@article{ChengDennisOsuohaetal.2023,
  author    = {Cheng, Feng and Dennis, Alice B. and Osuoha, Josephine Ijeoma and Canitz, Julia and Kirschbaum, Frank and Tiedemann, Ralph},
  title     = {A new genome assembly of an African weakly electric fish (Campylomormyrus compressirostris, Mormyridae) indicates rapid gene family evolution in Osteoglossomorpha},
  series = {BMC genomics},
  volume    = {24},
  journal   = {BMC genomics},
  number    = {1},
  publisher = {BMC},
  address   = {London},
  issn      = {1471-2164},
  doi       = {10.1186/s12864-023-09196-6},
  pages     = {13},
  year      = {2023},
  abstract  = {Background Teleost fishes comprise more than half of the vertebrate species. Within teleosts, most phylogenies consider the split between Osteoglossomorpha and Euteleosteomorpha/Otomorpha as basal, preceded only by the derivation of the most primitive group of teleosts, the Elopomorpha. While Osteoglossomorpha are generally species poor, the taxon contains the African weakly electric fish (Mormyroidei), which have radiated into numerous species. Within the mormyrids, the genus Campylomormyrus is mostly endemic to the Congo Basin. Campylomormyrus serves as a model to understand mechanisms of adaptive radiation and ecological speciation, especially with regard to its highly diverse species-specific electric organ discharges (EOD). Currently, there are few well-annotated genomes available for electric fish in general and mormyrids in particular. Our study aims at producing a high-quality genome assembly and to use this to examine genome evolution in relation to other teleosts. This will facilitate further understanding of the evolution of the osteoglossomorpha fish in general and of electric fish in particular. Results A high-quality weakly electric fish (C. compressirostris) genome was produced from a single individual with a genome size of 862 Mb, consisting of 1,497 contigs with an N50 of 1,399 kb and a GC-content of 43.69\%. Gene predictions identified 34,492 protein-coding genes, which is a higher number than in the two other available Osteoglossomorpha genomes of Paramormyrops kingsleyae and Scleropages formosus. A Computational Analysis of gene Family Evolution (CAFE5) comparing 33 teleost fish genomes suggests an overall faster gene family turnover rate in Osteoglossomorpha than in Otomorpha and Euteleosteomorpha. Moreover, the ratios of expanded/contracted gene family numbers in Osteoglossomorpha are significantly higher than in the other two taxa, except for species that had undergone an additional genome duplication (Cyprinus carpio and Oncorhynchus mykiss). As potassium channel proteins are hypothesized to play a key role in EOD diversity among species, we put a special focus on them, and manually curated 16 Kv1 genes. We identified a tandem duplication in the KCNA7a gene in the genome of C. compressirostris. Conclusions We present the fourth genome of an electric fish and the third well-annotated genome for Osteoglossomorpha, enabling us to compare gene family evolution among major teleost lineages. Osteoglossomorpha appear to exhibit rapid gene family evolution, with more gene family expansions than contractions. The curated Kv1 gene family showed seven gene clusters, which is more than in other analyzed fish genomes outside Osteoglossomorpha. The KCNA7a, encoding for a potassium channel central for EOD production and modulation, is tandemly duplicated which may related to the diverse EOD observed among Campylomormyrus species.},
  language  = {en}
}
@article{TomowskiLozadaGobilardJeltschetal.2023,
  author    = {Tomowski, Maxi and Lozada-Gobilard, Sissi Donna and Jeltsch, Florian and Tiedemann, Ralph},
  title     = {Recruitment and migration patterns reveal a key role for seed banks in the meta-population dynamics of an aquatic plant},
  series = {Scientific reports},
  volume    = {13},
  journal   = {Scientific reports},
  number    = {1},
  publisher = {Springer Nature},
  address   = {London},
  issn      = {2045-2322},
  doi       = {10.1038/s41598-023-37974-5},
  pages     = {16},
  year      = {2023},
  abstract  = {Progressive habitat fragmentation threatens plant species with narrow habitat requirements. While local environmental conditions define population growth rates and recruitment success at the patch level, dispersal is critical for population viability at the landscape scale. Identifying the dynamics of plant meta-populations is often confounded by the uncertainty about soil-stored population compartments. We combined a landscape-scale assessment of an amphibious plant's population structure with measurements of dispersal complexity in time to track dispersal and putative shifts in functional connectivity. Using 13 microsatellite markers, we analyzed the genetic structure of extant Oenanthe aquatica populations and their soil seed banks in a kettle hole system to uncover hidden connectivity among populations in time and space. Considerable spatial genetic structure and isolation-by-distance suggest limited gene flow between sites. Spatial isolation and patch size showed minor effects on genetic diversity. Genetic similarity found among extant populations and their seed banks suggests increased local recruitment, despite some evidence of migration and recent colonization. Results indicate stepping-stone dispersal across adjacent populations. Among permanent and ephemeral demes the resulting meta-population demography could be determined by source-sink dynamics. Overall, these spatiotemporal connectivity patterns support mainland-island dynamics in our system, highlighting the importance of persistent seed banks as enduring sources of genetic diversity.},
  language  = {en}
}
@misc{AmenNagelHedtetal.2020,
  author    = {Amen, Rahma and Nagel, Rebecca and Hedt, Maximilian and Kirschbaum, Frank and Tiedemann, Ralph},
  title     = {Morphological differentiation in African weakly electric fish (genus Campylomormyrus) relates to substrate preferences},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {3},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-51871},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-518714},
  pages     = {13},
  year      = {2020},
  abstract  = {Under an ecological speciation scenario, the radiation of African weakly electric fish (genus Campylomormyrus) is caused by an adaptation to different food sources, associated with diversification of the electric organ discharge (EOD). This study experimentally investigates a phenotype-environment correlation to further support this scenario. Our behavioural experiments showed that three sympatric Campylomormyrus species with significantly divergent snout morphology differentially react to variation in substrate structure. While the short snout species (C. tamandua) exhibits preference to sandy substrate, the long snout species (C. rhynchophorus) significantly prefers a stone substrate for feeding. A third species with intermediate snout size (C. compressirostris) does not exhibit any substrate preference. This preference is matched with the observation that long-snouted specimens probe deeper into the stone substrate, presumably enabling them to reach prey more distant to the substrate surface. These findings suggest that the diverse feeding apparatus in the genus Campylomormyrus may have evolved in adaptation to specific microhabitats, i.e., substrate structures where these fish forage. Whether the parallel divergence in EOD is functionally related to this adaptation or solely serves as a prezygotic isolation mechanism remains to be elucidated.},
  language  = {en}
}
@article{AmenNagelHedtetal.2020,
  author    = {Amen, Rahma and Nagel, Rebecca and Hedt, Maximilian and Kirschbaum, Frank and Tiedemann, Ralph},
  title     = {Morphological differentiation in African weakly electric fish (genus Campylomormyrus) relates to substrate preferences},
  series = {Evolutionary Ecology},
  volume    = {34},
  journal   = {Evolutionary Ecology},
  number    = {3},
  publisher = {Springer Science},
  address   = {Dordrecht},
  issn      = {0269-7653},
  doi       = {10.1007/s10682-020-10043-3},
  pages     = {427 -- 437},
  year      = {2020},
  abstract  = {Under an ecological speciation scenario, the radiation of African weakly electric fish (genus Campylomormyrus) is caused by an adaptation to different food sources, associated with diversification of the electric organ discharge (EOD). This study experimentally investigates a phenotype-environment correlation to further support this scenario. Our behavioural experiments showed that three sympatric Campylomormyrus species with significantly divergent snout morphology differentially react to variation in substrate structure. While the short snout species (C. tamandua) exhibits preference to sandy substrate, the long snout species (C. rhynchophorus) significantly prefers a stone substrate for feeding. A third species with intermediate snout size (C. compressirostris) does not exhibit any substrate preference. This preference is matched with the observation that long-snouted specimens probe deeper into the stone substrate, presumably enabling them to reach prey more distant to the substrate surface. These findings suggest that the diverse feeding apparatus in the genus Campylomormyrus may have evolved in adaptation to specific microhabitats, i.e., substrate structures where these fish forage. Whether the parallel divergence in EOD is functionally related to this adaptation or solely serves as a prezygotic isolation mechanism remains to be elucidated.},
  language  = {en}
}
@article{KorniienkoNguyenBaumgartneretal.2021,
  author    = {Korniienko, Yevheniia and Nguyen, Linh and Baumgartner, Stephanie and Vater, Marianne and Tiedemann, Ralph and Kirschbaum, Frank},
  title     = {Correction to: Intragenus F1-hybrids of African weakly electric fish (Mormyridae: Campylomormyrus tamandua male x C. compressirostris female) are fertile (vol 206, pg 571, 2020)},
  series = {Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology},
  volume    = {207},
  journal   = {Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology},
  number    = {6},
  publisher = {Springer},
  address   = {Heidelberg},
  issn      = {0340-7594},
  doi       = {10.1007/s00359-021-01513-2},
  pages     = {773 -- 773},
  year      = {2021},
  language  = {en}
}
@article{KiemelDeCahsanParaskevopoulouetal.2022,
  author    = {Kiemel, Katrin and De Cahsan, Binia and Paraskevopoulou, Sofia and Weithoff, Guntram and Tiedemann, Ralph},
  title     = {Mitochondrial genomes of the freshwater monogonont rotifer Brachionus fernandoi and of two additional B. calyciflorus sensu stricto lineages from Germany and the USA (Rotifera, Brachionidae)},
  series = {Mitochondrial DNA. Part B-Resources},
  volume    = {7},
  journal   = {Mitochondrial DNA. Part B-Resources},
  number    = {4},
  publisher = {Routledge, Taylor \& Francis Group},
  address   = {Abingdon},
  issn      = {2380-2359},
  doi       = {10.1080/23802359.2022.2060765},
  pages     = {646 -- 648},
  year      = {2022},
  abstract  = {The Brachionus calyciflorus species complex was recently subdivided into four species, but genetic resources to resolve phylogenetic relationships within this complex are still lacking. We provide two complete mitochondrial (mt) genomes from B. calyciflorus sensu stricto (Germany, USA) and the mt coding sequences (cds) from a German B. fernandoi. Phylogenetic analysis placed our B. calyciflorus sensu stricto strains close to the published genomes of B. calyciflorus, forming the putative sister species to B. fernandoi. Global representatives of B. calyciflorus sensu stricto (i.e. Europe, USA, and China) are genetically closer related to each other than to B. fernandoi (average pairwise nucleotide diversity 0.079 intraspecific vs. 0.254 interspecific).},
  language  = {en}
}
@article{DeCahsanNagelSchedinaetal.2020,
  author    = {De Cahsan, Binia and Nagel, Rebecca and Schedina, Ina-Maria and King, James J. and Bianco, Pier G. and Tiedemann, Ralph and Ketmaier, Valerio},
  title     = {Phylogeography of the European brook lamprey (Lampetra planeri) and the European river lamprey (Lampetra fluviatilis) species pair based on mitochondrial data},
  series = {Journal of fish biology},
  volume    = {96},
  journal   = {Journal of fish biology},
  number    = {4},
  publisher = {Wiley-Blackwell},
  address   = {Oxford [u.a.]},
  issn      = {0022-1112},
  doi       = {10.1111/jfb.14279},
  pages     = {905 -- 912},
  year      = {2020},
  abstract  = {The European river lamprey Lampetra fluviatilis and the European brook lamprey Lampetra planeri (Block 1784) are classified as a paired species, characterized by notably different life histories but morphological similarities. Previous work has further shown limited genetic differentiation between these two species at the mitochondrial DNA level. Here, we expand on this previous work, which focused on lamprey species from the Iberian Peninsula in the south and mainland Europe in the north, by sequencing three mitochondrial marker regions of Lampetra individuals from five river systems in Ireland and five in southern Italy. Our results corroborate the previously identified pattern of genetic diversity for the species pair. We also show significant genetic differentiation between Irish and mainland European lamprey populations, suggesting another ichthyogeographic district distinct from those previously defined. Finally, our results stress the importance of southern Italian L. planeri populations, which maintain several private alleles and notable genetic diversity.},
  language  = {en}
}
@article{FoersterAsratRamseyetal.2022,
  author    = {Foerster, Verena and Asrat, Asfawossen and Ramsey, Christopher Bronk and Brown, Erik T. and Chapot, Melissa S. and Deino, Alan and D{\"u}sing, Walter and Grove, Matthew and Hahn, Annette and Junginger, Annett and Kaboth-Bahr, Stefanie and Lane, Christine S. and Opitz, Stephan and Noren, Anders and Roberts, Helen M. and Stockhecke, Mona and Tiedemann, Ralph and Vidal, Celine M. and Vogelsang, Ralf and Cohen, Andrew S. and Lamb, Henry F. and Schaebitz, Frank and Trauth, Martin H.},
  title     = {Pleistocene climate variability in eastern Africa influenced hominin evolution},
  series = {Nature geoscience},
  volume    = {15},
  journal   = {Nature geoscience},
  number    = {10},
  publisher = {Nature Publ. Group},
  address   = {London},
  issn      = {1752-0894},
  doi       = {10.1038/s41561-022-01032-y},
  pages     = {805 -- 811},
  year      = {2022},
  abstract  = {Despite more than half a century of hominin fossil discoveries in eastern Africa, the regional environmental context of hominin evolution and dispersal is not well established due to the lack of continuous palaeoenvironmental records from one of the proven habitats of early human populations, particularly for the Pleistocene epoch. Here we present a 620,000-year environmental record from Chew Bahir, southern Ethiopia, which is proximal to key fossil sites. Our record documents the potential influence of different episodes of climatic variability on hominin biological and cultural transformation. The appearance of high anatomical diversity in hominin groups coincides with long-lasting and relatively stable humid conditions from similar to 620,000 to 275,000 years bp (episodes 1-6), interrupted by several abrupt and extreme hydroclimate perturbations. A pattern of pronounced climatic cyclicity transformed habitats during episodes 7-9 (similar to 275,000-60,000 years bp), a crucial phase encompassing the gradual transition from Acheulean to Middle Stone Age technologies, the emergence of Homo sapiens in eastern Africa and key human social and cultural innovations. Those accumulative innovations plus the alignment of humid pulses between northeastern Africa and the eastern Mediterranean during high-frequency climate oscillations of episodes 10-12 (similar to 60,000-10,000 years bp) could have facilitated the global dispersal of H. sapiens.},
  language  = {en}
}
@article{KiemelGurkeParaskevopoulouetal.2022,
  author    = {Kiemel, Katrin and Gurke, Marie and Paraskevopoulou, Sofia and Havenstein, Katja and Weithoff, Guntram and Tiedemann, Ralph},
  title     = {Variation in heat shock protein 40 kDa relates to divergence in thermotolerance among cryptic rotifer species},
  series = {Scientific reports},
  volume    = {12},
  journal   = {Scientific reports},
  number    = {1},
  publisher = {Macmillan Publishers Limited},
  address   = {London},
  issn      = {2045-2322},
  doi       = {10.1038/s41598-022-27137-3},
  pages     = {14},
  year      = {2022},
  abstract  = {Genetic divergence and the frequency of hybridization are central for defining species delimitations, especially among cryptic species where morphological differences are merely absent. Rotifers are known for their high cryptic diversity and therefore are ideal model organisms to investigate such patterns. Here, we used the recently resolved Brachionus calyciflorus species complex to investigate whether previously observed between species differences in thermotolerance and gene expression are also reflected in their genomic footprint. We identified a Heat Shock Protein gene (HSP 40 kDa) which exhibits cross species pronounced sequence variation. This gene exhibits species-specific fixed sites, alleles, and sites putatively under positive selection. These sites are located in protein binding regions involved in chaperoning and may therefore reflect adaptive diversification. By comparing three genetic markers (ITS, COI, HSP 40 kDa), we revealed hybridization events between the cryptic species. The low frequency of introgressive haplotypes/alleles suggest a tight, but not fully impermeable boundary between the cryptic species.},
  language  = {en}
}
@article{ParrySchlaegelTiedemannetal.2022,
  author    = {Parry, Victor and Schl{\"a}gel, Ulrike and Tiedemann, Ralph and Weithoff, Guntram},
  title     = {Behavioural responses of defended and undefended prey to their predator},
  series = {Biology : open access journal},
  volume    = {11},
  journal   = {Biology : open access journal},
  number    = {8},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2079-7737},
  doi       = {10.3390/biology11081217},
  pages     = {14},
  year      = {2022},
  abstract  = {Many animals that have to cope with predation have evolved mechanisms to reduce their predation risk. One of these mechanisms is change in morphology, for example, the development of spines. These spines are induced, when mothers receive chemical signals of a predator (kairomones) and their daughters are then equipped with defensive spines. We studied the behaviour of a prey and its predator when the prey is either defended or undefended. We used common aquatic micro-invertebrates, the rotifers Brachionus calyciflorus (prey) and Asplanchna brightwellii (predator) as experimental animals. We found that undefended prey increased its swimming speed in the presence of the predator. The striking result was that the defended prey did not respond to the predator's presence. This suggests that defended prey has a different response behaviour to a predator than undefended conspecifics. Our study provides further insights into complex zooplankton predator-prey interactions. Predation is a strong species interaction causing severe harm or death to prey. Thus, prey species have evolved various defence strategies to minimize predation risk, which may be immediate (e.g., a change in behaviour) or transgenerational (morphological defence structures). We studied the behaviour of two strains of a rotiferan prey (Brachionus calyciflorus) that differ in their ability to develop morphological defences in response to their predator Asplanchna brightwellii. Using video analysis, we tested: (a) if two strains differ in their response to predator presence and predator cues when both are undefended; (b) whether defended individuals respond to live predators or their cues; and (c) if the morphological defence (large spines) per se has an effect on the swimming behaviour. We found a clear increase in swimming speed for both undefended strains in predator presence. However, the defended specimens responded neither to the predator presence nor to their cues, showing that they behave indifferently to their predator when they are defended. We did not detect an effect of the spines on the swimming behaviour. Our study demonstrates a complex plastic behaviour of the prey, not only in the presence of their predator, but also with respect to their defence status.},
  language  = {en}
}
@article{KiemelWeithoffTiedemann2022,
  author    = {Kiemel, Katrin and Weithoff, Guntram and Tiedemann, Ralph},
  title     = {DNA metabarcoding reveals impact of local recruitment, dispersal, and hydroperiod on assembly of a zooplankton metacommunity},
  series = {Molecular ecology},
  volume    = {32},
  journal   = {Molecular ecology},
  number    = {23},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0962-1083},
  doi       = {10.1111/mec.16627},
  pages     = {20},
  year      = {2022},
  abstract  = {Understanding the environmental impact on the assembly of local communities in relation to their spatial and temporal connectivity is still a challenge in metacommunity ecology. This study aims to unravel underlying metacommunity processes and environmental factors that result in observed zooplankton communities. Unlike most metacommunity studies, we jointly examine active and dormant zooplankton communities using a DNA metabarcoding approach to overcome limitations of morphological species identification. We applied two-fragment (COI and 18S) metabarcoding to monitor communities of 24 kettle holes over a two-year period to unravel (i) spatial and temporal connectivity of the communities, (ii) environmental factors influencing local communities, and (iii) dominant underlying metacommunity processes in this system. We found a strong separation of zooplankton communities from kettle holes of different hydroperiods (degree of permanency) throughout the season, while the community composition within single kettle holes did not differ between years. Species richness was primarily dependent on pH and permanency, while species diversity (Shannon Index) was influenced by kettle hole location. Community composition was impacted by kettle hole size and surrounding field crops. Environmental processes dominated temporal and spatial processes. Sediment communities showed a different composition compared to water samples but did not differ between ephemeral and permanent kettle holes. Our results suggest that communities are mainly structured by environmental filtering based on pH, kettle hole size, surrounding field crops, and permanency. Environmental filtering based on specific conditions in individual kettle holes seems to be the dominant process in community assembly in the studied zooplankton metacommunity.},
  language  = {en}
}
@article{StieglerKiemelEccardetal.2021,
  author    = {Stiegler, Jonas and Kiemel, Katrin and Eccard, Jana and Fischer, Christina and Hering, Robert and Ortmann, Sylvia and Strigl, Lea and Tiedemann, Ralph and Ullmann, Wiebke and Blaum, Niels},
  title     = {Seed traits matter},
  series = {Ecology and evolution},
  volume    = {11},
  journal   = {Ecology and evolution},
  number    = {24},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {2045-7758},
  doi       = {10.1002/ece3.8440},
  pages     = {18477 -- 18491},
  year      = {2021},
  abstract  = {Although many plants are dispersed by wind and seeds can travel long distances across unsuitable matrix areas, a large proportion relies on co-evolved zoochorous seed dispersal to connect populations in isolated habitat islands. Particularly in agricultural landscapes, where remaining habitat patches are often very small and highly isolated, mobile linkers as zoochorous seed dispersers are critical for the population dynamics of numerous plant species. However, knowledge about the quali- or quantification of such mobile link processes, especially in agricultural landscapes, is still limited. In a controlled feeding experiment, we recorded the seed intake and germination success after complete digestion by the European brown hare (Lepus europaeus) and explored its mobile link potential as an endozoochoric seed disperser. Utilizing a suite of common, rare, and potentially invasive plant species, we disentangled the effects of seed morphological traits on germination success while controlling for phylogenetic relatedness. Further, we measured the landscape connectivity via hares in two contrasting agricultural landscapes (simple: few natural and semi-natural structures, large fields; complex: high amount of natural and semi-natural structures, small fields) using GPS-based movement data. With 34,710 seeds of 44 plant species fed, one of 200 seeds (0.51\%) with seedlings of 33 species germinated from feces. Germination after complete digestion was positively related to denser seeds with comparatively small surface area and a relatively slender and elongated shape, suggesting that, for hares, the most critical seed characteristics for successful endozoochorous seed dispersal minimize exposure of the seed to the stomach and the associated digestive system. Furthermore, we could show that a hare's retention time is long enough to interconnect different habitats, especially grasslands and fields. Thus, besides other seed dispersal mechanisms, this most likely allows hares to act as effective mobile linkers contributing to ecosystem stability in times of agricultural intensification, not only in complex but also in simple landscapes.},
  language  = {en}
}
@article{TebbeOttensmannHavensteinetal.2022,
  author    = {Tebbe, Jonas and Ottensmann, Meinolf and Havenstein, Katja and Efstratiou, Artemis and Lenz, Tobias L. and Caspers, Barbara A. and Forcada, Jaume and Tiedemann, Ralph and Hoffman, Joseph},
  title     = {Intronic primers reveal unexpectedly high major histocompatibility complex diversity in Antarctic fur seals},
  series = {Scientific reports},
  volume    = {12},
  journal   = {Scientific reports},
  number    = {1},
  publisher = {Nature Publishing Group},
  address   = {London},
  issn      = {2045-2322},
  doi       = {10.1038/s41598-022-21658-7},
  pages     = {14},
  year      = {2022},
  abstract  = {The major histocompatibility complex (MHC) is a group of genes comprising one of the most important components of the vertebrate immune system. Consequently, there has been much interest in characterising MHC variation and its relationship with fitness in a variety of species. Due to the exceptional polymorphism of MHC genes, careful PCR primer design is crucial for capturing all of the allelic variation present in a given species. We therefore developed intronic primers to amplify the full-length 267 bp protein-coding sequence of the MHC class II DQB exon 2 in the Antarctic fur seal. We then characterised patterns of MHC variation among mother-offspring pairs from two breeding colonies and detected 19 alleles among 771 clone sequences from 56 individuals. The distribution of alleles within and among individuals was consistent with a single-copy, classical DQB locus showing Mendelian inheritance. Amino acid similarity at the MHC was significantly associated with genome-wide relatedness, but no relationship was found between MHC heterozygosity and genome-wide heterozygosity. Finally, allelic diversity was several times higher than reported by a previous study based on partial exon sequences. This difference appears to be related to allele-specific amplification bias, implying that primer design can strongly impact the inference of MHC diversity.},
  language  = {en}
}
@article{NguyenMamonekeneVateretal.2020,
  author    = {Nguyen, Manh Duy Linh and Mamonekene, Victor and Vater, Marianne and Bartsch, Peter and Tiedemann, Ralph and Kirschbaum, Frank},
  title     = {Ontogeny of electric organ and electric organ discharge in Campylomormyrus rhynchophorus (Teleostei: Mormyridae)},
  series = {Journal of comparative physiology; A, Neuroethology, sensory, neural, and behavioral physiology},
  volume    = {206},
  journal   = {Journal of comparative physiology; A, Neuroethology, sensory, neural, and behavioral physiology},
  number    = {3},
  publisher = {Springer},
  address   = {Berlin ; Heidelberg},
  issn      = {0340-7594},
  doi       = {10.1007/s00359-020-01411-z},
  pages     = {453 -- 466},
  year      = {2020},
  abstract  = {The aim of this study was a longitudinal description of the ontogeny of the adult electric organ of Campylomormyrus rhynchophorus which produces as adult an electric organ discharge of very long duration (ca. 25 ms). We could indeed show (for the first time in a mormyrid fish) that the electric organ discharge which is first produced early during ontogeny in 33-mm-long juveniles is much shorter in duration and has a different shape than the electric organ discharge in 15-cm-long adults. The change from this juvenile electric organ discharges into the adult electric organ discharge takes at least a year. The increase in electric organ discharge duration could be causally linked to the development of surface evaginations, papillae, at the rostral face of the electrocyte which are recognizable for the first time in 65-mm-long juveniles and are most prominent at the periphery of the electrocyte.},
  language  = {en}
}
@article{TaguchiGotoMatsuokaetal.2023,
  author    = {Taguchi, Mioko and Goto, Mutsuo and Matsuoka, Koji and Tiedemann, Ralph and Pastene, Luis A.},
  title     = {Population genetic structure of Bryde's whales (Balaenoptera brydei) on the central and western North Pacific feeding grounds},
  series = {Canadian Journal of Fisheries and Aquatic Sciences},
  volume    = {80},
  journal   = {Canadian Journal of Fisheries and Aquatic Sciences},
  number    = {1},
  publisher = {Canadian science publishing},
  address   = {Ottawa},
  issn      = {0706-652X},
  doi       = {10.1139/cjfas-2022-0005},
  pages     = {142 -- 155},
  year      = {2023},
  abstract  = {The genetic structure of Bryde's whale (Balaenoptera brydei) on the central and western North Pacific feeding grounds was investigated using a total of 1195 mitochondrial control region sequences and 1182 microsatellite genotypes at 17 loci in specimens collected from three longitudinal areas, 1W (135 degrees E-165 degrees E), 1E (165 degrees E-180 degrees), and 2 (180 degrees-155 degrees W). Genetic diversities were similar among areas and a haplotype network did not show any geographic structure, while an analysis of molecular variance found evidence of genetic structure in this species. Pairwise FST and G'ST estimates and heterogeneity tests attributed this structure to weak but significant differentiation between areas 1W/1E and 2. A Mantel test and a high-resolution analysis of genetic diversity statistics showed a weak spatial cline of genetic differentiation. These findings could be reconciled by two possible stock structure scenarios: (1) a single population with kin-association affecting feeding ground preference and (2) two populations with feeding ground preference for either area 1W or area 2. An estimated dispersal rate between areas 1W and 2 indicates that both scenarios should be considered as a precautionary principle in stock assessments.},
  language  = {en}
}
@article{CanitzKirschbaumTiedemann2020,
  author    = {Canitz, Julia and Kirschbaum, Frank and Tiedemann, Ralph},
  title     = {Transcriptome-wide single nucleotide polymorphisms related to electric organ discharge differentiation among African weakly electric fish species},
  series = {PLoS one},
  volume    = {15},
  journal   = {PLoS one},
  number    = {10},
  publisher = {PLoS},
  address   = {San Francisco, California, US},
  issn      = {1932-6203},
  doi       = {10.1371/journal.pone.0240812},
  pages     = {21},
  year      = {2020},
  abstract  = {African weakly electric fish of the mormyrid genus Campylomormyrus generate pulse-type electric organ discharges (EODs) for orientation and communication. Their pulse durations are species-specific and elongated EODs are a derived trait. So far, differential gene expression among tissue-specific transcriptomes across species with different pulses and point mutations in single ion channel genes indicate a relation of pulse duration and electrocyte geometry/excitability. However, a comprehensive assessment of expressed Single Nucleotide Polymorphisms (SNPs) throughout the entire transcriptome of African weakly electric fish, with the potential to identify further genes influencing EOD duration, is still lacking. This is of particular value, as discharge duration is likely based on multiple cellular mechanisms and various genes. Here we provide the first transcriptome-wide SNP analysis of African weakly electric fish species (genus Campylomormyrus) differing by EOD duration to identify candidate genes and cellular mechanisms potentially involved in the determination of an elongated discharge of C. tshokwe. Non-synonymous substitutions specific to C. tshokwe were found in 27 candidate genes with inferred positive selection among Campylomormyrus species. These candidate genes had mainly functions linked to transcriptional regulation, cell proliferation and cell differentiation. Further, by comparing gene annotations between C. compressirostris (ancestral short EOD) and C. tshokwe (derived elongated EOD), we identified 27 GO terms and 2 KEGG pathway categories for which C. tshokwe significantly more frequently exhibited a species-specific expressed substitution than C. compressirostris. The results indicate that transcriptional regulation as well cell proliferation and differentiation take part in the determination of elongated pulse durations in C. tshokwe. Those cellular processes are pivotal for tissue morphogenesis and might determine the shape of electric organs supporting the observed correlation between electrocyte geometry/tissue structure and discharge duration. The inferred expressed SNPs and their functional implications are a valuable resource for future investigations on EOD durations.},
  language  = {en}
}
@article{KorniienkoNguyenBaumgartneretal.2020,
  author    = {Korniienko, Yevheniia and Nguyen, Linh and Baumgartner, Stephanie and Vater, Marianne and Tiedemann, Ralph and Kirschbaum, Frank},
  title     = {Intragenus F1-hybrids of African weakly electric fish (Mormyridae: Campylomormyrus tamandua male x C. compressirostris female) are fertile},
  series = {Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology},
  volume    = {206},
  journal   = {Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology},
  number    = {4},
  publisher = {Springer},
  address   = {Heidelberg},
  issn      = {0340-7594},
  doi       = {10.1007/s00359-020-01425-7},
  pages     = {571 -- 585},
  year      = {2020},
  abstract  = {Hybridization is widespread in fish and constitutes an important mechanism in fish speciation. There is, however, little knowledge about hybridization in mormyrids. F1-interspecies hybrids betweenCampylomormyrus tamandua male x C. compressirostris female were investigated concerning: (1) fertility; (2) survival of F2-fish and (3) new gene combinations in the F2-generation concerning the structure of the electric organ and features of the electric organ discharge. These F1-hybrids achieved sexual maturity at about 12-13.5 cm total length. A breeding group comprising six males and 13 females spawned 28 times naturally proving these F1-fish to be fertile. On average 228 eggs were spawned, the average fertilization rate was 47.8\%. Eggs started to hatch 70-72 h after fertilization, average hatching rate was 95.6\%. Average mortality rate during embryonic development amounted to 2.3\%. Average malformation rate during the free embryonic stage was 27.7\%. Exogenous feeding started on day 11. In total, we raised 353 normally developed larvae all of which died consecutively, the oldest specimen reaching an age of 5 months. During survival, the activities of the larval and adult electric organs were recorded and the structure of the adult electric organ was investigated histologically.},
  language  = {en}
}
@article{KorniienkoTiedemannVateretal.2020,
  author    = {Korniienko, Yevheniia and Tiedemann, Ralph and Vater, Marianne and Kirschbaum, Frank},
  title     = {Ontogeny of the electric organ discharge and of the papillae of the electrocytes in the weakly electric fish Campylomormyrus rhynchophorus (Teleostei: Mormyridae)},
  series = {The journal of comparative neurology},
  volume    = {529},
  journal   = {The journal of comparative neurology},
  number    = {5},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0021-9967},
  doi       = {10.1002/cne.25003},
  pages     = {1052 -- 1065},
  year      = {2020},
  abstract  = {The electric organ of the mormyrid weakly electric fish,Campylomormyrus rhynchophorus(Boulenger, 1898), undergoes changes in both the electric organ discharge (EOD) and the light and electron microscopic morphology as the fish mature from the juvenile to the adult form. Of particular interest was the appearance of papillae, surface specializations of the uninnervated anterior face of the electrocyte, which have been hypothesized to increase the duration of the EOD. In a 24.5 mm long juvenile the adult electric organ (EO) was not yet functional, and the electrocytes lacked papillae. A 40 mm long juvenile, which produced a short biphasic EOD of 1.3 ms duration, shows small papillae (average area 136 mu m(2)). In contrast, the EOD of a 79 mm long juvenile was triphasic. The large increase in duration of the EOD to 23.2 ms was accompanied by a small change in size of the papillae (average area 159 mu m(2)). Similarly, a 150 mm long adult produced a triphasic EOD of comparable duration to the younger stage (24.7 ms) but featured a prominent increase in size of the papillae (average area 402 mu m(2)). Thus, there was no linear correlation between EOD duration and papillary size. The most prominent ultrastructural change was at the level of the myofilaments, which regularly extended into the papillae, only in the oldest specimen-probably serving a supporting function. Physiological mechanisms, like gene expression levels, as demonstrated in someCampylomormyrusspecies, might be more important concerning the duration of the EOD.},
  language  = {en}
}
@misc{KiemelGurkeParaskevopoulouetal.2022,
  author    = {Kiemel, Katrin and Gurke, Marie and Paraskevopoulou, Sofia and Havenstein, Katja and Weithoff, Guntram and Tiedemann, Ralph},
  title     = {Variation in heat shock protein 40 kDa relates to divergence in thermotolerance among cryptic rotifer species},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {1305},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-57863},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-578635},
  pages     = {14},
  year      = {2022},
  abstract  = {Genetic divergence and the frequency of hybridization are central for defining species delimitations, especially among cryptic species where morphological differences are merely absent. Rotifers are known for their high cryptic diversity and therefore are ideal model organisms to investigate such patterns. Here, we used the recently resolved Brachionus calyciflorus species complex to investigate whether previously observed between species differences in thermotolerance and gene expression are also reflected in their genomic footprint. We identified a Heat Shock Protein gene (HSP 40 kDa) which exhibits cross species pronounced sequence variation. This gene exhibits species-specific fixed sites, alleles, and sites putatively under positive selection. These sites are located in protein binding regions involved in chaperoning and may therefore reflect adaptive diversification. By comparing three genetic markers (ITS, COI, HSP 40 kDa), we revealed hybridization events between the cryptic species. The low frequency of introgressive haplotypes/alleles suggest a tight, but not fully impermeable boundary between the cryptic species.},
  language  = {en}
}
@article{KiemelGurkeParaskevopoulouetal.2022,
  author    = {Kiemel, Katrin and Gurke, Marie and Paraskevopoulou, Sofia and Havenstein, Katja and Weithoff, Guntram and Tiedemann, Ralph},
  title     = {Variation in heat shock protein 40 kDa relates to divergence in thermotolerance among cryptic rotifer species},
  series = {Scientific Reports},
  volume    = {12},
  journal   = {Scientific Reports},
  publisher = {Springer Nature},
  address   = {London},
  issn      = {2045-2322},
  doi       = {10.1038/s41598-022-27137-3},
  pages     = {14},
  year      = {2022},
  abstract  = {Genetic divergence and the frequency of hybridization are central for defining species delimitations, especially among cryptic species where morphological differences are merely absent. Rotifers are known for their high cryptic diversity and therefore are ideal model organisms to investigate such patterns. Here, we used the recently resolved Brachionus calyciflorus species complex to investigate whether previously observed between species differences in thermotolerance and gene expression are also reflected in their genomic footprint. We identified a Heat Shock Protein gene (HSP 40 kDa) which exhibits cross species pronounced sequence variation. This gene exhibits species-specific fixed sites, alleles, and sites putatively under positive selection. These sites are located in protein binding regions involved in chaperoning and may therefore reflect adaptive diversification. By comparing three genetic markers (ITS, COI, HSP 40 kDa), we revealed hybridization events between the cryptic species. The low frequency of introgressive haplotypes/alleles suggest a tight, but not fully impermeable boundary between the cryptic species.},
  language  = {en}
}