Physella acuta
(Draparnaud,
1805
) is an aquatic pulmonate snail notorious for its high invasive potential. Of New World origin, this species now occurs on all continents. The aim of this study was ...to trace
P. acuta
dispersal through the Western Palearctic starting from its first arrival in the Old World and to determine possible drivers of this process. A range of literary sources as well as some rich European malacological collections have been consulted to ascertain the dates of the first finding of
P. acuta
in the countries of Europe, Transcaucasia, and Central Asia and to map the most significant localities. The shell characteristics of this species are so distinctive that they almost preclude misidentification and confusion with any native species. This allows one to rely on historical records, including older sources (18th to the first half of the 19th centuries). The earliest reliable records of
P. acuta
in the Old World can be dated to 1742, which implies an earlier date for the first arrival of the species in Europe, possibly in the 17th century. Its introduction may be explained either by accidental dispersal mediated by humans (for example, during transport of exotic plants to European botanical gardens) or by natural causes (long-distance dispersal from the Americas to Europe). Three successive phases leading to the current invasive range of
P. acuta
in the Western Palearctic can be identified. The species’ current Old World range can be viewed as a result of the interaction of natural and anthropogenic factors. The human-mediated drivers of dispersal include canal building, the aquarium trade and, more recently, alteration of natural freshwater habitats.
The case of naturalization of the zebra mussel, Dreissena polymorpha (Pallas, 1771), in countries lying beyond its native Ponto–Caspian range is remarkable as one of the first instances when the ...scientific community as early as the mid-19th century was fully aware of the non-indigenous status of a particular species as well as of the need for the study and monitoring of this process. Based on a study of contemporary sources, I reconstruct the early response of European naturalists (including those who today would be called “citizen scientist”) to the invasion of Dreissena and describe their attitudes to the problem, including the divergence in opinion about the origin and the means of dispersal of this bivalve species. An analysis of papers published in English, French, German, and Russian between 1774 and 1920 showed that the invasion of D. polymorpha was by no means “silent”; quite the opposite, it provoked an immediate reaction from naturalists. The scientific agenda for the study of the new invader was proposed in England as early as 1838.
Defining and recording the loss of species diversity is a daunting task, especially if identities of species under threat are not fully resolved. An example is the Pontocaspian biota. The mostly ...endemic invertebrate faunas that evolved in the Black Sea - Caspian Sea - Aral Sea region and live under variable salinity conditions are undergoing strong change, yet within several groups species boundaries are not well established. Collection efforts in the past decade have failed to produce living material of various species groups whose taxonomic status is unclear. This lack of data precludes an integrated taxonomic assessment to clarify species identities and estimate species richness of Pontocaspian biota combining morphological, ecological, genetic, and distribution data. In this paper, we present an expert-working list of Pontocaspian and invasive mollusc species associated to Pontocaspian habitats. This list is based on published and unpublished data on morphology, ecology, anatomy, and molecular biology. It allows us to (1) document Pontocaspian mollusc species, (2) make species richness estimates, and (3) identify and discuss taxonomic uncertainties. The endemic Pontocaspian mollusc species richness is estimated between 55 and 99 species, but there are several groups that may harbour cryptic species. Even though the conservation status of most of the species is not assessed or data deficient, our observations point to deterioration for many of the Pontocaspian species.
The use of the “integrative approach” for classification of organisms since its formal establishment in 2005 has become a recurrent theme of zoosystematics. A bibliometric survey of the publications ...on integrative taxonomy of animals, which is aimed at exploring the most popular areas of research and characterizing the practical systematists’ attitudes to this new approach, is presented. An analysis of 582 papers, which appeared between 2005 and 2017 in journals indexed by Scopus and the Web of Science Core Collection, has illustrated the gradual growth of the popularity of integrative taxonomy as well as some biases in the representation of higher taxa in “integrated” studies. It has been shown that the “integrative” papers have more chance of appearing in a top‐ranking journal and gain relatively more citations as compared with non‐integrative papers. The obtained results are discussed in the context of the “taxonomic impediment” problem thought to be a consequence of the institutional crisis of traditional taxonomy, which has been vividly debated over the past decades.
Molluscs are among the most diverse and widespread animal groups in freshwater habitats. Unfortunately, like most freshwater taxa, they are decreasing dramatically and are now among the most ...threatened animals on Earth, with many species already extinct or on the brink of extinction. Here, we review our current knowledge on the biodiversity and conservation of freshwater molluscs using the concept of knowledge shortfalls. We focus on seven previously proposed key shortfalls to review and analyse existing knowledge gaps relating to (1) taxonomy, the Linnean Shortfall; (2) distribution, the Wallacean Shortfall; (3) abundance and population dynamics, the Prestonian Shortfall: (4) evolution, the Darwinian Shortfall; (5) abiotic tolerances, the Hutchinsonian Shortfall; (6) traits, the Raunkiaeran Shortfall; and (7) biotic interactions, the Eltonian Shortfall. In addition, we address a new shortfall, which relates to the application and effectiveness of conservation measures, including assessments, methods, funding, and policies, the Ostromian Shortfall. Based on our review, we provide recommendations and suggest pathways to overcome these existing shortfalls. This work also introduces the articles in this special issue of Hydrobiologia, which represent key contributions to the First International Freshwater Mollusk Conservation Society Meeting held in Verbania, Italy, in 2018.
The progress towards mathematization or, in a broader context, towards an increased “objectivity” is one of the main trends in the development of biological systematics in the past century. It is ...commonplace to start the history of numerical taxonomy with the works of R. R. Sokal and P. H. A. Sneath that in the 1960s laid the foundations of this school of taxonomy. In this article, I discuss the earliest research program in this field, developed in the 1920s by the Russian entomologist and biometrician Eugen (Evgeniy Sergeevich) Smirnov. The theoretical and methodological grounds of this program are considered based on the published works of Smirnov as well as some archival sources. The influence of Smirnov’s evolutionary (mechano-Lamarckian) convictions on the development of this project of “exact systematics” is analyzed as well as the author’s attempts to establish a novel concept of “mathematical essentialism” in animal taxonomy. The probable causes of the failure of Smirnov’s project are viewed from both externalist and internalist perspectives, including the opposition to the use of quantitative methods in biology by some of the Lysenkoist ideologists in the USSR. A brief comparison of Smirnov’s research program with that developed 40 years later by Sokal and Sneath is provided.
Data on the historical change of the Transbaikalian malacofauna in the Neopleistocene and Holocene is presented. Aquatic mollusc shells from archaeological excavations of the ancient settlements ...dating from the Neolithic period to Medieval and also from a drill hole of the Neopleistocene alluvial deposits were collected. In total eight species of bivalve molluscs from the families Margaritiferidae, Unionidae, Lymnocardiidae, Glycymerididae marine, and two gastropod species from families Viviparidae and Planorbidae were identified. These species were aged using radiocarbon dating. It was found that the species ranged in age from more than 50.000 to 2.080-1.210 years BP. Five species inhabited the Transbaikal region which are locally extirpated today. Their disjunctive ranges in the past included southern Europe and Western and Eastern Siberia to Transbaikalia and in the east to Far East and Primorye Territory of Russia. A remarkable finding is that of the bivalve genus Monodacna, which was found very far from its native range, the Ponto-Caspian region. The time of existence and extirpation of the thermophilic species of genera Monodacna, Planorbis, Lanceolaria and Amuropaludina corresponds to cycles of the warming and cooling in Pleistocene and Holocene according to regional climate chronological scales. These species can be used as palaeoclimate indicators. Change of the regional malacofaunal species composition is connected with the natural climatochron cycles in the Pleistocene and Holocene resulting in evidence for succession. In the course of this succession, these stenothermal species became extirpated on a regional level, decreasing their global ranges.
The radicine pond snails represent a species-rich and widely distributed group, many species of which are key vectors of human and animal trematodoses. Here we clarify the taxonomy, distribution and ...evolutionary biogeography of the radicine lymnaeids in the Old World based on the most comprehensive multi-locus molecular dataset sampled to date. We show that the subfamily Amphipepleinae is monophyletic and contains at least ten genus-level clades: Radix Montfort, 1810, Ampullaceana Servain, 1881, Peregriana Servain, 1881, Tibetoradix Bolotov, Vinarski & Aksenova gen. nov., Kamtschaticana Kruglov & Starobogatov, 1984, Orientogalba Kruglov & Starobogatov, 1985, Cerasina Kobelt, 1881, Myxas G. B. Sowerby I, 1822, Bullastra Bergh, 1901, and Austropeplea Cotton, 1942. With respect to our phylogeny, species-delimitation model and morphological data, the Old World fauna includes 35 biological species of radicines. Tibet and Eastern Europe harbor the richest faunas, while East Asia and Africa appear to be the most species-poor areas. The radicine clade could have originated near the Cretaceous - Paleocene boundary. The Miocene great lakes in Eurasia seems to be the most important evolutionary hotspots shaping spatial patterns of recent species richness. Finally, we present the first DNA barcode reference library for the reliable molecular identification of species within this group.
The effects of climate change on oligotrophic rivers and their communities are almost unknown, albeit these ecosystems are the primary habitat of the critically endangered freshwater pearl mussel and ...its host fishes, salmonids. The distribution and abundance of pearl mussels have drastically decreased throughout Europe over the last century, particularly within the southern part of the range, but causes of this wide-scale extinction process are unclear. Here we estimate the effects of climate change on pearl mussels based on historical and recent samples from 50 rivers and 6 countries across Europe. We found that the shell convexity may be considered an indicator of the thermal effects on pearl mussel populations under warming climate because it reflects shifts in summer temperatures and is significantly different in viable and declining populations. Spatial and temporal modeling of the relationship between shell convexity and population status show that global climate change could have accelerated the population decline of pearl mussels over the last 100 years through rapidly decreasing suitable distribution areas. Simulation predicts future warming-induced range reduction, particularly in southern regions. These results highlight the importance of large-scale studies of keystone species, which can underscore the hidden effects of climate warming on freshwater ecosystems.
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