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Zilca Campos - One of the best experts on this subject based on the ideXlab platform.
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evidence of cryptic lineages within a small south american crocodilian the schneider s dwarf caiman Paleosuchus trigonatus alligatoridae caimaninae
PeerJ, 2019Co-Authors: Boris Marioni, Zilca Campos, Fabio Muniz, B. C. Souza, Pedro Senna Bittencourt, Ronis Da Silveira, Benoit De Thoisy, Tomas HrbekAbstract:: Schneider's dwarf caiman Paleosuchus trigonatus is one of the smallest living crocodilians. Due to its broad distribution, cryptic behavior, and small home range, the species is well suited for the study of phylogeographic patterns on a continental scale. Additionally, this species is under threat due to habitat loss, trade and harvest, but is considered at low conservation risk by the IUCN. In the present study we test the hypothesis that P. trigonatus is comprised of geographically structured lineages. Phylogenetic reconstructions of the mitochondrial cytochrome b gene and single locus species discovery methods revealed the existence of two well-supported lineages within P. trigonatus-an Amazonian and Guianan lineage. Fossil calibrated divergence of these lineages was estimated to have occurred in the Late Miocene (7.5 Ma). The hypothesis that the Atlantic coast drainages might have been colonized from the southeast or central Amazon is supported by demographic metrics and relatively low genetic diversity of the Coastal and upper Branco populations when compared to the Amazon basin populations. The Amazon basin lineage is structured along an east-west gradient, with a sharp transition in haplotype frequencies to the east and west of the Negro and Madeira rivers. These lineages are already under anthropogenic threat and, therefore, are conservation dependent. Recognition of these lineages will foster discussion of conservation future of P. trigonatus and these lineages.
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Asynchronous reproduction in three species of crocodilians in south-eastern Amazonia
Journal of Natural History, 2019Co-Authors: Zilca Campos, Fabio Muniz, William E MagnussonAbstract:We studied reproduction of three species of crocodilians, Paleosuchus trigonatus, Caiman crocodilus and Melanosuchus niger, in the Xingu River, near the Belo Monte hydroelectric dam. The periods of laying and hatching of eggs were estimated for each nest before (2013–2014) and after (2016–2017) the river was dammed and the reservoir was formed. Nesting of the three species occurred between August and December, but was largely asynchronous; nest construction peaked in September for P. trigonatus, October for M. niger and November for C. crocodilus. Reservoir filling had little effect on the laying period of any of the species. Nests of P. trigonatus and M. niger were always within 0–12 m of the bank, whereas nests of C. crocodilus, which nests later in the season when flooding is more likely, were up to 100 m from the nearest water body. There was no relationship between distance from water and the number of eggs in nests, suggesting that larger and presumably more experienced females do not lay at different distances from the bank in any of the species.
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delimitation of evolutionary units in cuvier s dwarf caiman Paleosuchus palpebrosus cuvier 1807 insights from conservation of a broadly distributed species
Conservation Genetics, 2018Co-Authors: Fabio Muniz, Zilca Campos, Tomas Hrbek, J. G. Martínez, B. C. Souza, B. Thoisy, S Hernandez M Rangel, R Boteroarias, Izeni Pires FariasAbstract:An important goal of evolutionary and conservation biology is the identification of units below the species level, such as Evolutionarily Significant Units (ESUs), providing objectively delimited units for species conservation and management. In this study we tested the hypothesis that Cuvier’s dwarf caiman (Paleosuchus palpebrosus)—a species broadly distributed across several biomes and watersheds of South America—is comprised of different ESUs. We analyzed mitochondrial cytochrome b sequences of 206 individuals and 532 unlinked ddRAD loci of 20 individuals chosen from amongst the mitochondrial haplogroups. Analysis of the cytochrome b sequences revealed four mitochondrial clusters, while STRUCTURE analysis of ddRAD loci detected three genomic clusters with different levels of mixture between them. Using the Adaptive Evolutionary Conservation (AEC) framework we identified three ESUs: “Amazon”, “Madeira-Bolivia” and “Pantanal”; one of them composed of two different Management Units (MUs), “Madeira” and “Bolivia”. In general, based on the comparisons with other crocodilian species, genetic diversity of each lineage was moderate however, the Madeira MU showed fivefold lower genetic diversity than other geographic groups. Considering the particularities of each Paleosuchus palpebrosus conservation unit, we recommend that the conservation status of each is evaluated separately. Tropical biodiversity is largely underestimated and in this context the broadly distributed species are the most likely candidates to harbor distinct evolutionary lineages. Thus, we suggest that conservation research should not neglect species that are generally considered of Least Concern by IUCN due to the taxon’s broad geographic distribution.
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extension of the geographical distribution of schneider s dwarf caiman Paleosuchus trigonatus schneider 1801 crocodylia alligatoridae in the amazon cerrado transition brazil
Check List, 2017Co-Authors: Zilca Campos, Fabio Muniz, William E MagnussonAbstract:This text present new records of occurrence of Schneider?s Dwarf Caiman, Paleosuchus trigonatus and extend its geographical distribution. Eight individuals were caught in the following locations: Sangue River, in the municipality of Campo Novo dos Parecis, Claro River and Marapi River, in the municipality of Sao Jose do Rio Claro, and tributaries of the Juruena River, in the state of Mato Grosso, Brazil. These records extend the geographical distribution of the species nearly 500 km south of the limit given in published range maps.
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the effect of dam construction on the movement of dwarf caimans Paleosuchus trigonatus and Paleosuchus palpebrosus in brazilian amazonia
PLOS ONE, 2017Co-Authors: Zilca Campos, Guilherme Mourao, William E MagnussonAbstract:Run-of-the-river hydroelectric dams cause changes in seasonal inundation of the floodplains, and this may cause displacement of semi-aquatic vertebrates present before dam construction. This study evaluated the movement of crocodilians before and after the filling of the Santo Antonio hydroelectric reservoir on the Madeira River in the Brazilian Amazon, which occurred in November 2011. We radio-tracked four adult male Paleosuchus palpebrosus and four adult male Paleosuchus trigonatus before and after the formation of the reservoir between 2011 and 2013. The home ranges of the P. palpebrosus varied from < 1 km2 to 91 km2 and the home ranges of the P. trigonatus varied from < 1km2 to 5 km2. The species responded differently to time since filling and water level in weekly movement and home range. However, overall the dam appears to have had little effect on the use of space by the individuals that were present before dam construction.
William E Magnusson - One of the best experts on this subject based on the ideXlab platform.
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Asynchronous reproduction in three species of crocodilians in south-eastern Amazonia
Journal of Natural History, 2019Co-Authors: Zilca Campos, Fabio Muniz, William E MagnussonAbstract:We studied reproduction of three species of crocodilians, Paleosuchus trigonatus, Caiman crocodilus and Melanosuchus niger, in the Xingu River, near the Belo Monte hydroelectric dam. The periods of laying and hatching of eggs were estimated for each nest before (2013–2014) and after (2016–2017) the river was dammed and the reservoir was formed. Nesting of the three species occurred between August and December, but was largely asynchronous; nest construction peaked in September for P. trigonatus, October for M. niger and November for C. crocodilus. Reservoir filling had little effect on the laying period of any of the species. Nests of P. trigonatus and M. niger were always within 0–12 m of the bank, whereas nests of C. crocodilus, which nests later in the season when flooding is more likely, were up to 100 m from the nearest water body. There was no relationship between distance from water and the number of eggs in nests, suggesting that larger and presumably more experienced females do not lay at different distances from the bank in any of the species.
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extension of the geographical distribution of schneider s dwarf caiman Paleosuchus trigonatus schneider 1801 crocodylia alligatoridae in the amazon cerrado transition brazil
Check List, 2017Co-Authors: Zilca Campos, Fabio Muniz, William E MagnussonAbstract:This text present new records of occurrence of Schneider?s Dwarf Caiman, Paleosuchus trigonatus and extend its geographical distribution. Eight individuals were caught in the following locations: Sangue River, in the municipality of Campo Novo dos Parecis, Claro River and Marapi River, in the municipality of Sao Jose do Rio Claro, and tributaries of the Juruena River, in the state of Mato Grosso, Brazil. These records extend the geographical distribution of the species nearly 500 km south of the limit given in published range maps.
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the effect of dam construction on the movement of dwarf caimans Paleosuchus trigonatus and Paleosuchus palpebrosus in brazilian amazonia
PLOS ONE, 2017Co-Authors: Zilca Campos, Guilherme Mourao, William E MagnussonAbstract:Run-of-the-river hydroelectric dams cause changes in seasonal inundation of the floodplains, and this may cause displacement of semi-aquatic vertebrates present before dam construction. This study evaluated the movement of crocodilians before and after the filling of the Santo Antonio hydroelectric reservoir on the Madeira River in the Brazilian Amazon, which occurred in November 2011. We radio-tracked four adult male Paleosuchus palpebrosus and four adult male Paleosuchus trigonatus before and after the formation of the reservoir between 2011 and 2013. The home ranges of the P. palpebrosus varied from < 1 km2 to 91 km2 and the home ranges of the P. trigonatus varied from < 1km2 to 5 km2. The species responded differently to time since filling and water level in weekly movement and home range. However, overall the dam appears to have had little effect on the use of space by the individuals that were present before dam construction.
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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: Zilca 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.
Fabio Muniz - One of the best experts on this subject based on the ideXlab platform.
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evidence of cryptic lineages within a small south american crocodilian the schneider s dwarf caiman Paleosuchus trigonatus alligatoridae caimaninae
PeerJ, 2019Co-Authors: Boris Marioni, Zilca Campos, Fabio Muniz, B. C. Souza, Pedro Senna Bittencourt, Ronis Da Silveira, Benoit De Thoisy, Tomas HrbekAbstract:: Schneider's dwarf caiman Paleosuchus trigonatus is one of the smallest living crocodilians. Due to its broad distribution, cryptic behavior, and small home range, the species is well suited for the study of phylogeographic patterns on a continental scale. Additionally, this species is under threat due to habitat loss, trade and harvest, but is considered at low conservation risk by the IUCN. In the present study we test the hypothesis that P. trigonatus is comprised of geographically structured lineages. Phylogenetic reconstructions of the mitochondrial cytochrome b gene and single locus species discovery methods revealed the existence of two well-supported lineages within P. trigonatus-an Amazonian and Guianan lineage. Fossil calibrated divergence of these lineages was estimated to have occurred in the Late Miocene (7.5 Ma). The hypothesis that the Atlantic coast drainages might have been colonized from the southeast or central Amazon is supported by demographic metrics and relatively low genetic diversity of the Coastal and upper Branco populations when compared to the Amazon basin populations. The Amazon basin lineage is structured along an east-west gradient, with a sharp transition in haplotype frequencies to the east and west of the Negro and Madeira rivers. These lineages are already under anthropogenic threat and, therefore, are conservation dependent. Recognition of these lineages will foster discussion of conservation future of P. trigonatus and these lineages.
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Asynchronous reproduction in three species of crocodilians in south-eastern Amazonia
Journal of Natural History, 2019Co-Authors: Zilca Campos, Fabio Muniz, William E MagnussonAbstract:We studied reproduction of three species of crocodilians, Paleosuchus trigonatus, Caiman crocodilus and Melanosuchus niger, in the Xingu River, near the Belo Monte hydroelectric dam. The periods of laying and hatching of eggs were estimated for each nest before (2013–2014) and after (2016–2017) the river was dammed and the reservoir was formed. Nesting of the three species occurred between August and December, but was largely asynchronous; nest construction peaked in September for P. trigonatus, October for M. niger and November for C. crocodilus. Reservoir filling had little effect on the laying period of any of the species. Nests of P. trigonatus and M. niger were always within 0–12 m of the bank, whereas nests of C. crocodilus, which nests later in the season when flooding is more likely, were up to 100 m from the nearest water body. There was no relationship between distance from water and the number of eggs in nests, suggesting that larger and presumably more experienced females do not lay at different distances from the bank in any of the species.
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schneider s smooth fronted caiman Paleosuchus trigonatus
2019Co-Authors: Z M Da S Campos, W E Magnusson, Fabio MunizAbstract:Conservation Overview; Ecology and Natural History; Conservation and Status; Priority Projects.
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cuvier s smooth fronted caiman Paleosuchus palpebrosus
2019Co-Authors: Z M Da S Campos, W E Magnusson, Fabio MunizAbstract:Conservation Overview; Ecology and Natural History; Conservation and Status; Priority Projects.
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delimitation of evolutionary units in cuvier s dwarf caiman Paleosuchus palpebrosus cuvier 1807 insights from conservation of a broadly distributed species
Conservation Genetics, 2018Co-Authors: Fabio Muniz, Zilca Campos, Tomas Hrbek, J. G. Martínez, B. C. Souza, B. Thoisy, S Hernandez M Rangel, R Boteroarias, Izeni Pires FariasAbstract:An important goal of evolutionary and conservation biology is the identification of units below the species level, such as Evolutionarily Significant Units (ESUs), providing objectively delimited units for species conservation and management. In this study we tested the hypothesis that Cuvier’s dwarf caiman (Paleosuchus palpebrosus)—a species broadly distributed across several biomes and watersheds of South America—is comprised of different ESUs. We analyzed mitochondrial cytochrome b sequences of 206 individuals and 532 unlinked ddRAD loci of 20 individuals chosen from amongst the mitochondrial haplogroups. Analysis of the cytochrome b sequences revealed four mitochondrial clusters, while STRUCTURE analysis of ddRAD loci detected three genomic clusters with different levels of mixture between them. Using the Adaptive Evolutionary Conservation (AEC) framework we identified three ESUs: “Amazon”, “Madeira-Bolivia” and “Pantanal”; one of them composed of two different Management Units (MUs), “Madeira” and “Bolivia”. In general, based on the comparisons with other crocodilian species, genetic diversity of each lineage was moderate however, the Madeira MU showed fivefold lower genetic diversity than other geographic groups. Considering the particularities of each Paleosuchus palpebrosus conservation unit, we recommend that the conservation status of each is evaluated separately. Tropical biodiversity is largely underestimated and in this context the broadly distributed species are the most likely candidates to harbor distinct evolutionary lineages. Thus, we suggest that conservation research should not neglect species that are generally considered of Least Concern by IUCN due to the taxon’s broad geographic distribution.
Izeni Pires Farias - One of the best experts on this subject based on the ideXlab platform.
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delimitation of evolutionary units in cuvier s dwarf caiman Paleosuchus palpebrosus cuvier 1807 insights from conservation of a broadly distributed species
Conservation Genetics, 2018Co-Authors: Fabio Muniz, Zilca Campos, Tomas Hrbek, J. G. Martínez, B. C. Souza, B. Thoisy, S Hernandez M Rangel, R Boteroarias, Izeni Pires FariasAbstract:An important goal of evolutionary and conservation biology is the identification of units below the species level, such as Evolutionarily Significant Units (ESUs), providing objectively delimited units for species conservation and management. In this study we tested the hypothesis that Cuvier’s dwarf caiman (Paleosuchus palpebrosus)—a species broadly distributed across several biomes and watersheds of South America—is comprised of different ESUs. We analyzed mitochondrial cytochrome b sequences of 206 individuals and 532 unlinked ddRAD loci of 20 individuals chosen from amongst the mitochondrial haplogroups. Analysis of the cytochrome b sequences revealed four mitochondrial clusters, while STRUCTURE analysis of ddRAD loci detected three genomic clusters with different levels of mixture between them. Using the Adaptive Evolutionary Conservation (AEC) framework we identified three ESUs: “Amazon”, “Madeira-Bolivia” and “Pantanal”; one of them composed of two different Management Units (MUs), “Madeira” and “Bolivia”. In general, based on the comparisons with other crocodilian species, genetic diversity of each lineage was moderate however, the Madeira MU showed fivefold lower genetic diversity than other geographic groups. Considering the particularities of each Paleosuchus palpebrosus conservation unit, we recommend that the conservation status of each is evaluated separately. Tropical biodiversity is largely underestimated and in this context the broadly distributed species are the most likely candidates to harbor distinct evolutionary lineages. Thus, we suggest that conservation research should not neglect species that are generally considered of Least Concern by IUCN due to the taxon’s broad geographic distribution.
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avaliacao do risco de extincao do jacare pagua Paleosuchus palpebrosus cuvier 1807 no brasil
Biodiversidade Brasileira, 2013Co-Authors: Zilca Campos, Boris Marioni, Luis Bassetti, Marcos E. Coutinho, Sônia H. S. T. De Mendonça, Tiago Quaggio Vieira, Luciano Martins Verdade, Izeni Pires Farias, W E MagnussonAbstract:O risco de extincao de Paleosuchus palpebrosus foi avaliado de acordo com os criterios da Uniao Internacional para a Conservacao da Natureza (IUCN 2001, 2003), com base nos dados disponiveis ate 2011. A especie ocorre em dez paises da America do Sul, porem a maior parte de sua distribuicao esta no Brasil, onde sua extensao de ocorrencia (EOO) foi calculada em 7.282.346,5 km2. Acredita-se que a area de ocupacao (AOO) seja maior que 20.000km2. Ocorre naturalmente em baixas densidades, ocupando ambientes de veredas, riachos, cabeceiras de rios e floresta inundada. Embora a especie enfrente ameacas da caca, oriunda de conflitos com moradores ribeirinhos, e fragmentacao, modificacao e perda de habitats, causadas por diversas atividades humanas, em especial construcao de hidreletricas, acredita-se que a especie nao tenha sofrido reducao populacional significativa, sendo categorizada como Menos Preocupante (LC). Ainda assim, a conservacao da especie e dependente da manutencao de areas de preservacao permanente, tanto de rios como de riachos, nascentes e veredas, e da conectividade hidrologica nesses ambientes. Ha contato com populacoes dos paises vizinhos, porem nao se sabe se ha mudancas significativas para justificar uma alteracao indicada na avaliacao brasileira.
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avaliacao do risco de extincao do jacare coroa Paleosuchus trigonatus schneider 1801 no brasil
Biodiversidade Brasileira, 2013Co-Authors: Zilca Campos, Boris Marioni, Luis Bassetti, Marcos E. Coutinho, Sônia H. S. T. De Mendonça, Tiago Quaggio Vieira, Luciano Martins Verdade, Izeni Pires Farias, W E MagnussonAbstract:O risco de extincao de Paleosuchus trigonatus foi avaliado de acordo com os criterios da Uniao Internacional para a Conservacao da Natureza (IUCN 2001, 2003), com base nos dados disponiveis ate 2011. A especie e encontrada em grande parte da Amazonia brasileira e em outros nove paises da America do Sul. Sua extensao de ocorrencia (EOO) no Brasil e de 3.339.916,7 km2 e acredita-se que a area de ocupacao (AOO) seja maior que 20.000 km2. A especie enfrenta ameacas como fragmentacao de habitats, causada pelo desmatamento de areas de preservacao permanente e perda de conectividade de rios e pequenos riachos, alem da caca, tanto de subsistencia como oriunda de conflitos com pescadores e moradores de vilas, assentamentos e cidades. Apesar dessas ameacas, acredita-se que ate o momento nao tenha sofrido reducao populacional significativa, sendo categorizada como Menos Preocupante (LC). Ainda assim, a conservacao da especie e dependente da manutencao da conectividade dos seus habitats amazonicos. Ha contato com populacoes dos paises vizinhos, porem nao se sabe se ha mudancas significativas em dados populacionais para justificar uma alteracao na categoria indicada na avaliacao brasileira.
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parental care in the dwarf caiman Paleosuchus palpebrosus cuvier 1807 reptilia crocodilia alligatoridae
Journal of Natural History, 2012Co-Authors: Zilca Campos, Izeni Pires Farias, Fabio Muniz, T Sanaiotti, William E MagnussonAbstract:Post-hatching parental care is common in crocodilians, but the little information available for Cuvier's dwarf caiman (Paleosuchus palpebrosus) indicates that they show little post-hatching parental care. During surveys undertaken between 2005 and 2011, we counted and captured groups of hatchlings and observed the presence or absence of attending adults in streams around the Pantanal, along the Guapore-Madeira River and flooded forest in central Amazonia, Brazil. We found 37 groups of hatchlings, of which 29 were accompanied by adults. We captured 13 of these adults and all were females. The groups of hatchlings remained with adults for up to 21 months. We monitored females and hatchlings in streams around the Pantanal using captures and with radiotelemetry and showed that females and hatchlings frequently remained together in burrows, especially during the dry season.
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Phylogenetic relationships of South American Alligatorids and the Caiman of Madeira River
Journal of Experimental Zoology, 2008Co-Authors: Tomas Hrbek, William Rangel Vasconcelos, George Rebelo, Izeni Pires FariasAbstract:We analyzed DNA sequences of the mitochondrial cytochrome b gene (cyt b), the nuclear Recombination Activating Gene 1 (RAG1) and the myelocytomatosis oncogene (MYC) to infer the phylogenetic relationship of Caiman crocodilus and Caiman yacare, and other South American alligatorid crocodilian species. Phylogenetic relationships were robustly supported with Paleosuchus sister to Melanosuchus and Caiman. Phylogenetic relationships of C. crocodilus and C. yacare were unclear as these two species share mitochondrial and nuclear haplotypes. Specifically this sharing occurs among specimens of C. yacare and C. crocodilus from the Madeira River drainage. Two potential explanations stand out: secondary contact followed by hybridization, and differentia- tion along a cline. Current data cannot resolve between these two competing hypotheses. In comparison with C. yacare and C. crocodilus, Paleosuchus trigonatus and Paleosuchus palpebrosus are very well differentiated and also show surprising haplotypic diversity in spite of their phenotypic similarity. J. Exp. Zool. 309A:588-599, 2008. r 2007 Wiley-Liss, Inc.
Tomas Hrbek - One of the best experts on this subject based on the ideXlab platform.
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evidence of cryptic lineages within a small south american crocodilian the schneider s dwarf caiman Paleosuchus trigonatus alligatoridae caimaninae
PeerJ, 2019Co-Authors: Boris Marioni, Zilca Campos, Fabio Muniz, B. C. Souza, Pedro Senna Bittencourt, Ronis Da Silveira, Benoit De Thoisy, Tomas HrbekAbstract:: Schneider's dwarf caiman Paleosuchus trigonatus is one of the smallest living crocodilians. Due to its broad distribution, cryptic behavior, and small home range, the species is well suited for the study of phylogeographic patterns on a continental scale. Additionally, this species is under threat due to habitat loss, trade and harvest, but is considered at low conservation risk by the IUCN. In the present study we test the hypothesis that P. trigonatus is comprised of geographically structured lineages. Phylogenetic reconstructions of the mitochondrial cytochrome b gene and single locus species discovery methods revealed the existence of two well-supported lineages within P. trigonatus-an Amazonian and Guianan lineage. Fossil calibrated divergence of these lineages was estimated to have occurred in the Late Miocene (7.5 Ma). The hypothesis that the Atlantic coast drainages might have been colonized from the southeast or central Amazon is supported by demographic metrics and relatively low genetic diversity of the Coastal and upper Branco populations when compared to the Amazon basin populations. The Amazon basin lineage is structured along an east-west gradient, with a sharp transition in haplotype frequencies to the east and west of the Negro and Madeira rivers. These lineages are already under anthropogenic threat and, therefore, are conservation dependent. Recognition of these lineages will foster discussion of conservation future of P. trigonatus and these lineages.
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delimitation of evolutionary units in cuvier s dwarf caiman Paleosuchus palpebrosus cuvier 1807 insights from conservation of a broadly distributed species
Conservation Genetics, 2018Co-Authors: Fabio Muniz, Zilca Campos, Tomas Hrbek, J. G. Martínez, B. C. Souza, B. Thoisy, S Hernandez M Rangel, R Boteroarias, Izeni Pires FariasAbstract:An important goal of evolutionary and conservation biology is the identification of units below the species level, such as Evolutionarily Significant Units (ESUs), providing objectively delimited units for species conservation and management. In this study we tested the hypothesis that Cuvier’s dwarf caiman (Paleosuchus palpebrosus)—a species broadly distributed across several biomes and watersheds of South America—is comprised of different ESUs. We analyzed mitochondrial cytochrome b sequences of 206 individuals and 532 unlinked ddRAD loci of 20 individuals chosen from amongst the mitochondrial haplogroups. Analysis of the cytochrome b sequences revealed four mitochondrial clusters, while STRUCTURE analysis of ddRAD loci detected three genomic clusters with different levels of mixture between them. Using the Adaptive Evolutionary Conservation (AEC) framework we identified three ESUs: “Amazon”, “Madeira-Bolivia” and “Pantanal”; one of them composed of two different Management Units (MUs), “Madeira” and “Bolivia”. In general, based on the comparisons with other crocodilian species, genetic diversity of each lineage was moderate however, the Madeira MU showed fivefold lower genetic diversity than other geographic groups. Considering the particularities of each Paleosuchus palpebrosus conservation unit, we recommend that the conservation status of each is evaluated separately. Tropical biodiversity is largely underestimated and in this context the broadly distributed species are the most likely candidates to harbor distinct evolutionary lineages. Thus, we suggest that conservation research should not neglect species that are generally considered of Least Concern by IUCN due to the taxon’s broad geographic distribution.
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Phylogenetic relationships of South American Alligatorids and the Caiman of Madeira River
Journal of Experimental Zoology, 2008Co-Authors: Tomas Hrbek, William Rangel Vasconcelos, George Rebelo, Izeni Pires FariasAbstract:We analyzed DNA sequences of the mitochondrial cytochrome b gene (cyt b), the nuclear Recombination Activating Gene 1 (RAG1) and the myelocytomatosis oncogene (MYC) to infer the phylogenetic relationship of Caiman crocodilus and Caiman yacare, and other South American alligatorid crocodilian species. Phylogenetic relationships were robustly supported with Paleosuchus sister to Melanosuchus and Caiman. Phylogenetic relationships of C. crocodilus and C. yacare were unclear as these two species share mitochondrial and nuclear haplotypes. Specifically this sharing occurs among specimens of C. yacare and C. crocodilus from the Madeira River drainage. Two potential explanations stand out: secondary contact followed by hybridization, and differentia- tion along a cline. Current data cannot resolve between these two competing hypotheses. In comparison with C. yacare and C. crocodilus, Paleosuchus trigonatus and Paleosuchus palpebrosus are very well differentiated and also show surprising haplotypic diversity in spite of their phenotypic similarity. J. Exp. Zool. 309A:588-599, 2008. r 2007 Wiley-Liss, Inc.
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Phylogeographic and conservation genetic analysis of the black caiman (Melanosuchus niger).
Journal of Experimental Zoology, 2008Co-Authors: William Rangel Vasconcelos, Tomas Hrbek, Ronis Da Silveira, Benoit De Thoisy, Luis Augusto Araújo Dos Santos Ruffeil, Izeni Pires FariasAbstract:We assessed the spatial distribution of the genetic variability of Melanosuchus niger from 11 localities in South America using 1,027 base pairs of the mitochondrial cytochrome b gene. Screening 132 animals, we found 41 haplotypes, high values of genetic diversity, low values of nucleotide diversity and significant deviations from neutral expectation of allelic frequencies in some localities. Mantel test and nested-clade analysis indicated that isolation-by-distance was an important population dynamic for the species as a whole. Wright's fixation indexes analyses showed that hydrogeographically separated populations from French Guiana together with Amapastate population in Brazil are genetically differentiated from all other populations that are found in the Amazon drainage basin. These indexes also disclosed that the population from Ecuador is genetically differentiated in relation to the populations from Brazil, Peru and French Guiana. Within the Amazon Basin little differentiation exists, and genetic and geographic distances are not correlated. Demographic data as well as population genetic data suggest that M. niger is recovering in some protected regions. However, part of this apparent recovery may be owing to the movement of animals into protected regions. J. Exp. Zool. 309A:600-613, 2008. r 2008 Wiley-Liss, Inc. How to cite this article: Vasconcelos WR, Hrbek T, Silveira RD, Thoisy BD, Ruffeil LAADS, Farias IP. 2008. Phylogeographic and conservation genetic analysis of the black caiman (Melanosuchus niger). J. Exp. Zool. 309A:600-613. The six crocodilian species that occur in Brazil belong to the family Alligatoridae (King and Burke, '81; Magnusson, '85) and are divided among three genera: Caiman, Paleosuchus and Melanosuchus. The last genus is monotypic, containing Melanosuchus niger, the black caiman, which is the largest alligatorid predator of con- tinental America, reaching to over 5 m in length (Medem, '83). The black caiman is a habitat specialist found in the Amazonian varzea flood- plain (Herron, '94). It is also found in the Rupununi Swamp of the Essequibo River wa- tershed, and in a number of drainages of Guiana Shield draining directly into the Atlantic Ocean (Ross, '98). Crocodilians have traditionally been subject to various forms of legal and illegal exploitation, and more recently to managed exploitation. Economic- ally important crocodilian products include eggs and meat that provide an important protein