ABSTRACT Understanding aspects of development in animals posessing certain “ancestral” traits can provide key insights into the evolution of various larval forms of invertebrates. Little is presently known concerning the neurodevelopment of Protobranchia, a group of bivalve mollusks. We are first to demonstrate that neurogenesis of the pericalymma larvae of the protobranch Acila insignis differs dramatically from that of the larval nervous system of autobranchia species as revealed by serotonin (5-HT) and FMRFamide antibodies and whole-mount confocal microscopy. Early in the development of pericalymma, two and then three flask-shaped cells immunopositive for 5-HT appear in the apical organ (AO). Later on, in mid-stage larvae, cells immunostained for FMRFamide appear in the dorsal portion of the larva, including a weak signal in the AO. Immediately prior to metamorphosis, the larval FMRFamide-ergic nervous system consists of a single cell in the AO together with several non-sensory cells in the posterior and dorsal regions. No neuronal connections between the larval neuronal cell groups were observed. However, despite the obvious differences in early neurogenesis, there are clear neuromorphological similarities of the studied protobranch species to (1) spiralians (by the presence of an AO), (2) certain trochozoans (by peripheral cells containing FMRFamide) and (3) bivalve mollusks (by AO including three flask-shaped cells revealed by immunostaining for 5-HT). Thus, the nervous system of A. insignis is similar to that of other mollusks and lophotrochozoans due to the presence of an AO, while differing from all the studied groups in other characters (location and composition of FMRFamide cells). Morphological and molecular development of key protobranch taxa need to be further studied in order to infer the evolution of mollusks.
{"title":"Characterization of Neurodevelopment in Larvae of the Protobranch Acila insignis (Gould, 1861) in Order to Reconstruct the Last Common Ancestor of Bivalves","authors":"O. Yurchenko, V. Dyachuk","doi":"10.4002/040.064.0207","DOIUrl":"https://doi.org/10.4002/040.064.0207","url":null,"abstract":"ABSTRACT Understanding aspects of development in animals posessing certain “ancestral” traits can provide key insights into the evolution of various larval forms of invertebrates. Little is presently known concerning the neurodevelopment of Protobranchia, a group of bivalve mollusks. We are first to demonstrate that neurogenesis of the pericalymma larvae of the protobranch Acila insignis differs dramatically from that of the larval nervous system of autobranchia species as revealed by serotonin (5-HT) and FMRFamide antibodies and whole-mount confocal microscopy. Early in the development of pericalymma, two and then three flask-shaped cells immunopositive for 5-HT appear in the apical organ (AO). Later on, in mid-stage larvae, cells immunostained for FMRFamide appear in the dorsal portion of the larva, including a weak signal in the AO. Immediately prior to metamorphosis, the larval FMRFamide-ergic nervous system consists of a single cell in the AO together with several non-sensory cells in the posterior and dorsal regions. No neuronal connections between the larval neuronal cell groups were observed. However, despite the obvious differences in early neurogenesis, there are clear neuromorphological similarities of the studied protobranch species to (1) spiralians (by the presence of an AO), (2) certain trochozoans (by peripheral cells containing FMRFamide) and (3) bivalve mollusks (by AO including three flask-shaped cells revealed by immunostaining for 5-HT). Thus, the nervous system of A. insignis is similar to that of other mollusks and lophotrochozoans due to the presence of an AO, while differing from all the studied groups in other characters (location and composition of FMRFamide cells). Morphological and molecular development of key protobranch taxa need to be further studied in order to infer the evolution of mollusks.","PeriodicalId":49895,"journal":{"name":"Malacologia","volume":"64 1","pages":"241 - 255"},"PeriodicalIF":1.3,"publicationDate":"2022-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45000181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mariana Díaz-Santana-Iturrios, Viridiana Zepeda-Benitez, Renata Pacheco-Ovando, Claudio F. Cornejo, J. Cerda, C. Salinas-Zavala, J. Granados-Amores
ABSTRACT Cephalopods have upper and lower chitinous beaks, and their shape can be used to identify species. However, the morphological attributes of beaks are commonly obtained from sources that contain little information on shape, compromising the determination of taxa. Thus, in this study, we used geometric morphometrics to analyze inter-specific differences in beak shape of six octopus species from the northeastern Pacific. We found evidence of species-level discrimination according to upper and lower beak shape. In addition, we provided a detailed description of these chitinous structures for each species, and we developed a key to identify the species based on upper and lower beak shape. The inter-specific morphological variation of beaks of the octopuses evaluated in our study could be the result of adaptive processes related to habitat and feeding habits. The information generated in our study can be used for identification of six octopus species from the northeastern Pacific based on upper and lower beak shape.
{"title":"Northeastern Pacific Octopus Beak Shape for Species-Level Detection","authors":"Mariana Díaz-Santana-Iturrios, Viridiana Zepeda-Benitez, Renata Pacheco-Ovando, Claudio F. Cornejo, J. Cerda, C. Salinas-Zavala, J. Granados-Amores","doi":"10.4002/040.064.0202","DOIUrl":"https://doi.org/10.4002/040.064.0202","url":null,"abstract":"ABSTRACT Cephalopods have upper and lower chitinous beaks, and their shape can be used to identify species. However, the morphological attributes of beaks are commonly obtained from sources that contain little information on shape, compromising the determination of taxa. Thus, in this study, we used geometric morphometrics to analyze inter-specific differences in beak shape of six octopus species from the northeastern Pacific. We found evidence of species-level discrimination according to upper and lower beak shape. In addition, we provided a detailed description of these chitinous structures for each species, and we developed a key to identify the species based on upper and lower beak shape. The inter-specific morphological variation of beaks of the octopuses evaluated in our study could be the result of adaptive processes related to habitat and feeding habits. The information generated in our study can be used for identification of six octopus species from the northeastern Pacific based on upper and lower beak shape.","PeriodicalId":49895,"journal":{"name":"Malacologia","volume":"64 1","pages":"169 - 184"},"PeriodicalIF":1.3,"publicationDate":"2022-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42953254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ABSTRACT Sequences of specimens of the xylophagaid genus Xyloredo revealed minimal molecular divergence among ten specimens from the North and South Atlantic and the northeast and southwest Pacific Oceans. Although genetically identical, the valves of two New Zealand specimens differ dramatically, likely due to their three-fold size difference. Comparable size differences among the type series of X. nooi, X. naceli and X. ingolfia and their disjunct distributions may have contributed to their recognition as distinct species; the species are synonymized here as Xyloredo nooi. The flattened umbonal-ventral ridge, the fold inside the posterior shell, the two elongate calcified strips of the mesoplax embedded in a periostracal anterior adductor cover and a two-parted siphon with the simple, separate openings are unique to members of Xyloredo. Molecular sequencing of the Japanese X. teramachii is needed to test if it is distinct.
{"title":"Species Synonymies in the Deep-Sea Wood-Boring Bivalve Genus Xyloredo (Mollusca: Xylophagaidae)","authors":"J. Voight","doi":"10.4002/040.064.0201","DOIUrl":"https://doi.org/10.4002/040.064.0201","url":null,"abstract":"ABSTRACT Sequences of specimens of the xylophagaid genus Xyloredo revealed minimal molecular divergence among ten specimens from the North and South Atlantic and the northeast and southwest Pacific Oceans. Although genetically identical, the valves of two New Zealand specimens differ dramatically, likely due to their three-fold size difference. Comparable size differences among the type series of X. nooi, X. naceli and X. ingolfia and their disjunct distributions may have contributed to their recognition as distinct species; the species are synonymized here as Xyloredo nooi. The flattened umbonal-ventral ridge, the fold inside the posterior shell, the two elongate calcified strips of the mesoplax embedded in a periostracal anterior adductor cover and a two-parted siphon with the simple, separate openings are unique to members of Xyloredo. Molecular sequencing of the Japanese X. teramachii is needed to test if it is distinct.","PeriodicalId":49895,"journal":{"name":"Malacologia","volume":"64 1","pages":"163 - 168"},"PeriodicalIF":1.3,"publicationDate":"2022-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46194348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ABSTRACT South American land snails are relatively poorly known, but their taxonomic relationships can be illuminated with the help of detailed anatomical descriptions and comparisons. The genus Habeas Simone, 2013, species of which are associated with caves, was tentatively described in the prosobranch family Diplommatinidae. Recently collected samples that permitted anatomical investigation, revealed that Habeas actually belongs to the eupulmonate family Urocoptidae. The genus is thus reviewed, including the three so far known species: H. corpus, H. data and H. priscus, all Simone, 2013. Four new species collected in Brazil are described: Habeas lekolus (from Cônego Marinho, Minas Gerais), H. peruassus (from Januária, Minas Gerais), H. lapensis (from Bom Jesus da Lapa, Bahia) and H. claudus (from Cocos, Bahia). Anatomical description is based on H. lekolus, revealing in its most interesting features, the absence of the ureter, presence of a pallial gland, lack of anterior duct to digestive gland, small penis and epiphallus, and absence of bursa copulatrix. Species in this genus usually inhabit cave habitats and are only found in Bahia (BA) and Minas Gerais (MG) Brazilian states, in areas close to São Francisco River. A brief discussion of the family attribution to Habeas is also performed. The present seven species in a genus recently discovered in a relatively small area demonstrate how weak the knowledge on the Brazilian malacofauna is.
南美洲的蜗牛相对来说鲜为人知，但它们的分类学关系可以通过详细的解剖描述和比较来阐明。Habeas Simone属，2013，与洞穴有关的种，暂定在吻鼻科外交科。最近收集的样本允许解剖调查，显示Habeas实际上属于eupulmonate家族尾足科。因此，对该属进行了综述，包括迄今为止已知的三个种:H. corpus, H. data和H. priscus，均为Simone, 2013。描述了在巴西收集到的4个新种:Habeas lekolus(来自Cônego Marinho, Minas Gerais)， H. peruassus(来自Januária, Minas Gerais)， H. lapensis(来自Bom Jesus da Lapa, Bahia)和H. claudus(来自Cocos, Bahia)。解剖描述是基于H. lekolus，揭示了其最有趣的特征，没有输尿管，有一个苍白腺，没有通往消化腺的前导管，小阴茎和附睾，没有性交囊。本属的物种通常栖息在洞穴栖息地，仅在巴西巴伊亚州(BA)和米纳斯吉拉斯州(MG)发现，在靠近奥弗朗西斯科河的地区。对人身保护令的家庭归属也进行了简要讨论。最近在一个相对较小的地区发现的一个属的7个物种表明，对巴西malacofauna的认识是多么薄弱。
{"title":"Review of the Genus Habeas from Brazil, with Description of Four New Species and in Which Anatomical Features Revealed That They Belong to Urocoptidae (Eupulmonata, Stylommatophora)","authors":"L. Simone","doi":"10.4002/040.064.0209","DOIUrl":"https://doi.org/10.4002/040.064.0209","url":null,"abstract":"ABSTRACT South American land snails are relatively poorly known, but their taxonomic relationships can be illuminated with the help of detailed anatomical descriptions and comparisons. The genus Habeas Simone, 2013, species of which are associated with caves, was tentatively described in the prosobranch family Diplommatinidae. Recently collected samples that permitted anatomical investigation, revealed that Habeas actually belongs to the eupulmonate family Urocoptidae. The genus is thus reviewed, including the three so far known species: H. corpus, H. data and H. priscus, all Simone, 2013. Four new species collected in Brazil are described: Habeas lekolus (from Cônego Marinho, Minas Gerais), H. peruassus (from Januária, Minas Gerais), H. lapensis (from Bom Jesus da Lapa, Bahia) and H. claudus (from Cocos, Bahia). Anatomical description is based on H. lekolus, revealing in its most interesting features, the absence of the ureter, presence of a pallial gland, lack of anterior duct to digestive gland, small penis and epiphallus, and absence of bursa copulatrix. Species in this genus usually inhabit cave habitats and are only found in Bahia (BA) and Minas Gerais (MG) Brazilian states, in areas close to São Francisco River. A brief discussion of the family attribution to Habeas is also performed. The present seven species in a genus recently discovered in a relatively small area demonstrate how weak the knowledge on the Brazilian malacofauna is.","PeriodicalId":49895,"journal":{"name":"Malacologia","volume":"64 1","pages":"269 - 286"},"PeriodicalIF":1.3,"publicationDate":"2022-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46566975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ABSTRACT Research on endangered species is important for species conservation. Some lines of conservation research require tissue or fluids so that molecular data can be obtained. Thus, there is an increasing demand for methods of DNA sampling in endangered species that minimize harm to live animals. This especially concerns such highly threatened and protected freshwater mussels as the thick-shelled river mussel Unio crassus. With two different field experiments in Germany under natural conditions, the short- and long-term survival of Unio crassus after hemolymph extraction from the foot tissue was evaluated. We detected no negative effects in individuals of over 40 mm shell length and older than five years. We also followed some individuals for up to three years after treatment and detected no harm to these individuals. DNA quality was high and proved fully suitable for single-gene sequencing (COI) and microsatellite analyses.
{"title":"Minimally Invasive DNA Sampling by Hemolymph Extraction Minimizes Risk to Freshwater Mussels: The Case of Endangered Unio crassus Philipsson, 1788 (Bivalvia: Unionidae)","authors":"I. Richling, C. Krause","doi":"10.4002/040.064.0212","DOIUrl":"https://doi.org/10.4002/040.064.0212","url":null,"abstract":"ABSTRACT Research on endangered species is important for species conservation. Some lines of conservation research require tissue or fluids so that molecular data can be obtained. Thus, there is an increasing demand for methods of DNA sampling in endangered species that minimize harm to live animals. This especially concerns such highly threatened and protected freshwater mussels as the thick-shelled river mussel Unio crassus. With two different field experiments in Germany under natural conditions, the short- and long-term survival of Unio crassus after hemolymph extraction from the foot tissue was evaluated. We detected no negative effects in individuals of over 40 mm shell length and older than five years. We also followed some individuals for up to three years after treatment and detected no harm to these individuals. DNA quality was high and proved fully suitable for single-gene sequencing (COI) and microsatellite analyses.","PeriodicalId":49895,"journal":{"name":"Malacologia","volume":"64 1","pages":"309 - 313"},"PeriodicalIF":1.3,"publicationDate":"2022-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44961183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Origin of Malacologia – the International Journal of Malacology – and Jack Burch (12 August 1929 – 3 June 2021)","authors":"G. Davis","doi":"10.4002/040.064.0213","DOIUrl":"https://doi.org/10.4002/040.064.0213","url":null,"abstract":"","PeriodicalId":49895,"journal":{"name":"Malacologia","volume":"64 1","pages":"317 - 318"},"PeriodicalIF":1.3,"publicationDate":"2022-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45354779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ABSTRACT Populations of many native freshwater mussels such as the California floater, Anodonta californiensis, are declining in the Columbia River Basin in the western United States. There are many possible reasons for this decline, including increased presence of nonnative fishes, especially piscivores that displace and reduce the abundance of native fishes. These nonnative fishes can negatively influence the early life history of A. californiensis, because this mussel uses native fishes to complete its life cycle. While Anodonta spp. can use nonnative fishes as hosts with limited success, the extent of this for A. californiensis is not well understood. We determined if the glochidia (larvae) of A. californiensis can successfully metamorphose using certain nonnative fishes, and we quantified differences in host effectiveness (number of juveniles produced) between native and nonnative fishes based on available fin area for attachment. Overall, native fishes hosted an average of 107.4 ± 39.9 (mean ± SE) juvenile mussels per fish while nonnative fishes hosted an average of 5.5 ± 4.9 juveniles per fish. This conclusion was unchanged when standardized for fish attachment area. Encystment of glochidia on native fishes yielded an average of 1.0 ± 0.1 juveniles/mm2 of attachable surface (total area of fins) area while nonnative fishes yielded an average of 0.16 ± 0.1 juveniles/mm2. The nonnative channel catfish, Ictalurus punctatus, did not yield any juvenile mussels and was identified as a nonhost species for A. californiensis. All other nonnative fishes tested were determined to be poor or marginal hosts. All native fishes were determined to be primary or secondary hosts for A. californiensis. The native fishes that yielded the highest number of juvenile mussels were sculpins, Cottus spp., and the redside shiner, Richardsonius balteatus, with an average of 196 and 151 juveniles per individual of each species, respectively. Our findings show that nonnative fishes are poor hosts for A. californiensis. However, nonnative fishes may contribute to the decline of native mussels in the Columbia River Basin by directly preying on and reducing the abundance of native host fishes and mussels. Future conservation plans for A. californiensis should consider the potential negative influence of nonnative fishes.
{"title":"Use of Native and Nonnative Fish Hosts by the Freshwater Mussel Anodonta californiensis (California Floater) in the Columbia River Basin","authors":"A. Maine, C. O'brien","doi":"10.4002/040.064.0204","DOIUrl":"https://doi.org/10.4002/040.064.0204","url":null,"abstract":"ABSTRACT Populations of many native freshwater mussels such as the California floater, Anodonta californiensis, are declining in the Columbia River Basin in the western United States. There are many possible reasons for this decline, including increased presence of nonnative fishes, especially piscivores that displace and reduce the abundance of native fishes. These nonnative fishes can negatively influence the early life history of A. californiensis, because this mussel uses native fishes to complete its life cycle. While Anodonta spp. can use nonnative fishes as hosts with limited success, the extent of this for A. californiensis is not well understood. We determined if the glochidia (larvae) of A. californiensis can successfully metamorphose using certain nonnative fishes, and we quantified differences in host effectiveness (number of juveniles produced) between native and nonnative fishes based on available fin area for attachment. Overall, native fishes hosted an average of 107.4 ± 39.9 (mean ± SE) juvenile mussels per fish while nonnative fishes hosted an average of 5.5 ± 4.9 juveniles per fish. This conclusion was unchanged when standardized for fish attachment area. Encystment of glochidia on native fishes yielded an average of 1.0 ± 0.1 juveniles/mm2 of attachable surface (total area of fins) area while nonnative fishes yielded an average of 0.16 ± 0.1 juveniles/mm2. The nonnative channel catfish, Ictalurus punctatus, did not yield any juvenile mussels and was identified as a nonhost species for A. californiensis. All other nonnative fishes tested were determined to be poor or marginal hosts. All native fishes were determined to be primary or secondary hosts for A. californiensis. The native fishes that yielded the highest number of juvenile mussels were sculpins, Cottus spp., and the redside shiner, Richardsonius balteatus, with an average of 196 and 151 juveniles per individual of each species, respectively. Our findings show that nonnative fishes are poor hosts for A. californiensis. However, nonnative fishes may contribute to the decline of native mussels in the Columbia River Basin by directly preying on and reducing the abundance of native host fishes and mussels. Future conservation plans for A. californiensis should consider the potential negative influence of nonnative fishes.","PeriodicalId":49895,"journal":{"name":"Malacologia","volume":"64 1","pages":"203 - 213"},"PeriodicalIF":1.3,"publicationDate":"2022-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47218181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ABSTRACT Cephalopods are a commercially important resource for the Indian coast. Species of Octopus alone account for around 10% of the global cephalopod fishery and roughly 3% of Indian fisheries. Proper identification of cephalopods in the field is difficult, and accurate identification of species is important for conservation as well as for sustainable fisheries management of octopus species. With a view to identify and genetically catalogue the octopus species from the southwest Indian coast, 28 specimens were collected from different landing centres in the region and identified morphologically. Molecular characterization was done with partial sequence information from the mitochondrial Cytochrome C Oxidase-I (COI) gene. All the specimens analysed in the study belong to the family Octopodidae. The specimens were identified as four species of Amphioctopus: Amphioctopus neglectus, A. marginatus, A. aegina and A. rex, and two Cistopus: Cistopus indicus and C. taiwanicus, as well as, Octopus vulgaris and Callistoctopus macropus. In the present study, Octopus vulgaris showed genetic similarity with Octopus vulgaris Type III but with 1% divergence from Octopus vulgaris Type II and 3% divergence from Octopus vulgaris Type IV.
{"title":"Integrated Taxonomic Approach for Identification of Octopus Species from the Southwest Coast of India","authors":"Sneha Vargheese, K. K. Sajikumar, V. S. Basheer","doi":"10.4002/040.064.0210","DOIUrl":"https://doi.org/10.4002/040.064.0210","url":null,"abstract":"ABSTRACT Cephalopods are a commercially important resource for the Indian coast. Species of Octopus alone account for around 10% of the global cephalopod fishery and roughly 3% of Indian fisheries. Proper identification of cephalopods in the field is difficult, and accurate identification of species is important for conservation as well as for sustainable fisheries management of octopus species. With a view to identify and genetically catalogue the octopus species from the southwest Indian coast, 28 specimens were collected from different landing centres in the region and identified morphologically. Molecular characterization was done with partial sequence information from the mitochondrial Cytochrome C Oxidase-I (COI) gene. All the specimens analysed in the study belong to the family Octopodidae. The specimens were identified as four species of Amphioctopus: Amphioctopus neglectus, A. marginatus, A. aegina and A. rex, and two Cistopus: Cistopus indicus and C. taiwanicus, as well as, Octopus vulgaris and Callistoctopus macropus. In the present study, Octopus vulgaris showed genetic similarity with Octopus vulgaris Type III but with 1% divergence from Octopus vulgaris Type II and 3% divergence from Octopus vulgaris Type IV.","PeriodicalId":49895,"journal":{"name":"Malacologia","volume":"64 1","pages":"287 - 299"},"PeriodicalIF":1.3,"publicationDate":"2022-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45382491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ABSTRACT Darina solenoides (P. P. King, 1832) is an abundant clam of sandy shores of southern South America. It has an essential ecologic role as a main food source for marine predators, including migratory seabirds, and is an intermediate host in parasitic life cycles. We describe the reproductive cycle and recruitment of D. solenoides in relation to environmental factors in central Patagonia, Argentina. Histological analysis of gonadal stages and quantitative indicators such as the condition index (CI), oocyte density and relative oocyte area (ROA) were examined monthly for two years (2016–2017; n = 1,315) from clams collected from two sandy shores of the San Jorge Gulf (SJG). Recruitment pattern was followed at a single site. The shell lengths ranged between 25.2 and 42.8 mm and the sex ratio did not differ significantly from 1:1. The proportion of clams showing total or partial castration by digenean trematodes was low (< 5%). A clear annual reproductive cycle was found and was characterized by high synchrony between sexes, years and sites. Proliferation of gonia extended throughout the colder months and vitellogenesis occurred mainly during the spring increase of seawater temperature and shortly after the major phytoplankton bloom. Maximum development of oocytes (mean diameter, 32.1 ± 12.9 µm) and presumed spawning by both males and females occurred during the austral summer. Settlement was also highest (mean = 162.8 ± 47.1 ind.m-2) during summer and was coincident with a second phytoplankton bloom that might favour larval development and subsequent early recruitment. This is the first reproductive study of a mactrid bivalve from the southwest Atlantic Ocean and provides useful information on the population dynamics of this key species from Patagonian sandy shores.
{"title":"Reproduction and Recruitment of the Intertidal Clam Darina solenoides (Bivalvia: Mactridae) in Patagonian Sandy Shores, Argentina","authors":"M. López, Damián G. Gil, M. Kroeck, E. Morsan","doi":"10.4002/040.064.0203","DOIUrl":"https://doi.org/10.4002/040.064.0203","url":null,"abstract":"ABSTRACT Darina solenoides (P. P. King, 1832) is an abundant clam of sandy shores of southern South America. It has an essential ecologic role as a main food source for marine predators, including migratory seabirds, and is an intermediate host in parasitic life cycles. We describe the reproductive cycle and recruitment of D. solenoides in relation to environmental factors in central Patagonia, Argentina. Histological analysis of gonadal stages and quantitative indicators such as the condition index (CI), oocyte density and relative oocyte area (ROA) were examined monthly for two years (2016–2017; n = 1,315) from clams collected from two sandy shores of the San Jorge Gulf (SJG). Recruitment pattern was followed at a single site. The shell lengths ranged between 25.2 and 42.8 mm and the sex ratio did not differ significantly from 1:1. The proportion of clams showing total or partial castration by digenean trematodes was low (< 5%). A clear annual reproductive cycle was found and was characterized by high synchrony between sexes, years and sites. Proliferation of gonia extended throughout the colder months and vitellogenesis occurred mainly during the spring increase of seawater temperature and shortly after the major phytoplankton bloom. Maximum development of oocytes (mean diameter, 32.1 ± 12.9 µm) and presumed spawning by both males and females occurred during the austral summer. Settlement was also highest (mean = 162.8 ± 47.1 ind.m-2) during summer and was coincident with a second phytoplankton bloom that might favour larval development and subsequent early recruitment. This is the first reproductive study of a mactrid bivalve from the southwest Atlantic Ocean and provides useful information on the population dynamics of this key species from Patagonian sandy shores.","PeriodicalId":49895,"journal":{"name":"Malacologia","volume":"64 1","pages":"185 - 202"},"PeriodicalIF":1.3,"publicationDate":"2022-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43214891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Biological research is frequently hampered, prevented, or biased by subject losses (Grafen, 1988; Weis, 2018). Subject losses force researchers to either repeat experiments or conduct analyses on a subset (the survivors) of the original experimental organisms. Repeating experiments has obvious financial and logistic consequences and offers no guarantee that losses will be fewer in subsequent efforts. Furthermore, data taken only on survivors is biased when mortality is correlated with variables of interest – the “missing fraction” problem (Grafen, 1988; Bennington & McGraw, 1995; Nakagawa & Freckleton, 2008). Subject losses reduce experimental sample size and balance and thereby also reduce statistical confidence, inferential power, and ultimately, the value of the research. Losses in aquatic research can stem from a wide range of causes such as inappropriate water chemistry, temperature, sudden change in physical parameters, or pathogens (Mori & Smith, 2019). Pathogens, in particular, can be a major cause of experimental subject mortality, even mass die-offs, due largely to the enclosed systems in which experiments are conducted (Kent et al., 2009; Mori et al., 2019). Yet even where pathogens cause little mortality, morbidity effects can similarly, though more cryptically, bias results (Kent et al. 2009). The best approach to protecting experiments where losses have been known to occur will often be to proactively prevent subject deaths and morbidity. Improved husbandry, including quarantines and preventive medication, can potentially reduce or eliminate subject losses and pathogen associated biases (McEwen & Fedorka-Cray, 2002). Preventive measures can introduce side-effects or bias of their own, such as gut or skin flora disruption which can impact experimental endpoints such as body weight (Carlson et al., 2017). Thus antibiotics should be considered only if benefits are likely to outweigh drawbacks for projects that are costly MALACOLOGIA, 2022, 64(2): 303–307
生物学研究经常受到受试者损失的阻碍、阻止或偏见(Grafen, 1988;Weis, 2018)。实验对象的丢失迫使研究人员要么重复实验，要么对原始实验生物的一个子集(幸存者)进行分析。重复实验会产生明显的财政和后勤后果，也不能保证以后的努力会减少损失。此外，当死亡率与感兴趣的变量(“缺失分数”问题)相关时，仅对幸存者采集的数据是有偏差的(Grafen, 1988;Bennington & McGraw, 1995;Nakagawa & Freckleton, 2008)。受试者损失减少了实验样本量和平衡，从而也降低了统计信心、推断能力，并最终降低了研究的价值。水生研究的损失可能源于多种原因，如不适当的水化学、温度、物理参数的突然变化或病原体(Mori & Smith, 2019)。特别是病原体，可能是实验对象死亡，甚至大规模死亡的主要原因，主要原因是进行实验的封闭系统(Kent等人，2009;Mori et al.， 2019)。然而，即使在病原体造成的死亡率很小的地方，发病率的影响也可能类似地(尽管更神秘)产生偏倚结果(Kent et al. 2009)。保护已知发生损失的实验的最佳方法往往是主动预防受试者死亡和发病。改进畜牧业，包括检疫和预防性用药，可以潜在地减少或消除受试者损失和病原体相关偏差(McEwen & Fedorka-Cray, 2002年)。预防措施本身可能会带来副作用或偏差，例如肠道或皮肤菌群破坏，这会影响体重等实验终点(Carlson et al.， 2017)。因此，只有在效益大于弊端的情况下，才应该考虑使用抗生素。中华生物医学工程学报，2022,64(2):303-307
{"title":"On the Need for Antibiotics to Reduce Subject Losses and Biases in Experiments with Aquatic Molluscs","authors":"T. DeWitt, H. L. Prestridge","doi":"10.4002/040.064.0211","DOIUrl":"https://doi.org/10.4002/040.064.0211","url":null,"abstract":"Biological research is frequently hampered, prevented, or biased by subject losses (Grafen, 1988; Weis, 2018). Subject losses force researchers to either repeat experiments or conduct analyses on a subset (the survivors) of the original experimental organisms. Repeating experiments has obvious financial and logistic consequences and offers no guarantee that losses will be fewer in subsequent efforts. Furthermore, data taken only on survivors is biased when mortality is correlated with variables of interest – the “missing fraction” problem (Grafen, 1988; Bennington & McGraw, 1995; Nakagawa & Freckleton, 2008). Subject losses reduce experimental sample size and balance and thereby also reduce statistical confidence, inferential power, and ultimately, the value of the research. Losses in aquatic research can stem from a wide range of causes such as inappropriate water chemistry, temperature, sudden change in physical parameters, or pathogens (Mori & Smith, 2019). Pathogens, in particular, can be a major cause of experimental subject mortality, even mass die-offs, due largely to the enclosed systems in which experiments are conducted (Kent et al., 2009; Mori et al., 2019). Yet even where pathogens cause little mortality, morbidity effects can similarly, though more cryptically, bias results (Kent et al. 2009). The best approach to protecting experiments where losses have been known to occur will often be to proactively prevent subject deaths and morbidity. Improved husbandry, including quarantines and preventive medication, can potentially reduce or eliminate subject losses and pathogen associated biases (McEwen & Fedorka-Cray, 2002). Preventive measures can introduce side-effects or bias of their own, such as gut or skin flora disruption which can impact experimental endpoints such as body weight (Carlson et al., 2017). Thus antibiotics should be considered only if benefits are likely to outweigh drawbacks for projects that are costly MALACOLOGIA, 2022, 64(2): 303–307","PeriodicalId":49895,"journal":{"name":"Malacologia","volume":"64 1","pages":"303 - 307"},"PeriodicalIF":1.3,"publicationDate":"2022-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46835886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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