Sergio Henriques | Institute of Zoology (original) (raw)
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Papers by Sergio Henriques
The diversity and distribution of spiders in the Iberian Peninsula are poorly known. However, the... more The diversity and distribution of spiders in the Iberian Peninsula are poorly known. However, the institutional arthropod collections that remain unexplored can provide a considerable amount of taxonomical and biogeographical data. Here we analyze the samples of the families Agelenidae, Dysderidae, Eresidae, Lycosidae, Nemesiidae and Pholcidae stored at the University of León (Spain). The 30 species that have been identified are here commented upon, and the male and female genitalia of Holocnemus caudatus, Holocnemus hispanicus and Holocnemus pluchei are presented. Also, a predictive distribution map of Nemesia ungoliant is provided. The review of the CaULE collection has proved to be a very efficient way to access previously untapped biodiversity information.
Acta Oecologica, 2008
Biodiversity assessment Iberian Peninsula
This study reports the observations of 54 species of amphibians and reptiles obtained during four... more This study reports the observations of 54 species of amphibians and reptiles obtained during four field surveys to Morocco, including the southern and southeastern regions. our records reveal a notable expansion of the current distribution range for several species especially in the eastern part of the country, highlighting the need for more intensive sampling within this region.
This study reports the observations of 54 species of amphibians and reptiles obtained during four... more This study reports the observations of 54 species of amphibians and reptiles obtained during four field surveys to Morocco, including the southern and southeastern regions. Our records reveal a notable expansion of the current distribution range for several species especially in the eastern part of the country, highlighting the need for more intensive sampling within this region.
Journal of Insect Conservation, 2009
Intensive fieldwork has been undertaken in Portugal in order to develop a standardized and optimi... more Intensive fieldwork has been undertaken in Portugal in order to develop a standardized and optimized sampling protocol for Mediterranean spiders. The present study had the objectives of testing the use of semi-quantitative sampling for obtaining an exhaustive species richness assessment of spiders and testing the effects of day, time of day, collector and sampling method on the collected species richness and composition of a Mediterranean scrubland. The collecting summed 224 samples corresponding to one person-hour of effective fieldwork each. In total, 115 species were captured, of which 110 were recorded inside a delimited one-hectare plot, corresponding to more than 70% of the about 160 estimated species. Although no estimator reached the asymptote, the Michaelis-Menten curve behaviour indicates that the estimated richness should be accurate. Most different sampling approaches (day, time of day, collector and sampling method) were found to influence richness, abundance or composition of the samples to some extent, although sampling method had the strongest influence whereas ''collector'' showed no effect at all. The results support the idea that the only variables that need to be controlled in similar protocols are the sampling methods and the time of day when each method is executed. We conclude that populations in structurally simple habitats present narrower peaks of adult abundance, which implies higher percentages of juveniles in samples. Finally, results also indicate that habitats with a relatively simple structure like scrublands may require as much sampling effort, in order to reach similar proportions of captured species in relation to the estimated richness, as habitats that are much more complex.
Diversity and Distributions, 2011
Biological Journal of the Linnean Society, 2013
Spider diversity is partitioned into three primary clades, namely Mesothelae, Mygalomorphae, and ... more Spider diversity is partitioned into three primary clades, namely Mesothelae, Mygalomorphae, and Araneomorphae. Mygalomorph cytogenetics is largely unknown. Our study revealed a remarkable karyotype diversity of mygalomorphs. Unlike araneomorphs, they show no general trend towards a decrease of 2n, as the chromosome number was reduced in some lineages and increased in others. A biarmed karyotype is a symplesiomorphy of mygalomorphs and araneomorphs. Male meiosis of some mygalomorphs is achiasmatic, or includes the diffuse stage. The sex chromosome system X1X20, which is supposedly ancestral in spiders, is uncommon in mygalomorphs. Many mygalomorphs exhibit more than two (and up to 13) X chromosomes in males. The evolution of X chromosomes proceeded via the duplication of chromosomes, fissions, X-X, and X-autosome fusions. Spiders also exhibit a homomorphic sex chromosome pair. In the germline of mygalomorph males these chromosomes are often deactivated; their deactivation and pairing is initiated already at spermatogonia. Remarkably, pairing of sex chromosomes in mygalomorph females is also initiated at gonial cells. Some mygalomorphs have two sex chromosome pairs. The second pair presumably arose in early-diverging mygalomorphs, probably via genome duplication. The unique behaviour of spider sex chromosomes in the germline may promote meiotic pairing of homologous sex chromosomes and structural differentiation of their duplicates, as well as the establishment of polyploid genomes.
Insect Conservation and Diversity, 2008
1. A thorough inventory of a Mediterranean oak forest spider fauna carried out during 2 weeks is ... more 1. A thorough inventory of a Mediterranean oak forest spider fauna carried out during 2 weeks is presented. It used a semi-quantitative sampling protocol to collect comparable data in a rigorous, rapid and efficient way. Four hundred and eighty samples of one person-hour of work each were collected, mostly inside a delimited 1-ha plot.
Insect Conservation and Diversity, 2012
1. The Iberian Peninsula is one of the most relevant areas in terms of species richness, rarity a... more 1. The Iberian Peninsula is one of the most relevant areas in terms of species richness, rarity and endemism in the Mediterranean Basin. Using spiders as a model, we studied the relative importance of environmental and non-environmental spatial variation along a gradient of mediterraneity on the western coast of the Iberian Peninsula.
Biodiversity and Conservation, 2011
The Iberian Peninsula is recognized for its high levels of species richness, rarity and endemicit... more The Iberian Peninsula is recognized for its high levels of species richness, rarity and endemicity. Our main aim was to study biogeographic patterns of spiders in coastal dunes along a gradient of mediterraneity. Distance-decay of similarity, nestedness and co-occurrence metrics were used to explore spider' distribution patterns. A similarity analysis was performed in order to obtain a hierarchical classification of sites. Indicator species analysis was conducted to identify indicator species for the various clustering levels of the site typology. The differentiation among assemblages was further explored by non-metric multidimensional scaling (NMDS) and analysis of similarities (ANOSIM). Assemblages' similarity among sites decreased with climatic/geographic distance. The observed values of nestedness metrics (T and NODF) were not significant, while the co-occurrence metrics (C-score and Checkerboard units) were higher than expected by chance. Cluster analysis showed that spider' assemblages were structured along a gradient from North to South, forming four geographically distinct clusters. ANOSIM tests and NMDS supported the biogeographic patterns identified by cluster analysis. Several indicator species were found for the different levels of the hierarchic site typology. Spider assemblages revealed a high degree of biogeographical structure along the Atlantic coast of the Iberian Peninsula. The coast is a ''biogeographic crossroad'', encompassing faunistic elements of different origins. The hierarchic typology of sites is generally consistent with the major biogeographic regions and the thermoclimatic belts recognized for the region.
This study reports the observations of 54 species of amphibians and reptiles obtained during four... more This study reports the observations of 54 species of amphibians and reptiles obtained during four field surveys to Morocco, including the southern and southeastern regions. our records reveal a notable expansion of the current distribution range for several species especially in the eastern part of the country, highlighting the need for more intensive sampling within this region.
Acta Oecologica, 2008
Biodiversity assessment Iberian Peninsula
The use of standardized and optimized protocols has been recently advocated for different arthrop... more The use of standardized and optimized protocols has been recently advocated for different arthropod taxa instead of ad-hoc sampling or sampling with protocols defined on a case-by-case basis. We present a comparison of both sampling approaches applied for spiders in a natural area of Portugal. Tests were made to their efficiency, over-collection of common species, singletons proportions, species abundance distributions, average specimen size, average taxonomic distinctness and behavior of richness estimators. The standardized protocol revealed three main advantages: (1) higher efficiency; (2) more reliable estimations of true richness; and (3) meaningful comparisons between undersampled areas.
The diversity and distribution of spiders in the Iberian Peninsula are poorly known. However, the... more The diversity and distribution of spiders in the Iberian Peninsula are poorly known. However, the institutional arthropod collections that remain unexplored can provide a considerable amount of taxonomical and biogeographical data. Here we analyze the samples of the families Agelenidae, Dysderidae, Eresidae, Lycosidae, Nemesiidae and Pholcidae stored at the University of León (Spain). The 30 species that have been identified are here commented upon, and the male and female genitalia of Holocnemus caudatus, Holocnemus hispanicus and Holocnemus pluchei are presented. Also, a predictive distribution map of Nemesia ungoliant is provided. The review of the CaULE collection has proved to be a very efficient way to access previously untapped biodiversity information.
Acta Oecologica, 2008
Biodiversity assessment Iberian Peninsula
This study reports the observations of 54 species of amphibians and reptiles obtained during four... more This study reports the observations of 54 species of amphibians and reptiles obtained during four field surveys to Morocco, including the southern and southeastern regions. our records reveal a notable expansion of the current distribution range for several species especially in the eastern part of the country, highlighting the need for more intensive sampling within this region.
This study reports the observations of 54 species of amphibians and reptiles obtained during four... more This study reports the observations of 54 species of amphibians and reptiles obtained during four field surveys to Morocco, including the southern and southeastern regions. Our records reveal a notable expansion of the current distribution range for several species especially in the eastern part of the country, highlighting the need for more intensive sampling within this region.
Journal of Insect Conservation, 2009
Intensive fieldwork has been undertaken in Portugal in order to develop a standardized and optimi... more Intensive fieldwork has been undertaken in Portugal in order to develop a standardized and optimized sampling protocol for Mediterranean spiders. The present study had the objectives of testing the use of semi-quantitative sampling for obtaining an exhaustive species richness assessment of spiders and testing the effects of day, time of day, collector and sampling method on the collected species richness and composition of a Mediterranean scrubland. The collecting summed 224 samples corresponding to one person-hour of effective fieldwork each. In total, 115 species were captured, of which 110 were recorded inside a delimited one-hectare plot, corresponding to more than 70% of the about 160 estimated species. Although no estimator reached the asymptote, the Michaelis-Menten curve behaviour indicates that the estimated richness should be accurate. Most different sampling approaches (day, time of day, collector and sampling method) were found to influence richness, abundance or composition of the samples to some extent, although sampling method had the strongest influence whereas ''collector'' showed no effect at all. The results support the idea that the only variables that need to be controlled in similar protocols are the sampling methods and the time of day when each method is executed. We conclude that populations in structurally simple habitats present narrower peaks of adult abundance, which implies higher percentages of juveniles in samples. Finally, results also indicate that habitats with a relatively simple structure like scrublands may require as much sampling effort, in order to reach similar proportions of captured species in relation to the estimated richness, as habitats that are much more complex.
Diversity and Distributions, 2011
Biological Journal of the Linnean Society, 2013
Spider diversity is partitioned into three primary clades, namely Mesothelae, Mygalomorphae, and ... more Spider diversity is partitioned into three primary clades, namely Mesothelae, Mygalomorphae, and Araneomorphae. Mygalomorph cytogenetics is largely unknown. Our study revealed a remarkable karyotype diversity of mygalomorphs. Unlike araneomorphs, they show no general trend towards a decrease of 2n, as the chromosome number was reduced in some lineages and increased in others. A biarmed karyotype is a symplesiomorphy of mygalomorphs and araneomorphs. Male meiosis of some mygalomorphs is achiasmatic, or includes the diffuse stage. The sex chromosome system X1X20, which is supposedly ancestral in spiders, is uncommon in mygalomorphs. Many mygalomorphs exhibit more than two (and up to 13) X chromosomes in males. The evolution of X chromosomes proceeded via the duplication of chromosomes, fissions, X-X, and X-autosome fusions. Spiders also exhibit a homomorphic sex chromosome pair. In the germline of mygalomorph males these chromosomes are often deactivated; their deactivation and pairing is initiated already at spermatogonia. Remarkably, pairing of sex chromosomes in mygalomorph females is also initiated at gonial cells. Some mygalomorphs have two sex chromosome pairs. The second pair presumably arose in early-diverging mygalomorphs, probably via genome duplication. The unique behaviour of spider sex chromosomes in the germline may promote meiotic pairing of homologous sex chromosomes and structural differentiation of their duplicates, as well as the establishment of polyploid genomes.
Insect Conservation and Diversity, 2008
1. A thorough inventory of a Mediterranean oak forest spider fauna carried out during 2 weeks is ... more 1. A thorough inventory of a Mediterranean oak forest spider fauna carried out during 2 weeks is presented. It used a semi-quantitative sampling protocol to collect comparable data in a rigorous, rapid and efficient way. Four hundred and eighty samples of one person-hour of work each were collected, mostly inside a delimited 1-ha plot.
Insect Conservation and Diversity, 2012
1. The Iberian Peninsula is one of the most relevant areas in terms of species richness, rarity a... more 1. The Iberian Peninsula is one of the most relevant areas in terms of species richness, rarity and endemism in the Mediterranean Basin. Using spiders as a model, we studied the relative importance of environmental and non-environmental spatial variation along a gradient of mediterraneity on the western coast of the Iberian Peninsula.
Biodiversity and Conservation, 2011
The Iberian Peninsula is recognized for its high levels of species richness, rarity and endemicit... more The Iberian Peninsula is recognized for its high levels of species richness, rarity and endemicity. Our main aim was to study biogeographic patterns of spiders in coastal dunes along a gradient of mediterraneity. Distance-decay of similarity, nestedness and co-occurrence metrics were used to explore spider' distribution patterns. A similarity analysis was performed in order to obtain a hierarchical classification of sites. Indicator species analysis was conducted to identify indicator species for the various clustering levels of the site typology. The differentiation among assemblages was further explored by non-metric multidimensional scaling (NMDS) and analysis of similarities (ANOSIM). Assemblages' similarity among sites decreased with climatic/geographic distance. The observed values of nestedness metrics (T and NODF) were not significant, while the co-occurrence metrics (C-score and Checkerboard units) were higher than expected by chance. Cluster analysis showed that spider' assemblages were structured along a gradient from North to South, forming four geographically distinct clusters. ANOSIM tests and NMDS supported the biogeographic patterns identified by cluster analysis. Several indicator species were found for the different levels of the hierarchic site typology. Spider assemblages revealed a high degree of biogeographical structure along the Atlantic coast of the Iberian Peninsula. The coast is a ''biogeographic crossroad'', encompassing faunistic elements of different origins. The hierarchic typology of sites is generally consistent with the major biogeographic regions and the thermoclimatic belts recognized for the region.
This study reports the observations of 54 species of amphibians and reptiles obtained during four... more This study reports the observations of 54 species of amphibians and reptiles obtained during four field surveys to Morocco, including the southern and southeastern regions. our records reveal a notable expansion of the current distribution range for several species especially in the eastern part of the country, highlighting the need for more intensive sampling within this region.
Acta Oecologica, 2008
Biodiversity assessment Iberian Peninsula
The use of standardized and optimized protocols has been recently advocated for different arthrop... more The use of standardized and optimized protocols has been recently advocated for different arthropod taxa instead of ad-hoc sampling or sampling with protocols defined on a case-by-case basis. We present a comparison of both sampling approaches applied for spiders in a natural area of Portugal. Tests were made to their efficiency, over-collection of common species, singletons proportions, species abundance distributions, average specimen size, average taxonomic distinctness and behavior of richness estimators. The standardized protocol revealed three main advantages: (1) higher efficiency; (2) more reliable estimations of true richness; and (3) meaningful comparisons between undersampled areas.