Daphnia in the Tatra Mountain lakes: multiple colonisation and hidden species diversity revealed by molecular markers (original) (raw)
Related papers
Ecological consequences of intraspecific variation in lake Daphnia
Freshwater Biology, 2010
1. Although populations harbour considerable diversity, most ecological studies still assume they are homogeneous. However, mounting evidence suggests that intraspecific diversity is not only common, but also important for interactions with community members. Here, intraspecific variation in Daphnia dentifera in haemoglobin content is shown to be a marker of hypolimnion use.2. Hypolimnion use differed substantially within and among D. dentifera populations. Daphnia dentifera with haemoglobin resided primarily in the hypolimnion, while D. dentifera lacking haemoglobin migrated vertically. These ‘deep’ and ‘migratory’D. dentifera had different seasonal phenologies and dynamics.3. Deep and migratory D. dentifera had qualitatively different relationships with an important competitor, Daphnia pulicaria. Deep D. dentifera density was negatively correlated with D. pulicaria density, whereas migratory density was not correlated with D. pulicaria density.4. Given that D. pulicaria tends to reside in the hypolimnion, this negative correlation probably reflects competition between D. pulicaria and the deep D. dentifera. This pattern would have been missed if only the relationship between the overall lake populations of D. dentifera and D. pulicaria had been studied.5. Abundances of deep D. dentifera and D. pulicaria were both correlated with the size of the hypolimnetic refuge from fish predation, but in opposite directions. Lakes with large refuges generally had high D. pulicaria and low deep D. dentifera densities.
Hydrobiologia, 2011
This study explores changes in cladoceran composition in a high mountain lake of the Retezat (Lake Brazi), the South Carpathian Mountains of Romania, during the Late Glacial-Early Holocene (14,500-11,600 cal. yr. BP) transition using a paleolimnological approach. The lake had a species poor cladoceran community throughout this period. Daphnia longispina, Chydorus sphaericus and Alona affinis were the most common, showing marked fluctuations in their relative abundances through time. Distinct faunal response to warming at the Younger Dryas (YD)/Preboreal transition was recorded by increasing fossil densities and distinct community composition change: Alona affinis became dominant while numbers of Chydorus sphaericus dramatically decreased. In the Early Holocene, the productivity of Lake Brazi seem to have increased as reflected by higher numbers of Cladocera due to appearance of new species (Alona rectangula, A. quadrangularis and A. guttata) which are common in productive waters. Significant negative correlation was found between average dorsal length of daphnid ephippia and the NGRIP d18 O isotope values. Given the absence of fish predation, changes in Daphnia ephippia size were taken to indicate climatic change: larger ephippium size inferred cold conditions during the Late Glacial, while smaller size reflected climate warming during the Early Holocene. We conclude that Cladocera fossils are good indicators of climatic change that happened during the transition from the Late Glacial to the Holocene. We found that climatic conditions can be tracked either by size distribution of Daphnia ephippia (larger ephippium size under colder climate) and/or by community change of cladocerans.
Hydrobiologia, 2011
This study explores changes in cladoceran composition in a high mountain lake of the Retezat (Lake Brazi), the South Carpathian Mountains of Romania, during the Late Glacial-Early Holocene (14,500-11,600 cal. yr. BP) transition using a paleolimnological approach. The lake had a species poor cladoceran community throughout this period. Daphnia longispina, Chydorus sphaericus and Alona affinis were the most common, showing marked fluctuations in their relative abundances through time. Distinct faunal response to warming at the Younger Dryas (YD)/Preboreal transition was recorded by increasing fossil densities and distinct community composition change: Alona affinis became dominant while numbers of Chydorus sphaericus dramatically decreased. In the Early Holocene, the productivity of Lake Brazi seem to have increased as reflected by higher numbers of Cladocera due to appearance of new species (Alona rectangula, A. quadrangularis and A. guttata) which are common in productive waters. Significant negative correlation was found between average dorsal length of daphnid ephippia and the NGRIP d18 O isotope values. Given the absence of fish predation, changes in Daphnia ephippia size were taken to indicate climatic change: larger ephippium size inferred cold conditions during the Late Glacial, while smaller size reflected climate warming during the Early Holocene. We conclude that Cladocera fossils are good indicators of climatic change that happened during the transition from the Late Glacial to the Holocene. We found that climatic conditions can be tracked either by size distribution of Daphnia ephippia (larger ephippium size under colder climate) and/or by community change of cladocerans.
Although the Daphnia species of Lake Balaton have long been studied, there was no consensus on the species composition. In this paper we attempted to clarify their specific status using allozyme electrophoresis. Zooplankton samples were collected between 2002 and 2004 from each basin of Lake Balaton. Daphnia specimens were counted and analysed using cellulose acetate gelelectrophoresis. The analysis revealed the presence of Daphnia cucullata, D. galeata and their hybrid in the lake. While Daphnia galeata was very rare, D. cucullata and the hybrids were abundant during the growing season.
Hydrobiologia, 2013
The occurrence of members of the highly diverse Daphnia longispina complex in Southern and Central Asian high-mountain lakes has been recognized for more than a century. Until now, however, no molecular data have been available for these populations inhabiting the ''Roof of the World.'' Here, we present the first identification for D. gr. longispina from that region based on a molecular phylogeny. Our findings show that alpine lakes in the Pamir and Himalaya mountains host populations of widespread species of the complex, for which these are the highest known localities. A spineless morph from the Himalaya region, previously labeled as D. longispina var.
2014
We investigated sedimentary zooplankton (Cladocera) assemblages since the Little Ice Age in two 21 high elevation and morphologically divergent lakes (Twenger Almsee and Oberer Landschitzsee) in 22 Austria by utilizing sediment traps and previously available sediment data. We aimed to detect lake-23 specific long-term changes in pelagic community composition potentially attributable to the well-24 documented climate warming in the greater Alpine region. Both lakes showed a similar and gradual 25 2 community turnover over the last century, as the pelagic grazer Daphnia was first replaced by 26 Chydorus cf. sphaericus and eventually during the 20 th and 21 st centuries by the latest colonizer 27 Bosmina, which was absent in the older sediments. Despite the centennial species succession was 28 highly similar among the lakes and consistent with Alpine temperature increase, the species 29 succession differed with the taxa in question (e.g. D. longispina-versus D. pulex-type), temporal 30 occurrence, and magnitude of change. We propose that the observed community shifts were mainly 31 governed by increasing temperatures and its limnoecological consequences (e.g. deeper mixing). 32 We also suggest that Bosmina distribution may be extending to lakes at higher altitudes as a 33 response to climate warming, replacing Daphnia as the key component of pelagic alpine food webs. 34 35
BMC Evolutionary Biology, 2014
Background: In natural communities of cyclical parthenogens, rapid response to environmental change is enabled by switching between two reproduction modes. While long periods of asexual reproduction allow some clones to outcompete others, and may result in "clonal erosion", sexual reproduction restores genetic variation in such systems. Moreover, sexual reproduction may result in the formation of interspecific hybrids. These hybrids can then reach high abundances, through asexual clonal reproduction. In the present study, we explored genetic variation in water fleas of the genus Daphnia. The focus was on the short-term dynamics within several clonal assemblages from the hybridizing Daphnia longispina complex and the impact of gene flow at small spatial scales. Results: Daphnia individuals belonged either to the parental species D. galeata and D. longispina, or to different hybrid classes, as identified by 15 microsatellite markers. The distribution and genotypic structure of parental species, but not hybrids, corresponded well with the geographical positions of the lakes. Within parental species, the genetic distance among populations of D. galeata was lower than among populations of D. longispina. Moreover, D. galeata dominance was associated with higher phosphorous load. Finally, there was no evidence for clonal erosion. Conclusions: Our results suggest that the contemporary structure of hybridizing Daphnia communities from ten nearby lakes is influenced by colonization events from neighbouring habitats as well as by environmental factors. Unlike the parental species, however, there was little evidence for successful dispersal of hybrids, which seem to be produced locally. Finally, in contrast to temporary Daphnia populations, in which a decrease in clonal diversity was sometimes detectable over a single growing season, the high clonal diversity and lack of clonal erosion observed here might result from repeated hatching of sexually produced offspring. Overall, our study provides insights into spatio-temporal dynamics in a hybridizing Daphnia species complex in a recently established lake system, and relates genetic similarities of populations to a scenario of secondary invasion enhanced by environmental factors.
Gene flow in the Daphnia longispina hybrid complex (Crustacea, Cladocera) inhabiting large lakes
Heredity, 1997
The significance of short-term exchange between populations relative to long-term local selection was evaluated in the Daphnia longispina hybrid complex. In a hierarchical analysis, the genetic structure of D. cucullata, D. hyalina and their interspecific hybrid c x h was studied by allozyme electrophoresis. Two data sets based on the variation at three and nine loci revealed high genetic variation in all populations. Significant genetic differentiation, FST, was found between lakes that are less than 14 km apart. FST between subpopulations was around 0.2 for D. hyalina and D. cucullata averaged over three and nine loci. Selection on hybrid genomes may explain why, in c x h hybrids, only 10 per cent of the total genetic variation found was attributable to differences between populations. FST and genetic distances, Dnej,were compared between pairs of populations from different hierarchical levels. In both data sets, differences were highest between species. Between parent species and hybrids, they were intermediate, and they were lowest within species. A regression of log Nm against log distance was used to test for isolation by distance. Mantel tests showed a highly significant decrease in Nm with distance for populations of D. hyalina in both data sets. A negative trend was also found for populations of D. cucullata and c x h. Thus, in contrast to littoral cladoceran species, the pattern of geographical variation between populations of pelagic species seems to be more strongly influenced by gene flow.