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Jørgen Olesen - One of the best experts on this subject based on the ideXlab platform.
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first molecular phylogeny of laevicaudata crustacea Branchiopoda with description of a new species of lynceus from chile and an updated key to species in the americas
Invertebrate Systematics, 2019Co-Authors: Zandra M S Sigvardt, Christopher D Rogers, Patricio De Los Rios, Ferran Palero, Jørgen OlesenAbstract:The first molecular phylogeny of Lynceus (Crustacea: Branchiopoda: Laevicaudata) is presented together with a description of a new species of laevicaudatan branchiopod from Chile, Lynceus huentelauquensis, sp. nov. DNA sequences were obtained from six species of Lynceus using freshly collected specimens from Europe, North America, South America, and Australia and combined with GenBank sequences from previous studies. Specimens of the new species were collected from a pool on the Huentelauquen Plains near Huentelauquen City. Our molecular analyses placed L. huentelauquensis, sp. nov. within Lynceus and close to a cluster of Australian species, and revealed morphological misidentifications, cross-contamination, or incorrect upload in earlier GenBank sequences. L. huentelauquensis, sp. nov. is separated from other Lynceus primarily by the morphology of the rostrum and the male claspers. L. huentelauquensis, sp. nov. is the first described laevicaudatan from Chile, the sixth from South America, and the 13th from the Americas. The morphology of laevicaudatans from the Americas is reviewed and an updated key to the (male) Lynceidae of the region is provided. Our study highlights the necessity of a revision of Laevicaudata using multiple genetic markers as well as thorough morphological studies on a greater number of taxa. urn:lsid:zoobank.org:pub:9A783D96-B270-40DF-8361-11BA063C9A0F
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Functional morphology of amplexus (clasping) in spinicaudatan clam shrimps (Crustacea, Branchiopoda) and its evolution in bivalved branchiopods: A video-based analysis.
Journal of Morphology, 2017Co-Authors: Zandra M S Sigvardt, D. Christopher Rogers, Jørgen OlesenAbstract:Male clam shrimps (Crustacea: Branchiopoda: Laevicaudata, Spinicaudata, and Cyclestherida) have their first one or two trunk limb pairs modified as "claspers," which are used to hold the female during mating and mate guarding. Clasper morphology has traditionally been important for clam shrimp taxonomy and classification, but little is known about how the males actually use the claspers during amplexus (clasping). Homologies of the various clasper parts ("movable finger," "large palp," "palm," "gripping area," and "small palp") have long been discussed between the three clam shrimp taxa, and studies have shown that only some structures are homologous while others are convergent ("partial homology"). We studied the clasper functionality in four spinicaudatan species using video recordings and scanning electron microscopy, and compared our results with other clam shrimp groups. General mating behavior and carapace morphology was also studied. Generally, spinicaudatan and laevicaudatan claspers function similarly despite some parts being nonhomologous. We mapped clasper morphology and functionality aspects on a branchiopod phylogeny. We suggest that the claspers of the three groups were adapted from an original, simpler clasper, each for a "stronger" grip on the female's carapace margin: 1) Spinicaudata have two clasper pairs bearing an elongated apical club/gripping area with one setal type; 2); Cyclestherida have one clasper pair with clusters of molariform setae on the gripping area and at the movable finger apex; and 3) Laevicaudata have one clasper pair, but have incorporated an additional limb portion into the clasper palm and bear a diverse set of setae. J. Morphol. 278:523-546, 2017. © 2017 Wiley Periodicals, Inc.
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evolution classification and global diversity of large Branchiopoda
Journal of Crustacean Biology, 2015Co-Authors: Christopher D Rogers, Jørgen Olesen, Martin Schwentner, Stefan RichterAbstract:We introduce this Branchiopoda Special Issue of the Journal of Crustacean Biology, providing a brief outline of the 13 research papers presented at the 8 th International Crustacean Congress in Frankfurt, Germany, August 2014. We also discuss the current status and direction of research on the large branchiopod crustaceans.
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The development of the nervous system in Laevicaudata (Crustacea, Branchiopoda): insights into the evolution and homologies of branchiopod limbs and ‘frontal organs’
Zoomorphology, 2013Co-Authors: Martin Fritsch, Jørgen Olesen, Tomonari Kaji, Stefan RichterAbstract:We investigated the development of the external morphology and of the nervous system in Lynceus biformis and Lynceus brachyurus (Laevicaudata, Branchiopoda), by using immunohistochemical methods in combination with a confocal laser scanning analysis. In both Lynceus species, a free-swimming nauplius larva, equipped with three appendages, hatches from resting eggs. Despite their close phylogenetic relationship to each other, considerable differences are present in their external morphology. Hatching L. brachyurus larvae are equipped with a large and flattened labrum, where in contrast, the L. biformis larvae possess a smaller labrum with four conspicuous posteriorly directed spines at its margin. Despite these differences, the development of the nervous system is quite similar in both species. The hatching larvae are equipped with a naupliar nervous system, and only in the more advanced stages, the development of the ventral nerve cord starts. Furthermore, our investigation into the nervous system provided insights into architecture and evolution of protocerebral sensory organs, the dorsal setae field and the dorsal frontal organ, only present in Laevicaudata. The identification of frontal filaments with an associated frontal filament organ in Lynceus revealed—after a comprehensive comparison with other branchiopods—that these organs exist throughout Branchiopoda and are comparable to those in other crustaceans. Additionally, our results of the peripheral nervous system analysis showed that the innervation pattern of the naupliar appendages (antenna and mandible) and the trunk appendages could be serially homologized, despite much difference in gross morphology of these. Based on the innervation pattern of limbs, we suggest that the larval uniramous mandibular palp, found in the larvae of all ‘large’ branchiopods, is largely exopodal of nature (contrary to most earlier statements) and that the endopodite of the trunk limbs consists of only one distal endite-like segment (confirming some earlier statements) and not of three as proposed by others.
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larval development of japanese conchostracans part 3 larval development of lynceus biformis crustacea Branchiopoda laevicaudata based on scanning electron microscopy and fluorescence microscopy
Journal of Morphology, 2013Co-Authors: Jørgen Olesen, Martin Fritsch, Mark J GrygierAbstract:For comparison with the remarkable larvae of the laevicaudatan (clam shrimp) Lynceus brachyurus ,a basic description of the larval sequence of another laevi- caudatan branchiopod, the Japanese Lynceus biformis ,i s provided. Four larval stages have been identified, ranging in size from 258 to 560 lm in length. The first stage has no flattened dorsal shield, in contrast to the three follow- ing stages, in which such a shield is present. During de- velopment, the only significant changes to the naupliar appendages occur in the antenna at the molt from stage 1 to 2, with the addition of a fourth apical seta to the endopod and a change in the form of the naupliar pro- cess, used for food manipulation, from a long, unbranched, pointed spine to a bifid structure. In addi- tion, buds of trunk limbs (five pairs) first appear exter- nally in stage 4 but can be recognized through the cuticle in the previous stage. The larval sequence and larval morphology of L. biformis differ from those of L. brachyu- rus in at least two respects. L. brachyurus has a dorsal shield in the earliest known stages, but such a shield is lacking in the first stage of L. biformis. Another differ- ence is that L. brachyurus has a huge, flattened, kidney- shaped labrum, whereas that of L. biformis is smaller and bears four robust, denticulate spines on the distal margin. Based on out-group comparison, the morphology of L. biformis, at least in these respects, is likely to repre- sent the ancestral morphology. Despite the partly peculiar morphology of the larvae of Lynceus species, they share many similarities with other branchiopod larvae, at least two of which, the naupliar swimming/feeding apparatus and the mode of development of the trunk limbs, could be considered synapomorphies for the Branchiopoda. J. Mor-
Luc Brendonck - One of the best experts on this subject based on the ideXlab platform.
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Egg morphology may underpin the successful distribution of large branchiopods in temporary waters
Aquatic Ecology, 2021Co-Authors: Elizabeth Meyer-milne, Luc Brendonck, Tom PinceelAbstract:Invertebrate species from temporary aquatic ecosystems produce resistant dormant stages (i.e. eggs) that accumulate in long lived mixed egg banks in the sediment. These dormant eggs not only bridge dry phases but also act as propagules for passive dispersal. Large branchiopod crustaceans (e.g. Notostraca, Anostraca and Spinicaudata) produce dormant eggs of variable shapes, sizes and external ornamentation. While these characteristics are often species-specific and have been used in taxonomy, little is known about their ecological significance, for example, their contribution to colonisation success. Here, we explore the idea that variation in egg morphology may impact vector-mediated dispersal and colonisation success of large branchiopods. We studied egg banks from 98 temporary waters across the Northern Cape, South Africa and assessed whether distribution and densities of eggs carried a morphological signal. Overall, our results imply that both size and external structures may impact dispersal to and successful colonisation of temporary waters by large branchiopods. Specifically, our results show that small propagules ( 400 µm), smooth eggs and medium sized (200–300 µm), polygonal eggs were most widely distributed. Ultimately, our approach provides insight in actual colonisation success of species with different egg types and not only on the propensity of the eggs to be picked up and transported by vectors.
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exploring links between geology hydroperiod and diversity and distribution patterns of anostracans and notostracans Branchiopoda in a tropical savannah habitat in se zimbabwe
Journal of Crustacean Biology, 2015Co-Authors: Karen Tuytens, Tamuka Nhiwatiwa, Bram Vanschoenwinkel, Bruce Clegg, Luc BrendonckAbstract:Southern Africa is recognized as one of the world’s diversity hotspots for large branchiopod crustaceans. Nonetheless, many areas including large parts of Zimbabwe remain poorly studied. We report on the diversity of anostracans and notostracans in a tropical and geologically diverse savannah area in SE Zimbabwe. We explored the links between geology, hydroperiod and diversity and distribution patterns of anostracans and notostracans. In a large survey, 160 temporary clay pans distributed over the four major and diverse geological regions were sampled every fortnight. Seven fairy shrimp and one tadpole shrimp species were recorded. Although the study area is characterized by substantial variation in soil geology, we did not find strong effects of geology on the composition of anostracan and notostracan assemblages in pools of different sizes and hydrology. All species occurred in all four geological regions but the abundance of pools without large branchiopods differed between the four investigated regions.
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A hotspot of large branchiopod diversity in south-eastern Zimbabwe
African Journal of Aquatic Science, 2014Co-Authors: Tamuka Nhiwatiwa, B.j. Riddoch, Aline Waterkeyn, Luc BrendonckAbstract:Large branchiopods are considered threatened across much of their global range. However, because several regions, including Zimbabwe in general and its south-eastern lowveld in particular, remain largely unstudied, interpretations of species distribution patterns are often based on limited data. A detailed study of large branchiopods was carried out, with repeated sampling of 36 seasonal pans, in 2004-2008 in the Save Valley Conservancy, south-eastern lowveld. Sixteen large branchiopod species were collected, comprising eight Anostraca, one Notostraca, two Laevicaudata, four Spinicaudata and one cyclestherid species, representing 33% of all species known in southern Africa. Most species were new records for Zimbabwe. The enigmatic morphotype, Streptocephalus cf. bidentatus, was encountered for the first time in Zimbabwe, presenting an opportunity to resolve its taxonomic status. Streptocephalus wirminghausi, a species endemic to Zimbabwe, was also recorded. Large endorheic pans had higher species richness...
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Global diversity of large branchiopods (Crustacea: Branchiopoda) in freshwater
Hydrobiologia, 2008Co-Authors: Luc Brendonck, D. Christopher Rogers, Jørgen Olesen, Stephen Weeks, Walter R. HoehAbstract:With about 500 known species worldwide, the large brachiopods are a relatively small group of primitive crustaceans. With few exceptions they live in temporary aquatic systems that are most abundant in arid and semi arid areas. As many regions remain unexplored and as especially the number of species in clam shrimps and tadpole shrimps is underestimated due to difficult identification, the species list will increase with future surveys. The Branchiopoda are monophyletic, but inter-ordinal relationships, as well as many evolutionary relationships at lower taxonomic levels are still unclear. Ongoing molecular studies will more accurately depict species diversity and phylogenetic patterns. With the exception of some anostracan families, most families are not restricted to the northern or southern hemisphere or specific zoogeographical regions. Large branchiopods are used for the assessment of the quality and function of temporary wetlands. Due to the reduction in number and quality of temporary wetlands, several species became endangered and are red listed by the IUCN.
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diapause quiescence hatching requirements what we can learn from large freshwater branchiopods crustacea Branchiopoda anostraca notostraca conchostraca
Hydrobiologia, 1996Co-Authors: Luc BrendonckAbstract:The extent to which dormancy in large freshwater branchiopods is controlled endogenously (diapause) or exogenously (quiescence) is not always clear. It is assumed that both processes occur even within the same brood. Based on the effectiveness of common diapause-deactivating processes such as desiccation, hibernation, and resting, it can be stated that diapause is not a general process controlling responsiveness of large freshwater branchiopod eggs. Only in limited cases unequivocal evidence for the positive influence of these treatments is found.
Barbara Mantovani - One of the best experts on this subject based on the ideXlab platform.
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Mitochondrial genome diversity and evolution in Branchiopoda (Crustacea)
Zoological Letters, 2019Co-Authors: Andrea Luchetti, Giobbe Forni, Alyza M. Skaist, Sarah J. Wheelan, Barbara MantovaniAbstract:Background The crustacean class Branchiopoda includes fairy shrimps, clam shrimps, tadpole shrimps, and water fleas. Branchiopods, which are well known for their great variety of reproductive strategies, date back to the Cambrian and extant taxa can be mainly found in freshwater habitats, also including ephemeral ponds. Mitochondrial genomes of the notostracan taxa Lepidurus apus lubbocki (Italy), L. arcticus (Iceland) and Triops cancriformis (an Italian and a Spanish population) are here characterized for the first time and analyzed together with available branchiopod mitogenomes. Results Overall, branchiopod mitogenomes share the basic structure congruent with the ancestral Pancrustacea model. On the other hand, rearrangements involving tRNAs and the control region are observed among analyzed taxa. Remarkably, an unassigned region in the L. apus lubbocki mitogenome showed a chimeric structure, likely resulting from a non-homologous recombination event between the two flanking trnC and trnY genes. Notably, Anostraca and Onychocaudata mitogenomes showed increased GC content compared to both Notostraca and the common ancestor, and a significantly higher substitution rate, which does not correlate with selective pressures, as suggested by dN/dS values. Conclusions Branchiopod mitogenomes appear rather well-conserved, although gene rearrangements have occurred. For the first time, it is reported a putative non-homologous recombination event involving a mitogenome, which produced a pseudogenic tRNA sequence. In addition, in line with data in the literature, we explain the higher substitution rate of Anostraca and Onychocaudata with the inferred GC substitution bias that occurred during their evolution.
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mitochondrial genome diversity and evolution in Branchiopoda crustacea
Zoological Letters, 2019Co-Authors: Andrea Luchetti, Giobbe Forni, Alyza M. Skaist, Sarah J. Wheelan, Barbara MantovaniAbstract:The crustacean class Branchiopoda includes fairy shrimps, clam shrimps, tadpole shrimps, and water fleas. Branchiopods, which are well known for their great variety of reproductive strategies, date back to the Cambrian and extant taxa can be mainly found in freshwater habitats, also including ephemeral ponds. Mitochondrial genomes of the notostracan taxa Lepidurus apus lubbocki (Italy), L. arcticus (Iceland) and Triops cancriformis (an Italian and a Spanish population) are here characterized for the first time and analyzed together with available branchiopod mitogenomes. Overall, branchiopod mitogenomes share the basic structure congruent with the ancestral Pancrustacea model. On the other hand, rearrangements involving tRNAs and the control region are observed among analyzed taxa. Remarkably, an unassigned region in the L. apus lubbocki mitogenome showed a chimeric structure, likely resulting from a non-homologous recombination event between the two flanking trnC and trnY genes. Notably, Anostraca and Onychocaudata mitogenomes showed increased GC content compared to both Notostraca and the common ancestor, and a significantly higher substitution rate, which does not correlate with selective pressures, as suggested by dN/dS values. Branchiopod mitogenomes appear rather well-conserved, although gene rearrangements have occurred. For the first time, it is reported a putative non-homologous recombination event involving a mitogenome, which produced a pseudogenic tRNA sequence. In addition, in line with data in the literature, we explain the higher substitution rate of Anostraca and Onychocaudata with the inferred GC substitution bias that occurred during their evolution.
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draft genomes and genomic divergence of two lepidurus tadpole shrimp species crustacea Branchiopoda notostraca
Molecular Ecology Resources, 2019Co-Authors: Castrense Savojardo, Andrea Luchetti, Pier Luigi Martelli, Rita Casadio, Barbara MantovaniAbstract:Crustaceans of the order Notostraca (Branchiopoda) are distributed worldwide and are known for the remarkable morphological stasis between their extant and Permian fossil species. Moreover, these crustaceans show relevant ecological traits and a wide range of reproductive strategies. However, genomic studies on notostracans are fairly limited. Here, we present the genome sequences of two notostracan taxa, Lepidurus arcticus and Lepidurus apus lubbocki. Taking advantage of the small genome sizes (~0.11 pg) of these taxa, genomes were sequenced for one individual per species with one run on the Illumina HiSeq X platform. We finally assembled 73.2 Mbp (L. arcticus) and 90.3 Mbp (L. apus lubbocki) long genomes. Assemblies cover up to 84% of the estimated genome size, with a gene completeness >97% for both genomes. In total, 13%-16% of the assembled genomes consist of repeats, and based on read mapping, L. apus lubbocki shows a significantly lower transposable element content than L. arcticus. The analysis of 2,376 orthologous genes indicates an ~7% divergence between the two Lepidurus taxa, with a nucleotide substitution rate significantly lower than that of Daphnia taxa. Ka /Ks analysis suggests purifying selection in both branchiopod lineages, raising the question of whether the low substitution rate of Lepidurus is correlated with morphological conservation or is linked to specific biological traits. Our analysis demonstrates that, in these organisms, it is possible to obtain high-quality draft genomes from single individuals with a relatively low sequencing effort. This result makes Lepidurus and Notostraca interesting models for genomic studies at taxonomic, ecological and evolutionary levels.
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Draft genomes and genomic divergence of two Lepidurus tadpole shrimp species (Crustacea, Branchiopoda, Notostraca)
2018Co-Authors: Castrense Savojardo, Andrea Luchetti, Pier Luigi Martelli, Rita Casadio, Barbara MantovaniAbstract:Crustaceans of the order Notostraca (Branchiopoda) are worldwide-distributed and known for their remarkable morphological stasis between extant and Permian fossil species. Moreover, they show relevant ecological traits and a wide panel of reproductive strategies. However, genomic studies on notostracans are fairly limited. We here present the genome sequences of two notostracan taxa, Lepidurus arcticus and L. apus lubbocki. Taking advantage of the small genome size (~0.11 pg), we set the sequencing on Illumina HiSeq X platform for a single run on a single individual per species. We finally assembled 73.2 Mbp - L. arcticus - and 90.3 Mbp - L. apus lubbocki long genomes. Assembly cover up to 80% of estimated genome size, with a gene completeness >97% for both genomes. 10-15% of assembled genomes consist of repeats and, although L. apus lubbocki experienced a marked increase of LTR and DNA transposons, there is no significant difference in copy number. The analysis of 2,376 ortholog genes indicates a ~7% of divergence between the two Lepidurus species, with a nucleotide substitution rate significantly lower than the Daphnia one. Ka/Ks analyses suggests purifying selection in both branchiopod lineages, raising the question whether the lower substitution rate is correlated with the Lepidurus morphological conservation or it is attributable to specific biological traits. Our analysis demonstrates that in these organisms it is possible to obtain draft genomes with high completeness from single individuals with a relatively small sequencing effort. This makes Lepidurus, and Notostraca, an interesting model for studies in population, ecological and evolutionary genomics.
Henri J Dumont - One of the best experts on this subject based on the ideXlab platform.
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c 1997 Kluwer Academic Publishers. Printed in Belgium. Large branchiopod assemblages common to Mexico and the United States
2015Co-Authors: Alejandro M. Maeda-martı́nez, Henri J DumontAbstract:We present observations on the frequency of large branchiopod associations found in north-central Mexico, and in Arizona, USA. Of a total of 25 species involved in these assemblages, 12 were common in both areas. Fifty-eight (43.3%) of the ponds in Mexico, and seventy-eight (47%) of those in Arizona had two or more species present. The combinations of species which occurred with highest frequency were Streptocephalus mackini with Thamnocephalus platyurus for Arizona, and T. platyurus, Triops sp., and Leptestheria compleximanus for Mexico. In Mexico, and Arizona, as in many parts of the world, multispecies assemblages of large branchiopods are a common phenomenon. Therefore, the ‘common rule ’ of ‘one-phyllopod-per-habitat ’ advanced by Weise (1964) is inconsistent with field observations. Furthermore, since cases of co-occurrence of two or more congeneric species of Anostraca and Notostraca are not uncommon, generalizations about congeners not coexisting remain applicable only for the Spinicaudata and Laevicaudata. On the basis of the literature, and of observations in the field and in the laboratory, we list potential factors contributing to the co-occurrence of several species within a pond
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The large branchiopods (Anostraca, Notostraca and Spinicaudata) of Numidia (Algeria)
Hydrobiologia, 2002Co-Authors: Boudjema Samraoui, Henri J DumontAbstract:Between 1995 and 1999, we surveyed the large branchiopods (Crustacea, Branchiopoda) of Numidia, the coastal plain of northeastern Algeria. Samples from ca 100 sites yielded two species of Anostraca ( Chirocephalus diaphanus , new to Numidia, and Tanymastix stagnalis ), one notostracan ( Lepidurus apus lubbocki ) and one spinicaudatan ( Cyzicus tetracerus ). The absence of Streptocephalus torvicornis bucheti is noteworthy. An annotated check-list of all large branchiopods known from Algeria is also presented and discussed. Several species appear to be in danger of extinction.
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Phylogeny, evolution and classification of the Branchiopoda (Crustacea)
Hydrobiologia, 1999Co-Authors: Stefan Negrea, Nicolae Botnariuc, Henri J DumontAbstract:We present a cladistic analysis of all branchiopod groups, using a total of 42 morphological characters. The class Branchiopoda is composed of five superorders and 11 orders (nine recent, two fossil). The orders Ctenopoda, Anomopoda and Onychopoda form a monophyletic group, combined in the superorder Cladocera. The order Haplopoda, the fourth so-called cladoceran order ( s. lat. ), belongs to a new monotypic superorder, the Leptodorida. The circumtropical Cyclesteria hislopi is the sole representative of a new conchostracan order, the Cyclestherida.
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Large branchiopod assemblages common to Mexico and the United States
Hydrobiologia, 1997Co-Authors: Alejandro M. Maeda-martínez, Hortencia Obregón-barboza, Denton Belk, Henri J DumontAbstract:We present observations on the frequency of large branchiopod associations found in north-central Mexico, and in Arizona, USA. Of a total of 25 species involved in these assemblages, 12 were common in both areas. Fifty-eight (43.3%) of the ponds in Mexico, and seventy-eight (47%) of those in Arizona had two or more species present. The combinations of species which occurred with highest frequency were Streptocephalus mackini with Thamnocephalus platyurus for Arizona, and T. platyurus, Triops sp., and Leptestheria compleximanus for Mexico. In Mexico, and Arizona, as in many parts of the world, multispecies assemblages of large branchiopods are a common phenomenon. Therefore, the ’common rule‘ of’one-phyllopod-per-habitat‘ advanced by Weise (1964) is inconsistent with field observations. Furthermore, since cases of co-occurrence of two or more congeneric species of Anostraca and Notostraca are not uncommon, generalizations about congeners not coexisting remain applicable only for the Spinicaudata and Laevicaudata. On the basis of the literature, and of observations in the field and in the laboratory, we list potential factors contributing to the co-occurrence of several species within a pond.
D. Christopher Rogers - One of the best experts on this subject based on the ideXlab platform.
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A Review of Recently Discovered Remains of the Pleistocene Branchiopods (Anostraca, Notostraca) from NE Siberia and Arctic Canada
Water, 2021Co-Authors: D. Christopher Rogers, A. A. Zharov, A. N. Neretina, Svetlana A. Kuzmina, Alexey A. KotovAbstract:In this study, we examine, identify, and discuss fossil remains of large branchiopod crustaceans collected from six sites across the Beringian region (north-eastern Asia and north-western North America). Eggs and mandibles from Anostraca and Notostraca, as well as a notostracan telson fragment and a possible notostracan second maxilla, were collected from both paleosediment samples and also from large mammal hair. The remains of large branchiopods and other species that are limited to seasonally astatic aquatic habitats (temporary wetlands) could be useful indicator organisms of paleoecological conditions. Different recent large branchiopod species have very different ecological preferences, with each species limited to specific geochemical component tolerance ranges regarding various salinity, cation, and gypsum concentrations. Our purpose is to bring the potential usefulness of these common fossil organisms to the attention of paleoecologists.
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Acute sensitivity of the vernal pool fairy shrimp, Branchinecta lynchi (Anostraca; Branchinectidae), and surrogate species to 10 chemicals.
Environmental toxicology and chemistry, 2017Co-Authors: Chris D. Ivey, D. Christopher Rogers, John M. Besser, Christopher G. Ingersoll, Ning Wang, Sandy Raimondo, Candice R. Bauer, Edward J. HammerAbstract:Vernal pool fairy shrimp, Branchinecta lynchi, (Branchiopoda; Anostraca) and other fairy shrimp species have been listed as ‘threatened’ or ‘endangered’ under the United States' Endangered Species Act. Little information about the sensitivity of Branchinecta spp. to toxic effects of contaminants, make it difficult to determine whether they are adequately protected by water quality criteria. A series of acute (24 hr) lethality/immobilization tests were conducted with three species of fairy shrimp (Branchinecta lynchi, Branchinecta lindahli, and Thamnocephalus platyurus) and 10 chemicals with varying modes of toxic action: ammonia, potassium, chloride, sulfate, chromium(VI), copper, nickel, zinc, alachlor, and metolachlor. The same chemicals were tested in 48-h tests with other branchiopods (cladocerans, Daphnia magna and Ceriodaphnia dubia) and an amphipod (Hyalella azteca), and 96-h tests with snails (Physa gyrina and Lymnaea stagnalis). Median effect concentrations (EC50s) for B. lynchi were strongly correlated (r2 = 0.975) with EC50s for the commercially available fairy shrimp species, T. platyurus, for most chemicals tested. Comparison of EC50s for fairy shrimp and EC50s for invertebrate taxa tested concurrently and to other published toxicity data indicated that fairy shrimp were relatively sensitive to potassium and several trace metals compared to other invertebrate taxa, although cladocerans, amphipods and mussels had similar broad toxicant sensitivity. Interspecies Correlation Estimation models for predicting toxicity to fairy shrimp from surrogate species indicated that models with cladocerans and freshwater mussels as surrogates produced best predictions of the sensitivity of fairy shrimp to contaminants. Results of these studies indicate that fairy shrimp are relatively sensitive to a range of toxicants, but ESA-listed fairy shrimp of the genus Branchinecta were not consistently more sensitive than other fairy shrimp taxa. This article is protected by copyright. All rights reserved
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Functional morphology of amplexus (clasping) in spinicaudatan clam shrimps (Crustacea, Branchiopoda) and its evolution in bivalved branchiopods: A video-based analysis.
Journal of Morphology, 2017Co-Authors: Zandra M S Sigvardt, D. Christopher Rogers, Jørgen OlesenAbstract:Male clam shrimps (Crustacea: Branchiopoda: Laevicaudata, Spinicaudata, and Cyclestherida) have their first one or two trunk limb pairs modified as "claspers," which are used to hold the female during mating and mate guarding. Clasper morphology has traditionally been important for clam shrimp taxonomy and classification, but little is known about how the males actually use the claspers during amplexus (clasping). Homologies of the various clasper parts ("movable finger," "large palp," "palm," "gripping area," and "small palp") have long been discussed between the three clam shrimp taxa, and studies have shown that only some structures are homologous while others are convergent ("partial homology"). We studied the clasper functionality in four spinicaudatan species using video recordings and scanning electron microscopy, and compared our results with other clam shrimp groups. General mating behavior and carapace morphology was also studied. Generally, spinicaudatan and laevicaudatan claspers function similarly despite some parts being nonhomologous. We mapped clasper morphology and functionality aspects on a branchiopod phylogeny. We suggest that the claspers of the three groups were adapted from an original, simpler clasper, each for a "stronger" grip on the female's carapace margin: 1) Spinicaudata have two clasper pairs bearing an elongated apical club/gripping area with one setal type; 2); Cyclestherida have one clasper pair with clusters of molariform setae on the gripping area and at the movable finger apex; and 3) Laevicaudata have one clasper pair, but have incorporated an additional limb portion into the clasper palm and bear a diverse set of setae. J. Morphol. 278:523-546, 2017. © 2017 Wiley Periodicals, Inc.
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Global diversity of large branchiopods (Crustacea: Branchiopoda) in freshwater
Hydrobiologia, 2008Co-Authors: Luc Brendonck, D. Christopher Rogers, Jørgen Olesen, Stephen Weeks, Walter R. HoehAbstract:With about 500 known species worldwide, the large brachiopods are a relatively small group of primitive crustaceans. With few exceptions they live in temporary aquatic systems that are most abundant in arid and semi arid areas. As many regions remain unexplored and as especially the number of species in clam shrimps and tadpole shrimps is underestimated due to difficult identification, the species list will increase with future surveys. The Branchiopoda are monophyletic, but inter-ordinal relationships, as well as many evolutionary relationships at lower taxonomic levels are still unclear. Ongoing molecular studies will more accurately depict species diversity and phylogenetic patterns. With the exception of some anostracan families, most families are not restricted to the northern or southern hemisphere or specific zoogeographical regions. Large branchiopods are used for the assessment of the quality and function of temporary wetlands. Due to the reduction in number and quality of temporary wetlands, several species became endangered and are red listed by the IUCN.
