Identification of polymorphic species within groups of morphologically conservative taxa: combining morphological and molecular techniques

Identification of small species with high levels of intra-specific polymorphism within groups of inter-specific morphologically-conservative taxa, presents numerous obstacles for biodiversity and ecological studies. This is particularly true for deep-sea studies that often reveal a great number of species but only few numbers of specimens. It is here proposed to deal with such cases by extrapolating information obtained from highly detailed baseline studies. Such baseline studies should include information about sexual and ontogenetic variation and should include a combination of both morphological and molecular techniques

Divergencia genética de tanaidáceos (Crustacea: Peracarida) con baja capacidad de dispersión

In this study, the phylogeographic patterns of nuclear, ribosomal and mtDNA gene fragments of five tanaidacean species (Zeuxo, Tanaidae) from the Atlantic, Pacific and Mediterranean Sea were investigated. We aimed to interpret results in the framework of current hypotheses on the distribution of small invertebrates with very limited dispersal ability. Evidence for a surprisingly high genetic divergence was found for intertidal tanaidaceans from the North Atlantic. This is a result of poor dispersal potential, as tanaidaceans have direct development, no pelagic stage, and very limited swimming capacity. However, lower genetic divergence was found between an intertidal tanaid species from the North Atlantic and two from the North Pacific, which suggests a scenario of recent colonization following the last glacial maximum. The species Zeuxo normani was found to be a species complex consisting, at least, of Z. normani (California), Z. cf. normani (Japan), Z. cf. normani (Australia), Z. sp. A (Korea), and Z. holdichi (Spain and France). Our results showed that traditional species identification underestimates tanaidacean diversity and that what have been previously perceived as reliable diagnostic morphological characters, are, however, variable and unreliable.En este estudio, investigamos los patrones filogeográficos de fragmentos de ADN nuclear, ribosómico y mitocondrial de 5 especies de tanaidáceos (Zeuxo, Tanaidae) del Atlántico, Pacífico y Mediterráneo. Nos propusimos interpretar los resultados en el marco de hipótesis sobre la distribución de pequeños invertebrados con limitada capacidad de dispersión. Encontramos evidencia de una sorprendentemente alta diferenciación genética para tanaidáceos del medio intermareal del Atlántico Norte. Esto es resultado de una limitada capacidad de dispersión, ya que los tanaidáceos poseen desarrollo directo, carecen de estadíos pelágicos, y una limitada capacidad natatoria. Sin embargo, encontramos una baja diferenciación genética para una especie de tanaidáceo del Atlántico Norte y dos del Pacífico Norte, lo que sugiere un escenario de reciente colonización tras la última glaciación. La especie Zeuxo normani constituye un complejo de especies que, al menos, agrupa a Z. normani (Califonia), Z. cf. normani (Japón), Z. cf. normani (Australia), Z. sp. A (Corea) y Z. holdichi (España y Francia). Nuestros resultados mostraron que la forma tradicional de identificar tanaidáceos subestima su diversidad y que lo que previamente se consideraron como caracteres morfológicos claramente diferenciadores son, sin embargo, variables y poco fiables

The evolutionary history of sharp- and blunt-snouted lenok (Brachymystax lenok (Pallas, 1773)) and its implications for the paleo-hydrological history of Siberia

<p>Abstract</p> <p>Background</p> <p>Broad-scale phylogeographic studies of freshwater organisms provide not only an invaluable framework for understanding the evolutionary history of species, but also a genetic imprint of the paleo-hydrological dynamics stemming from climatic change. Few such studies have been carried out in Siberia, a vast region over which the extent of Pleistocene glaciation is still disputed. <it>Brachymystax lenok </it>is a salmonid fish distributed throughout Siberia, exhibiting two forms hypothesized to have undergone extensive range expansion, genetic exchange, and multiple speciation. A comprehensive phylogeographic investigation should clarify these hypotheses as well as provide insights on Siberia's paleo-hydrological stability.</p> <p>Results</p> <p>Molecular-sequence (mtDNA) based phylogenetic and morphological analysis of <it>Brachymystax </it>throughout Siberia support that sharp- and blunt-snouted lenok are independent evolutionary lineages, with the majority of their variation distributed among major river basins. Their evolutionary independence was further supported through the analysis of 11 microsatellite loci in three areas of sympatry, which revealed little to no evidence of introgression. Phylogeographic structure reflects climatic limitations, especially for blunt-snouted lenok above 56° N during one or more glacial maxima. Presumed glacial refugia as well as interbasin exchange were not congruent for the two lineages, perhaps reflecting differing dispersal abilities and response to climatic change. Inferred demographic expansions were dated earlier than the Last Glacial Maximum (LGM). Evidence for repeated trans-basin exchange was especially clear between the Amur and Lena catchments. Divergence of sharp-snouted lenok in the Selenga-Baikal catchment may correspond to the isolation of Lake Baikal in the mid-Pleistocene, while older isolation events are apparent for blunt-snouted lenok in the extreme east and sharp-snouted lenok in the extreme west of their respective distributions.</p> <p>Conclusion</p> <p>Sharp- and blunt-snouted lenok have apparently undergone a long, independent, and demographically dynamic evolutionary history in Siberia, supporting their recognition as two good biological species. Considering the timing and extent of expansions and trans-basin dispersal, it is doubtful that these historical dynamics could have been generated without major rearrangements in the paleo-hydrological network, stemming from the formation and melting of large-scale glacial complexes much older than the LGM.</p

When and how? Freshwater mussel recolonization in Lake Orta

Thanks to a video posted on a social network, live mussels of Unio elongatulus, have been recorded from Lake Orta (Italy) over one century after the last (and only) report. With its long and well documented history of pollution, Lake Orta offers the opportunity to document the post-extirpation recovery of freshwater unionid mussels. This case evidences that recovery/recolonization is possible despite a high devastation in the past, and permits to evaluate how fast recolonization may occur, in which way, and in what conditions. The answer to the \u27how fast\u27 was sought by estimating the age of the larger and seemingly older individuals of the population. To address the \u27in which way\u27 we compared the haplotypes of Lake Orta specimens of Unio elongatulus (the only species present) with those of surrounding populations. We concluded that, since Lake Orta lacks a direct connection with the putative source populations, colonizing mussels were almost certainly transported by fish carrying glochidia that were used for lake restocking after liming. Data from the long-term monitoring of water chemistry and sediments have allowed defining what conditions proved to be suitable for survival making possible the start of mussels recovery. But not only water and sediment quality matters for mussels recovery, which was delayed by nearly ten years after the reappearance of fish. This delay reflects the need of the whole trophic chain to be reestablished to allow the survival of the suitable and healthy host-fish populations necessary for mussels reproduction

The role of social networks and citizen science in environmental research: the unexpected revival of freshwater mussels in Lake Orta

Social networks are increasingly used for many conservation and environmental educational purposes. The usefulness for ecological studies is exemplified by the casual discovery of the recovery of freshwater mussels in Lake Orta. Mussels were extirpated by severe industrial pollution soon after 1926 and over the following decades their recovery was prevented by acidification and increase of metal concentrations. Even after the improvement of water conditions obtained by limning, the lack of mussels was taken for granted based on the legacy effects of accumulated toxins in the sediments, and on the limited potential for most extirpated species of mussels to naturally recolonize. The probability of mussel\u27s recovery in Lake Orta was considered poor also for the apparent lack of access to restocking populations, which is essential to start the natural recolonization of an area. Because of the assumption that mussels were absent and of the difficulties of locating mussels their recolonization went unnoticed for about 15 years. Only in 2014 the casual discovery of mussels in Lake Orta was made possible thanks to an amateur video posted on YouTube and delivered to one of us through Facebook: this highlights once more the potential role of social networks for conservation and environmental issues. Freshwater mussels are challenging to locate because they are often rare, spatially clustered, and difficult to detect. The recolonization of Lake Orta went unnoticed probably due to the limited extent of the colonized area, low density and, at least initially, the small size of individuals. In such cases the contribution of citizen science can be crucial to provide the reporting even of small populations present in restricted areas and/or not easily accessible. An extensive search along the lake perimeter is being performed through the volunteer collaboration of local SCUBA divers and an online survey through social networks

Symbolic Computation of Variational Symmetries in Optimal Control

We use a computer algebra system to compute, in an efficient way, optimal control variational symmetries up to a gauge term. The symmetries are then used to obtain families of Noether's first integrals, possibly in the presence of nonconservative external forces. As an application, we obtain eight independent first integrals for the sub-Riemannian nilpotent problem (2,3,5,8).Comment: Presented at the 4th Junior European Meeting on "Control and Optimization", Bialystok Technical University, Bialystok, Poland, 11-14 September 2005. Accepted (24-Feb-2006) to Control & Cybernetic

FRESHCO project – preliminary results assessing the multiple implications of invasive species on freshwater mussel decline and coexistence processes

The Iberian freshwater ecosystems are highly invaded by a myriad of organisms that threaten their native biodiversity, including fish and mussels. FRESHCO project is evaluating the direct and indirect impacts of selected invasive alien species (IAS) belonging to distinct fuinctional groups (from plants to vertebrates) on the native Iberian freshwater mussels (FM) and its fí.sh host fauna. Preliminary results for the designed tasks (T) were obtained: Tl - based on field and lab experiments, FM exhibited lower growth, lower physiological condition, and higher locomotor activity at higher Corbicula fluminea density, suggesting that FM are negatively affected by C. fluminea and may be displaced to less favourable habitats; T2 - only native Iberian fishes are effective hosts for Unio delphinus and Potomida littoralis, while Anodonta anatína hás a more wide range of host fishes that may include non-native species; T3- molecular and classical detection tools hás been used to analyze the diets of selected IAS (Lepomis gibbosus, Pacifastacus leniusculus, Procambarus clarkii, Neovison vison) and preliminary results showed that ali these IAS predate FM; T4 - 150 sampling sites in Douro basin (Portugal and Spain) were surveyed and mussel and fish assemblages and their habitats characterized. In opposition to salmonid streams, which maintain a good ecológica! status, large number of median-sized and lowland rivers display marked changes in abiotic conditions and biotic composition, including a higher proportion of non-native species presence. From an ecological point ofview, overall results would help to clarify the real impacts of the most prominent IAS on the threatened native FM and íish species in Iberia. From a management point ofview, this project will contribute with information that can be used in a more effective conservation of native species and management of IASMultiple implications of invasive species on freshwater mussel decline and coextinction processes" was funded by FCT - Science and Technological National Portuguese Foundation - Project PTDC/AGR-FOR/1627/2014 - 04/SAICT/2015 and by the Project 3599 -Promoting Scientific Production and Technological Development and the Establishment of Thematic Networks 3599-PPCDT supported by FEDER - European Community Fundinfo:eu-repo/semantics/publishedVersio

FRESHCO: multiple implications of invasive species on freshwater mussel decline and coextinction processes

Freshwater mussels (FM) are among the most threatened faunistic groups worldwide. FM depend on fish to complete their life cycle, where mussel larvae (glochidia) use a specifíc range offish hosts. This trait makes them particularly threatened by invasive alien species (IAS) since changes on the host físh populations may eventually lead to the decline or co-extinction ofthe dependent species. The Iberian Península holds a high levei ofthreatened freshwater species, including físh and mussels. Furthermore, Iberian freshwater systems are among the most heavily invaded ecosystems in the world. Under those considerations, FRESHCO project aims to estimate the direct and indirect impacts of selected highly IAS belonging to distinct functional groups (from plants to vertebrates) on the native Iberian FM and its fish host fauna. Five tasks (T) will be executed: Tl will use fíeld and lab experiments to assess the possible competition between the IAS C. fl.uminea and native FM; T2 will be composed ofa series oflab experiments to assess host fish suitability of native FM; T3 will use molecular and classical detection tools to analyze the diets ofselected IAS and assess their predation on FM larvae, juveniles and adults; T4 will use a battery offíeld and lab experiments to assess the impact ofmassive annual die-offs ofthe invasive aquatic plant E. crassipes on the native FM; and in T5, 150 sites ofthe Douro river basin will be surveyed where mussel and fish assemblages and their habitats will be characterized, in arder to evaluate and distinguish the impacts of IAS and habitat degradation on the native fauna. From an ecological point of view, expected results from this project would help to elucidate the real impacts ofthe most prominent IAS on the threatened native FM and fish species in Iberia. From a management point ofview, this project will facilitate a more effective allocation ofresources spent on both native species conservation and IAS management.info:eu-repo/semantics/publishedVersio

Threatened fish and mussel populations in Douro basin (Northern Portugal): in-situ and ex-situ conservation measures

Freshwater ecosystems are threatened by human activities and their biodiversity declines far greater than those on marine and terrestrial ecosystems. Severa! impacts such as habitat loss and fragmentation, pollution, river regulation, overexploitation, introduction ofinvasive species and envoronmental changes are responsible for increasing the extinction risk ofnative species and for the dismption of important ecosystem functions and services. Freshwater mussels (Bivalvia: Unionoida) are among the most threatened faunistic groups in these freshwater ecosystems. These mussels depend on fish to complete their life cycle, where mussel larvae use a specific range of fish hosts to metamorphose. Therefore, the persistence of freshwater mussel species will ultimately depend on the conservation oftheir físh hosts. The Iberian Península holds a high levei ofspatially restricted species and endemisms. Many native físh and mussel species oflberia are listed as vulnerable, endangered or critically endangered and their populations are declining. In this study, we will use data collected in the last 5 years in the main tributaries ofRiver Douro in Portugal to assess the conservation status of native freshwater mussel and fish species and, in particular, the impact of environmental changes. Despite the low human density in three basins (Sabor, Tâmega and Tua), some river stretches are suffering of habitat loss and degradation. Furthermore, the increase in intensity and magnitude of extreme climatic events are inducing higher mortality rates in fish and mussel populations. There are reports of massive die-offs of mussel populations due to a succession of irregular drought and fíood events. For ali these reasons, several in-situ and ex-situ conservation measures have been developed to protect endangered native species ofNE Portugal. In addition, other actions were oriented to the training and public awareness for the conservation ofthreatened species and habitais.info:eu-repo/semantics/publishedVersio

Revisiting the North American freshwater mussel genus Quadrula sensu lato (Bivalvia Unionidae): phylogeny, taxonomy and species delineation

© 2019 Royal Swedish Academy of Sciences Freshwater mussels (Bivalvia, Unionidae) have suffered strong declines over the last century. High morphological plasticity of Unionidae causes disturbances in their systematics and taxonomy, hampering conservation efforts. Species that have historically been placed under the North American genus Quadrula have suffered from numerous taxonomic and species delineation problems since its inception. Four genera are presently recognized within Quadrula sensu lato, that is, Cyclonaias, Quadrula, Theliderma and Tritogonia, but their phylogenetic basis remains incompletely tested. In the present study, we reconstructed several two-marker (mtDNA cytochrome c oxidase subunit I—COI and NADH dehydrogenase subunit 1—ND1) phylogenies with newly collected specimens and all previously available sequences covering most species within this group. We then delineated the species within the group using an integrative approach with the application of molecular statistical methods, morphometric (Fourier Shape) analyses and geographic distribution data. Four clades corresponding to these genera were consistently recovered in all phylogenies. To validate the generic status of these clades, molecular analyses were complemented with morphological, anatomical and ecological data compiled from the literature. Several revisions are here proposed to the current systematics and taxonomy of these genera, including the synonymization of Cyclonaias asperata under Cyclonaias kieneriana; the inclusion of Quadrula apiculata and Quadrula rumphiana under Quadrula quadrula; the placement of Quadrula nobilis under Tritogonia; and finally the separation of the Mobile River basin populations of Theliderma metanevra as a new species, that is, Theliderma johnsoni n. sp. The conservation implications of the proposed changes are then discussed