A molecular study of diversity in european water fleas Daphnia pulicaria

Katedra ekologieDepartment of EcologyFaculty of SciencePřírodovědecká fakult

Daphnia diversity in water bodies of the Po River Basin

Shallow water bodies dominate the areal extent of continental waters and host a proportion of biodiversity higher than the percentage of Earth's surface they cover. Daphnia is a key component of small aquatic ecosystems food webs. Here we present the result of a survey in 24 ponds located in the core of Po river Basin, to assess the actual spreading of Daphnia species in one of the most productive areas of the Northern hemisphere. By using diagnostic genetic markers (12S rRNA and ND5 genes) we identified five Daphnia species: D. ambigua, D. curvirostris, D. longispina, D. obtusa and D. pulex in fourteen ponds. Additional analyses of two nuclear genes (LdhA and Rab4) revealed that D. pulex in the study area is native European strain. In opposite, D. ambigua shared haplotype with the North-Eastern American lineage that was introduced to Europe by long-distance dispersal. In the Po river Basin we identified a highly divergent lineage of D. longispina group that formed a clade with individuals from northern European Russia and might represent a new Daphnia species. Daphnia species in the Cremona province have European origin, except for D. ambigua which is a North American species spreading across Europe. Future attention will require monitoring of invasive species, particularly D. ambigua and the North American invasive clone of D. pulex that is already present in Northern Italy. </p

phenology of daphnia in a northern italy pond during the weather anomalous 2014

This note reports a comparison between Daphnia phenology in the weather anomalous 2014 and a previous three years period (2011-2013), in a shallow water body of Northern Italy (Bodrio del pastore III) where we recorded D. pulex. In 2011-2013, Daphnia population showed 1-2 density peaks from mid spring to early summer, it declined in July-August and did not recover, from ephippia, until the following spring. The seasonal dynamics was probably related to the species thermal tolerance. Males and ephippial females appeared at the beginning of growth season according to a typical feature of Daphnia populations from temporary habitats. The presence of the Chaoborus larvae resulted in juvenile adaptive predator-avoidance cyclomorphosis. In 2014, in the study area, mean winter air temperature was much warmer than average recorded during the past three years while it was much colder than average in July and August. This reflected the relatively rainy and cloudy summer months: the winter and summer precipitations total was above the previous three years average. In 2014, Daphnia was found all over the year and showed a maximum peak of density in November. The general increase of Daphnia was related to a shift in D. pulex population phenology, seasonal growth started earlier and lasted longer, and to the occurrence of D. longispina. Both species were identified by genetic markers and phylogenetic analyses of ND5 sequences placed isolates from the Bodrio del pastore III into the European D. pulex group. Both populations reproduced by cyclical parthenogenesis and showed cyclomorphosis. However, D. pulex produced more males and ephippial females than D. longispina. Their seasonal dynamics were quite different: D. longispina dominated in late summer while D. pulex showed the highest density in November. The presence of D. pulex in the Bodrio is important in the framework of conservation ecology especially because we have showed that it is native European strain instead of the invasive North American clone that replaced native D. pulex throughout Africa and was already recorded in Italy. We provide some indications and discuss how Daphnia phenology of shallow lakes of temperate areas may be susceptible to inter-annual variability in weather conditions.</p

Diversity in the Reproductive Modes of European Daphnia pulicaria Deviates from the Geographical Parthenogenesis

10 páginas, 5 figuras, 3 tablas.Background: Multiple transitions to obligate parthenogenesis have occurred in the Daphnia pulex complex in North America. These newly formed asexual lineages are differentially distributed being found predominantly at high latitudes. This conforms to the rule of geographical parthenogenesis postulating prevalence of asexuals at high latitudes and altitudes. While the reproductive mode of high-latitude populations is relatively well studied, little is known about the reproduction mode in high altitudes. This study aimed to assess the reproductive mode of Daphnia pulicaria, a species of the D. pulex complex, from high altitude lakes in Europe. Methodology/Principal Findings: Variation at eight microsatellite loci revealed that D. pulicaria from the High Tatra Mountains (HTM) had low genotype richness and showed excess of heterozygotes and significant deviations from Hardy- Weinberg expectations, and was thus congruent with reproduction by obligate parthenogenesis. By contrast, populations from the Pyrenees (Pyr) were generally in Hardy-Weinberg equilibrium and had higher genotypic richness, suggesting that they are cyclic parthenogens. Four lakes from lowland areas (LLaP) had populations with an uncertain or mixed breeding mode. All D. pulicaria had mtDNA ND5 haplotypes of the European D. pulicaria lineage. Pyr were distinct from LLaP and HTM at the ND5 gene. By contrast, HTM shared two haplotypes with LLaP and one with Pyr. Principal Coordinate Analysis of the microsatellite data revealed clear genetic differentiation into three groups. HTM isolates were intermediate to Pyr and LLaP, congruent with a hybrid origin. Conclusion/Significance: Inferred transitions to obligate parthenogenesis have occurred only in HTM, most likely as a result of hybridizations. In contrast to North American populations, these transitions do not appear to involve meiosis suppressor genes and have not been accompanied by polyploidy. The absence of obligate parthenogenesis in Pyr, an environment highly similar to the HTM, may be due to the lack of opportunities for hybridization.Peer reviewe

A molecular study of diversity in european water fleas Daphnia pulicaria

Katedra ekologieDepartment of EcologyFaculty of SciencePřírodovědecká fakult

Playing Hide-and-Seek in Beta-Globin Genes: Gene Conversion Transferring a Beneficial Mutation between Differentially Expressed Gene Duplicates

Increasing evidence suggests that adaptation to diverse environments often involves selection on existing variation rather than new mutations. A previous study identified a nonsynonymous single nucleotide polymorphism (SNP) in exon 2 of two paralogous ?-globin genes of the bank vole (Clethrionomys glareolus) in Britain in which the ancestral serine (Ser) and the derived cysteine (Cys) allele represent geographically partitioned functional variation affecting the erythrocyte antioxidative capacity. Here we studied the geographical pattern of the two-locus Ser/Cys polymorphism throughout Europe and tested for the geographic correlation between environmental variables and allele frequency, expected if the polymorphism was under spatially heterogeneous environment-related selection. Although bank vole population history clearly is important in shaping the dispersal of the oxidative stress protective Cys allele, analyses correcting for population structure suggest the Europe-wide pattern is affected by geographical variation in environmental conditions. The ?-globin phenotype is encoded by the major paralog HBB-T1 but we found evidence of bidirectional gene conversion of exon 2 with the low-expression paralog HBB-T2. Our data support the model where gene conversion reshuffling genotypes between high- and low- expressed paralogs enables tuning of erythrocyte thiol levels, which may help maintain intracellular redox balance under fluctuating environmental conditions. Therefore, our study suggests a possible role for gene conversion between differentially expressed gene duplicates as a mechanism of physiological adaptation of populations to new or changing environments.The study was carried out with the financial support from the Czech Science Foundation (grant number 16-032485) and Ministry of Education, Youth and Sports of the Czech Republic (projects KONTAKT II LH15255 and EXCELLENCE CZ.02.1.01/0.0/0.0/15_003/0000460 OP RDE) and with the institutional support RVO 67985904. Part of this research was performed while P.K. was at sabbatical at Cornell, supported by the project CZ.02.2.69/0.0/0.0/16_027/0008502, under the call 02_16_027 International Mobility of Researchers (MEYS, OP RDE)

Eleutherodactylus marnockii (Cliff Chirping Frog). Fighting Behavior

This video demonstrates behavior. Most videos in this collection have no audible language and for those that do, the language isn't necessary to understand the behavior. For that reason, transcripts are not provided.Integrative Biolog

Comparison of Two Approaches for an Estimation of the Mean Annual Flood at Ungauged Sites in Slovakia

Regional flood frequency analysis is considered to be an important and popular method for estimating different hydrological variables at ungauged sites. The estimation of the index flood is the essential problem when this method is applied. The objective of the study is a comparison of the estimation of the mean annual flood (or index flood) by using two approaches based on the ‘so-called’ index flood method and top-kriging. The concept behind these methods permits estimating the mean annual flood at ungauged locations using information taken from gauged sites located within the same homogeneous pooling groups. The study area comprises 104 gauging stations on the whole territory of Slovakia. The observation period of the annual maximum discharges of the selected stations was from 1961-2010. The identification of the homogeneous pooling group was performed using a non-hierarchical k-means clustering algorithm. The optimal number of clusters is determined by the Silhouette method. As a result, eight homogeneous pooling group clusters were identified. Finally, the results of the estimated mean annual floods using the index flood method and top-kriging were compared with the observed data. Top-kriging provided better results than the classical index flood method for estimating the mean annual flood at ungauged sites

GM Procesos, Lafayette

The North American ecological species Daphniapulicaria and Daphniapulex are thought to have diverged from a common ancestor by adaptation to sympatric but ecologically distinct lake and pond habitats respectively. Based on mtDNA relationships, European D. pulicaria is considered a different species only distantly related to its North American counterpart, but both species share a lactate dehydrogenase (Ldh) allele F supposedly involved in lake adaptation in North America, and the same allele is also carried by the related Holarctic Daphniatenebrosa. The correct inference of the species' ancestral relationships is therefore critical for understanding the origin of their adaptive divergence. Our species tree inferred from unlinked nuclear loci for D. pulicaria and D. pulex resolved the European and North American D. pulicaria as sister clades, and we argue that the discordant mtDNA gene tree is best explained by capture of D. pulex mtDNA by D. pulicaria in North America. The Ldh gene tree shows that F-class alleles in D. pulicaria and D. tenebrosa are due to common descent (as opposed to introgression), with D. tenebrosa alleles paraphyletic with respect to D. pulicaria alleles. That D. tenebrosa still segregates the ancestral and derived amino acids at the two sites distinguishing the pond and lake alleles suggests that D. pulicaria inherited the derived states from the D. tenebrosa ancestry. Our results suggest that some adaptations restricting the gene flow between D. pulicaria and D. pulex might have evolved in response to selection in ancestral environments rather than in the species' current sympatric habitats. The Arctic (D. tenebrosa) populations are likely to provide important clues about these issues