-Ricart, M. | bioRxiv Science

bioRxiv2025

Which are the most heat-tolerant animals? Insights from a Mediterranean lepismatid under thermal stress in the context of climate change

Measuring behavioural and physiological thermal limits is crucial to understanding how they interact with the environment under a climate change scenario. We experimentally assessed the effects of acclimation on sequentially measured voluntary (VTmax), critical (CTmax), and upper thermal limit (UTL) limits in the Mediterranean silverfish Sceletolepisma guadianicum. Individuals were acclimated for six days at either 25{degrees}C (n=32) or 35{degrees}C (n=29) and heated at [~]0.5{degrees}C min-1, and VTmax, CTmax, and lethal limits were recorded. S. guadianicum exhibited some of the highest thermal limits reported to date among terrestrial arthropods. VTmax showed limited (1.04 {degrees}C) but statistically detectable plasticity, increasing with high acclimation temperature and heating rate, whereas CTmax rate and lethal limits remained unchanged. We provide hypotheses explaining the co-ocurrence of exceptional heat tolerance levels together with their reduced plasticity in this and other extremely heat-tolerant species. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=124 SRC="FIGDIR/small/690525v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@1f01660org.highwire.dtl.DTLVardef@14cfcb2org.highwire.dtl.DTLVardef@1621c39org.highwire.dtl.DTLVardef@2aec20_HPS_FORMAT_FIGEXP M_FIG C_FIG

zoology↗

bioRxiv2023

Co-habiting ants and silverfish display a converging feeding ecology

O_LISpecies from a great number of animal taxa have specialized to living with social hosts. Depending on their level of specialization, these symbiotic animals are characterized by distinct behavioural, chemical, and morphological traits that enable close heterospecific interactions. Despite its functional importance, our understanding of the feeding ecology of specialized animals living with social hosts remains limited. C_LIO_LIIn this study, we examined how host specialization of silverfish co-habiting with ants affects several components of their feeding ecology. We combined stable isotope profiling, feeding assays, phylogenetic reconstruction, and microbial community characterization of the Neoasterolepisma silverfish genus and a wider nicoletiid and lepismatid silverfish panel where divergent myrmecophilous lifestyles are observed. C_LIO_LIStable isotope profiling ({delta}13C and {delta}15N) showed that the isotopic niches (proxy for trophic niches) of granivorous Messor ants and Messor-specialized Neoasterolepisma exhibit a remarkable overlap within an ant nest. Trophic experiments and gut dissections further supported that these specialized Neoasterolepisma silverfish transitioned to a diet that includes plant seeds. In contrast, the isotopic niches of generalist Neoasterolepisma silverfish and generalist nicoletiid silverfish were clearly different from their ant hosts within the shared nest environment. C_LIO_LIThe impact of the myrmecophilous lifestyle on feeding ecology was also evident in the internal silverfish microbiome. Compared to generalists, Messor-specialists exhibited a higher bacterial density and a higher proportion of heterofermentative lactic acid bacteria. Moreover, the nest environment explained the infection profile (or the 16S rRNA genotypes) of Weissella bacteria in Messor-specialized silverfish and the ant hosts. C_LIO_LITogether, we show that social hosts are important determinants for the feeding ecology of symbiotic animals, and can induce diet convergence. C_LI

ecology↗