The coast of Acapulco is located within the Marine Priority Region No. 32 (MPR No. 32) at the State of Guerrero, Mexico. The National Commission for the Knowledge and Use of Biodiversity has stated the lack of informa...The coast of Acapulco is located within the Marine Priority Region No. 32 (MPR No. 32) at the State of Guerrero, Mexico. The National Commission for the Knowledge and Use of Biodiversity has stated the lack of information on marine species that live there, among which are the Class Polyplacophora. This study aimed to: 1) determine species richness, 2) the community structure based on the representative families, 3) estimate the density, 4) locate species distribution, 5) determine their degree of occurrence (hierarchical position) within the community, 6) analyze the structure of length and width across the populations and 7) estimate the diversity index. The intertidal rocky substrate at seven beaches was sampled from 2009 to 2012. The sampling unit 1 m2, while the area sampled was 10 m2. It was analyzed 2.548 specimens of Polyplacophora, with 20 species identified. Tonicellidae and Ischnochitonidae were the Families better represented inspecies richness and Chitonidae in abundance. Lepidochitona flectens is a new record for the Mexican Tropical Pacific and Stenoplax mariposa for MPR. No. 32. The density was 25.48 specimens/m2. Eight dominant species were determined. Chiton albolineatus had the highest density. Ischnochiton muscarius, Chaetopleura unilineata, Chiton albolineatus and Chiton articulatus presented wide distribution. Chiton articulatus showed the largest size in length and width. H’ = 2.01 bits/ individual. Numerous dominant species were present with broad and regular distribution, probably due to Polyplacophora body design, which allows for better adaptation to the rigorous environmental conditions of the rocky intertidal.展开更多
Marine Priority Region No. 33 (MPR 33) lies in the State of Guerrero, where the National Commission for Knowledge and Use of Biodiversity has declared a lack of information on marine species, Class POLYPLACOPHORA amon...Marine Priority Region No. 33 (MPR 33) lies in the State of Guerrero, where the National Commission for Knowledge and Use of Biodiversity has declared a lack of information on marine species, Class POLYPLACOPHORA among others. This program was carried out on the rocky intertidal zone of MPR 33 with the objectives to: 1) determine species richness, 2) community composition based on families represented, 3) estimate the density, 4) index of diversity, 5) analyze body proportions and 6) geographic distribution of species. Three surveys on five sites were conducted during 2009 and 2012, using one mt2 quadrant for systematic sampling procedure;collecting all POLYPLACOPHORA specimens found within the quadrants, then proceeding with their preservation. 441 organisms were analyzed where 17 species were identified, on nine genera within six families. Fifteen new species were recorded for the MPR 33. Family ISCHNOCHITONIDAE Dall, 1889 was the best represented in species richness and CHITONIDAE Rafinesque, 1815 in abundance. Density of 8.82 organisms/m2, the H′ index was 2.38 bits/individuals and J′ = 0.57. The species Chiton (Chiton) articulatus Sowerby, 1832 showed the highest density, greater size and was found in all five collection sites. Three species, (Chiton (C.) articulatus, Ischnochiton (Ischnochiton) muscarius (Reeve, 1847) and Chiton (Chiton) alboli-neatus Broderip & Sowerby, 1829), were considered wide. Intertidal species richness was associated with habitat stability and wave intensity;the more unstable sites had greater richness while most stable sites lower. Species inventory and understanding the communities’ interactions of the marine fauna of the State of Guerrero are important;therefore these efforts must be continued.展开更多
The Late Pleistocene littoral ridges of southern South America,especially those of the north of Argentinean Patagonia,contain remains of mollusk shells with bioerosion traces.Eleven sites from marine isotope stages(2 ...The Late Pleistocene littoral ridges of southern South America,especially those of the north of Argentinean Patagonia,contain remains of mollusk shells with bioerosion traces.Eleven sites from marine isotope stages(2 from MIS 7,4 from MIS 5 e)and five sites from modern beaches from northern Río Negro Province,with 40 taxa(17 bivalves and 23 gastropods)were analyzed,in the area between west of Baliza San Matías and Las Grutas(41°S).Three ichnogenera were identified in deposits of MIS 7:Entobia,Gastrochaenolites(Domichnia)and Oichnus(Praedichnia)with one ichnospecies(G.torpedo).Six ichnogenera were identified in deposits of MIS 5 e:Entobia,Meandropolydora,Pinaceocladichnus,Iramena,Caulostrepsis and Oichnus with one ichnospecies(O.simplex).Seven ichnogenera were identified from modern beaches:Entobia,Meandropolydora,Iramena,Caulostrepsis,Pinaceocladichnus,Gastrochaenolites(Domichnia)and Oichnus(Praedicnia),with two ichnospecies(O.simplex and O.paraboloides).On this basis,it is inferred that Pleistocene benthic communities were constituted from cheilostome bryzoans and polychaete annelids,together with drilling bivalves,predatory gastropods and overall warm-water species of mollusks.Of these,Chama iudicai was found on Plicatula gibbosa from MIS 7 and MIS 5 e.The record of warm temperature species suggests a higher sea surface temperature(SST)than the present one and/or the influence of the warm southward Brazilian Current affecting the waters of Golfo San Matías.On the modern beaches surveyed,there is an increase in polychaete annelids,cheilostome bryzoans,temperate-cold species and drilling bivalves,as well as sandy substrate species,which together with an increase of Gastrochaenolites and Caulostrepsis,suggest a colder climate due to the greater influence of the Malvinas Current during the Holocene.展开更多
Mollusca is the second-largest animal phylum with over 100,000 extant species representing eight classes.Across 1000 extant species in the class Polyplacophora,chitons have a relatively constrained morphology but with...Mollusca is the second-largest animal phylum with over 100,000 extant species representing eight classes.Across 1000 extant species in the class Polyplacophora,chitons have a relatively constrained morphology but with some notable deviations.Several genera possess“shell eyes”,i.e.,true eyes with a lens and retina that are embedded within the dorsal shells.The phylogeny of the major chiton clades is mostly well established,in a set of superfamily-level and higher level taxa supported by various approaches,including morphological studies,multiple gene markers,mitogenome-phylogeny,and phylotranscriptomic approaches.However,one critical lineage has remained unclear,namely Schizochiton which was controversially suggested as being the potential independent origin of chiton shell eyes.Here,with the draft genome sequencing of Schizochiton incisus(superfamily Schizochitonoidea)plus assemblies of transcriptome data from other polyplacophorans,we present phylogenetic reconstructions using both mitochondrial genomes and phylogenomic approaches with multiple methods.We found that phylogenetic trees from mitogenomic data are inconsistent,reflecting larger scale confounding factors in molluscan mitogenomes.However,a consistent and robust topology was generated with protein-coding genes using different models and methods.Our results support Schizochitonoidea as the sister group to other Chitonoidea in Chitonina,in agreement with the established classification.Combined with evidence from fossils,our phylogenetic results suggest that the earliest origin of shell eyes is in Schizochitonoidea,and that these structures were also gained secondarily in other genera in Chitonoidea.Our results have generated a holistic review of the internal relationship within Polyplacophora,and a better understanding of the evolution of Polyplacophora.展开更多
The renowned Yangtze micromolluscan fauna has a total of 61 species, assigned to 48 genera, 26 families and 6 classes. The appearance of the Yangtze micromolluscan fauna indicated another maior event in the systematic...The renowned Yangtze micromolluscan fauna has a total of 61 species, assigned to 48 genera, 26 families and 6 classes. The appearance of the Yangtze micromolluscan fauna indicated another maior event in the systematically evolutionary history of invertebrates following the Ediacaran faunas, representing the diversification and radial evolution for the first time in the phylogenetic history of the shelled molluscs, and also providing the best substantial evidence for the division and correlation of the international Precambrian-Cambrian boundary.展开更多
基金partly funded by CONACYT(Consejo Nacional de Ciencia y Tegnologia-National Council of Science and Technology)the state government of Guerrero through the research project No.91624 Ecological study of the Acapulco Bay FOMIX 2008-C01 and the research project No.91724 Diversity and abundance of marine cock-roach off the coast of Guerrero state Fomix 2008-C01.
文摘The coast of Acapulco is located within the Marine Priority Region No. 32 (MPR No. 32) at the State of Guerrero, Mexico. The National Commission for the Knowledge and Use of Biodiversity has stated the lack of information on marine species that live there, among which are the Class Polyplacophora. This study aimed to: 1) determine species richness, 2) the community structure based on the representative families, 3) estimate the density, 4) locate species distribution, 5) determine their degree of occurrence (hierarchical position) within the community, 6) analyze the structure of length and width across the populations and 7) estimate the diversity index. The intertidal rocky substrate at seven beaches was sampled from 2009 to 2012. The sampling unit 1 m2, while the area sampled was 10 m2. It was analyzed 2.548 specimens of Polyplacophora, with 20 species identified. Tonicellidae and Ischnochitonidae were the Families better represented inspecies richness and Chitonidae in abundance. Lepidochitona flectens is a new record for the Mexican Tropical Pacific and Stenoplax mariposa for MPR. No. 32. The density was 25.48 specimens/m2. Eight dominant species were determined. Chiton albolineatus had the highest density. Ischnochiton muscarius, Chaetopleura unilineata, Chiton albolineatus and Chiton articulatus presented wide distribution. Chiton articulatus showed the largest size in length and width. H’ = 2.01 bits/ individual. Numerous dominant species were present with broad and regular distribution, probably due to Polyplacophora body design, which allows for better adaptation to the rigorous environmental conditions of the rocky intertidal.
基金partly funded by CONACYT(Consejo Nacional de Ciencia y Tecnologia-National Council for Science and Technology)and the State Government of Guerrero through the research project No.91.724 Diversity,abundance and development of the marine cockroach in the coast of the State Guerrero,Mexico.
文摘Marine Priority Region No. 33 (MPR 33) lies in the State of Guerrero, where the National Commission for Knowledge and Use of Biodiversity has declared a lack of information on marine species, Class POLYPLACOPHORA among others. This program was carried out on the rocky intertidal zone of MPR 33 with the objectives to: 1) determine species richness, 2) community composition based on families represented, 3) estimate the density, 4) index of diversity, 5) analyze body proportions and 6) geographic distribution of species. Three surveys on five sites were conducted during 2009 and 2012, using one mt2 quadrant for systematic sampling procedure;collecting all POLYPLACOPHORA specimens found within the quadrants, then proceeding with their preservation. 441 organisms were analyzed where 17 species were identified, on nine genera within six families. Fifteen new species were recorded for the MPR 33. Family ISCHNOCHITONIDAE Dall, 1889 was the best represented in species richness and CHITONIDAE Rafinesque, 1815 in abundance. Density of 8.82 organisms/m2, the H′ index was 2.38 bits/individuals and J′ = 0.57. The species Chiton (Chiton) articulatus Sowerby, 1832 showed the highest density, greater size and was found in all five collection sites. Three species, (Chiton (C.) articulatus, Ischnochiton (Ischnochiton) muscarius (Reeve, 1847) and Chiton (Chiton) alboli-neatus Broderip & Sowerby, 1829), were considered wide. Intertidal species richness was associated with habitat stability and wave intensity;the more unstable sites had greater richness while most stable sites lower. Species inventory and understanding the communities’ interactions of the marine fauna of the State of Guerrero are important;therefore these efforts must be continued.
文摘The Late Pleistocene littoral ridges of southern South America,especially those of the north of Argentinean Patagonia,contain remains of mollusk shells with bioerosion traces.Eleven sites from marine isotope stages(2 from MIS 7,4 from MIS 5 e)and five sites from modern beaches from northern Río Negro Province,with 40 taxa(17 bivalves and 23 gastropods)were analyzed,in the area between west of Baliza San Matías and Las Grutas(41°S).Three ichnogenera were identified in deposits of MIS 7:Entobia,Gastrochaenolites(Domichnia)and Oichnus(Praedichnia)with one ichnospecies(G.torpedo).Six ichnogenera were identified in deposits of MIS 5 e:Entobia,Meandropolydora,Pinaceocladichnus,Iramena,Caulostrepsis and Oichnus with one ichnospecies(O.simplex).Seven ichnogenera were identified from modern beaches:Entobia,Meandropolydora,Iramena,Caulostrepsis,Pinaceocladichnus,Gastrochaenolites(Domichnia)and Oichnus(Praedicnia),with two ichnospecies(O.simplex and O.paraboloides).On this basis,it is inferred that Pleistocene benthic communities were constituted from cheilostome bryzoans and polychaete annelids,together with drilling bivalves,predatory gastropods and overall warm-water species of mollusks.Of these,Chama iudicai was found on Plicatula gibbosa from MIS 7 and MIS 5 e.The record of warm temperature species suggests a higher sea surface temperature(SST)than the present one and/or the influence of the warm southward Brazilian Current affecting the waters of Golfo San Matías.On the modern beaches surveyed,there is an increase in polychaete annelids,cheilostome bryzoans,temperate-cold species and drilling bivalves,as well as sandy substrate species,which together with an increase of Gastrochaenolites and Caulostrepsis,suggest a colder climate due to the greater influence of the Malvinas Current during the Holocene.
基金supported by the Fundamental Research Funds for the Central Universities(202241002 and 202172002)Science and Technology Innovation Project of Laoshan Laboratory(No.LSKJ202203104)the Young Taishan Scholars Program of Shandong Province(tsqn202103036).
文摘Mollusca is the second-largest animal phylum with over 100,000 extant species representing eight classes.Across 1000 extant species in the class Polyplacophora,chitons have a relatively constrained morphology but with some notable deviations.Several genera possess“shell eyes”,i.e.,true eyes with a lens and retina that are embedded within the dorsal shells.The phylogeny of the major chiton clades is mostly well established,in a set of superfamily-level and higher level taxa supported by various approaches,including morphological studies,multiple gene markers,mitogenome-phylogeny,and phylotranscriptomic approaches.However,one critical lineage has remained unclear,namely Schizochiton which was controversially suggested as being the potential independent origin of chiton shell eyes.Here,with the draft genome sequencing of Schizochiton incisus(superfamily Schizochitonoidea)plus assemblies of transcriptome data from other polyplacophorans,we present phylogenetic reconstructions using both mitochondrial genomes and phylogenomic approaches with multiple methods.We found that phylogenetic trees from mitogenomic data are inconsistent,reflecting larger scale confounding factors in molluscan mitogenomes.However,a consistent and robust topology was generated with protein-coding genes using different models and methods.Our results support Schizochitonoidea as the sister group to other Chitonoidea in Chitonina,in agreement with the established classification.Combined with evidence from fossils,our phylogenetic results suggest that the earliest origin of shell eyes is in Schizochitonoidea,and that these structures were also gained secondarily in other genera in Chitonoidea.Our results have generated a holistic review of the internal relationship within Polyplacophora,and a better understanding of the evolution of Polyplacophora.
文摘The renowned Yangtze micromolluscan fauna has a total of 61 species, assigned to 48 genera, 26 families and 6 classes. The appearance of the Yangtze micromolluscan fauna indicated another maior event in the systematically evolutionary history of invertebrates following the Ediacaran faunas, representing the diversification and radial evolution for the first time in the phylogenetic history of the shelled molluscs, and also providing the best substantial evidence for the division and correlation of the international Precambrian-Cambrian boundary.
