ABSTRACT
This study has been carried out at the central region of the Araguaia river on the border between the states of Goiás and Mato Grosso in the Brazilian Amazon Basin from September to December 2000. We recorded temperature fluctuation, clutch-size, incubation period and hatching success rate and hatchlings' sex ratio of five nests of Podocnemis expansa (Schweigger, 1812). Despite the relatively small sample size we infer that: a) nests of P. expansa in the central Araguaia river have a lower incubation temperature than nests located further south; however, incubation period is shorter, hatching success rate is lower and clutch-size is larger; b) Podocnemis expansa may present a female-male-female (FMF) pattern of temperature sex-determination (TSD); c) thermosensitive period of sex determination apparently occur at the last third of the incubation period; and, d) future studies should prioritize the relationship between temperature variation (i.e., range and cycle) and embryos development, survivorship and sex determination.
Este estudo foi realizado na região central do rio Araguaia, na fronteira entre os estados de Goiás e Mato Grosso, na Amazônia brasileira, durante os meses de setembro a dezembro de 2000. Além da variação da temperatura, foram avaliados o tamanho da ninhada, período de incubação, o sucesso de eclosão e a razão sexual dos filhotes recém eclodidos de cinco ninhos de Podocnemis expansa (Schweigger, 1812). Apesar do esforço amostral relativamente restrito, nós inferimos que: a) os ninhos estudados de P. expansa na região central do Rio Araguaia exibem temperaturas mais baixas do que ninhos mais ao sul, porém o período de incubação é menor, a taxa de eclosão é mais baixa e o tamanho de ninhada é maior; b) Podocnemis expansa pode mostrar um padrão fêmea-macho-fêmea (FMF) de determinação do sexo pela temperatura (TSD); c) o período termo-sensível para a determinação sexual aparentemente ocorre no último terço do período de incubação; e, d) futuros estudos devem priorizar a relação entre a variação da temperatura (i.e., amplitude e frequência) e o desenvolvimento embrionário, sobrevivência e a determinação sexual dos filhotes.
ABSTRACT
The isotopic composition ( 13C and 15N) of muscle, carapace and claw was determined from six wild individuals of Phrynops geoffroanus (Schweigger, 1812) in order to verify the variation between those tissues. The mean values of 13C e 15N were, respectively, -19.48 ± 0.81 (-20.8 - -18.64) and 7.23 ± 0.67 (6.49 - 8.3) for muscle, -16.52 ± 0.98 (-17.88 - -15.43) and 7.29 ± 0.54 (6.74 - 7.97) for carapace and -18.57 ± 0.97 (-19.97 - -17.26) and 4.36 ± 0.33 (3.93 - 4.79) for claw. We found a significant difference for the tissues evaluated for both 13C and 15N. Muscle and claw were statistically similar and more depleted in 13C than the carapace. Nonetheless, claw was more depleted in 15N than muscle and carapace tissues. These results are likely related to differences in metabolic processes involved on each tissue formation. The description of the isotopic signatures variation in P. geoffroanus tissues provides a baseline for future investigations on the diet reconstruction of this species when more than one tissue is involved.
ABSTRACT
This study has been carried out at the central region of the Araguaia river on the border between the states of Goiás and Mato Grosso in the Brazilian Amazon Basin from September to December 2000. We recorded temperature fluctuation, clutch-size, incubation period and hatching success rate and hatchlings' sex ratio of five nests of Podocnemis expansa (Schweigger, 1812). Despite the relatively small sample size we infer that: a) nests of P. expansa in the central Araguaia river have a lower incubation temperature than nests located further south; however, incubation period is shorter, hatching success rate is lower and clutch-size is larger; b) Podocnemis expansa may present a female-male-female (FMF) pattern of temperature sex-determination (TSD); c) thermosensitive period of sex determination apparently occur at the last third of the incubation period; and, d) future studies should prioritize the relationship between temperature variation (i.e., range and cycle) and embryos development, survivorship and sex determination.
Este estudo foi realizado na região central do rio Araguaia, na fronteira entre os estados de Goiás e Mato Grosso, na Amazônia brasileira, durante os meses de setembro a dezembro de 2000. Além da variação da temperatura, foram avaliados o tamanho da ninhada, período de incubação, o sucesso de eclosão e a razão sexual dos filhotes recém eclodidos de cinco ninhos de Podocnemis expansa (Schweigger, 1812). Apesar do esforço amostral relativamente restrito, nós inferimos que: a) os ninhos estudados de P. expansa na região central do Rio Araguaia exibem temperaturas mais baixas do que ninhos mais ao sul, porém o período de incubação é menor, a taxa de eclosão é mais baixa e o tamanho de ninhada é maior; b) Podocnemis expansa pode mostrar um padrão fêmea-macho-fêmea (FMF) de determinação do sexo pela temperatura (TSD); c) o período termo-sensível para a determinação sexual aparentemente ocorre no último terço do período de incubação; e, d) futuros estudos devem priorizar a relação entre a variação da temperatura (i.e., amplitude e frequência) e o desenvolvimento embrionário, sobrevivência e a determinação sexual dos filhotes.
ABSTRACT
The isotopic composition ( 13C and 15N) of muscle, carapace and claw was determined from six wild individuals of Phrynops geoffroanus (Schweigger, 1812) in order to verify the variation between those tissues. The mean values of 13C e 15N were, respectively, -19.48 ± 0.81 (-20.8 - -18.64) and 7.23 ± 0.67 (6.49 - 8.3) for muscle, -16.52 ± 0.98 (-17.88 - -15.43) and 7.29 ± 0.54 (6.74 - 7.97) for carapace and -18.57 ± 0.97 (-19.97 - -17.26) and 4.36 ± 0.33 (3.93 - 4.79) for claw. We found a significant difference for the tissues evaluated for both 13C and 15N. Muscle and claw were statistically similar and more depleted in 13C than the carapace. Nonetheless, claw was more depleted in 15N than muscle and carapace tissues. These results are likely related to differences in metabolic processes involved on each tissue formation. The description of the isotopic signatures variation in P. geoffroanus tissues provides a baseline for future investigations on the diet reconstruction of this species when more than one tissue is involved.
ABSTRACT
The isotopic composition ( 13C and 15N) of muscle, carapace and claw was determined from six wild individuals of Phrynops geoffroanus (Schweigger, 1812) in order to verify the variation between those tissues. The mean values of 13C e 15N were, respectively, -19.48 ± 0.81 (-20.8 - -18.64) and 7.23 ± 0.67 (6.49 - 8.3) for muscle, -16.52 ± 0.98 (-17.88 - -15.43) and 7.29 ± 0.54 (6.74 - 7.97) for carapace and -18.57 ± 0.97 (-19.97 - -17.26) and 4.36 ± 0.33 (3.93 - 4.79) for claw. We found a significant difference for the tissues evaluated for both 13C and 15N. Muscle and claw were statistically similar and more depleted in 13C than the carapace. Nonetheless, claw was more depleted in 15N than muscle and carapace tissues. These results are likely related to differences in metabolic processes involved on each tissue formation. The description of the isotopic signatures variation in P. geoffroanus tissues provides a baseline for future investigations on the diet reconstruction of this species when more than one tissue is involved.
ABSTRACT
Phrynops geoffroanus (Schweigger, 1812) is the freshwater turtle with the widest geographical distribution in South America. During 2006, physical examination and hematological evaluation were performed on free-ranging turtles from two polluted rivers, the Piracicaba River (n = 51) and its tributary Piracicamirim (n = 42), in southeastern Brazil. Red blood cell and thrombocyte counts, mean corpuscular volume and mean corpuscular hemoglobin levels differed in turtles from the two water courses. Although free-ranging turtles showed ectoparasites and boat propeler lesions, animals apparently had no signs of clinical disease. In spite of our results, further monitoring of the demography and health status of Phrynops geoffroanus in anthropogenically altered environments is recommended.
ABSTRACT
The innate immune activity of the freshwater turtle Phrynops geoffroanus (Schweigger, 1812) was investigated, using a sheep-red-blood cell hemolysis assay. The time- and concentration-dependent hemolytic activity of the turtle plasma was low compared to that reported for other reptiles. However the plasma of P. geoffroanus exhibited higher activity at elevated temperatures, resulting in temperature-dependent hemolysis. The sensitivity of turtle plasma to temperature could be interpreted as a mechanism by which freshwater turtles use basking behavior to elevate body temperature, thus enhancing the innate immune response. However, we cannot discard the possibility that environmental contaminants could be affecting the turtle's immune response, since the animals in this investigation were captured in a polluted watercourse.
ABSTRACT
The innate immune activity of the freshwater turtle Phrynops geoffroanus (Schweigger, 1812) was investigated, using a sheep-red-blood cell hemolysis assay. The time- and concentration-dependent hemolytic activity of the turtle plasma was low compared to that reported for other reptiles. However the plasma of P. geoffroanus exhibited higher activity at elevated temperatures, resulting in temperature-dependent hemolysis. The sensitivity of turtle plasma to temperature could be interpreted as a mechanism by which freshwater turtles use basking behavior to elevate body temperature, thus enhancing the innate immune response. However, we cannot discard the possibility that environmental contaminants could be affecting the turtle's immune response, since the animals in this investigation were captured in a polluted watercourse.
ABSTRACT
The innate immune activity of the freshwater turtle Phrynops geoffroanus (Schweigger, 1812) was investigated, using a sheep-red-blood cell hemolysis assay. The time- and concentration-dependent hemolytic activity of the turtle plasma was low compared to that reported for other reptiles. However the plasma of P. geoffroanus exhibited higher activity at elevated temperatures, resulting in temperature-dependent hemolysis. The sensitivity of turtle plasma to temperature could be interpreted as a mechanism by which freshwater turtles use basking behavior to elevate body temperature, thus enhancing the innate immune response. However, we cannot discard the possibility that environmental contaminants could be affecting the turtle's immune response, since the animals in this investigation were captured in a polluted watercourse.
ABSTRACT
Phrynops geoffroanus (Schweigger, 1812) is the freshwater turtle with the widest geographical distribution in South America. During 2006, physical examination and hematological evaluation were performed on free-ranging turtles from two polluted rivers, the Piracicaba River (n = 51) and its tributary Piracicamirim (n = 42), in southeastern Brazil. Red blood cell and thrombocyte counts, mean corpuscular volume and mean corpuscular hemoglobin levels differed in turtles from the two water courses. Although free-ranging turtles showed ectoparasites and boat propeler lesions, animals apparently had no signs of clinical disease. In spite of our results, further monitoring of the demography and health status of Phrynops geoffroanus in anthropogenically altered environments is recommended.
ABSTRACT
Los neonatos de yacaré overo (Caiman latirostris) presentan un dimorfismo sexual en la forma y tamaño de su cráneo. Los neonatos machos tienen cráneos más pequeños que las hembras. Mediante el uso de análisis estadísticos multivariados es posible discriminar el sexo de los neonatos de yacaré overo en función de su forma y tamaño con una razonable eficiencia. La comprensión del dimorfismo sexual de los neonatos de crocodilianos podría ser mejorada mediante un abordaje experimental de variables genéticas y fenotípicas, tales como la temperatura de incubación y el nido de origen.
Broad-snouted caiman (Caiman latirostris) hatchlings present a consistent sexual dimorphism in their cranium shape and size. Male hatchlings have smaller crania than females. Using multivariate statistical analyses it is possible to discriminate sex in broad-snouted caiman hatchlings by their cranial shape with a reasonable efficiency. The understanding of sexual dimorphism of crocodilian hatchlings might be possibly improved by experimental approach considering, genetic and phenotypic variables such as incubation temperature and clutch of origin.
ABSTRACT
Los neonatos de yacaré overo (Caiman latirostris) presentan un dimorfismo sexual en la forma y tamaño de su cráneo. Los neonatos machos tienen cráneos más pequeños que las hembras. Mediante el uso de análisis estadísticos multivariados es posible discriminar el sexo de los neonatos de yacaré overo en función de su forma y tamaño con una razonable eficiencia. La comprensión del dimorfismo sexual de los neonatos de crocodilianos podría ser mejorada mediante un abordaje experimental de variables genéticas y fenotípicas, tales como la temperatura de incubación y el nido de origen.
Broad-snouted caiman (Caiman latirostris) hatchlings present a consistent sexual dimorphism in their cranium shape and size. Male hatchlings have smaller crania than females. Using multivariate statistical analyses it is possible to discriminate sex in broad-snouted caiman hatchlings by their cranial shape with a reasonable efficiency. The understanding of sexual dimorphism of crocodilian hatchlings might be possibly improved by experimental approach considering, genetic and phenotypic variables such as incubation temperature and clutch of origin.