TY  - JOUR
A1  - Amen, Rahma
A1  - Nagel, Rebecca
A1  - Hedt, Maximilian
A1  - Kirschbaum, Frank
A1  - Tiedemann, Ralph
T1  - Morphological differentiation in African weakly electric fish (genus Campylomormyrus) relates to substrate preferences
JF  - Evolutionary Ecology
N2  - 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.
KW  - ecological speciation
KW  - feeding behaviour
KW  - electric fish
KW  - trophic apparatus
KW  - evolutionary ecology
Y1  - 2020
U6  - https://doi.org/10.1007/s10682-020-10043-3
SN  - 0269-7653
SN  - 1573-8477
VL  - 34
IS  - 3
SP  - 427
EP  - 437
PB  - Springer Science
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Korniienko, Yevheniia
A1  - Nguyen, Linh
A1  - Baumgartner, Stephanie
A1  - Vater, Marianne
A1  - Tiedemann, Ralph
A1  - Kirschbaum, Frank
T1  - 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)
JF  - Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology
Y1  - 2021
U6  - https://doi.org/10.1007/s00359-021-01513-2
SN  - 0340-7594
SN  - 1432-1351
VL  - 207
IS  - 6
SP  - 773
EP  - 773
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Kiemel, Katrin
A1  - De Cahsan, Binia
A1  - Paraskevopoulou, Sofia
A1  - Weithoff, Guntram
A1  - Tiedemann, Ralph
T1  - 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)
JF  - Mitochondrial DNA. Part B-Resources
N2  - 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).
KW  - Mitogenome
KW  - cryptic species
KW  - Brachionus calyciflorus s
KW  - Brachionus
KW  - fernandoi
KW  - monogonont rotifer
Y1  - 2022
U6  - https://doi.org/10.1080/23802359.2022.2060765
SN  - 2380-2359
VL  - 7
IS  - 4
SP  - 646
EP  - 648
PB  - Routledge, Taylor & Francis Group
CY  - Abingdon
ER  - 
TY  - JOUR
A1  - De Cahsan, Binia
A1  - Nagel, Rebecca
A1  - Schedina, Ina-Maria
A1  - King, James J.
A1  - Bianco, Pier G.
A1  - Tiedemann, Ralph
A1  - Ketmaier, Valerio
T1  - Phylogeography of the European brook lamprey (Lampetra planeri) and the European river lamprey (Lampetra fluviatilis) species pair based on mitochondrial data
JF  - Journal of fish biology
N2  - 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.
KW  - European lamprey
KW  - Lampetra
KW  - paired species
KW  - phylogeography
KW  - population
KW  - structure
Y1  - 2020
U6  - https://doi.org/10.1111/jfb.14279
SN  - 0022-1112
SN  - 1095-8649
VL  - 96
IS  - 4
SP  - 905
EP  - 912
PB  - Wiley-Blackwell
CY  - Oxford [u.a.]
ER  - 
TY  - JOUR
A1  - Foerster, Verena
A1  - Asrat, Asfawossen
A1  - Ramsey, Christopher Bronk
A1  - Brown, Erik T.
A1  - Chapot, Melissa S.
A1  - Deino, Alan
A1  - Düsing, Walter
A1  - Grove, Matthew
A1  - Hahn, Annette
A1  - Junginger, Annett
A1  - Kaboth-Bahr, Stefanie
A1  - Lane, Christine S.
A1  - Opitz, Stephan
A1  - Noren, Anders
A1  - Roberts, Helen M.
A1  - Stockhecke, Mona
A1  - Tiedemann, Ralph
A1  - Vidal, Celine M.
A1  - Vogelsang, Ralf
A1  - Cohen, Andrew S.
A1  - Lamb, Henry F.
A1  - Schaebitz, Frank
A1  - Trauth, Martin H.
T1  - Pleistocene climate variability in eastern Africa influenced hominin evolution
JF  - Nature geoscience
N2  - 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.
KW  - Evolutionary ecology
KW  - Limnology
KW  - Palaeoclimate
Y1  - 2022
U6  - https://doi.org/10.1038/s41561-022-01032-y
SN  - 1752-0894
SN  - 1752-0908
VL  - 15
IS  - 10
SP  - 805
EP  - 811
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Kiemel, Katrin
A1  - Gurke, Marie
A1  - Paraskevopoulou, Sofia
A1  - Havenstein, Katja
A1  - Weithoff, Guntram
A1  - Tiedemann, Ralph
T1  - Variation in heat shock protein 40 kDa relates to divergence in thermotolerance among cryptic rotifer species
JF  - Scientific reports
N2  - 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.
Y1  - 2022
U6  - https://doi.org/10.1038/s41598-022-27137-3
SN  - 2045-2322
VL  - 12
IS  - 1
PB  - Macmillan Publishers Limited
CY  - London
ER  - 
TY  - JOUR
A1  - Parry, Victor
A1  - Schlägel, Ulrike E.
A1  - Tiedemann, Ralph
A1  - Weithoff, Guntram
T1  - Behavioural responses of defended and undefended prey to their predator
BT  - a case study of rotifera
JF  - Biology : open access journal
N2  - 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.
KW  - animal behaviour
KW  - transgenerational response
KW  - Brachionus calyciflorus
KW  - Asplanchna brightwellii
KW  - video analysis
Y1  - 2022
U6  - https://doi.org/10.3390/biology11081217
SN  - 2079-7737
VL  - 11
IS  - 8
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Kiemel, Katrin
A1  - Weithoff, Guntram
A1  - Tiedemann, Ralph
T1  - DNA metabarcoding reveals impact of local recruitment, dispersal, and hydroperiod on assembly of a zooplankton metacommunity
JF  - Molecular ecology
N2  - 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.
KW  - bulk DNA
KW  - dispersal
KW  - DNA-metabarcoding
KW  - environmental filtering;
KW  - metacommunity
KW  - zooplankton
Y1  - 2022
U6  - https://doi.org/10.1111/mec.16627
SN  - 0962-1083
SN  - 1365-294X
VL  - 32
IS  - 23
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Stiegler, Jonas
A1  - Kiemel, Katrin
A1  - Eccard, Jana
A1  - Fischer, Christina
A1  - Hering, Robert
A1  - Ortmann, Sylvia
A1  - Strigl, Lea
A1  - Tiedemann, Ralph
A1  - Ullmann, Wiebke
A1  - Blaum, Niels
T1  - Seed traits matter
BT  - endozoochoric dispersal through a pervasive mobile linker
JF  - Ecology and evolution
N2  - 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.
KW  - agricultural landscapes
KW  - endozoochory
KW  - Lepus europaeus
KW  - mobile links
KW  - seed dispersal
KW  - seed dispersal syndrome
Y1  - 2021
U6  - https://doi.org/10.1002/ece3.8440
SN  - 2045-7758
VL  - 11
IS  - 24
SP  - 18477
EP  - 18491
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Tebbe, Jonas
A1  - Ottensmann, Meinolf
A1  - Havenstein, Katja
A1  - Efstratiou, Artemis
A1  - Lenz, Tobias L.
A1  - Caspers, Barbara A.
A1  - Forcada, Jaume
A1  - Tiedemann, Ralph
A1  - Hoffman, Joseph
T1  - Intronic primers reveal unexpectedly high major histocompatibility complex diversity in Antarctic fur seals
JF  - Scientific reports
N2  - 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.
Y1  - 2022
U6  - https://doi.org/10.1038/s41598-022-21658-7
SN  - 2045-2322
VL  - 12
IS  - 1
PB  - Nature Publishing Group
CY  - London
ER  - 
TY  - JOUR
A1  - Nguyen, Manh Duy Linh
A1  - Mamonekene, Victor
A1  - Vater, Marianne
A1  - Bartsch, Peter
A1  - Tiedemann, Ralph
A1  - Kirschbaum, Frank
T1  - Ontogeny of electric organ and electric organ discharge in Campylomormyrus rhynchophorus (Teleostei: Mormyridae)
JF  - Journal of comparative physiology; A, Neuroethology, sensory, neural, and behavioral physiology
N2  - 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.
KW  - Weakly electric fish
KW  - Development
KW  - Electric organ discharge
KW  - Electric
KW  - organ
KW  - Electrocyte features
Y1  - 2020
U6  - https://doi.org/10.1007/s00359-020-01411-z
SN  - 0340-7594
SN  - 1432-1351
VL  - 206
IS  - 3
SP  - 453
EP  - 466
PB  - Springer
CY  - Berlin ; Heidelberg
ER  - 
TY  - JOUR
A1  - Taguchi, Mioko
A1  - Goto, Mutsuo
A1  - Matsuoka, Koji
A1  - Tiedemann, Ralph
A1  - Pastene, Luis A.
T1  - Population genetic structure of Bryde's whales (Balaenoptera brydei) on the central and western North Pacific feeding grounds
JF  - Canadian Journal of Fisheries and Aquatic Sciences
N2  - 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.
KW  - stock structure
KW  - stock assessment
KW  - fisheries management
KW  - conservation
KW  - cetacean
Y1  - 2023
U6  - https://doi.org/10.1139/cjfas-2022-0005
SN  - 0706-652X
SN  - 1205-7533
VL  - 80
IS  - 1
SP  - 142
EP  - 155
PB  - Canadian science publishing
CY  - Ottawa
ER  - 
TY  - JOUR
A1  - Canitz, Julia
A1  - Kirschbaum, Frank
A1  - Tiedemann, Ralph
T1  - Transcriptome-wide single nucleotide polymorphisms related to electric organ discharge differentiation among African weakly electric fish species
JF  - PLoS one
N2  - 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.
Y1  - 2020
U6  - https://doi.org/10.1371/journal.pone.0240812
SN  - 1932-6203
VL  - 15
IS  - 10
PB  - PLoS
CY  - San Francisco, California, US
ER  - 
TY  - JOUR
A1  - Korniienko, Yevheniia
A1  - Nguyen, Linh
A1  - Baumgartner, Stephanie
A1  - Vater, Marianne
A1  - Tiedemann, Ralph
A1  - Kirschbaum, Frank
T1  - Intragenus F1-hybrids of African weakly electric fish (Mormyridae: Campylomormyrus tamandua male x C. compressirostris female) are fertile
JF  - Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology
N2  - 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.
KW  - mormyridae
KW  - campylomormyrus
KW  - F1-hybrids
KW  - F2-hybrids
KW  - fertility
Y1  - 2020
U6  - https://doi.org/10.1007/s00359-020-01425-7
SN  - 0340-7594
SN  - 1432-1351
VL  - 206
IS  - 4
SP  - 571
EP  - 585
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Korniienko, Yevheniia
A1  - Tiedemann, Ralph
A1  - Vater, Marianne
A1  - Kirschbaum, Frank
T1  - Ontogeny of the electric organ discharge and of the papillae of the electrocytes in the weakly electric fish Campylomormyrus rhynchophorus (Teleostei: Mormyridae)
JF  - The journal of comparative neurology
N2  - 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.
KW  - Campylomormyrus
KW  - electric organ discharge
KW  - electrocyte ontogeny
KW  - electrocyte ultrastructure
KW  - papillae
Y1  - 2020
U6  - https://doi.org/10.1002/cne.25003
SN  - 0021-9967
SN  - 1096-9861
VL  - 529
IS  - 5
SP  - 1052
EP  - 1065
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Kiemel, Katrin
A1  - Gurke, Marie
A1  - Paraskevopoulou, Sofia
A1  - Havenstein, Katja
A1  - Weithoff, Guntram
A1  - Tiedemann, Ralph
T1  - Variation in heat shock protein 40 kDa relates to divergence in thermotolerance among cryptic rotifer species
JF  - Scientific Reports
N2  - 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.
Y1  - 2022
U6  - https://doi.org/10.1038/s41598-022-27137-3
SN  - 2045-2322
VL  - 12
PB  - Springer Nature
CY  - London
ER  - 
TY  - JOUR
A1  - Parry, Victor
A1  - Schlägel, Ulrike E.
A1  - Tiedemann, Ralph
A1  - Weithoff, Guntram
T1  - Behavioural Responses of Defended and Undefended Prey to Their Predator
BT  - A Case Study of Rotifera
JF  - Biology
N2  - 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.
KW  - animal behaviour
KW  - transgenerational response
KW  - Brachionus calyciflorus
KW  - Asplanchna brightwellii
KW  - video analysis
Y1  - 2022
U6  - https://doi.org/10.3390/biology11081217
SN  - 2079-7737
VL  - 11
IS  - 8
PB  - MDPI
CY  - Basel, Schweiz
ER  - 
TY  - JOUR
A1  - Gross, Stephanie
A1  - Claus, Philip
A1  - Wohlsein, Peter
A1  - Kesselring, Tina
A1  - Lakemeyer, Jan
A1  - Reckendorf, Anja
A1  - Roller, Marco
A1  - Tiedemann, Ralph
A1  - Siebert, Ursula
T1  - Indication of lethal interactions between a solitary bottlenose dolphin (Tursiops truncatus) and harbor porpoises (Phocoena phocoena) in the German Baltic Sea
JF  - BMC zoology
N2  - Background Aggressive interactions between bottlenose dolphins (Tursiops truncatus) and harbor porpoises (Phocoena phocoena) have been reported in different parts of the world since the late 1990s. In the Baltic Sea, harbor porpoises are the only native cetacean species, while bottlenose dolphins may appear there temporarily. In the fall of 2016, a solitary male photo-identified bottlenose dolphin stayed in the German Baltic Sea of Schleswig-Holstein for 3 months. During that time, the necropsies of the stranded harbor porpoises revealed types of trauma of varying degrees in six animals, which is unusual in this area. The purpose of this study was to determine if the appearance of the bottlenose dolphin could be linked to the trauma of the harbor porpoise carcasses. Results Pathological findings in these animals included subcutaneous, thoracic and abdominal hemorrhages, multiple, mainly bilateral, rib fractures, and one instance of lung laceration. These findings correspond with the previously reported dolphin-caused injuries in other regions. Moreover, public sighting reports showed a spatial and temporal correlation between the appearance of the dolphin and the stranding of fatally injured harbor porpoises. Conclusion Despite the fact that no attack has been witnessed in German waters to date, our findings indicate the first record of lethal interactions between a bottlenose dolphin and harbor porpoises in the German Baltic Sea. Furthermore, to our knowledge, this is the first report of porpoise aggression by a socially isolated bottlenose dolphin.
KW  - Cetaceans
KW  - Interspecific aggression
KW  - Porpicide
KW  - Blunt trauma
KW  - Mortality
KW  - Stranding
Y1  - 2020
U6  - https://doi.org/10.1186/s40850-020-00061-7
SN  - 2056-3132
VL  - 5
IS  - 1
PB  - BMC
CY  - London
ER  - 
TY  - JOUR
A1  - Nagel, Rebecca
A1  - Kirschbaum, Frank
A1  - Tiedemann, Ralph
T1  - Electric organ discharge diversification in mormyrid weakly electric fish is associated with differential expression of voltage-gated ion channel genes
JF  - Journal of comparative physiology : A, Neuroethology, sensory, neural, and behavioral physiology
N2  - In mormyrid weakly electric fish, the electric organ discharge (EOD) is used for species recognition, orientation and prey localization. Produced in the muscle-derived adult electric organ, the EOD exhibits a wide diversity across species in both waveform and duration. While certain defining EOD characteristics can be linked to anatomical features of the electric organ, many factors underlying EOD differentiation are yet unknown. Here, we report the differential expression of 13 Kv1 voltage-gated potassium channel genes, two inwardly rectifying potassium channel genes, two previously studied sodium channel genes and an ATPase pump in two sympatric species of the genus Campylomormyrus in both the adult electric organ and skeletal muscle. Campylomormyrus compressirostris displays a basal EOD, largely unchanged during development, while C. tshokwe has an elongated, putatively derived discharge. We report an upregulation in all Kv1 genes in the electric organ of Campylomormyrus tshokwe when compared to both skeletal muscle and C. compressirostris electric organ. This pattern of upregulation in a species with a derived EOD form suggests that voltage-gated potassium channels are potentially involved in the diversification of the EOD signal among mormyrid weakly electric fish.
KW  - Weakly electric fish
KW  - Ion channels
KW  - Electric organ
KW  - Gene expression
KW  - Campylomormyrus
Y1  - 2017
U6  - https://doi.org/10.1007/s00359-017-1151-2
SN  - 0340-7594
SN  - 1432-1351
VL  - 203
SP  - 183
EP  - 195
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Krüger, Johanna
A1  - Foerster, Verena Elisabeth
A1  - Trauth, Martin H.
A1  - Hofreiter, Michael
A1  - Tiedemann, Ralph
T1  - Exploring the Past Biosphere of Chew Bahir/Southern Ethiopia: Cross-Species Hybridization Capture of Ancient Sedimentary DNA from a Deep Drill Core
JF  - Frontiers in Earth Science
N2  - Eastern Africa has been a prime target for scientific drilling because it is rich in key paleoanthropological sites as well as in paleolakes, containing valuable paleoclimatic information on evolutionary time scales. The Hominin Sites and Paleolakes Drilling Project (HSPDP) explores these paleolakes with the aim of reconstructing environmental conditions around critical episodes of hominin evolution. Identification of biological taxa based on their sedimentary ancient DNA (sedaDNA) traces can contribute to understand past ecological and climatological conditions of the living environment of our ancestors. However, sedaDNA recovery from tropical environments is challenging because high temperatures, UV irradiation, and desiccation result in highly degraded DNA. Consequently, most of the DNA fragments in tropical sediments are too short for PCR amplification. We analyzed sedaDNA in the upper 70 m of the composite sediment core of the HSPDP drill site at Chew Bahir for eukaryotic remnants. We first tested shotgun high throughput sequencing which leads to metagenomes dominated by bacterial DNA of the deep biosphere, while only a small fraction was derived from eukaryotic, and thus probably ancient, DNA. Subsequently, we performed cross-species hybridization capture of sedaDNA to enrich ancient DNA (aDNA) from eukaryotic remnants for paleoenvironmental analysis, using established barcoding genes (cox1 and rbcL for animals and plants, respectively) from 199 species that may have had relatives in the past biosphere at Chew Bahir. Metagenomes yielded after hybridization capture are richer in reads with similarity to cox1 and rbcL in comparison to metagenomes without prior hybridization capture. Taxonomic assignments of the reads from these hybridization capture metagenomes also yielded larger fractions of the eukaryotic domain. For reads assigned to cox1, inferred wet periods were associated with high inferred relative abundances of putative limnic organisms (gastropods, green algae), while inferred dry periods showed increased relative abundances for insects. These findings indicate that cross-species hybridization capture can be an effective approach to enhance the information content of sedaDNA in order to explore biosphere changes associated with past environmental conditions, enabling such analyses even under tropical conditions.
KW  - Chew Bahir
KW  - hybridization capture
KW  - ICDP
KW  - paleoclimate
KW  - past biosphere
KW  - sedaDNA
KW  - sediment core
Y1  - 2021
U6  - https://doi.org/10.3389/feart.2021.683010
SN  - 2296-6463
SP  - 1
EP  - 20
PB  - Frontiers in Earth Science
CY  - Lausanne, Schweiz
ER  -