Pungitius Pungitius Research Articles

Consensus Decision Making by Fish

Decisions reached through consensus are often more accurate, because they efficiently utilize the diverse information possessed by group members [1-3]. A trust in consensus decision making underlies many of our democratic political and judicial institutions [4], as well as the design of web tools such as Google, Wikipedia, and prediction markets [5, 6]. In theory, consensus for the option favored by the majority of group members will lead to improved decision-making accuracy as group size increases [2, 4]. Although group-living animals are known to utilize social information [7-10], little is known about whether or not decision accuracy increases with group size. In order to reach consensus, group members must be able to integrate the disparate information they possess. Positive feedback, resulting from copying others, can spread information quickly through the group, but it can also result in all individuals making the same, possibly incorrect, choice [8, 11, 12]. On the other hand, if individuals never copy each other, their decision making remains independent and they fail to benefit from information exchange [4]. Here, we show how small groups of sticklebacks (Gasterosteus aculeatus) reach consensus when choosing which of two replica fish to follow. As group size increases, the fish make more accurate decisions, becoming better at discriminating subtle phenotypic differences of the replicas. A simple quorum rule proves sufficient to explain our observations, suggesting that animals can make accurate decisions without the need for complicated comparison of the information they possess. Furthermore, although submission to peers can lead to occasional cascades of incorrect decisions, these can be explained as a byproduct of what is usually accurate consensus decision making.

Community structure, population structure and topographical specialisation of Gyrodactylus (Monogenea) ectoparasites living on sympatric stickleback species

In order to disentangle the contribution of host and parasite biology to host specificity, we compared the structure and population dynamics of the Gyrodactylus (von Nordmann, 1832) flatworm community living on sympatric three-spined Gasterosteus aculeatus L. and nine-spined Pungitius pungitius (L.) stickleback. Between April 2002 and March 2003, a small lowland creek was sampled monthly. Species identity of about 75% of the worms per host was determined with a genetic nuclear marker (ITS1). Each stickleback species hosted a characteristic gill- and fin-parasitic Gyrodactylus: G. arcuatus Bychowsky, 1933 and G. gasterostei Gläser, 1974 respectively infecting the three-spined stickleback, with G. rarus Wegener, 1910 and G. pungitii Malmberg, 1964 infecting the nine-spined stickleback. Host size and seasonal dynamics were strong determinants of parasite abundance. A strong interaction between host and parasite species determined infection levels and affected three levels of parasite organisation: community structure, population structure and topographical specialisation. Community and population structure were shaped by asymmetric cross-infections, resulting in a net transmission of the Gyro-dactylus species typical of the nine-spined stickleback towards the three-spined stickleback. Host density was not a major determinant of parasite exchange. Aggregation and topographical specialisation of the Gyrodactylus species of the three-spined stickleback were more pronounced than that of the nine-spined stickleback.

Effects of water-level regulation on the nearshore fish community in boreal lakes

The fish community in the littoral areas of eight regulated lakes and five reference lakes in Finland was sampled by electrofishing. No significant effect of winter drawdown on species richness was recorded across lakes. Total fish density for stony bottoms of the regulated and reference lakes averaged 19.3 and 32.7 individuals per 100 m2, respectively, but this difference was not statistically significant. The combined proportion of littoral fish species, including minnow (Phoxinus phoxinus), bullhead (Cottus gobio), alpine bullhead (Cottus poecilopus), nine-spined stickleback (Pungitius pungitius), and stone loach (Barbatula barbatula), supplemented with zoobenthos feeders ruffe (Gymnocephalus cernuus) and young burbot (Lota lota), was much lower in the regulated lakes than in the reference lakes. Besides winter drawdown, other variables, such as nutrient level and lake size, affected the fish community.

Heteromorphic sex chromosomes in the ninespine stickleback Pungitius pungitius

Specimens from two freshwater populations of the ninespine stickleback Pungitius pungitius in Poland showed morphologically differentiated sex chromosomes. A heteromorphic pair of chromosomes appeared only in male diploid cells. The Y chromosome was the largest chromosome in the P. pungitius karyotype.

Nearshore Habitat and Fish Community Associations of Coaster Brook Trout in Isle Royale, Lake Superior

AbstractWe characterized the nearshore habitat and fish community composition of approximately 300 km of shoreline within and adjacent to the major embayments of Isle Royale, Lake Superior. Sampling yielded 17 species, of which 12 were widespread and represented a common element of the Lake Superior fish community, including cisco Coregonus artedi, lake whitefish C. clupeaformis, round whitefish Prosopium cylindraceum, lake trout Salvelinus namaycush, rainbow smelt Osmerus mordax, lake chub Couesius plumbeus, longnose sucker Catostomus catostomus, white sucker C. commersonii, trout‐perch Percopsis omiscomaycus, ninespine stickleback Pungitius pungitius, burbot Lota lota, and slimy sculpin Cottus cognatus. The presence of brook trout S. fontinalis in an embayment was associated with the common species of the Isle Royale nearshore fish community, particularly cisco, longnose sucker, and round whitefish. However, brook trout were present in only five embayments and were common only in Tobin Harbor. Most Isle Royale embayments had broadly overlapping ranges of nearshore habitats. Within embayments, fish were distributed along a habitat gradient from less‐protected rocky habitat near the mouth to highly protected habitat with mixed and finer substrates at the head. Embayments with brook trout had greater mean protection from the open lake, greater variation in depth, greater mean cover, and higher mean frequencies of large substrates (cobble, boulder, and bedrock). Within those embayments, brook trout were associated with habitat patches with higher mean frequencies of small substrates (particularly sand and coarse gravel). Within Tobin Harbor, brook trout were associated with midembayment habitat and species assemblages, especially those locations with a mixture of sand, gravel, and cobble substrates, an absence of bedrock, and the presence of round whitefish, white sucker, and trout‐perch. Comparison of embayments with the model, Tobin Harbor, showed that six embayments without brook trout had very similar arrays of habitat. However, four embayments with brook trout had relatively different arrays of habitat from Tobin Harbor. These results suggest that there is potential for further recovery of brook trout populations across Isle Royale nearshore habitats.

Diverse migratory histories in a brackish water type of the ninespine stickleback, Pungitius pungitius

The life history in a brackish water type of the ninespine stickleback, Pungitius pungitius, was studied by examining the strontium (Sr) and calcium (Ca) concentrations in the otoliths. The fluctuating patterns of Sr/Ca ratios along the life history transect in the otoliths varied widely among fish in spite of their identification as brackish water type as estimated by morphological characteristics. More than 70% fish showed the intermediate otolith Sr/Ca ratio throughout, averaging 5.23–7.71 × 10−3. Besides this brackish water resident life history type of P. pungitius, other sticklebacks had anadromous (25%) and freshwater amphidromous (2.5%) life history types. These findings clearly indicate that the migration of the ninespine stickleback between fresh and sea waters is obligatory but facultative having an ability to utilize the full range of salinity in its life history.

Conservation of threespine and ninespine stickleback radiations in the Cook Inlet Basin, Alaska

Summary Threespine stickleback (Gasterosteus aculeatus) and ninespine stickleback (Pungitius pungitius) are both species complexes with many unique and reproductively isolated biological species throughout their range. Both complexes exhibit phenomenal morphological and ecological diversity, including rare phenotypes, in the Cook Inlet Basin in Southcentral Alaska. The Cook Inlet threespine stickleback radiation has been used intensively since the early 1990s to study the genetic and behavioural mechanisms of rapid evolution and speciation, loss of skeletal elements and armor structures, body shape evolution, evolution of development and developmental abnormalities, behavioural evolution, life history evolution, trophic ecology, parasitism, genetic structure and function, and effects of environmental contaminants. Unique populations from both species complexes should be conserved to protect the scientific investment in these radiations and their future utility for research. Many of these populations are now threatened by invasive northern pike (Esox lucius). Northern pike have already caused the local extinction of a rare, weakly-armored threespine stickleback in Prator Lake, and pike are a potential future threat to threespine stickleback in nearby Bear Paw Lake, the source population for the stickleback genome project. Other threats in the Cook Inlet Basin include salmonid stocking in isolated lakes, human impacts on water quality, water withdrawals for human use, and climate change. These threats should be addressed through targeted pike eradication and educational programs on introduced species, a new lake stocking policy that incorporates stickleback conservation, discontinuation of ichthyocide use, research to improve water quality, restrictions on water withdrawals, and a comprehensive stickleback monitoring program. The goals of these actions should be to secure the future viability of special research populations, as well as the maintenance of phenotypic diversity within both stickleback radiations.

Follow-Up on Habitat Preservation Works for Ninespine Sticklebacks in Shika Town, Ishikawa, Japan

Follow-Up on Habitat Preservation Works for Ninespine Sticklebacks in Shika Town, Ishikawa, Japan

Nesting habitat use and partitioning of three sympatric ninespine sticklebacks (genus Pungitius): implications for reproductive isolation

The nest site characteristics and distribution patterns of nests of three sympatric ninespine sticklebacks, the brackish- and fresh-water types and Pungitius tymensis, were investigated in the Shiomi River, eastern Hokkaido, Japan. In this river, most of the males of the brackish-water type were found to build their nests in the lower reach with higher salinity (mean 13.5‰) and water temperature (mean 13.3°C), whereas the males of the freshwater type and P. tymensis built their nests in the upper reach with lower salinity (mean 0.6 and 0.8‰, respectively) and water temperature (both mean 11.3°C). The ranges of their nesting areas, however, overlapped within the river, because the nests of the brackish-water type were widely distributed in the river. A comparison of the nest site characteristics in the area where nest overlapped indicated that there were no significant differences for all of five characteristics (the distance from the nest to the shore, the distance from the nest to the bottom, the distance to the nearest nest, the nest density and the amount of cover around the nest). Using canonical discriminant analysis, the nests of the three sticklebacks could not be distinguished using the five nest characteristics. These results suggest that habitat isolation through physical factors functions as an important mechanism of reproductive isolation between the brackish-water type and the other two sticklebacks.

Isolation and characterization of polymorphic microsatellite DNA markers in the Omono type of ninespine stickleback, genus Pungitius

AbstractWe isolated and characterized 25 polymorphic microsatellite loci for the Omono type of ninespine stickleback, genus Pungitius, an endangered species in streams including agricultural canals in Japan. The number of observed alleles per locus ranged from two to 15 within 32 individuals each collected from three populations in the Omono River, and the values of observed and expected heterozygosities ranged from 0.031 to 0.906 and from 0.031 to 0.856, respectively. All loci conformed to the Hardy–Weinberg equilibrium. Genetic linkage disequilibrium analysis between all pairs of the loci showed no significant departure from the null hypothesis between any of the loci.

HETEROSPECIFIC AGGRESSION AND ADAPTIVE DIVERGENCE IN BROOK STICKLEBACK (CULAEA INCONSTANS)

Agonistic behavior between heterospecifics, in which individuals of one species attack another, may cause a subordinate species to shift resource or habitat use. Subsequent evolutionary responses to selection may mimic shifts expected under ecological character displacement, but with no role played by exploitative competition. Alternatively, aggressive behavior can evolve when fitness is improved by excluding members of a coexisting species from a defendable resource through interference. We tested whether heterospecific agonistic behavior has evolved in brook stickleback (Culaea inconstans) by comparing replicate allopatric populations to those sympatric with ninespine stickleback (Pungitius pungitius). We also tested for heritable variation in heterospecific aggressive behavior by rearing family groups in a common environment. Allopatric populations of brook stickleback were more aggressive than ninespine stickleback, suggesting that pre-existing aggression in brook stickleback contributed to niche shifts by ninespine stickleback. In addition, sympatric adult brook stickleback were more aggressive toward ninespine stickleback than brook stickleback from allopatric populations. Overt heterospecific aggressive behaviors were heritable, and aggression in juvenile brook stickleback increased with age in sympatric but not in allopatric populations reared in a common environment. Brook stickleback have evolved increased aggression when they coexist with ninespine stickleback. These stickleback communities have been structured by both evolved and pre-existing variation in heterospecific aggressive behavior in brook stickleback.

Resource partitioning and asymmetric competition between sympatric freshwater and Omono types of ninespine stickleback,Pungitius pungitius

The freshwater and Omono types of ninespine stickleback, Pungitius pungitius (L., 1758), coexist in several ponds and a stream in the Omono River system, Japan. We tested the hypothesis that coexistence of the two types is accomplished by resource partitioning through interspecific competition. First, the stomach contents of the two types were compared between sympatric and allopatric populations: the stomach contents of the sympatric freshwater type consisted of almost all Copepoda, whereas those of the sympatric Omono type consisted of not only Copepoda, but also many large benthic invertebrates; the stomach contents of both allopatric types were similar, consisting of Copepoda and large benthic invertebrates. Second, behaviour related to resource use in a sympatric pond was observed in the nonbreeding season: the freshwater type showed little aggressive behaviour, but the Omono type had a high frequency of aggressive behaviour. These results indicate that the sympatric freshwater type does not hold a feeding territory and its food resource is almost all Copepoda, whereas the Omono type has a feeding territory and its food resources are various. This suggests that asymmetric interference competition causes a diet shift of the sympatric freshwater type, allowing the two types to coexist by their resource partitioning.

Fish assemblages in the large lowland Narew River system (Poland): Application of the self-organizing map algorithm

The section of the lowland Narew River within Polish borders (432 km long) flowing between two big reservoirs, and its tributaries were selected for the study. At 321 sites a total of 49,675 fish and lamprey specimens, representing 36 taxa, were collected. The sites were classified using the Kohonen self-organizing map (SOM) on the basis of fish and lamprey relative biomass data. The trained SOM (lattice 6 × 4) showed three main clusters of samples assigned to the neurons: (1) A1–B4, (2) C1–D4, and (3) E1–F4, differing not only in fish fauna composition but also in some environmental variables not presented to the SOM. Generally, sites from small, regulated streams with few trees along banks were dominant in cluster AB, while sites from natural larger rivers with many trees along banks were assigned to cluster EF. Cluster CD contained sites of intermediate character. In AB we distinguished an assemblage with five species present in each neuron (gudgeon, loach, stickleback, ten-spined stickleback and pike), and in EF an assemblage with seven ones (stickleback, ide, perch, roach, pike, burbot and bleak), but 100% occurrence stability in each neuron was recorded only for roach in EF. A significantly lowest species richness and values of the Shannon index of biodiversity were recorded in AB, that is for the smallest streams. Additionally, many environmental, population and assemblage variables also showed more subtle gradients within each cluster. The clear differences between clusters and gradients within them, recorded even for variables indirectly analysed with SOM, prove that the obtained classification was very effective, which additionally testifies to the reliability of the distinguished fish assemblages. SOM provides more detailed information on the mutual relations between species through component planes than the detrended correspondence analysis through points in a multivariate space, thus being much useful for coenological studies. Moreover, such rich data as in this study diminish the legibility of scatterplots in the detrended correspondence analysis, while SOM provides much more clear visualization of results.

Extensive lineage-specific gene duplication and evolution of the spiggin multi-gene family in stickleback

BackgroundThe threespine stickleback (Gasterosteus aculeatus) has a characteristic reproductive mode; mature males build nests using a secreted glue-like protein called spiggin. Although recent studies reported multiple occurrences of genes that encode this glue-like protein spiggin in threespine and ninespine sticklebacks, it is still unclear how many genes compose the spiggin multi-gene family.ResultsGenome sequence analysis of threespine stickleback showed that there are at least five spiggin genes and two pseudogenes, whereas a single spiggin homolog occurs in the genomes of other fishes. Comparative genome sequence analysis demonstrated that Muc19, a single-copy mucous gene in human and mouse, is an ortholog of spiggin. Phylogenetic and molecular evolutionary analyses of these sequences suggested that an ancestral spiggin gene originated from a member of the mucin gene family as a single gene in the common ancestor of teleosts, and gene duplications of spiggin have occurred in the stickleback lineage. There was inter-population variation in the copy number of spiggin genes and positive selection on some codons, indicating that additional gene duplication/deletion events and adaptive evolution at some amino acid sites may have occurred in each stickleback population.ConclusionA number of spiggin genes exist in the threespine stickleback genome. Our results provide insight into the origin and dynamic evolutionary process of the spiggin multi-gene family in the threespine stickleback lineage. The dramatic evolution of genes for mucous substrates may have contributed to the generation of distinct characteristics such as "bio-glue" in vertebrates.

Comparison of taste preferences in the three-spined Gasterosteus aculeatus and nine-spined Pungitius pungitius sticklebacks from the White Sea Basin

Similarity between the taste preferences of classical taste substances and free L-amino acids in adult three-spined stickleback Gasterosteus aculeatus (forma leiurus) and nine-spined stickleback Pungitius pungitius (forma laevis) was found. The strongest and the most significant responses in both species were evoked by citric acid and cysteine, asparatic, and glutamic acids. Sodium chloride, calcium chloride, sucrose, and the remaining 18 amino acids do not elicit a statistically significant effect on the consumption of agar-agar pellets by the fish or have weak taste attractiveness. Similarity of taste preferences in the three-spined and nine-spined sticklebacks are supported by correlation analysis. Absolute values of the consumption of pellets of the same types are also similar in the two species. There were, however, differences in the behavioral taste response, repeated snaps, and the duration of processing of the pellets. The taste response of the nine-spined stickleback is more similar to taste responses in fish of the limnophilic complex than to the response in the three-spined stickleback. It is hypothesized that taste spectra may be very similar in fish with similar ecology and feeding patterns not only in sticklebacks, but also in other related species.

Parasite diversity of sticklebacks from the Baltic Sea

In the brackish Baltic Sea, the species richness and diversity of parasite communities of three- (Gasterosteus aculeatus) and nine-spined sticklebacks (Pungitius pungitius) were investigated. The studies regarded four localities at the Schleswig-Holstein and Mecklenburg coasts, northern Germany, where salinities were between 10 and 18 per thousand. Species richness was relatively high, attaining 15 parasite species in G. aculeatus and 16 in P. pungitius, which are only surpassed by former investigations that lasted a year or more. An analysis of parasite species identity revealed clear differences in diverse localities referring to different supracommunities. The infracommunity comprised maximally of eight species in G. aculeatus and seven in P. pungitius, which corresponds to former investigations. The mean value of infracommunity with 5.3 parasites is the highest value ever found in small-sized fish. An infracommunity index revealed that the digenean Podocotyle atomon and Magnibursatus caudofilamentosa and the copepod Thersitina gasterostei were the most abundant parasites. The relationship of component community to mean infracommunity can judge about the threshold level, which allows parasite to settle successfully. An important factor to form parasite communities is the season of their appearance, which depends also on their reproduction and on the presence of intermediate hosts. In addition, the choice of prey (for passive infection) and quality of habitats (for active infection) influences the constitution of the parasite communities. The diversity values of parasites were low in all hosts, which is due to the brackish milieu and by different levels of eutrophication, which both create extreme environments. These do not mirror in every case the biodiversity of the respective habitats. The parasite community was in a level of early heterotrophic succession where low diversity is combined with high population density, which is characteristic for extreme environments. Therefore, intraspecific competition dominates and niches are wide. Under this aspect and regard of the actually valid definition that niches are dynamic systems between organisms and environment, the theory of vacant niches of some authors can be rejected.

Parallel genetic origins of pelvic reduction in vertebrates

Despite longstanding interest in parallel evolution, little is known about the genes that control similar traits in different lineages of vertebrates. Pelvic reduction in stickleback fish (family Gasterosteidae) provides a striking example of parallel evolution in a genetically tractable system. Previous studies suggest that cis-acting regulatory changes at the Pitx1 locus control pelvic reduction in a population of threespine sticklebacks (Gasterosteus aculeatus). In this study, progeny from intergeneric crosses between pelvic-reduced threespine and ninespine (Pungitius pungitius) sticklebacks also showed severe pelvic reduction, implicating a similar genetic origin for this trait in both genera. Comparative sequencing studies in complete and pelvic-reduced Pungitius revealed no differences in the Pitx1 coding sequences, but Pitx1 expression was absent from the prospective pelvic region of larvae from pelvic-reduced parents. A much more phylogenetically distant example of pelvic reduction, loss of hindlimbs in manatees, shows a similar left-right size bias that is a morphological signature of Pitx1-mediated pelvic reduction in both sticklebacks and mice. These multiple lines of evidence suggest that changes in Pitx1 may represent a key mechanism of morphological evolution in multiple populations, species, and genera of sticklebacks, as well as in distantly related vertebrate lineages.

Isolated Ninespine stickleback population, Pungitius pungitius (L.), in northeast Finland: large fish with reduced pelvis

Isolated Ninespine stickleback population, <i>Pungitius pungitius</i> (L.), in northeast Finland: large fish with reduced pelvis

Multiple occurrences of spiggin genes in sticklebacks

The threespine stickleback ( Gasterosteus aculeatus) is known to have a unique reproductive mode including male nest-building with a secreted glue-like protein named spiggin. Spiggin is a key character for studying the molecular mechanism in the evolution of this intriguing nest-building behavior, since the glue-like protein is essential for nest-building. However, it is unclear whether spiggin is encoded by a single gene or multiple genes; there are conflicting reports on this point. To resolve this discrepancy, we cloned this gene in a threespine stickleback collected in Japan. We found seven types of cDNAs including at least four genes, indicating that spiggin is encoded by a multi-gene family. On close inspection of the cDNAs, we found that one of these spiggin genes had four splicing variants. Although the cDNA sequences conserved functional domain structures, considerable diversity was observed in the sequence of each domain. Altogether, the current results imply that the structure and function of the spiggins are more complex than ever previously thought. Phylogenetic analysis of the cDNAs with related sequences including ninespine stickleback ( Pungitius pungitius) spiggin genes and homologues of zebrafish ( Danio rerio), torafugu ( Takifugu rubripes), and spotted green pufferfish ( Tetraodon nigroviridis) implied the existence of an ancestral “spiggin” gene and multiple duplication events of the gene in the stickleback lineage before and after the divergence of the threespine and ninespine sticklebacks.

Ecological consequences of biological invasions: three invertebrate case studies in the north-eastern Baltic Sea

Population dynamics and ecological impacts of the cirriped Balanus improvisus, the polychaete Marenzelleria neglecta and the cladoceran Cercopagis pengoi were investigated in the north-eastern Baltic Sea. After an increase during the first decade of invasion, the density of M. neglecta and C. pengoi declined afterwards. The studied abiotic environmental variables did not explain the interannual variability in the seasonal cycles of M. neglecta and C. pengoi indicating that the species are at their initial phase of invasion. The population dynamics of B. improvisus was best described by water temperature. B. improvisus promoted the growth of the green alga Enteromorpha intestinalis. M. neglecta enhanced the content of sediment chlorophyll a and reduced growth and survival of the polychaete Hediste diversicolor and growth of the amphipod Monoporeia affinis. Concurrent with the invasion of C. pengoi the abundance of small-sized cladocerans declined, especially above the thermocline. C. pengoi had become an important food for nine-spined stickleback, bleak, herring and smelt.