Nanoparticulate TiO₂ (TiO₂ NPs) is a widely used material, whose potential toxicity towards eukaryotic cells has been addressed by multiple studies. TiO₂ NPs are considered toxic due to their production of reactive oxygen species (ROS), which can, among others, lead to cellular damage, inflammatory responses, and differences in gene expression. TiO₂ NPs exhibited toxicity in multiple organs in animals, generating potential health risks also in humans, such as developing tumors or progress of preexisting cancer processes. On the other hand, the capability of TiO₂ NPs to induce cell death has found application in photodynamic therapy of cancers. In aquatic environments, much has been done in understanding the impact of TiO₂ on bivalves, in which an effect on hemocytes, among others, is reported. Adversities are also reported from other aquatic organisms, including primary producers. These are affected also on land and though some potential benefit might exist when it comes to agricultural plants, TiO₂ can also lead to cellular damage and should be considered when it comes to transfer along the food chain towards human consumers. In general, much work still needs to be done to unravel the delicate balance between beneficial and detrimental effects of TiO₂ NPs on eukaryotic cells.

Today’s biodiversity was strongly impacted by glacial cycles during the Pleistocene. They generated species diversity and population structuring, which can easily remain undetected, if populations differentiation is not accompanied by divergence in external morphological traits. This phenomenon, described as cryptic diversity, has been intensively researched in bats, which are known to harbour cryptic phylogenetic lineages. Many studies however have a regional focus or suffer from geographical gaps. Widely understudied areas include Central and Western Asia, although they connect the western and eastern Palearctic fauna. These areas are characterized by topographic heterogeneity and therefore high ecosystem diversity. In this study we investigated the phylogeography of the Savii’s pipistrelle (Hypsugo savii), a bat species assumed to be widely distributed across the Palaearctic. We compiled published sequences from four mitochondrial genes (ND1, CytB, COI and 16 S), added new sequences especially from the Asian part of the distribution range and performed phylogenetic and phylogeographic analyses. They indicate that H. savii is a taxonomic unit with extensive cryptic diversity, comprising at least four major mitochondrial lineages with allopatric or parapatric distribution ranges. Divergence time dating reveals the impact of Pleistocene glaciations on shaping highly structured populations of a highly mobile mammal across the Palearctic. Our study also revealed several zones of secondary contact among populations where hybridization and gene flow likely occur. This study highlights the necessity for studying biodiversity in Western and Central Asia in order to understand biogeographic patterns, evolutionary processes and conservation needs in the area that connects eastern and western Palearctic faunas.