Biology subjects

Ribera, I.

Publications and source records attributed to Ribera, I..

3 recordsLinked to original sources

bioRxiv2022

Highly dynamic evolution of the chemosensory gene repertoire driven by gene gain and expansion across subterranean beetles

Chemical cues in subterranean habitats differ highly from those on the surface due to the contrasting environmental conditions, such as absolute darkness, high humidity or food scarcity. Subterranean animals underwent changes to their sensory systems to facilitate the perception of essential stimuli for underground lifestyles. Despite representing unique systems to understand biological adaptation, the genomic basis of chemosensation across cave-dwelling species remains unexplored from a macroevolutionary perspective. Here, we explore the evolution of chemoreception in three beetle tribes that underwent at least six independent transitions to the underground, through a phylogenomics spyglass. Our findings suggest that the chemosensory gene repertoire varies dramatically between species. Overall, no parallel changes in the net rate of evolution of chemosensory gene families were detected prior, during, or after the habitat shift among subterranean lineages. Contrarily, we found evidence of lineage-specific changes within surface and subterranean lineages. However, our results reveal key duplications and losses shared between some of the lineages transitioning to the underground, including the loss of sugar receptors and gene duplications of the highly conserved ionotropic receptors IR25a and IR8a, involved in thermal and humidity sensing among other olfactory roles in insects. These duplications were detected both in independent subterranean lineages and their surface relatives, suggesting parallel evolution of these genes across lineages giving rise to cave-dwelling species. Overall, our results shed light on the genomic basis of chemoreception in subterranean beetles and contribute to our understanding of the genomic underpinnings of adaptation to the subterranean lifestyle at a macroevolutionary scale.

evolutionary biology↗

bioRxiv2020

Smelling in the dark: phylogenomic insights on the chemosensory system of a subterranean beetle

The chemosensory system has experienced relevant changes in subterranean animals, facilitating the orientation into darkness via the perception of specific chemical signals critical to survive in this particular environment. However, the genomic basis of chemoreception in cave-dwelling fauna is largely unexplored. We generated de novo transcriptomes for antennae and body samples of the troglobitic beetle Speonomus longicornis (whose characters suggest an extreme adaptation to the deep subterranean) in order to interrogate the evolutionary origin and diversification of the chemosensory gene repertoire across coleopterans through a phylogenomic approach. Our results suggested a diminished diversity of odorant and gustatory gene repertoires compared to polyphagous epigean beetles. Moreover, S. longicornis showed a large diversity of odorant-binding proteins, suggesting an important role of these proteins in capturing airborne chemical cues. We identified a gene duplication in the ionotropic co-receptor I R25a, a highly conserved single-copy gene in protostomes involved in thermal and humidity sensing. In addition, no homologous genes to sugar receptors or the ionotropic receptor IR41a were detected. Our findings suggest that the chemosensory gene repertoire of this cave beetle may have been reshaped by the low complexity of chemical signals of this particular environment, and that gene duplication and loss may have played an important role in the evolution of genes involved in chemoreception. Altogether, our results shed light on the genomic basis of chemoreception in a cave-dwelling invertebrate and pave the road towards understanding the genomic underpinnings of adaptation to the subterranean lifestyle at a deeper level.

evolutionary biology↗

bioRxiv2019

Heat tolerance and acclimation capacity in unrelated subterranean arthropods living under common and stable thermal conditions

Cave-dwelling ectotherms, which have evolved for millions of years under stable thermal conditions, could be expected to have adjusted their physiological limits to the narrow range of temperatures they experience and be highly vulnerable to global warming. However, the few existing studies on thermal physiology in subterranean invertebrates point that they have lost some of the thermoregulatory mechanisms common in surface species, but there is a lack of evolutionary adjustment to ambient temperature. The question remains whether this surprising homogeneous thermal niche is common for the whole subterranean biodiversity or just a peculiarity of the species tested. In order to test for the generality of such previous findings, we studied basal heat tolerance and thermal plasticity in four species of distant arthropod groups (Coleoptera, Diplopoda and Collembola) with different evolutionary histories but under similar selection pressures, as they have been exposed to the same constant environmental conditions for a long time (inhabiting the same cave). Adult specimens were exposed at different temperatures for one week to determine upper lethal temperatures. Then, surviving individuals from each treatment were exposed to a fixed stressful temperature to determine acclimation capacity. Upper lethal temperatures were similar to those reported for other subterranean species (between 20-25{degrees}C), except from that of the diplopod (28{degrees}C), widely exceeding the cave temperature (13-14{degrees}C). Acclimation responses differed from a positive acclimation response in two of the species to no acclimation capacity or detrimental acclimation effects in the others. Our results show that thermal niche features are not as homogeneous as expected across the subterranean fauna and unrelated to ambient conditions. We show that some species, likely those that colonized subterranean environments more recently, still retain thermoregulation capacity to face temperature changes. Thus, subterranean species, even those living under similar climatic conditions, might be very differently affected by global warming.

ecology↗