Valeria Rizzo

Thermal niche estimators and the capability of poor dispersal species to cope with climate change.

For management strategies in the context of global warming, accurate predictions of species response are mandatory. However, to date most predictions are based on niche (bioclimatic) models that usually overlook biotic interactions, behavioral adjustments or adaptive evolution, and assume that species can disperse freely without constraints. The deep subterranean environment minimises these uncertainties, as it is simple, homogeneous and with constant environmental conditions. It is thus an ideal model system to study the effect of global change in species with poor dispersal capabilities. We assess the potential fate of a lineage of troglobitic beetles under global change predictions using different approaches to estimate their thermal niche: bioclimatic models, rates of thermal niche change estimated from a molecular phylogeny, and data from physiological studies. Using bioclimatic models, at most 60% of the species were predicted to have suitable conditions in 2080. Considering the rates of thermal niche change did not improve this prediction. However, physiological data suggest that subterranean species have a broad thermal tolerance, allowing them to stand temperatures never experienced through their evolutionary history. These results stress the need of experimental approaches to assess the capability of poor dispersal species to cope with temperatures outside those they currently experience.

Limited thermal acclimation capacity in cave beetles

Thermal tolerance is a key vulnerability factor for species that cannot cope with changing conditions by behavioural adjustments or dispersal, such as subterranean species. Previous studies of thermal tolerance in cave beetles suggest that these species may have lost some of the thermoregulatory mechanisms common in temperate insects, and appear to have a very limited thermal acclimation ability. However, it might be expected that both thermal tolerance and acclimation ability should be related with the degree of specialization to deep subterranean environments, being more limited in highly specialized species. To test this hypothesis, we use an experimental approach to determine the acclimation capacity of cave beetles within the tribe Leptodirini (family Leiodidae) with different degrees of specialization to the deep subterranean environment. For this, we acclimate groups of individuals at 1. a temperature close to their upper thermal limit (20oC) or 2. a control temperature (approximately that of the cave in which they were found) for 2 or 10 days (shortvs. long-term acclimation). ‡ § | ¶ # ¤ ‡

A new species of Troglocharinus Reitter, 1908 (Coleoptera, Leiodidae, Cholevinae, Leptodirini) from southern Catalonia, with a molecular phylogeny of the related species group

In this paper we describe T. pallisei sp. n., a new representative of the genus Troglocharinus Reitter, 1908 (Coleoptera, Leiodidae, Leptodirini), a strictly subterranean genus restricted to the Eastern Pyrenees and some coastal areas in Catalonia. All known specimens of T. pallisei sp. n. were collected in a cave next to the town of La Riba, in the province of Tarragona (Spain), situated between the distribution areas of the species of the T. orcinus complex and T. espanoli Jeannel, 1930. It can be separated from the other members of the T. orcinus complex by the presence of penicillus in the apex of the parameres of the aedeagus and from T. espanoli by the presence of a mesoventral keel; it also differs from both by its long and erect pubescence. A Bayesian molecular phylogeny including representatives of the main lineages within the genus Troglocharinus, based on ca. 5211 Kb of 5 mitochondrial and 4 nuclear genes, placed T. pallisei sp. n. as sister to T. orcinus Jeannel, 1910, and both sister to T. espanoli, in perfect agreement with their geographic distributions and the inferred geographic expansion of the genus to the south, with an estimated divergence of ca. 1.3 Ma. In agreement with the results of a previous phylogenetic study, the subgenus Antrocharidius Jeannel, 1910 is synonymised with Troglocharinus (syn.n.).