Molecular taxonomy often uncovers cryptic species, reminding us that taxonomic incompleteness is even more severe than previous thought. The importance of cryptic species for conservation is poorly ...understood. Although some cryptic species may be seriously threatened or otherwise important, they are rarely included in conservation programs as most of them remain undescribed. We analysed the importance of cryptic species in conservation by scrutinizing the South European cryptic complex of the subterranean amphipod Niphargus stygius sensu lato. Using uni- and multilocus delineation methods we show that it consists of 15 parapatric and sympatric species, which we describe using molecular diagnoses. The new species are not mere "taxonomic inflation" as they originate from several distinct branches within the genus and coexist with no evidence of lineage sharing. They are as evolutionarily distinct as average nominal species of the same genus. Ignoring these cryptic species will underestimate the number of subterranean endemics in Slovenia by 12 and in Croatia by four species, although alpha diversity of single caves remains unchanged. The new taxonomy renders national Red Lists largely obsolete, as they list mostly large-ranged species but omit critically endangered single-site endemics. Formal naming of cryptic species is critical for them to be included in conservation policies and faunal listings.
Adaptive radiations are bursts of evolutionary species diversification that have contributed to much of the species diversity on Earth. An exception is modern Europe, where descendants of ancient ...adaptive radiations went extinct, and extant adaptive radiations are small, recent and narrowly confined. However, not all legacy of old radiations has been lost. Subterranean environments, which are dark and food-deprived, yet buffered from climate change, have preserved ancient lineages. Here we provide evidence of an entirely subterranean adaptive radiation of the amphipod genus Niphargus, counting hundreds of species. Our modelling of lineage diversification and evolution of morphological and ecological traits using a time-calibrated multilocus phylogeny suggests a major adaptive radiation, comprised of multiple subordinate adaptive radiations. Their spatio-temporal origin coincides with the uplift of carbonate massifs in South-Eastern Europe 15 million years ago. Emerging subterranean environments likely provided unoccupied, predator-free space, constituting ecological opportunity, a key trigger of adaptive radiation. This discovery sheds new light on the biodiversity of Europe.
Leeches (Hirudinea) constitute a relatively small monophyletic group of highly specialized annelids, but may play important roles as invertebrate predators in freshwater, while others are infamous ...for their ectoparasitic bloodsucking. About 15% of the 680 described species are marine and slightly less have switched to terrestrial life; the rest are freshwater, divided among 91 genera. They are globally distributed on all continents except Antarctica, reaching the highest diversity in the Holarctic region with one-half of all continental species. Known areas of local endemism are the ancient Siberian lake Bajkal and lake Ohrid (about 10 species each) on the Balkan Peninsula, which is an endemicity area in itself. A small number of sanguivorous species known as “medicinal leeches” have played an important role in traditional and modern medicine, most noticeably four Hirudo spp. from the Western Palearctic.
Europe's obligate cave-dwelling amphibian Proteus anguinus inhabits subterranean waters of the north-western Balkan Peninsula. Because only fragments of its habitat are accessible to humans, this ...endangered salamander's exact distribution has been difficult to establish. Here we introduce a quantitative real time polymerase chain reaction-based environmental DNA (eDNA) approach to detect the presence of Proteus using water samples collected from karst springs, wells or caves. In a survey conducted along the southern limit of its known range, we established a likely presence of Proteus at seven new sites, extending its range to Montenegro. Next, using specific molecular probes to discriminate the rare black morph of Proteus from the closely related white morph, we detected its eDNA at five new sites, thus more than doubling the known number of sites. In one of these we found both black and white Proteus eDNA together. This finding suggests that the two morphs may live in contact with each other in the same body of groundwater and that they may be reproductively isolated species. Our results show that the eDNA approach is suitable and efficient in addressing questions in biogeography, evolution, taxonomy and conservation of the cryptic subterranean fauna.
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► The three medicinal leech species have vast ranges but low genetic diversity. ► Commercial medicinal leeches sold in the West are H. verbana and originate from Turkey and Krasnodar, ...Russia. ► The cold-adapted H. medicinalis and H. orientalis are likely sister species. ► Only Hirudo verbana has geographic genetic structure, subdivided into Western and Eastern phylogroup. ► Rapid expansion, rather than isolation by distance, shaped the genetic structure of H. medicinalis and H. verbana.
Medicinal leeches (Hirudo spp.) are among the best-studied invertebrates in many aspects of their biology. Yet, relatively little is known about their biogeography, ecology and evolution. Previous studies found vast ranges but suggested low genetic diversity for some species. To examine this apparent contradiction, the phylogeny and phylogeography of the widespread Hirudo verbana, Hirudo medicinalis and Hirudo orientalis were investigated in a comparative manner. Populations from across their ranges in Europe, Asia Minor, the Caucasus and Central Asia, were analyzed by various phylogenetic and population genetic approaches using both mitochondrial (COI and 12S) and nuclear DNA sequences (ITS1, 5.8S and ITS2). The populations showed surprisingly little genetic differentiation despite vast ranges. The only clear structure was observed in H. verbana. This species is subdivided into an Eastern (southern Ukraine, North Caucasus, Turkey and Uzbekistan) and a Western phylogroup (Balkans and Italy). The two phylogroups do not overlap, suggesting distinct postglacial colonization from separate refugia. Leeches supplied by commercial facilities belong to the Eastern phylogroup of H. verbana; they originate from Turkey and the Krasnodar Territory in Russia, two leading areas of leech export. H. verbana and H. medicinalis have experienced recent rapid population growth and range expansion, while isolation by distance has shaped the genetic setup of H. orientalis. The habitat of the latter is patchy and scattered about inhospitable arid and alpine areas of Central Asia and Transcaucasia. Centuries of leech collecting and transport across Europe seem not to have affected the natural distribution of genetic diversity, as the observed patterns can be explained by a combination of historical factors and present day climatic influences.
Understanding the process of evolution is one of the great challenges in biology. Cave animals are one group with immense potential to address the mechanisms of evolutionary change. Amazingly, ...similar morphological alterations, such as enhancement of sensory systems and the loss of eyes and pigmentation, have evolved multiple times in a diverse assemblage of cave animals. Our goal is to develop an invertebrate model to study cave evolution so that, in combination with a previously established vertebrate cave system, we can address genetic questions concerning evolutionary parallelism and convergence. We chose the isopod crustacean, Asellus aquaticus. and generated a genome-wide linkage map for this species. Our map, composed of 117 markers, of which the majority are associated with genes known to be involved in pigmentation, eye, and appendage development was used to identify loci of large effect responsible for several pigmentation traits and eye loss. Our study provides support for the prediction that significant morphological change can be mediated through one or a few genes. Surprisingly, we found that within population variability in eye size occurs through multiple mechanisms; eye loss has a different genetic basis than reduced eye size. Similarly, again within a population, the phenotype of albinism can be achieved by two different genetic pathways—either by a recessive genotype at one locus or doubly recessive genotypes at two other loci. Our work shows the potential of Asellus for studying the extremes of parallel and convergent evolution—spanning comparisons within populations to comparisons between vertebrate and arthropod systems.
1. Various groundwater habitats have exceptionally high levels of endemism caused by strong hydrographical isolation and low dispersal abilities of their inhabitants. More than 10% of ...macro-stygobiotic species nevertheless occupy relatively large ranges, measuring from some hundred to over 2000 km in length. These species represent a challenge because their distributions disregard hydrographical boundaries, and their means to disperse and maintain long-term gene flow are unknown. 2. Based on mitochondrial and nuclear gene sequences, we examined the phylogeographic structure of six formally recognised stygobiotic species (Niphargus virei, N. rhenorhodanensis, Troglocaris anophthalmus, T. hercegovinensis, Spelaeocaris pretneri, Proteus anguinus) and searched for cryptic lineage diversity in a genus-wide phylogeny of Niphargus. Using tree-based criteria as well as comparative divergence measures, we identified cryptic lineages, which may tentatively be equated with cryptic species. 3. Fourteen analysed nominal stygobiotic species with large ranges emerged as highly diversified, splitting into 51 tentative cryptic lineages. The degree of divergence was within the range or larger than the divergence of other related pairs of sister species. A substantial part (94%) of the cryptic lineages had ranges <200 km in length. One half of them were recorded at single sites only. The largest range recorded was that of a cryptic N. virei lineage (700 km), while none of the very large traditional ranges (e.g. Niphargus aquilex- 2300 km, N. tauri- 1900 km) could be corroborated. 4. These data suggest that small ranges of macro-stygobionts are the rule, and ranges over 200 km are extremely rare. 5. The implications of this result for groundwater biodiversity assessment and conservation include a considerable increase in overall diversity at the regional and continental scale and a strong decrease in faunal similarities among regions, coupled with greater endemism.
Abstract
Throughout most of the kingdom Animalia, evolutionary transitions from surface life to a life permanently bound to caves and other subterranean habitats have occurred innumerous times. Not ...so in tetrapods, where a mere 14 cave-obligate species—all plethodontid and proteid salamanders—are known. We discuss why cave tetrapods are so exceptional and why only salamanders have made the transition. Their evolution follows predictable and convergent, albeit independent pathways. Among the many known changes associated with transitions to subterranean life, eye degeneration, starvation resistance, and longevity are especially relevant to human biomedical research. Recently, sequences of salamander genomes have become available opening up genomic research for cave tetrapods. We discuss new genomic methods that can spur our understanding of the evolutionary mechanisms behind convergent phenotypic change, the relative roles of selective and neutral evolution, cryptic species diversity, and data relevant for conservation such as effective population size and demography.
The present study explores the utility of mitochondrial COI gene sequences to reveal phylogenetic and phylogeographic relationships for the entire European freshwater crayfish genus
Austropotamobius. ...The two traditional taxa,
Austropotamobius pallipes and
Austropotamobius torrentium, were monophyletic, showing similar genetic diversity, with 28 and 25 haplotypes, respectively, and an uncorrected average pairwise divergence of 0.059 and 0.041. A third distinct haplotype clade, in sister relation to
A. torrentium, was discovered at the Upper Kolpa drainage in the northern Dinaric area. All populations north and west of the Alps are genetically impoverished (nucleotide diversity (
π)
=
0.000–0.001), while southern populations are more diverse (
π
=
0.001–0.034).
A. pallipes reaches the highest diversity in the region of Istra, probably its primary center of radiation. The genetic diversity center for
A. torrentium is the southern Balkan peninsula. Other potential glacial refugia were identified in Southern France, Northwestern Italy, the Apennine Peninsula, and in the northern Dinaric area. The Iberian Peninsula has been stocked artificially from Northern Italy. Three main periods of radiation were tentatively identified: late Miocene/early Pliocene for the divergence of species and main lineages, the Pleistocene for the divergence within populations south from Alps, and a postPleistocene expansion north and west from Alps.
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