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Sally R Isberg - One of the best experts on this subject based on the ideXlab platform.
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Dermatological conditions of farmed Crocodilians: a review of pathogenic agents and their proposed impact on skin quality
Veterinary microbiology, 2018Co-Authors: M. J. Lott, Rhiannon L. Moore, Natalie L. Milic, Michelle L. Power, Catherine M. Shilton, Sally R IsbergAbstract:The control of pathogens that target Crocodilian skin is essential to the long-term success and sustainability of intensive farming operations worldwide. To understand the impact these pathogens may have on the skin, a brief overview of skin histology is given. A review of the known viral, bacterial, fungal and helminth taxa associated with skin conditions in commercially significant Crocodilian species is presented. Best management practices are discussed, with an emphasis on addressing extrinsic factors that influence transmission and pathogenicity. It is argued that, in the past, reduced immune function arising from inadequate thermal regulation was the leading cause of skin disease in captive Crocodilians. Consequently, innovations such as temperature control, coupled with the adoption of more stringent hygiene standards, have greatly reduced the prevalence of many infectious skin conditions in intensively farmed populations. However, despite improvements in animal husbandry and disease management, viral pathogens such as West Nile virus, herpesvirus and poxvirus continue to afflict Crocodilians in modern captive production systems.
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Evolution and gene capture in ancient endogenous retroviruses - insights from the Crocodilian genomes
Retrovirology, 2014Co-Authors: Amanda Y Chong, Sally R Isberg, Kenji K Kojima, Jerzy Jurka, David A Ray, Arian F A Smit, Jaime GongoraAbstract:Background Crocodilians are thought to be hosts to a diverse and divergent complement of endogenous retroviruses (ERVs) but a comprehensive investigation is yet to be performed. The recent sequencing of three Crocodilian genomes provides an opportunity for a more detailed and accurate representation of the ERV diversity that is present in these species. Here we investigate the diversity, distribution and evolution of ERVs from the genomes of three key Crocodilian species, and outline the key processes driving Crocodilian ERV proliferation and evolution. Results ERVs and ERV related sequences make up less than 2% of Crocodilian genomes. We recovered and described 45 ERV groups within the three Crocodilian genomes, many of which are species specific. We have also revealed a new class of ERV, ERV4, which appears to be common to Crocodilians and turtles, and currently has no characterised exogenous counterpart. For the first time, we formally describe the characteristics of this ERV class and its classification relative to other recognised ERV and retroviral classes. This class shares some sequence similarity and sequence characteristics with ERV3, although it is phylogenetically distinct from the other ERV classes. We have also identified two instances of gene capture by Crocodilian ERVs, one of which, the capture of a host KIT-ligand mRNA has occurred without the loss of an ERV domain. Conclusions This study indicates that Crocodilian ERVs comprise a wide variety of lineages, many of which appear to reflect ancient infections. In particular, ERV4 appears to have a limited host range, with current data suggesting that it is confined to Crocodilians and some lineages of turtles. Also of interest are two ERV groups that demonstrate evidence of host gene capture. This study provides a framework to facilitate further studies into non-mammalian vertebrates and highlights the need for further studies into such species.
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Evolution and gene capture in ancient endogenous retroviruses - insights from the Crocodilian genomes
Retrovirology, 2014Co-Authors: Amanda Y Chong, Sally R Isberg, Kenji K Kojima, Jerzy Jurka, Arian F A Smit, Jaime GongoraAbstract:Background Crocodilians are thought to be hosts to a diverse and divergent complement of endogenous retroviruses (ERVs) but a comprehensive investigation is yet to be performed. The recent sequencing of three Crocodilian genomes provides an opportunity for a more detailed and accurate representation of the ERV diversity that is present in these species. Here we investigate the diversity, distribution and evolution of ERVs from the genomes of three key Crocodilian species, and outline the key processes driving Crocodilian ERV proliferation and evolution. Results ERVs and ERV related sequences make up less than 2% of Crocodilian genomes. We recovered and described 45 ERV groups within the three Crocodilian genomes, many of which are species specific. We have also revealed a new class of ERV, ERV4, which appears to be common to Crocodilians and turtles, and currently has no characterised exogenous counterpart. For the first time, we formally describe the characteristics of this ERV class and its classification relative to other recognised ERV and retroviral classes. This class shares some sequence similarity and sequence characteristics with ERV3, although it is phylogenetically distinct from the other ERV classes. We have also identified two instances of gene capture by Crocodilian ERVs, one of which, the capture of a host KIT-ligand mRNA has occurred without the loss of an ERV domain. Conclusions This study indicates that Crocodilian ERVs comprise a wide variety of lineages, many of which appear to reflect ancient infections. In particular, ERV4 appears to have a limited host range, with current data suggesting that it is confined to Crocodilians and some lineages of turtles. Also of interest are two ERV groups that demonstrate evidence of host gene capture. This study provides a framework to facilitate further studies into non-mammalian vertebrates and highlights the need for further studies into such species.
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Evolution and gene capture in ancient endogenous retroviruses - insights from the Crocodilian genomes
Retrovirology, 2014Co-Authors: Amanda Y Chong, Sally R Isberg, Kenji K Kojima, Jerzy Jurka, David A Ray, Arian F A Smit, Jaime GongoraAbstract:Background Crocodilians are thought to be hosts to a diverse and divergent complement of endogenous retroviruses (ERVs) but a comprehensive investigation is yet to be performed. The recent sequencing of three Crocodilian genomes provides an opportunity for a more detailed and accurate representation of the ERV diversity that is present in these species. Here we investigate the diversity, distribution and evolution of ERVs from the genomes of three key Crocodilian species, and outline the key processes driving Crocodilian ERV proliferation and evolution.
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Cross-species amplification of microsatellites in Crocodilians: assessment and applications for the future
Conservation Genetics, 2009Co-Authors: Lee G Miles, Chris Moran, Stacey L. Lance, Sally R Isberg, Travis C GlennAbstract:Microsatellite DNA loci have emerged as the dominant genetic tool for addressing questions associated with genetic diversity in many wildlife species, including Crocodilians. Despite their usefulness, their isolation and development can be costly, as well as labour intensive, limiting their wider use in many Crocodilian species. In this study, we investigate the cross-species amplification success of 82 existing microsatellites previously isolated for the saltwater crocodile ( Crocodylus porosus ) in 18 non-target Crocodilian species; Alligator sinensis , Caiman crocodylus , Caiman latirostris , Caiman yacare , Melanosuchus niger , Paleosuchus palpebrosus , Crocodylus acutus , Mecistops cataphractus , Crocodylus intermedius , Crocodylus johnstoni , Crocodylus mindorensis , Crocodylus moreletii , Crocodylus niloticus , Crocodylus novaeguineae , Crocodylus palustis , Crocodylus rhombifer , Crocodylus siamensis , and Osteolaemus tetraspis . Our results show a high level of microsatellites cross-amplification making available polymorphic markers for a range of Crocodilian species previously lacking informative genetic markers.
Jaime Gongora - One of the best experts on this subject based on the ideXlab platform.
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Surveys of endogenous retroviruses (ERVs) in the freshwater crocodile ( Crocodylus johnstoni ) suggest that ERVs in Crocodylus spp. vary between species
Virus Genes, 2015Co-Authors: Amanda Y Chong, Shannon R. Kjeldsen, Jaime GongoraAbstract:Endogenous retroviruses (ERVs) are one of many families of transposable elements present in vertebrate genomes. We have examined the ERV complement of the freshwater crocodile (Crocodylus johnstoni) in order to investigate the diversity of ERVs present and possibility of ERV or retroviral activity in a diseased individual of this species. Amplification and sequencing of the highly conserved retroviral pro-pol domains revealed high levels of sequence variation in these ERVs. Phylogenetic analyses of these ERVs and those previously identified in other Crocodilian species suggest that although many Crocodilians share the same ERV lineages, the relative numbers of retroelement insertions from each of these lineages may vary greatly between species. The data generated in this study provide evidence for the presence of a unique and varied complement of ERVs in Crocodilians. This study has also demonstrated the presence of species-specific evolution in ancient retroviral infections.
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Evolution and gene capture in ancient endogenous retroviruses - insights from the Crocodilian genomes
Retrovirology, 2014Co-Authors: Amanda Y Chong, Sally R Isberg, Kenji K Kojima, Jerzy Jurka, David A Ray, Arian F A Smit, Jaime GongoraAbstract:Background Crocodilians are thought to be hosts to a diverse and divergent complement of endogenous retroviruses (ERVs) but a comprehensive investigation is yet to be performed. The recent sequencing of three Crocodilian genomes provides an opportunity for a more detailed and accurate representation of the ERV diversity that is present in these species. Here we investigate the diversity, distribution and evolution of ERVs from the genomes of three key Crocodilian species, and outline the key processes driving Crocodilian ERV proliferation and evolution. Results ERVs and ERV related sequences make up less than 2% of Crocodilian genomes. We recovered and described 45 ERV groups within the three Crocodilian genomes, many of which are species specific. We have also revealed a new class of ERV, ERV4, which appears to be common to Crocodilians and turtles, and currently has no characterised exogenous counterpart. For the first time, we formally describe the characteristics of this ERV class and its classification relative to other recognised ERV and retroviral classes. This class shares some sequence similarity and sequence characteristics with ERV3, although it is phylogenetically distinct from the other ERV classes. We have also identified two instances of gene capture by Crocodilian ERVs, one of which, the capture of a host KIT-ligand mRNA has occurred without the loss of an ERV domain. Conclusions This study indicates that Crocodilian ERVs comprise a wide variety of lineages, many of which appear to reflect ancient infections. In particular, ERV4 appears to have a limited host range, with current data suggesting that it is confined to Crocodilians and some lineages of turtles. Also of interest are two ERV groups that demonstrate evidence of host gene capture. This study provides a framework to facilitate further studies into non-mammalian vertebrates and highlights the need for further studies into such species.
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Evolution and gene capture in ancient endogenous retroviruses - insights from the Crocodilian genomes
Retrovirology, 2014Co-Authors: Amanda Y Chong, Sally R Isberg, Kenji K Kojima, Jerzy Jurka, Arian F A Smit, Jaime GongoraAbstract:Background Crocodilians are thought to be hosts to a diverse and divergent complement of endogenous retroviruses (ERVs) but a comprehensive investigation is yet to be performed. The recent sequencing of three Crocodilian genomes provides an opportunity for a more detailed and accurate representation of the ERV diversity that is present in these species. Here we investigate the diversity, distribution and evolution of ERVs from the genomes of three key Crocodilian species, and outline the key processes driving Crocodilian ERV proliferation and evolution. Results ERVs and ERV related sequences make up less than 2% of Crocodilian genomes. We recovered and described 45 ERV groups within the three Crocodilian genomes, many of which are species specific. We have also revealed a new class of ERV, ERV4, which appears to be common to Crocodilians and turtles, and currently has no characterised exogenous counterpart. For the first time, we formally describe the characteristics of this ERV class and its classification relative to other recognised ERV and retroviral classes. This class shares some sequence similarity and sequence characteristics with ERV3, although it is phylogenetically distinct from the other ERV classes. We have also identified two instances of gene capture by Crocodilian ERVs, one of which, the capture of a host KIT-ligand mRNA has occurred without the loss of an ERV domain. Conclusions This study indicates that Crocodilian ERVs comprise a wide variety of lineages, many of which appear to reflect ancient infections. In particular, ERV4 appears to have a limited host range, with current data suggesting that it is confined to Crocodilians and some lineages of turtles. Also of interest are two ERV groups that demonstrate evidence of host gene capture. This study provides a framework to facilitate further studies into non-mammalian vertebrates and highlights the need for further studies into such species.
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Evolution and gene capture in ancient endogenous retroviruses - insights from the Crocodilian genomes
Retrovirology, 2014Co-Authors: Amanda Y Chong, Sally R Isberg, Kenji K Kojima, Jerzy Jurka, David A Ray, Arian F A Smit, Jaime GongoraAbstract:Background Crocodilians are thought to be hosts to a diverse and divergent complement of endogenous retroviruses (ERVs) but a comprehensive investigation is yet to be performed. The recent sequencing of three Crocodilian genomes provides an opportunity for a more detailed and accurate representation of the ERV diversity that is present in these species. Here we investigate the diversity, distribution and evolution of ERVs from the genomes of three key Crocodilian species, and outline the key processes driving Crocodilian ERV proliferation and evolution.
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Distribution of Endogenous Retroviruses in Crocodilians
Journal of Virology, 2009Co-Authors: Weerachai Jaratlerdsiri, Clara J. Rodríguez-zárate, Chandramaya Siska Damayanti, Lee G Miles, Nantarika Chansue, Chris Moran, Lorna Melville, Sally R Isberg, Jaime GongoraAbstract:Knowledge of endogenous retroviruses (ERVs) in Crocodilians (Crocodylia) is limited, and their distribution among extant species is unclear. Here we analyzed the phylogenetic relationships of these retroelements in 20 species of Crocodilians by studying the pro-pol gene. The results showed that Crocodilian ERVs (CERVs) cluster into two major clades (CERV 1 and CERV 2). CERV 1 clustered as a sister group of the genus Gammaretrovirus, while CERV 2 clustered distantly with respect to all known ERVs. Interestingly, CERV 1 was found only in crocodiles (Crocodylidae). The data generated here could assist future studies aimed at identifying orthologous and paralogous ERVs among Crocodilians.
Nicolas Mathevon - One of the best experts on this subject based on the ideXlab platform.
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Size does matter: crocodile mothers react more to the voice of smaller offspring
Scientific Reports, 2015Co-Authors: T. Chabert, Thierry Aubin, Ruth M. Elsey, Amy Colin, V. Shacks, Stéphane L. Bourquin, Jesús D. González-acosta, Nicolas MathevonAbstract:Parental care is widespread in Archosaurs (birds, Crocodilians, dinosaurs and pterosaurs), and this group provides a useful model for the evolution of parent-offspring interactions. While offspring signalling has been well-studied in birds, the modulation of parental care in Crocodilians remains an open question. Here we show that acoustic communication has a key role in the dynamics of Crocodilian' mother-offspring relationships. We found embedded information about the emitter's size in juvenile calls of several species, and experimentally demonstrated that Nile crocodile mothers breeding in the wild are less receptive to the calls of larger juveniles. Using synthetized sounds, we further showed that female' reaction depends on call pitch, an important cue bearing size information. Changes in acoustic interactions may thus go with the break of maternal care as well as dispersal of juvenile Crocodilians. This process could have characterized other archosaurs displaying rapid early growth such as dinosaurs and pterosaurs.
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Acoustic communication in Crocodilians: information encoding and species specificity of juvenile calls
Animal Cognition, 2012Co-Authors: Amélie L. Vergne, Samuel Martin, Thierry Aubin, Nicolas MathevonAbstract:In the Crocodylia order, all species are known for their ability to produce sounds in several communication contexts. Though recent experimental studies have brought evidence of the important biological role of young Crocodilian calls, especially at hatching time, the juvenile vocal repertoire still needs to be clarified in order to describe thoroughly the Crocodilian acoustic communication channel. The goal of this study is to investigate the acoustic features (structure and information coding) in the contact call of juveniles from three different species (Nile crocodile Crocodylus niloticus , Black caiman, Melanosuchus niger and Spectacled caiman, Caiman crocodilus ). We have shown that even though substantial structural differences exist between the calls of different species, they do not seem relevant for Crocodilians. Indeed, juveniles and adults from the species studied use a similar and non-species-specific way of encoding information, which relies on frequency modulation parameters. Interestingly, using conditioning experiments, we demonstrated that this tolerance in responses to signals of different acoustic structures was unlikely to be related to a lack of discriminatory abilities. This result reinforced the idea that Crocodilians have developed adaptations to use sounds efficiently for communication needs.
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Acoustic communication in Crocodilians : Information coding and species-specificity of juvenile calls.
Animal Cognition, 2012Co-Authors: Amélie L. Vergne, Samuel Martin, Thierry Aubin, Nicolas MathevonAbstract:In the Crocodylia order, all species are known for their ability to produce sounds in several communication contexts. Though recent experimental studies have brought evidence of the important biological role of young Crocodilian calls, especially at hatching time, the juvenile vocal repertoire still needs to be clarified in order to describe thoroughly the Crocodilian acoustic communication channel. The goal of this study is to investigate the acoustic features (structure and information coding) in the contact call of juveniles from three different species (Nile crocodile Crocodylus niloticus , Black caiman, Melanosuchus niger and Spectacled caiman, Caiman crocodilus ). We have shown that even though substantial structural differences exist between the calls of different species, they do not seem relevant for Crocodilians. Indeed, juveniles and adults from the species studied use a similar and non-species-specific way of encoding information, which relies on frequency modulation parameters. Interestingly, using conditioning experiments, we demonstrated that this tolerance in responses to signals of different acoustic structures was unlikely to be related to a lack of discriminatory abilities. This result reinforced the idea that Crocodilians have developed adaptations to use sounds efficiently for communication needs.
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Acoustic communication in crocodiles
2012Co-Authors: Nicolas MathevonAbstract:All species of crocodiles are known for their ability to produce sounds in several communication contexts. However and despite the importance of sound communication in the life of Crocodilians, knowledge about their vocal world remains superficial. This paper aims to present recent advances in our understanding of crocodile bioacoustics. Through experiments both in the laboratory and the field , we have brought evidence of the biological role of young Crocodilian calls, especially at hatching time and later on during mother-offspring interactions. By analyzing the acoustic structure of emitted signals and by using playback experiments with modified signals, it has also been possible to identify the relevant acoustic cues that elicit behavioral responses of offspring and mothers. It is now time to do more comparative research among Crocodilian species.
Lee G Miles - One of the best experts on this subject based on the ideXlab platform.
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Cross-species amplification of microsatellites in Crocodilians: assessment and applications for the future
Conservation Genetics, 2009Co-Authors: Lee G Miles, Chris Moran, Stacey L. Lance, Sally R Isberg, Travis C GlennAbstract:Microsatellite DNA loci have emerged as the dominant genetic tool for addressing questions associated with genetic diversity in many wildlife species, including Crocodilians. Despite their usefulness, their isolation and development can be costly, as well as labour intensive, limiting their wider use in many Crocodilian species. In this study, we investigate the cross-species amplification success of 82 existing microsatellites previously isolated for the saltwater crocodile ( Crocodylus porosus ) in 18 non-target Crocodilian species; Alligator sinensis , Caiman crocodylus , Caiman latirostris , Caiman yacare , Melanosuchus niger , Paleosuchus palpebrosus , Crocodylus acutus , Mecistops cataphractus , Crocodylus intermedius , Crocodylus johnstoni , Crocodylus mindorensis , Crocodylus moreletii , Crocodylus niloticus , Crocodylus novaeguineae , Crocodylus palustis , Crocodylus rhombifer , Crocodylus siamensis , and Osteolaemus tetraspis . Our results show a high level of microsatellites cross-amplification making available polymorphic markers for a range of Crocodilian species previously lacking informative genetic markers.
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a genetic linkage map for the saltwater crocodile crocodylus porosus
BMC Genomics, 2009Co-Authors: Lee G Miles, Pauline Dalzell, P C Thomson, Stacey L. Lance, Sally R Isberg, Travis C Glenn, C MoranAbstract:Genome elucidation is now in high gear for many organisms, and whilst genetic maps have been developed for a broad array of species, surprisingly, no such maps exist for a Crocodilian, or indeed any other non-avian member of the Class Reptilia. Genetic linkage maps are essential tools for the mapping and dissection of complex quantitative trait loci (QTL), and in order to permit systematic genome scans for the identification of genes affecting economically important traits in farmed Crocodilians, a comprehensive genetic linage map will be necessary. A first-generation genetic linkage map for the saltwater crocodile (Crocodylus porosus) was constructed using 203 microsatellite markers amplified across a two-generation pedigree comprising ten full-sib families from a commercial population at Darwin Crocodile Farm, Northern Territory, Australia. Linkage analyses identified fourteen linkage groups comprising a total of 180 loci, with 23 loci remaining unlinked. Markers were ordered within linkage groups employing a heuristic approach using CRIMAP v3.0 software. The estimated female and male recombination map lengths were 1824.1 and 319.0 centimorgans (cM) respectively, revealing an uncommonly large disparity in recombination map lengths between sexes (ratio of 5.7:1). We have generated the first genetic linkage map for a Crocodilian, or indeed any other non-avian reptile. The uncommonly large disparity in recombination map lengths confirms previous preliminary evidence of major differences in sex-specific recombination rates in a species that exhibits temperature-dependent sex determination (TSD). However, at this point the reason for this disparity in saltwater crocodiles remains unclear. This map will be a valuable resource for Crocodilian researchers, facilitating the systematic genome scans necessary for identifying genes affecting complex traits of economic importance in the crocodile industry. In addition, since many of the markers placed on this genetic map have been evaluated in up to 18 other extant species of Crocodilian, this map will be of intrinsic value to comparative mapping efforts aimed at understanding genome content and organization among Crocodilians, as well as the molecular evolution of reptilian and other amniote genomes. As researchers continue to work towards elucidation of the Crocodilian genome, this first generation map lays the groundwork for more detailed mapping investigations, as well as providing a valuable scaffold for future genome sequence assembly.
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Distribution of Endogenous Retroviruses in Crocodilians
Journal of Virology, 2009Co-Authors: Weerachai Jaratlerdsiri, Clara J. Rodríguez-zárate, Chandramaya Siska Damayanti, Lee G Miles, Nantarika Chansue, Chris Moran, Lorna Melville, Sally R Isberg, Jaime GongoraAbstract:Knowledge of endogenous retroviruses (ERVs) in Crocodilians (Crocodylia) is limited, and their distribution among extant species is unclear. Here we analyzed the phylogenetic relationships of these retroelements in 20 species of Crocodilians by studying the pro-pol gene. The results showed that Crocodilian ERVs (CERVs) cluster into two major clades (CERV 1 and CERV 2). CERV 1 clustered as a sister group of the genus Gammaretrovirus, while CERV 2 clustered distantly with respect to all known ERVs. Interestingly, CERV 1 was found only in crocodiles (Crocodylidae). The data generated here could assist future studies aimed at identifying orthologous and paralogous ERVs among Crocodilians.
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Distribution of Endogenous Retroviruses in Crocodilians
Journal of Virology, 2009Co-Authors: Weerachai Jaratlerdsiri, Clara J. Rodríguez-zárate, Chandramaya Siska Damayanti, Lee G Miles, Nantarika Chansue, Chris Moran, Lorna Melville, Sally R Isberg, Jaime GongoraAbstract:Knowledge of endogenous retroviruses (ERVs) in Crocodilians (Crocodylia) is limited, and their distribution among extant species is unclear. Here we analyzed the phylogenetic relationships of these retroelements in 20 species of Crocodilians by studying the pro-pol gene. The results showed that Crocodilian ERVs (CERVs) cluster into two major clades (CERV 1 and CERV 2). CERV 1 clustered as a sister group of the genus Gammaretrovirus, while CERV 2 clustered distantly with respect to all known ERVs. Interestingly, CERV 1 was found only in crocodiles (Crocodylidae). The data generated here could assist future studies aimed at identifying orthologous and paralogous ERVs among Crocodilians.
William E Magnusson - One of the best experts on this subject based on the ideXlab platform.
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Opportunistic top predators partition food resources in a tropical freshwater ecosystem
Freshwater Biology, 2017Co-Authors: Francisco Villamarín, Boris Marioni, Timothy D. Jardine, Stuart E. Bunn, William E MagnussonAbstract:The structure of food webs may be strongly influenced by the distribution of top predators in space and time. The Amazon biome is the only region in the world where four alligatorid species are known to occur in sympatry, and they attain high densities in some regions. As top predators with a diverse range of prey species occupying different trophic levels, their impact upon food webs should be substantial, but the degree to which Crocodilians differ in their food sources, and potentially avoid competitive exclusion where they occur syntopically is not well understood. Although most Crocodilians are considered generalist opportunistic predators that feed on any source of protein available in the environment, Amazonian Crocodilians show broad differences in the proportions of prey items they consume. It is believed that these differences may in part reflect habitat use, but it is unknown to what extent they represent interspecific differences in prey preferences or are a direct function of habitat selection. Stable carbon isotope data (δ13C) of Crocodilians and their potential prey were used to assess differences in reliance on terrestrial versus aquatic resources. These data were then placed in a spatial context using classified maps that reflect habitat types (headwater streams, mid-order flooded-forest streams and varzea floodplains) to elucidate whether dietary differences are explained by habitat selection or are more likely a reflection of prey preferences. We found evidence for differences in types of basal resources supporting these Crocodilians. Mean δ13C values were highest in Paleosuchus trigonatus (Schneider's dwarf caiman, −25.7 ± 1.2‰), intermediate in Caiman crocodilus (spectacled caiman, −27.4 ± 1.2‰) and Paleosuchus palpebrosus (Cuvier's dwarf caiman, −27.7 ± 1.1‰) and lowest in Melanosuchus niger (black caiman, −29.9 ± 1.3‰). A progressive decrease in δ13C values of Crocodilian tissues occurred from headwaters to floodplains, which most likely reflects a progressive increase in autochthonous over allochthonous inputs in lower reaches of streams. The shift from terrestrial to aquatic resources sustaining these sympatric predators mirrors their spatial distribution along this ecotone. However, after taking into account the habitat in which pairs of syntopic individuals of distinct species occurred, significant differences in δ13C values suggest that P. trigonatus and P. palpebrosus have different prey bases. Thus, despite being opportunistic predators, our results show that differences in Crocodilian diets likely result from prey preferences and not only from habitat selection. These findings suggest that some species of Crocodilians may be less generalist than traditionally thought and their influence on terrestrial or aquatic food webs might be species specific.
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density and biomass estimates by removal for an amazonian Crocodilian paleosuchus palpebrosus
PLOS ONE, 2016Co-Authors: Z. Campos, William E MagnussonAbstract:Direct counts of Crocodilians are rarely feasible and it is difficult to meet the assumptions of mark-recapture methods for most species in most habitats. Catch-out experiments are also usually not logistically or morally justifiable because it would be necessary to destroy the habitat in order to be confident that most individuals had been captured. We took advantage of the draining and filling of a large area of flooded forest during the building of the Santo Antonio dam on the Madeira River to obtain accurate estimates of the density and biomass of Paleosuchus palpebrosus. The density, 28.4 non-hatchling individuals per km2, is one of the highest reported for any Crocodilian, except for species that are temporarily concentrated in small areas during dry-season drought. The biomass estimate of 63.15 kg*km-2 is higher than that for most or even all mammalian carnivores in tropical forest. P. palpebrosus may be one of the World´s most abundant Crocodilians.