Marine and inland biogeographical processes shaped Earth's singular brackish biodiversity hotspot.

Life radiated in aquatic environments worldwide. Brackish waters, however, seemingly hinder diversification as their physiologically demanding environmental stochasticity favours transient and impoverished communities assembled from widespread generalist species. Yet, the Ponto-Caspian basin (Aral, Azov, Black and Caspian seas) defies this rule, its rich endemic biota representing the only brackish biodiversity hotspot on Earth.

The subarctic ancient Lake El'gygytgyn harbours the world's northernmost 'limnostygon community' and reshuffles crangonyctoid systematics (Crustacea, Amphipoda).

The northward distribution limit of groundwater fauna is generally dictated by the extent of glacial ice sheets during the Pleistocene. However, some taxa can be found far above this limit, sometimes on isolated oceanic islands, implying long-term survival in subglacial subterranean refugia. Here we report a peculiar assemblage comprising two new depigmented and blind (stygomorphic) amphipods from the subarctic ancient lake El'gygytgyn (northern Far East): Palearcticarellus hyperboreus sp.

Taming the terminological tempest in invasion science.

Standardised terminology in science is important for clarity of interpretation and communication. In invasion science - a dynamic and rapidly evolving discipline - the proliferation of technical terminology has lacked a standardised framework for its development. The result is a convoluted and inconsistent usage of terminology, with various discrepancies in descriptions of damage and interventions.

Sexual dimorphism in subterranean amphipod crustaceans covaries with subterranean habitat type.

Sexual dimorphism can evolve in response to sex-specific selection pressures that vary across habitats. We studied sexual differences in subterranean amphipods Niphargus living in shallow subterranean habitats (close to the surface), cave streams (intermediate), and cave lakes (deepest and most isolated). These three habitats differ because at greater depths there is lower food availability, reduced predation, and weaker seasonality.

The remarkable Ponto-Caspian amphipod diversity of the lower Durso River (SW Caucasus) with the description of Litorogammarus dursi gen. et sp. nov.

The first insight into the unexpectedly diverse amphipod assemblage of the Durso River (Novorossiysk area) in the SW mountainous pre-Caucasian area is presented. The presence of six species is revealed, including three new records for the area and one species new to science. The phylogenetic relationships of all studied species and their relatives were examined based on the divergence of the COI mtDNA gene marker (barcoding).

Cryptic Species in Ecotoxicology.

The advent of genetic methods has led to the discovery of an increasing number of species that previously could not be distinguished from each other on the basis of morphological characteristics. Even though there has been an exponential growth of publications on cryptic species, such species are rarely considered in ecotoxicology. Thus, the particular question of ecological differentiation and the sensitivity of closely related cryptic species is rarely addressed.

Turcogammarus aralensis (Uljanin, 1875), a relict pontogammarid amphipod crustacean from the Aralo-Caspian paleobasin: redescription, phylogenetic position and biogeography.

The Ponto-Caspian region harbours the world's second most diverse lacustrine radiation of amphipod crustaceans. The taxonomic position of some of these species is unclear, due to incorrectly defined species limits, poor descriptions, and in some cases, poorly understood characters, such as armament of dorsal integuments. A pertinent example is Turcogammarus aralensis (Uljanin, 1875), which inhabits the Aral Sea and adjacent water bodies like the brackish lake Shalkar (Charkhal), lower reaches of the Syr Darya and Volga, and extends ca.

Morphology, nuclear SNPs and mate selection reveal that COI barcoding overestimates species diversity in a Mediterranean freshwater amphipod by an order of magnitude.

DNA sequence information has revealed many morphologically cryptic species worldwide. For animals, DNA-based assessments of species diversity usually rely on the mitochondrial cytochrome c oxidase subunit I (COI) gene. However, a growing amount of evidence indicate that mitochondrial markers alone can lead to misleading species diversity estimates due to mito-nuclear discordance.

A DNA barcode reference library for endemic Ponto-Caspian amphipods.

The Ponto-Caspian region is an endemicity hotspot that harbours several crustacean radiations, among which amphipods are the most diverse. These poorly known species are severely threatened in their native range, while at the same time they are invading European inland waters with significant ecological consequences. A proper taxonomic knowledge of this fauna is paramount for its conservation within the native region and monitoring outside of it.

No room for males in caves: Female-biased sex ratio in subterranean amphipods of the genus Niphargus.

Sex allocation theory predicts that the proportion of daughters to sons will evolve in response to ecological conditions that determine the costs and benefits of producing each sex. All else being equal, the adult sex ratio (ASR) should also vary with ecological conditions. Many studies of subterranean species reported female-biased ASR, but no systematic study has yet been conducted.

Continental-scale patterns of hyper-cryptic diversity within the freshwater model taxon Gammarus fossarum (Crustacea, Amphipoda).

Traditional morphological diagnoses of taxonomic status remain widely used while an increasing number of studies show that one morphospecies might hide cryptic diversity, i.e. lineages with unexpectedly high molecular divergence.

The late blooming amphipods: Global change promoted post-Jurassic ecological radiation despite Palaeozoic origin.

The ecological radiation of amphipods is striking among crustaceans. Despite high diversity, global distribution and key roles in all aquatic environments, little is known about their ecological transitions, evolutionary timescale and phylogenetic relationships. It has previously been proposed that the amphipod ecological diversification began in the Late Palaeozoic.

Is subterranean lifestyle reversible? Independent and recent large-scale dispersal into surface waters by two species of the groundwater amphipod genus Niphargus.

Groundwater is an extreme environment due to its absence of light, resource scarcity and highly fragmentary nature. Successful groundwater colonizers underwent major evolutionary changes and exhibit eye and pigment loss (troglomorphies). Consequently, their chances of dispersal and survival in the well-connected surface waters are greatly decreased, resulting in significant endemism.

Contrasting life history strategies in a phylogenetically diverse community of freshwater amphipods (Crustacea: Malacostraca).

Differences in life histories are commonly exhibited within ecological communities, especially among species that display increased variations in body size and morphology and are phylogenetically distant. To examine the relationship between morphological dissimilarity and life history divergence, we investigated three morphologically distinct and distantly related species of freshwater amphipods that co-occur throughout the Danube lowlands - Gammarus balcanicus dacicus, Niphargus valachicus and Synurella ambulans - by collecting monthly samples during a one-year period. Results revealed that the studied species differ significantly with respect to fecundity, size at maturity, number of generations per year, duration and timing of the reproductive period and egg volume.

The southwestern Carpathians as an ancient centre of diversity of freshwater gammarid amphipods: insights from the Gammarus fossarum species complex.

Gammarus fossarum is a diverse species complex of epigean freshwater amphipods throughout Europe. Due to their poor dispersal capabilities and ubiquity, these crustaceans may serve as a model for investigating the influence of historical factors on the contemporary distribution and diversity patterns of freshwater macrozoobenthos. Here, we investigate the fine-scale phylogeographic structure of this complex across its range in the southwestern Carpathian Mountains, which comprises two areas that are geographically isolated from its main European distribution area as well as from each other.

Zoogeography of epigean freshwater Amphipoda (Crustacea) in Romania: fragmented distributions and wide altitudinal variability.

Inland epigean freshwater amphipods of Romania are diverse and abundant for this region has a favourable geographical position between the Balkans and the Black Sea. Excluding Ponto-Caspian species originating in brackish waters and freshwater subterranean taxa, there are 11 formally recognized epigean freshwater species recorded from this country. They belong to 3 genera, each representing a different family: Gammarus (Gammaridae, 8 species or species complexes), Niphargus (Niphargidae, 2 epigean species) and Synurella (Crangonyctidae, one species).