Papers by Kęstutis Arbačiauskas
bioRxiv (Cold Spring Harbor Laboratory), Jan 20, 2023
The Baltic countries harbor a diverse assemblage of alien amphipods of Ponto-Caspian origin. The ... more The Baltic countries harbor a diverse assemblage of alien amphipods of Ponto-Caspian origin. The composition of this fauna was shaped by three invasion waves: 1) pre-20 th century dispersals via watershed-connecting canals, 2) deliberate introductions in the 1960s, and 3) new dispersals during the last decade via shipping and pre-existing canals. Given this rich invasion history, we test whether genetic diversity (mitochondrial and nuclear) differs between the native and invaded ranges and between the deliberately introduced species and the ones that dispersed on their own. Our results show a significant decrease in mitochondrial but not nuclear genetic diversity in the invaded Baltic range. We also find that in the invaded range the introduced species exhibit a higher mitochondrial and nuclear genetic diversity than the species that dispersed on their own, while in the native range only the nuclear diversity is higher in introduced species. Mitochondrial diversity was more structured geographically in the native range and the dominant invasive haplotypes were detected in the native populations of all but one species, further highlighting the utility of this marker in tracing invasion sources. Our comparative approach provides important insight into the inter-range genetic diversity of Ponto-Caspian invaders, highlighting the role of introduction mode.
Conservation Genetics Resources, Oct 20, 2013
Ten polymorphic microsatellite loci were developed for the butterfly Erebia palarica (Nymphalidae... more Ten polymorphic microsatellite loci were developed for the butterfly Erebia palarica (Nymphalidae, Satyrinae), endemic to NW Spain. Polymorphism for 20 individuals from a NW Spanish population (Ancares) and 15 more from two other nearby localities (Courel, Trevinca) was assessed. Overall, the number of alleles per locus ranged from six to 24. Ancares showed an average number of alleles per locus of 14.30 (SD = 5.32), observed heterozygosity of 0.753 (SD = 0.14) and unbiased expected heterozygosity of 0.818 (SD = 0.114). Genotypic frequencies conformed to the Hardy-Weinberg equilibrium at Ancares, and there was no evidence of linkage disequilibrium. Multilocus genotypes resulting from this set of markers will be useful for determining genetic diversity and differentiation within and among populations of this local endemic butterfly in NW Spain. Of the six loci amplified in the closely related species, Erebia meolans, five were polymorphic.
BioInvasions Records, 2018
The Ponto-Caspian amphipod Dikerogammarus bispinosus is regarded as a native species throughout t... more The Ponto-Caspian amphipod Dikerogammarus bispinosus is regarded as a native species throughout the lower stretches of rivers that drain into the Black Sea. Its occurrence in the Caspian Sea basin was uncertain due to conflicting reports. Here, we provide the first conclusive evidence for its presence in this basin. Individuals of both sexes, including ovigerous females, were collected in May 2000 from the Ural River in Kazakhstan, suggesting full establishment. If it was a recent invasion, the most probable dispersal pathway into the Caspian basin would have been via the Volga-Don canal as D. bispinosus was reported in the early 2000s from the lower Don River and the Saratov reservoir on the Volga River. However, given that until relatively recently D. bispinosus was considered a subspecies of D. villosus, we cannot rule out that it has been overlooked in earlier reports from the Caspian Sea basin by being mentioned as D. villosus or even D. haemobaphes. We also provide new data on the distribution of Gammarus lacustris, Obesogammarus platycheir, Pontogammarus abbreviatus, P. robustoides, Turcogammarus aralensis and Wolgagammarus dzjubani in western Kazakhstan and southwestern Russia.
Journal of Limnology, Sep 1, 2004
Life-history and physiology of post-diapause and directly developing offspring in Daphnia were co... more Life-history and physiology of post-diapause and directly developing offspring in Daphnia were compared to determine differences in life-history pattern between offspring origins, identify the basic traits effecting pattern distinction, assess the consequencies of differing life-history for relative fitness, and qualify this seasonal phenomenon. Although the size of ex-ephippial hatchlings was positively correlated with maternal size, ephippia produced by differently sized females of D. magna yielded neonates which body size and it's variation were similar to those for the first-clutch parthenogenetic neonates produced under high food conditions. Otherwise, post-diapause neonates of D. pulex were larger than first-clutch parthenogenetic neonates and varied in size close to that for neonates from the later clutches. Ex-ephippial offspring showed elevated metabolic activity. Under rich food, they grew faster during juvenile development and were larger at maturation than parthenogenetic females. Post-diapause offspring of D. magna showed higher juvenile growth rates also at limited food availability. Female origins during early maturity differed in resource allocation strategy. A greater allocation to progeny in offspring exiting diapause, however, resulted in increased progeny numbers and higher relative fitness only under rich food environments. Whereas, parthenogenetic females of D. magna exhibited a trend for higher fitness across limited food concentrations. For D. pulex, variability of fitness across differing nutritional environments was lower in directly developing females than that for ex-ephippial offspring. Higher metabolic activity in combination with small initial size resulted in lower resistance to starvation of post-diapause offspring of D. magna. Descendants of female origins in this species showed similar fitness. We conclude that although some traits of ex-ephippial offspring in comparison to parthenogenetic ones may differ across Daphnia species, the life-history strategy of post-diapause females in Daphnia is the same. Ex-ephippial females are adapted to predictable optimal conditions, whereas parthenogenetic females are adapted to unpredictably varying environment. Daphnia have evolved two alternative seasonal phenotypes matching environmental conditions in which they occur, and perform in accordance with predictions of seasonal polyphenism. Due to higher metabolic activity, which must lead to increased resource acquisition and probably is associated to larger allocation to progeny, post-diapause females are superior to directly developing offspring under high food conditions, which are expected during early season, but inferior under limiting food environments, which frequently occur later in the season. In seasonal climate, the adjustment of resource acquisition with respect to resource availability may be a general evolutionary trend for multivoltine organisms resulting in a seasonal polyphenism.
Freshwater Biology, Feb 18, 2013
1. Ponto-Caspian peracaridans, and mysids and amphipods in particular, are among the most success... more 1. Ponto-Caspian peracaridans, and mysids and amphipods in particular, are among the most successful aquatic invaders. However, species differ in the trophic-status range of ecosystems they can invade while establishment rates and impacts can vary substantially between habitats. There is limited knowledge of the environmental factors and species characteristics that drive such variation in invasion success. 2. Here we test how trophic level and body stoichiometry vary among peracaridan species and in relation to body size. The amphipod Pontogammarus robustoides and the mysids Limnomysis benedeni and Paramysis lacustris were investigated in ecosystems differing considerably in productivity and nutrient supply, namely an N-limited eutrophic lagoon and P-limited mesotrophic lakes. 3. As revealed by stable isotope (15 N ⁄ 14 N) analysis, herbivory was inferred to be the main feeding mode of L. benedeni. In contrast, the mysid P. lacustris and the amphipod P. robustoides displayed a higher propensity for predatory feeding at larger body sizes, a pattern that was more pronounced in the eutrophic lagoon than in the mesotrophic lakes. 4. Their mean stoichiometric composition (P.
Hydrobiologia, Apr 25, 2023
Hydrobiologia, Sep 1, 2004
Daphnids of ex-ephippial and parthenogenetic origin differ substantially in life-history. Possibl... more Daphnids of ex-ephippial and parthenogenetic origin differ substantially in life-history. Possible maternally transmitted ex-diapause effects of differing female origin on the fitness of their offspring were studied across multiple clones in Daphnia magna. Ex-ephippial daphnids responded in egg size to different constant food concentrations with the same pattern as parthenogenetic females. Significant differences in egg characteristics between females of different origin were only found for the first clutch produced under high food. The smaller size of eggs in ex-ephippial females, however, did not translate into size differences of first-clutch neonates. A trend for lower mass density per body volume was detected in offspring from ex-ephippial females in comparison with parthenogenetic daphnids. Hence, an ex-diapause effect transmitted by exephippial mothers to their parthenogenetic offspring is likely. However, there was no difference in life-histories and fitness between offspring produced by females of ex-ephippial and parthenogenetic origin at both, high and low food concentrations across multiple clones. Thus, a significant ex-diapause effect on fitness in successive parthenogenetic generations may not be expected in D. magna at the population level.
Acta Ichthyologica Et Piscatoria, Jun 30, 2013
Background. The round goby, Neogobius melanostomus (Pallas, 1814), is a recent invader in the Cur... more Background. The round goby, Neogobius melanostomus (Pallas, 1814), is a recent invader in the Curonian Lagoon, SE Baltic Sea. As invasive species are among the most severe threats for biodiversity loss and can induce food web alterations, the development of round goby population in the Curonian Lagoon and its possible impacts on fish community and the entire ecosystem are of great scientific interest. This research reports on the expansion and trophic role of round goby in the Curonian Lagoon. Materials and methods. Occurrence and abundance of round goby was investigated using a beach seine and gill nets at the northern and central parts of the Curonian Lagoon during a six-year period from 2007 to 2012. The trophic niche of the newcomer was revealed by applying gut content and stable isotope analyses (SIA). A total of 61 samples of other fish species were taken for SIA in order to reveal with which resident fish species the exploitative competition could be expected. Stable isotope mixing models were used to evaluate the contribution of round goby to the nutrition of top predators of the Curonian Lagoon: European perch, Perca fluviatilis Linnaeus, 1758; pike-perch, Sander lucioperca (Linnaeus, 1758); great cormorant, Phalacrocorax carbo; and grey heron, Ardea cinerea. Results. The survey showed that round goby expanded its distribution area and recently occurs in the entire Lithuanian part of the Curonian Lagoon. Variation in the density of round goby suggests that the invader's abundance may be stabilised in the northern part of the lagoon. Gut content and stable isotope analyses showed round goby being mainly benthivorous. The largest trophic overlap with respect to SIA was detected between the invader and ruffe, Gymnocephalus cernua (Linnaeus, 1758), the fish which presumably exploits the same habitat type. According to stable isotope mixing models round goby was included with considerable shares into the diet of top predators. Conclusion. The further expansion of round goby inside the Curonian Lagoon is ongoing. However, there is evidence on population density stabilisation in the northern part of the lagoon. Native benthivorous fish, especially ruffe, may be affected through competition for food resources in habitats where the newcomer is numerous. Round goby significantly contributes to the diet of piscivorous fish and birds. That may promote the regulation of invader population abundance in the lagoon.
Functional Ecology, Aug 1, 2003
1. Physiology and life history of ex-ephippial and parthenogenetic offspring of Daphnia magna Str... more 1. Physiology and life history of ex-ephippial and parthenogenetic offspring of Daphnia magna Straus were compared to test the hypothesis that females hatching from resting eggs are well adapted to the predictable high-food conditions of the spring algal bloom. 2. Although ex-ephippial neonates were smaller than parthenogenetic neonates, they showed higher juvenile growth rates that compensated for the size difference by the time of maturation. 3. At high food concentration, ex-ephippial females were even larger at maturation than parthenogenetic females, produced more eggs, and reached a higher rate of population increase. 4. The high activity of the ex-ephippial females was accompanied by higher metabolic rates, which in combination with the low initial mass resulted in reduced survival times under starvation. 5. Thus, the two phenotypic types of offspring produced by Daphnia are adapted to differing conditions. Ex-ephippial females are superior to parthenogenetic offspring under high food conditions, but inferior when food is limiting. 6. This pattern selects for synchronous hatching of resting eggs in spring when the spring algal bloom is to be expected.
Aquatic Ecosystem Health & Management, Dec 13, 2017
Ponto-Caspian peracaridan Crustaceans first invaded the Baltic Sea basin from the basin of the Bl... more Ponto-Caspian peracaridan Crustaceans first invaded the Baltic Sea basin from the basin of the Black Sea via artificial canals in the 18th Century. In the 1960s, the number of these species substantially increased due to deliberate introduction of Mysids and Amphipods into Lithuanian waters to enhance fish production. Range expansion of Ponto-Caspian peracaridan Crustaceans is continuing due to secondary dispersal and invasion by new species. Historically the main invasion vectors were inland shipping, deliberate introductions and natural dispersal across inland waterways; more recently the significance of marine invasions related to shipping seems to be increasing. These invaders have had detrimental impacts on local macroinvertebrates and may even have caused local extinctions of native species. Such impacts likely result from predatory and competitive interactions between alien and native species. The magnitude of predatory impacts of omnivorous Ponto-Caspian peracaridan Crustaceans can rise with increasing productivity of the environment. These Crustaceans, especially large-sized species, have proved to be prone to carnivorous feeding and high plasticity when acquiring nutrients for reproduction and growth. It seems that stoichiometric plasticity related to their flexible feeding strategy may favour their invasiveness. Another undesirable outcome of these invasions is distortion of conventional metrics of ecological status for aquatic systems. Meanwhile, at least in lakes, the primary goal of introduction, i.e. enhancement of fish production, has not been achieved. Some invasive Crustaceans seem to be adapting to previously unsuitable habitats in their invaded range, which may exacerbate their negative impacts. Further expansion of accumulated and new Ponto-Caspian peracaridan Crustaceans can be expected in Lithuanian waters as well as in the Baltic Sea basin, and their impacts may increase in the future.
Effects of acid deposition on forest ecosystems despite a drastic decrease in sulphur emission an... more Effects of acid deposition on forest ecosystems despite a drastic decrease in sulphur emission and deposition at the end of the 1990s are still among the most significant ecological issues. The key reason for this is that atmospheric concentrations of ammonium and nitrate which have a tendency to increase in the last period became the main acidifying compounds of precipitation. These changes in acid deposition resulted in main objectives of the presented study which were to estimate the effect of rain acidity and atmospheric deposition of pollutants on crown defoliation and diversity of soil microarthropods, stream macrobenthos and small mammals (rodents) on territories under changing regional pollution level. Investigation was carried out in 3 Lithuanian Integrated Monitoring Stations over the period 1994-2004. The obtained data indicated that lower life forms were more affected than higher. Acid deposition was shown to have the most significant effect on pine tree defoliation as well as on the diversity of soil microarthropods and diversity of stream macroinvertebrates and least on the diversity of small mammals. These results have indicated that regional pollution level which is below the critical level for forest ecosystem has a significant effect on the biota.
Acta Zoologica Lituanica, 2010
... Vytautas RAKAUSKAS, Simona SMILGEVIČIENĖ, Kęstutis ARBAČIAUSKAS ... 1992; Dick 1996;Dick &... more ... Vytautas RAKAUSKAS, Simona SMILGEVIČIENĖ, Kęstutis ARBAČIAUSKAS ... 1992; Dick 1996;Dick & Platvoet 1996; Arbačiauskas & Gumuliauskaitė 2007), have a strong impact on composi-tion of benthic and planktonic communities, may cause sizeable changes in species ...
Zoological Journal of the Linnean Society
Amphipods have diversified greatly in the Ponto-Caspian region. Although many of these species ar... more Amphipods have diversified greatly in the Ponto-Caspian region. Although many of these species are prominent invaders their systematics remains unclear. Taking an integrative approach, we investigate the taxonomy of Trichogammarus trichiatus, a widespread invader in European inland waters. It was initially described from the north-eastern Black Sea coast as Chaetogammarus trichiatus by Martynov in 1932. A similar taxon, Chaetogammarus tenellus major, was described by Cărăușu from the western Black Sea in 1943 but later synonymized with C. trichiatus. Chaetogammarus trichiatus was itself shuffled between Chaetogammarus and the Atlanto-Mediterranean Echinogammarus, currently being assigned to Trichogammarus. Our analyses (six DNA markers, 60 measurements and scanning electron microscopic imaging) reveal that T. trichiatus and C. tenellus major are distinct species; the former is a Caucasian endemic, whereas the latter invaded Europe. Unexpectedly, T. trichiatus is an incipient species...
The Ponto-Caspian region is an endemicity hotspot that harbors several crustacean radiations, amo... more The Ponto-Caspian region is an endemicity hotspot that harbors 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 and monitoring outside the native region. Here, we assemble a DNA barcode reference library for nearly 60% of all known Ponto-Caspian amphipod species. We use several methods to define molecular operational taxonomic units (MOTUs) based on two mitochondrial markers (COI and 16S) and assess their congruence with current species-level taxonomy based on morphology. Depending on the method, we find that 54–69% of species had congruent morpho-molecular boundaries. The cases of incongruence resulted from lumping distinct morphospecies into a single MOTU (7–27%), splitting a morphospecies into s...
Biological Invasions, 2017
Identifying the origins and colonization routes of alien species is critical to understanding the... more Identifying the origins and colonization routes of alien species is critical to understanding the mechanisms, consequences and management of invasions. This study aims to demonstrate and explain conflicting genetic signals in a widespread invasive Ponto-Caspian mysid Paramysis lacustris using mitochondrial DNA and microsatellite markers. Native Black Sea populations of P. lacustris are divided into three distinct phylogeographic groups: Danube-Dniester region, coastal Danube lakes, and Dnieper River delta. In the 1950s-1970s the species has been extensively used for relatively well documented transplantations in Eastern Europe. However, the populations in the newly established distribution area do not match any of the known native groups, and their genetic signal does not correspond with the recorded transplantation history. Using Bayesian Approximate Computation we explore alternative scenarios that could explain the unexpected mitochondrial and nuclear signals in the introduced populations. We suggest that reservoir construction and break-up of natural dispersal barriers on the River Dnieper have brought about a novel stock, probably admixed from a previously isolated and unknown ''relict'' population in the middle Dnieper and the genetically distinct Dnieper delta lineage. Through further intentional transfers this new P. lacustris lineage is now widely present in Eastern Europe and is likely to have new gene and trait combinations. The conflicting mitochondrial-nuclear signal in non-native populations also highlights the importance of using multiple genetic markers when tracing invasion sources and pathways. Keywords Approximate Bayesian Computation Á Genetic admixture Á Intentional transplantations Á Invasive species Á mtDNA introgression Á Ponto-Caspian phylogeography Electronic supplementary material The online version of this article (
Acta Zoologica Lituanica, 2008
Acta Zoologica Lituanica, 2008
Acta Zoologica Lituanica, 2008
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Papers by Kęstutis Arbačiauskas