2019 IEEE International Reliability Physics Symposium (IRPS), 2019
We investigate time-dependent dielectric breakdown (TDDB) in AlGaN/GaN Metal-Insulator-Semiconduc... more We investigate time-dependent dielectric breakdown (TDDB) in AlGaN/GaN Metal-Insulator-Semiconductor High Electron Mobility Transistors (MIS-HEMTs) under forward bias AC stress which better emulates real-world operational conditions. To this end, we have performed TDDB experiments across a wide range of frequencies, temperatures, and recovery voltage levels. We find that TDDB under AC stress shows longer breakdown times than under DC stress and that this increase is more prominent with higher frequency, lower temperature, and more negative recovery voltage. We hypothesize that this is due to the dynamics of the gate stack in GaN MIS-HEMTs biased with a high positive gate voltage. Under these conditions, a second electron channel forms at the dielectric/AlGaN interface. This process is relatively slow as these electrons come from the 2DEG at the AlGaN/GaN interface and must overcome the energy barrier presented by the AlGaN. At the same gate voltage then, the electric field across the gate oxide is lower in magnitude under AC stress at high enough frequency than under DC stress explaining the obtained results.
Evaluación de palmas prolíficas en la especie Elaeis oleífera e híbridos interespecíficos de E. o... more Evaluación de palmas prolíficas en la especie Elaeis oleífera e híbridos interespecíficos de E. oleífera x E. guineensis' Evaluation of prolific oil palms in the Elaeis oleífera species and interspecific hybrids of E. oleífera x E. guineensis.
This paper contains a concise overview of the deployment of scattered solar power plants across P... more This paper contains a concise overview of the deployment of scattered solar power plants across Poland, mainly from the perspective of their communication networks, and how the recent development of the Polish 4G networks has a very positive impact for the performance of the whole monitoring system (production control and video-surveillance), with a special emphasis on video-analytics, due to its higher bandwidth demand. All the information will be shown from the point of view of the solar photovoltaics developer I+D Energías, and therefore it constitutes a real user’s experience.
Uncovering the mechanism behind the increase in capacitance of a 2D WS2 supercapacitor electrode ... more Uncovering the mechanism behind the increase in capacitance of a 2D WS2 supercapacitor electrode upon cycling using KPFM analysis.
Estudios Atacameños. Arqueología y antropología surandinas., 1998
madres a hijos y de hombre a mujer bajo condiciones naturales. Para explicar esta transposición ú... more madres a hijos y de hombre a mujer bajo condiciones naturales. Para explicar esta transposición única del HTLV-I desde los asiáticos del Japón a los andinos de Sudamérica se han desarrollado diferentes modelos hipotéticos de esta histórica migración de los porta dores de HTLV-I y HTLV-II. La similitud en el antecedente genético que muestran los japoneses del sur y los pueblos andinos de Sudamérica sugiere una hipótesis migratoria plau sible, pero que no encuentra general aceptación entre antropólogos y arqueólogos. Suponemos que los portadores de HTLV-I llegaron a América del Sur y a los Andes a través de una ruta transpacífica, mucho después que los portadores de HTLV-II venidos de Asia arribaran al continente Sudamerica no.
Vesicomyid clams are among the dominant invertebrates of chemosynthesis-based communities found a... more Vesicomyid clams are among the dominant invertebrates of chemosynthesis-based communities found at deep-sea cold seeps and hydrothermal vents, yet there is considerable taxonomic confusion within the family Vesicomyidae. The present study examined phylogenetic relationships among vesicomyid clams belonging to a cryptic-species complex that includes Vesicomya (previously Calyptogena) pacifica (Dall, 1891) and Vesicomya lepta (Dall, 1896). Mitochondrial (mt) COI sequences from clams collected between 1991 and 2001 along the western margin of North America from the San Clemente Basin (32°N latitude) to the Juan de Fuca Ridge (48°N latitude) revealed five discrete evolutionary lineages: V. pacifica (mt-type I), V. lepta (mt-type IV), and three undescribed species defined by mttypes II, III, and V. Separation of the three lineages defined by mt-types I, II, and III was also revealed by an independent nuclear gene (ribosomal ITS-1), and by DNA sequences from vertically transmitted bacterial endosymbionts found in the gills of these clams. Lineages I, II, and III occur in Monterey Bay, California, and the data suggest that bathymetric segregation may have played a role in their isolation and divergence.
Around 2% of the population in developed nations are affected by mitral valve disease and availab... more Around 2% of the population in developed nations are affected by mitral valve disease and available valvular replacements are not designed for the atrioventricular position. Recently our group developed the first tissue-engineered heart valve (TEHV) specifically designed for the mitral position – the TexMi valve. The valve recapitulates the main components of the native valve, i.e. annulus, asymmetric leaflets and the crucial
The 70 kDa Heat Shock Proteins (HSP70) are considered the most conserved members of the HSP famil... more The 70 kDa Heat Shock Proteins (HSP70) are considered the most conserved members of the HSP family. These proteins are primordial to the cell, because of their implications in many cellular pathways (e. g., development, immunity) and also because they minimize the effects of multiple stresses (e. g., temperature, pollutants, salinity, radiations). In the cytosol, two ubiquitous HSP70s with either a constitutive (HSC70) or an inducible (HSP70) expression pattern are found in all metazoan species, encoded by 5 or 6 genes (Drosophila melanogaster or yeast and human respectively). The cytosolic HSP70 protein family is considered a major actor in environmental adaptation, and widely used in ecology as an important biomarker of environmental stress. Nevertheless, the diversity of cytosolic HSP70 remains unclear amongst the Athropoda phylum, especially within decapods. Using 122 new and 311 available sequences, we carried out analyses of the overall cytosolic HSP70 diversity in arthropods ...
Brachyuran crabs of the family Bythograeidae are endemic to deep-sea hydrothermal vents and repre... more Brachyuran crabs of the family Bythograeidae are endemic to deep-sea hydrothermal vents and represent one of the most successful groups of macroinvertebrates that have colonized this extreme environment. Occurring worldwide, the family includes six genera (Allograea, Austinograea, Bythograea, Cyanagraea, Gandalfus, and Segonzacia) and fourteen formally described species. To investigate their evolutionary relationships, we conducted Maximum Likelihood and Bayesian molecular phylogenetic analyses, based on DNA sequences from fragments of three mitochondrial genes (16S rDNA, Cytochrome oxidase I, and Cytochrome b) and three nuclear genes (28S rDNA, the sodium-potassium ATPase a-subunit 'NaK', and Histone H3A). We employed traditional concatenated (i.e., supermatrix) phylogenetic methods, as well as three recently developed Bayesian multilocus methods aimed at inferring species trees from potentially discordant gene trees. We found strong support for two main clades within Bythograeidae: one comprising the members of the genus Bythograea; and the other comprising the remaining genera. Relationships within each of these two clades were partially resolved. We compare our results with an earlier hypothesis on the phylogenetic relationships among bythograeid genera based on morphology. We also discuss the biogeography of the family in the light of our results. Our species tree analyses reveal differences in how each of the three methods weighs conflicting phylogenetic signal from different gene partitions and how limits on the number of outgroup taxa may affect the results.
Supralittoral and high intertidal coastal zones are exposed to pollution from both marine and ter... more Supralittoral and high intertidal coastal zones are exposed to pollution from both marine and terrestrial sources and undergo higher deposition rates than the subtidal zone. It is therefore important to identify organisms for this section of the coastal area that can be tolerant to contaminants. The aim of this study was to determine if supralittoral isopods of the genus Ligia can be used as biomonitors, since they are abundant and widely distributed. For this purpose, concentrations of trace elements were determined in Ligia isopods in toto from 26 locations across the Gulf of California and Pacific coast of the Baja California peninsula, which were collected during the summers of 2009 and 2010. The concentrations of trace elements followed the order of; ZnZCu4As4Cd4Pb4Hg. Elevated concentrations of copper (up to 1010 μg/g) were detected in Ligia from Santa Rosalía (SRo), a locality where industrial mining of copper has historically occurred. Industrial and municipal sewage discharges appear to have contributed to the high concentrations of zinc (326 μg/g) and lead (144 μg/g) found in organisms from Guaymas location. The high mercury concentration in organisms from Mazatlán (M) (2.01 μg/g) was associated with a thermoelectric plant. Natural sources of metals were also detected; coastal upwelling appears to be associated with high cadmium concentrations in Ligia from Punta Baja (PB) (256 μg/g) in the Pacific coast, whereas hydrothermal vents may have contributed to high concentrations of arsenic at Ensenada (E) (61 μg/g). Our results suggest that Ligia isopods reflect the natural and anthropogenic inputs of trace metals in the environment and could potentially be used as biomonitor organisms of the intertidal rocky shores of the Gulf of California and Pacific coast.
Background: Ligia isopods are widely distributed in the Pacific rocky intertidal shores from cent... more Background: Ligia isopods are widely distributed in the Pacific rocky intertidal shores from central California to central Mexico, including the Gulf of California. Yet, their biological characteristics restrict them to complete their life cycles in a very narrow range of the rocky intertidal supralittoral. Herein, we examine phylogeographic patterns of Ligia isopods from 122 localities between central California and central Mexico. We expect to find high levels of allopatric diversity. In addition, we expect the phylogeographic patterns to show signatures of past vicariant events that occurred in this geologically dynamic region. Methodology/Principal Findings: We sequenced two mitochondrial genes (Cytochrome Oxidase I and 16S ribosomal DNA). We conducted Maximum Likelihood and Bayesian phylogenetic analyses. We found many divergent clades that, in general, group according to geography. Some of the most striking features of the Ligia phylogeographic pattern include: (1) deep mid-peninsular phylogeographic breaks on the Pacific and Gulf sides of Baja peninsula; (2) within the Gulf lineages, the northern peninsula is most closely related to the northern mainland, while the southern peninsula is most closely related to the central-southern mainland; and, (3) the southernmost portion of the peninsula (Cape Region) is most closely related to the southernmost portion of mainland. Conclusions/Significance: Our results shed light on the phylogenetic relationships of Ligia populations in the study area. This study probably represents the finest-scale phylogeographic examination for any organism to date in this region. Presence of highly divergent lineages suggests multiple Ligia species exist in this region. The phylogeographic patterns of Ligia in the Gulf of California and Baja peninsula are incongruent with a widely accepted vicariant scenario among phylogeographers, but consistent with aspects of alternative geological hypotheses and phylo-and biogeographic patterns of several other taxa. Our findings contribute to the ongoing debate regarding the geological origin of this important biogeographic region.
Population genetic and phylogenetic analyses of mitochondrial COI from five deep-sea hydrothermal... more Population genetic and phylogenetic analyses of mitochondrial COI from five deep-sea hydrothermal vent annelids provided insights into their dispersal modes and barriers to gene flow. These polychaetes inhabit vent fields located along the East Pacific Rise (EPR) and Galapagos Rift (GAR), where hundreds to thousands of kilometers can separate island-like populations. Long-distance dispersal occurs via larval stages, but larval life histories differ among these taxa. Mitochondrial gene flow between populations of Riftia pachyptila , a siboglinid worm with neutrally buoyant lecithothrophic larvae, is diminished across the Easter Microplate region, which lies at the boundary of Indo-Pacific and Antarctic deep-sea provinces. Populations of the siboglinid Tevnia jerichonana are similarly subdivided. Oasisia alvinae is not found on the southern EPR, but northern EPR populations of this siboglinid are subdivided across the Rivera Fracture Zone. Mitochondrial gene flow of Alvinella pompejana , an alvinellid with large negatively buoyant lecithotrophic eggs and arrested embryonic development, is unimpeded across the Easter Microplate region. Gene flow in the polynoid Branchipolynoe symmytilida also is unimpeded across the Easter Microplate region. However, A. pompejana populations are subdivided across the equator, whereas B. symmitilida populations are subdivided between the EPR and GAR axes. The present findings are compared with similar evidence from codistributed species of annelids, molluscs and crustaceans to identify potential dispersal filters in these eastern Pacific ridge systems.
The patchy distribution of rocky intertidal communities in the tropical eastern PaciWc (TEP) may ... more The patchy distribution of rocky intertidal communities in the tropical eastern PaciWc (TEP) may impose severe constraints on the genetic connectivity among populations of marine invertebrates associated with this habitat. In this study, we analyzed a portion of the mitochondrial cytochrome c oxidase subunit I (COI) gene in two sympatric species of marine snails, Nerita scabricosta and Nerita funiculata, common inhabitants of the rocky intertidal from the Gulf of California (Sea of Cortez) and outer PaciWc coast of the southern Baja California (Baja) peninsula to northern South America, to assess genetic connectivity among populations of each species. One of our aims was to determine whether the morphological, behavioral, and ecological diVerences observed among populations of both species throughout their range in the TEP corresponded to population genetic diVerences. In addition, we were interested in elucidating the demographic history of both species. We found no evidence of genetic structure throughout the Gulf of California and outer coast of the Baja peninsula region for either species. Comparisons between Gulf of California/Baja and Panama populations, however, showed signiWcant genetic diVerentiation for N. scabricosta, but not for N. funiculata. The genetic diVerences between Mexican and Panamanian populations of N. scabricosta were consistent with previously reported ecological and behavioral diVerences for this species between these two distant regions. However, previously reported size diVerences between northern and central/southern Gulf of California individuals of N. scabricosta do not correspond with our Wndings of genetic connectivity among these populations. Results from neutrality tests (Tajima's D and Fu's F S), the mismatch distribution, and Bayesian skyline analyses suggested that both species have experienced dramatic population expansions dating to the Pleistocene.
We report the development of nine polymorphic nuclear-encoded microsatellite DNA loci for the Afr... more We report the development of nine polymorphic nuclear-encoded microsatellite DNA loci for the African bonytongue (Heterotis niloticus), the only species of the osteoglossiform family Arapaimidae distributed in the Eastern Hemisphere. We describe the process to isolate these loci, and the primers and conditions for amplifying them using the polymerase chain reaction. We tested these primers with a sample of 40 individuals from two natural populations in Benin, West Africa. The number of alleles for the nine microsatellites ranged from 2 to 9, observed heterozygosity from 0.125 to 0.882, and expected heterozygosity from 0.156 to 0.810. No significant deviations from Hardy-Weinberg equilibrium or linkage disequilibrium were observed, and there is no indication of null alleles.
2019 IEEE International Reliability Physics Symposium (IRPS), 2019
We investigate time-dependent dielectric breakdown (TDDB) in AlGaN/GaN Metal-Insulator-Semiconduc... more We investigate time-dependent dielectric breakdown (TDDB) in AlGaN/GaN Metal-Insulator-Semiconductor High Electron Mobility Transistors (MIS-HEMTs) under forward bias AC stress which better emulates real-world operational conditions. To this end, we have performed TDDB experiments across a wide range of frequencies, temperatures, and recovery voltage levels. We find that TDDB under AC stress shows longer breakdown times than under DC stress and that this increase is more prominent with higher frequency, lower temperature, and more negative recovery voltage. We hypothesize that this is due to the dynamics of the gate stack in GaN MIS-HEMTs biased with a high positive gate voltage. Under these conditions, a second electron channel forms at the dielectric/AlGaN interface. This process is relatively slow as these electrons come from the 2DEG at the AlGaN/GaN interface and must overcome the energy barrier presented by the AlGaN. At the same gate voltage then, the electric field across the gate oxide is lower in magnitude under AC stress at high enough frequency than under DC stress explaining the obtained results.
Evaluación de palmas prolíficas en la especie Elaeis oleífera e híbridos interespecíficos de E. o... more Evaluación de palmas prolíficas en la especie Elaeis oleífera e híbridos interespecíficos de E. oleífera x E. guineensis' Evaluation of prolific oil palms in the Elaeis oleífera species and interspecific hybrids of E. oleífera x E. guineensis.
This paper contains a concise overview of the deployment of scattered solar power plants across P... more This paper contains a concise overview of the deployment of scattered solar power plants across Poland, mainly from the perspective of their communication networks, and how the recent development of the Polish 4G networks has a very positive impact for the performance of the whole monitoring system (production control and video-surveillance), with a special emphasis on video-analytics, due to its higher bandwidth demand. All the information will be shown from the point of view of the solar photovoltaics developer I+D Energías, and therefore it constitutes a real user’s experience.
Uncovering the mechanism behind the increase in capacitance of a 2D WS2 supercapacitor electrode ... more Uncovering the mechanism behind the increase in capacitance of a 2D WS2 supercapacitor electrode upon cycling using KPFM analysis.
Estudios Atacameños. Arqueología y antropología surandinas., 1998
madres a hijos y de hombre a mujer bajo condiciones naturales. Para explicar esta transposición ú... more madres a hijos y de hombre a mujer bajo condiciones naturales. Para explicar esta transposición única del HTLV-I desde los asiáticos del Japón a los andinos de Sudamérica se han desarrollado diferentes modelos hipotéticos de esta histórica migración de los porta dores de HTLV-I y HTLV-II. La similitud en el antecedente genético que muestran los japoneses del sur y los pueblos andinos de Sudamérica sugiere una hipótesis migratoria plau sible, pero que no encuentra general aceptación entre antropólogos y arqueólogos. Suponemos que los portadores de HTLV-I llegaron a América del Sur y a los Andes a través de una ruta transpacífica, mucho después que los portadores de HTLV-II venidos de Asia arribaran al continente Sudamerica no.
Vesicomyid clams are among the dominant invertebrates of chemosynthesis-based communities found a... more Vesicomyid clams are among the dominant invertebrates of chemosynthesis-based communities found at deep-sea cold seeps and hydrothermal vents, yet there is considerable taxonomic confusion within the family Vesicomyidae. The present study examined phylogenetic relationships among vesicomyid clams belonging to a cryptic-species complex that includes Vesicomya (previously Calyptogena) pacifica (Dall, 1891) and Vesicomya lepta (Dall, 1896). Mitochondrial (mt) COI sequences from clams collected between 1991 and 2001 along the western margin of North America from the San Clemente Basin (32°N latitude) to the Juan de Fuca Ridge (48°N latitude) revealed five discrete evolutionary lineages: V. pacifica (mt-type I), V. lepta (mt-type IV), and three undescribed species defined by mttypes II, III, and V. Separation of the three lineages defined by mt-types I, II, and III was also revealed by an independent nuclear gene (ribosomal ITS-1), and by DNA sequences from vertically transmitted bacterial endosymbionts found in the gills of these clams. Lineages I, II, and III occur in Monterey Bay, California, and the data suggest that bathymetric segregation may have played a role in their isolation and divergence.
Around 2% of the population in developed nations are affected by mitral valve disease and availab... more Around 2% of the population in developed nations are affected by mitral valve disease and available valvular replacements are not designed for the atrioventricular position. Recently our group developed the first tissue-engineered heart valve (TEHV) specifically designed for the mitral position – the TexMi valve. The valve recapitulates the main components of the native valve, i.e. annulus, asymmetric leaflets and the crucial
The 70 kDa Heat Shock Proteins (HSP70) are considered the most conserved members of the HSP famil... more The 70 kDa Heat Shock Proteins (HSP70) are considered the most conserved members of the HSP family. These proteins are primordial to the cell, because of their implications in many cellular pathways (e. g., development, immunity) and also because they minimize the effects of multiple stresses (e. g., temperature, pollutants, salinity, radiations). In the cytosol, two ubiquitous HSP70s with either a constitutive (HSC70) or an inducible (HSP70) expression pattern are found in all metazoan species, encoded by 5 or 6 genes (Drosophila melanogaster or yeast and human respectively). The cytosolic HSP70 protein family is considered a major actor in environmental adaptation, and widely used in ecology as an important biomarker of environmental stress. Nevertheless, the diversity of cytosolic HSP70 remains unclear amongst the Athropoda phylum, especially within decapods. Using 122 new and 311 available sequences, we carried out analyses of the overall cytosolic HSP70 diversity in arthropods ...
Brachyuran crabs of the family Bythograeidae are endemic to deep-sea hydrothermal vents and repre... more Brachyuran crabs of the family Bythograeidae are endemic to deep-sea hydrothermal vents and represent one of the most successful groups of macroinvertebrates that have colonized this extreme environment. Occurring worldwide, the family includes six genera (Allograea, Austinograea, Bythograea, Cyanagraea, Gandalfus, and Segonzacia) and fourteen formally described species. To investigate their evolutionary relationships, we conducted Maximum Likelihood and Bayesian molecular phylogenetic analyses, based on DNA sequences from fragments of three mitochondrial genes (16S rDNA, Cytochrome oxidase I, and Cytochrome b) and three nuclear genes (28S rDNA, the sodium-potassium ATPase a-subunit 'NaK', and Histone H3A). We employed traditional concatenated (i.e., supermatrix) phylogenetic methods, as well as three recently developed Bayesian multilocus methods aimed at inferring species trees from potentially discordant gene trees. We found strong support for two main clades within Bythograeidae: one comprising the members of the genus Bythograea; and the other comprising the remaining genera. Relationships within each of these two clades were partially resolved. We compare our results with an earlier hypothesis on the phylogenetic relationships among bythograeid genera based on morphology. We also discuss the biogeography of the family in the light of our results. Our species tree analyses reveal differences in how each of the three methods weighs conflicting phylogenetic signal from different gene partitions and how limits on the number of outgroup taxa may affect the results.
Supralittoral and high intertidal coastal zones are exposed to pollution from both marine and ter... more Supralittoral and high intertidal coastal zones are exposed to pollution from both marine and terrestrial sources and undergo higher deposition rates than the subtidal zone. It is therefore important to identify organisms for this section of the coastal area that can be tolerant to contaminants. The aim of this study was to determine if supralittoral isopods of the genus Ligia can be used as biomonitors, since they are abundant and widely distributed. For this purpose, concentrations of trace elements were determined in Ligia isopods in toto from 26 locations across the Gulf of California and Pacific coast of the Baja California peninsula, which were collected during the summers of 2009 and 2010. The concentrations of trace elements followed the order of; ZnZCu4As4Cd4Pb4Hg. Elevated concentrations of copper (up to 1010 μg/g) were detected in Ligia from Santa Rosalía (SRo), a locality where industrial mining of copper has historically occurred. Industrial and municipal sewage discharges appear to have contributed to the high concentrations of zinc (326 μg/g) and lead (144 μg/g) found in organisms from Guaymas location. The high mercury concentration in organisms from Mazatlán (M) (2.01 μg/g) was associated with a thermoelectric plant. Natural sources of metals were also detected; coastal upwelling appears to be associated with high cadmium concentrations in Ligia from Punta Baja (PB) (256 μg/g) in the Pacific coast, whereas hydrothermal vents may have contributed to high concentrations of arsenic at Ensenada (E) (61 μg/g). Our results suggest that Ligia isopods reflect the natural and anthropogenic inputs of trace metals in the environment and could potentially be used as biomonitor organisms of the intertidal rocky shores of the Gulf of California and Pacific coast.
Background: Ligia isopods are widely distributed in the Pacific rocky intertidal shores from cent... more Background: Ligia isopods are widely distributed in the Pacific rocky intertidal shores from central California to central Mexico, including the Gulf of California. Yet, their biological characteristics restrict them to complete their life cycles in a very narrow range of the rocky intertidal supralittoral. Herein, we examine phylogeographic patterns of Ligia isopods from 122 localities between central California and central Mexico. We expect to find high levels of allopatric diversity. In addition, we expect the phylogeographic patterns to show signatures of past vicariant events that occurred in this geologically dynamic region. Methodology/Principal Findings: We sequenced two mitochondrial genes (Cytochrome Oxidase I and 16S ribosomal DNA). We conducted Maximum Likelihood and Bayesian phylogenetic analyses. We found many divergent clades that, in general, group according to geography. Some of the most striking features of the Ligia phylogeographic pattern include: (1) deep mid-peninsular phylogeographic breaks on the Pacific and Gulf sides of Baja peninsula; (2) within the Gulf lineages, the northern peninsula is most closely related to the northern mainland, while the southern peninsula is most closely related to the central-southern mainland; and, (3) the southernmost portion of the peninsula (Cape Region) is most closely related to the southernmost portion of mainland. Conclusions/Significance: Our results shed light on the phylogenetic relationships of Ligia populations in the study area. This study probably represents the finest-scale phylogeographic examination for any organism to date in this region. Presence of highly divergent lineages suggests multiple Ligia species exist in this region. The phylogeographic patterns of Ligia in the Gulf of California and Baja peninsula are incongruent with a widely accepted vicariant scenario among phylogeographers, but consistent with aspects of alternative geological hypotheses and phylo-and biogeographic patterns of several other taxa. Our findings contribute to the ongoing debate regarding the geological origin of this important biogeographic region.
Population genetic and phylogenetic analyses of mitochondrial COI from five deep-sea hydrothermal... more Population genetic and phylogenetic analyses of mitochondrial COI from five deep-sea hydrothermal vent annelids provided insights into their dispersal modes and barriers to gene flow. These polychaetes inhabit vent fields located along the East Pacific Rise (EPR) and Galapagos Rift (GAR), where hundreds to thousands of kilometers can separate island-like populations. Long-distance dispersal occurs via larval stages, but larval life histories differ among these taxa. Mitochondrial gene flow between populations of Riftia pachyptila , a siboglinid worm with neutrally buoyant lecithothrophic larvae, is diminished across the Easter Microplate region, which lies at the boundary of Indo-Pacific and Antarctic deep-sea provinces. Populations of the siboglinid Tevnia jerichonana are similarly subdivided. Oasisia alvinae is not found on the southern EPR, but northern EPR populations of this siboglinid are subdivided across the Rivera Fracture Zone. Mitochondrial gene flow of Alvinella pompejana , an alvinellid with large negatively buoyant lecithotrophic eggs and arrested embryonic development, is unimpeded across the Easter Microplate region. Gene flow in the polynoid Branchipolynoe symmytilida also is unimpeded across the Easter Microplate region. However, A. pompejana populations are subdivided across the equator, whereas B. symmitilida populations are subdivided between the EPR and GAR axes. The present findings are compared with similar evidence from codistributed species of annelids, molluscs and crustaceans to identify potential dispersal filters in these eastern Pacific ridge systems.
The patchy distribution of rocky intertidal communities in the tropical eastern PaciWc (TEP) may ... more The patchy distribution of rocky intertidal communities in the tropical eastern PaciWc (TEP) may impose severe constraints on the genetic connectivity among populations of marine invertebrates associated with this habitat. In this study, we analyzed a portion of the mitochondrial cytochrome c oxidase subunit I (COI) gene in two sympatric species of marine snails, Nerita scabricosta and Nerita funiculata, common inhabitants of the rocky intertidal from the Gulf of California (Sea of Cortez) and outer PaciWc coast of the southern Baja California (Baja) peninsula to northern South America, to assess genetic connectivity among populations of each species. One of our aims was to determine whether the morphological, behavioral, and ecological diVerences observed among populations of both species throughout their range in the TEP corresponded to population genetic diVerences. In addition, we were interested in elucidating the demographic history of both species. We found no evidence of genetic structure throughout the Gulf of California and outer coast of the Baja peninsula region for either species. Comparisons between Gulf of California/Baja and Panama populations, however, showed signiWcant genetic diVerentiation for N. scabricosta, but not for N. funiculata. The genetic diVerences between Mexican and Panamanian populations of N. scabricosta were consistent with previously reported ecological and behavioral diVerences for this species between these two distant regions. However, previously reported size diVerences between northern and central/southern Gulf of California individuals of N. scabricosta do not correspond with our Wndings of genetic connectivity among these populations. Results from neutrality tests (Tajima's D and Fu's F S), the mismatch distribution, and Bayesian skyline analyses suggested that both species have experienced dramatic population expansions dating to the Pleistocene.
We report the development of nine polymorphic nuclear-encoded microsatellite DNA loci for the Afr... more We report the development of nine polymorphic nuclear-encoded microsatellite DNA loci for the African bonytongue (Heterotis niloticus), the only species of the osteoglossiform family Arapaimidae distributed in the Eastern Hemisphere. We describe the process to isolate these loci, and the primers and conditions for amplifying them using the polymerase chain reaction. We tested these primers with a sample of 40 individuals from two natural populations in Benin, West Africa. The number of alleles for the nine microsatellites ranged from 2 to 9, observed heterozygosity from 0.125 to 0.882, and expected heterozygosity from 0.156 to 0.810. No significant deviations from Hardy-Weinberg equilibrium or linkage disequilibrium were observed, and there is no indication of null alleles.
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Papers by Luis Hurtado