RESUMO
The neotropical genus Mabuya are obligate placentotrophic viviparous lizards, which have a short vitellogenesis that produces microlecithal oocytes and a prolonged time of gestation (9 to 10 months). The hormonal control of female reproductive activity during follicular growth and pregnancy has not been studied, although it is known that the corpus luteum can produce progesterone, but regresses early in pregnancy, being replaced in this function by the placenta. Through enzyme immunoassay (EIA) we measured the plasma concentrations of estradiol (E2) and progesterone (P4) in females of a population of Mabuya sp at different stages of their reproductive cycle. Previously, we confirmed the presence of P4 in plasma by high-performance liquid chromatography methods with diode-array detector ultraviolet (HPLC-DAD-UV). The average concentration values of E2 and P4 were compared among reproductive stages and their dynamics were related to what is known in other oviparous and viviparous amniotes. The plasma E2 concentrations of Mabuya sp. are below the levels found in other viviparous reptiles, probably related to the substantial reduction of its follicular growth phase. Its highest concentration was detected during vitellogenesis, related to its function in the growth and maturation of the ovarian follicles and oviduct preparation for pregnancy; lower levels were observed during pregnancy, but they increase at the end when a new vitellogenesis event begins and massive placental maternal-fetal nutrient transfer occurs. High concentrations of P4 were found during pregnancy, related to its function in the maintenance of the developing embryos within the oviduct. The highest levels of P4 were found at early gestation, then they descend from mid-gestation to the end of gestation. Although some characteristics of hormonal control related to the high level of placentotrophy were observed in this species, the changes in plasma sex steroid concentrations during the reproductive cycle in females of Mabuya sp. follow patterns seen in other viviparous amniotes.
Assuntos
Estradiol/sangue , Lagartos/sangue , Lagartos/fisiologia , Placenta/metabolismo , Progesterona/sangue , Reprodução/fisiologia , Viviparidade não Mamífera , Animais , Cromatografia Líquida de Alta Pressão , Feminino , Imunoensaio , Gravidez , Reprodutibilidade dos TestesRESUMO
Knowledge of how contemporary and historical factors drive patterns of genetic structure across geographic space can shed light on the processes underlying diversification. This approach is especially fruitful in studies of widespread species or species clades that occur across multiple environmental conditions and biomes. In the Neotropics, specifically, molecular data from widespread vertebrate species have revealed high levels of lineage diversity and spatial genetic structure - yet studies that explore the possible correlates of local structure patterns are lacking. We investigate the distribution of lineage diversity within two widespread South American skink species complexes of the genus Mabuya. We characterize genetic structure and diversity in these widely ranged lizards, and identify potential geographic and environmental correlates, to shed light on the processes that promote lineage diversification across the heterogeneous landscapes which they occupy. In both groups, we found mitochondrial lineages to be spatially structured along the coastal forests and the savannas of Brazil. These mtDNA patterns are, however, not shared with those inferred from nuclear DNA markers. The geographic location of major mitochondrial genetic breaks is consistent with those of other taxa, suggesting common responses to former landscape change in eastern South America, particularly along geological faults. Genetic differentiation is correlated with environmental turnover and geographic separation in one, but not in the other, group of skinks. Compared to other studies of similarly widely distributed organisms, the link between spatial environmental gradients and genetic differentiation is not as strong or consistent, suggesting a more complex history underlying current phylogeographic patterns. Our genetic data indicate the existence of yet undescribed diversity in wide-ranging lizards, and the value of phylogenetic and phylogeographic studies of similarly understudied species.
Assuntos
Lagartos/classificação , Lagartos/genética , Animais , Brasil , Núcleo Celular/genética , DNA Mitocondrial/química , Ecossistema , Florestas , Estruturas Genéticas , Variação Genética , Pradaria , Filogenia , Filogeografia , Clima TropicalRESUMO
Understanding the phylogenetic and geographical history of Neotropical lineages requires having adequate geographic and taxonomic sampling across the region. However, Colombia has remained a geographical gap in many studies of Neotropical diversity. Here we present a study of Neotropical skinks of the genus Mabuya, reptiles that are difficult to identify or delimit due to their conservative morphology. The goal of the present study is to propose phylogenetic and biogeographic hypotheses of Mabuya including samples from the previously under-studied territory of Colombia, and address relevant biogeographic and taxonomic issues. We combined molecular and morphological data sampled densely by us within Colombia with published data representing broad sampling across the Neotropical realm, including DNA sequence data from two mitochondrial (12S rRNA and cytochrome b) and three nuclear genes (Rag2, NGFB and R35). To evaluate species boundaries we employed a general mixed Yule-coalescent (GMYC) model applied to the mitochondrial data set. Our results suggest that the diversity of Mabuya within Colombia is higher than previously recognized, and includes lineages from Central America and from eastern and southern South America. The genus appears to have originated in eastern South America in the Early Miocene, with subsequent expansions into Central America and the Caribbean in the Late Miocene, including at least six oceanic dispersal events to Caribbean Islands. We identified at least four new candidate species for Colombia and two species that were not previously reported in Colombia. The populations of northeastern Colombia can be assigned to M. zuliae, while specimens from Orinoquia and the eastern foothills of the Cordillera Oriental of Colombia correspond to M. altamazonica. The validity of seven species of Mabuya sensu lato was not supported due to a combination of three factors: (1) non-monophyly, (2) <75% likelihood bootstrap support and <0.95 Bayesian posterior probability, and (3) GMYC analysis collapsing named species. Finally, we suggest that Mabuya sensu stricto may be regarded as a diverse monophyletic genus, widely distributed throughout the Neotropics.
Assuntos
Lagartos/genética , Distribuição Animal , Animais , Sequência de Bases , Teorema de Bayes , Colômbia , Citocromos b/genética , DNA Mitocondrial/genética , Especiação Genética , Filogenia , Filogeografia , Proteínas de Répteis/genética , Análise de Sequência de DNARESUMO
We examined the stomach contents of 21 specimens of Mabuya agilis (Sauria; Scincidae) collected during February 2001 at the restinga habitat of Praia do Sul, in Ilha Grande, RJ, Brazil. Diet was composed of various types of small arthropods, with no plant material being eaten. Spiders were the most important items in the diet, followed by orthopterans. Apart from the absence of isopterans, the diet of Mabuya agilis from this insular area was similar to those of other conspecific mainland populations. This suggests that factors such as insularity and the absence of other small sympatric lizards may not have a significant effect on the feeding habits of the Praia do Sul population.
Examinamos os conteúdos dos estômagos de 21 espécimes de Mabuya agilis (Sauria; Scincidae) coletados em fevereiro de 2001 no habitat de restinga de Praia do Sul, na Ilha Grande, RJ, Brasil. A dieta estava composta de vários tipos de artrópodes pequenos, sem consumo de material vegetal. Aranhas foram os itens mais importantes na dieta, seguidos por ortópteros. Exceto pela ausência de isópteros, a dieta de Mabuya agilis dessa área insular foi semelhante à de outras populações continentais coespecíficas. Isto sugere que fatores como a insularidade e a ausência de outros pequenos lagartos simpátricos podem não ter efeito significativo nos hábitos alimentares da população de Praia do Sul.
RESUMO
We analysed the helminth fauna associated with the lizard Mabuya dorsivittata (Scincidae) from a high-altitude area in Itatiaia National Park, Rio de Janeiro State, Brazil. Of the 16 lizards examined, 12 (75%) were infected by at least one helminth. Only two helminth species were found: Physaloptera retusa and Skrjabinodon spinosulus (Nematoda), the former with a prevalence of 68.8% and a mean infection intensity of 3.6 ± 2.8 and the latter with a prevalence of 56.3% and a mean infection intensity of 2.6 ± 2.6. The helminth fauna of the studied population of Mabuya dorsivittata was considerably poorer than those of other previously studied populations of congeners.
Analisamos a fauna de helmintos associada ao lagarto Mabuya dorsivittata (Scincidae) de uma área de altitude no Parque Nacional do Itatiaia, Rio de Janeiro, Brasil. Dos 16 lagartos examinados, 12 (75%) estavam infectados por pelo menos um helminto. Apenas duas espécies de helminto foram encontradas: Physaloptera retusa e Skrjabinodon spinosulus (Nematoda), tendo a primeira prevalência de 68,8% e intensidade média de infecção de 3,6 ± 2,8 e a segunda prevalência de 56,3% e intensidade média de infecção de 2,6 ± 2,6. A fauna de helmintos da população de Mabuya dorsivittata estudada foi consideravelmente pobre em comparação com as de outras populações congenéricas previamente estudadas.
RESUMO
We have studied the terrestrial reptile fauna of the Abrolhos Archipelago (a group of five islands located ca. 70 km off the southern coast of the State of Bahia, Brazil) and analyze here some of its ecological aspects such as diet, thermal ecology, activity, and some reproductive parameters. Three lizards comprise the archipelago's terrestrial reptile fauna: Tropidurus torquatus (Tropiduridae), Mabuya agilis (Scincidae), and Hemidactylus mabouia (Gekkonidae). The first two are diurnal and the latter is crepuscular/nocturnal (initiating activity at ca. 17:30). The activity period of T. torquatus extended from 5:30 to 18:30 h. Mean field body temperatures of active T. torquatus, M. agilis, and H. mabouia were, respectively, 34.0 ± 3.7ºC (range 23.8-38.0ºC; N = 75), 34.5 ± 2.2ºC (range 30.8-37.0ºC; N = 6), and 26.3 ± 1.1ºC (range 24.8-28.0ºC; N = 8). The predominant prey items in the diet of T. torquatus were ants, coleopterans, and hemipterans. In the diet of M. agilis, coleopterans were the most frequent prey items. For H. mabouia, the most important dietary items were orthopterans. Clutch size of T. torquatus averaged 4.1 ± 1.1 (range 2-6; N = 15) and was significantly related to female size (R² = 0.618; p = 0.001; N = 15). Clutch size for H. mabouia was fixed (two) and mean litter size of the viviparous M. agilis was 3.3 ± 0.6 (range 3-4; N = 3). Tropidurus torquatus and H. mabouia deposit their eggs under rocks in the study area, with the former burying them but not the latter; in both species, more than one female often oviposit under the same rock.
Estudamos a fauna de répteis terrestre do Arquipélago de Abrolhos (um conjunto de cinco ilhas localizadas a 70 km da costa sul do Estado da Bahia, Brasil) e analisamos alguns aspectos da ecologia das espécies, como a dieta, ecologia termal, atividade e alguns parâmetros reprodutivos. A fauna de répteis do arquipélago compreende três lagartos: Tropidurus torquatus (Tropiduridae), Mabuya agilis (Scincidae) e Hemidactylus mabouia (Gekkonidae). Os dois primeiros são diurnos e o último é crepuscular/noturno (iniciando atividade às 17h30). O período de atividade de T. torquatus se estendeu de 5h30 a 18h30. As temperaturas corpóreas médias em atividade de T. torquatus, M. agilis e H. mabouia foram, respectivamente, de 34,0 ± 3.7ºC (amplitude 23,8-38,0ºC; N = 75), 34,5 ± 2,2ºC (amplitude 30,8-37,0ºC; N = 6) e 26,3 ± 1,1ºC (amplitude 24,8-28,0ºC; N = 8). Os itens alimentares predominantes na dieta de T. torquatus foram formigas, coleópteros e hemípteros. Na dieta de M. agilis, coleópteros foram os itens mais freqüentes. Para H. mabouia, os itens alimentares mais importantes na dieta foram ortópteros. O tamanho médio da ninhada de T. torquatus foi de 4,1 ± 1,1 (amplitude 2-6; N = 15) e estava significativamente relacionado com o tamanho da fêmea (R² = 0,618; p = 0,001; N = 15). O número de ovos para H. mabouia foi fixo (dois) e o tamanho médio da ninhada para a espécie vivípara M. agilis foi de 3,3 ± 0,6 (amplitude 3-4; N = 3). Tropidurus torquatus e H. mabouia depositam seus ovos sob rochas na área estudada, sendo que o primeiro enterra seus ovos e o segundo não; em ambas as espécies, mais de uma fêmea freqüentemente utiliza a mesma rocha para oviposição.
RESUMO
We have studied the terrestrial reptile fauna of the Abrolhos Archipelago (a group of five islands located ca. 70 km off the southern coast of the State of Bahia, Brazil) and analyze here some of its ecological aspects such as diet, thermal ecology, activity, and some reproductive parameters. Three lizards comprise the archipelago's terrestrial reptile fauna: Tropidurus torquatus (Tropiduridae), Mabuya agilis (Scincidae), and Hemidactylus mabouia (Gekkonidae). The first two are diurnal and the latter is crepuscular/nocturnal (initiating activity at ca. 17:30). The activity period of T. torquatus extended from 5:30 to 18:30 h. Mean field body temperatures of active T. torquatus, M. agilis, and H. mabouia were, respectively, 34.0 ± 3.7ºC (range 23.8-38.0ºC; N = 75), 34.5 ± 2.2ºC (range 30.8-37.0ºC; N = 6), and 26.3 ± 1.1ºC (range 24.8-28.0ºC; N = 8). The predominant prey items in the diet of T. torquatus were ants, coleopterans, and hemipterans. In the diet of M. agilis, coleopterans were the most frequent prey items. For H. mabouia, the most important dietary items were orthopterans. Clutch size of T. torquatus averaged 4.1 ± 1.1 (range 2-6; N = 15) and was significantly related to female size (R² = 0.618; p = 0.001; N = 15). Clutch size for H. mabouia was fixed (two) and mean litter size of the viviparous M. agilis was 3.3 ± 0.6 (range 3-4; N = 3). Tropidurus torquatus and H. mabouia deposit their eggs under rocks in the study area, with the former burying them but not the latter; in both species, more than one female often oviposit under the same rock.
Estudamos a fauna de répteis terrestre do Arquipélago de Abrolhos (um conjunto de cinco ilhas localizadas a 70 km da costa sul do Estado da Bahia, Brasil) e analisamos alguns aspectos da ecologia das espécies, como a dieta, ecologia termal, atividade e alguns parâmetros reprodutivos. A fauna de répteis do arquipélago compreende três lagartos: Tropidurus torquatus (Tropiduridae), Mabuya agilis (Scincidae) e Hemidactylus mabouia (Gekkonidae). Os dois primeiros são diurnos e o último é crepuscular/noturno (iniciando atividade às 17h30). O período de atividade de T. torquatus se estendeu de 5h30 a 18h30. As temperaturas corpóreas médias em atividade de T. torquatus, M. agilis e H. mabouia foram, respectivamente, de 34,0 ± 3.7ºC (amplitude 23,8-38,0ºC; N = 75), 34,5 ± 2,2ºC (amplitude 30,8-37,0ºC; N = 6) e 26,3 ± 1,1ºC (amplitude 24,8-28,0ºC; N = 8). Os itens alimentares predominantes na dieta de T. torquatus foram formigas, coleópteros e hemípteros. Na dieta de M. agilis, coleópteros foram os itens mais freqüentes. Para H. mabouia, os itens alimentares mais importantes na dieta foram ortópteros. O tamanho médio da ninhada de T. torquatus foi de 4,1 ± 1,1 (amplitude 2-6; N = 15) e estava significativamente relacionado com o tamanho da fêmea (R² = 0,618; p = 0,001; N = 15). O número de ovos para H. mabouia foi fixo (dois) e o tamanho médio da ninhada para a espécie vivípara M. agilis foi de 3,3 ± 0,6 (amplitude 3-4; N = 3). Tropidurus torquatus e H. mabouia depositam seus ovos sob rochas na área estudada, sendo que o primeiro enterra seus ovos e o segundo não; em ambas as espécies, mais de uma fêmea freqüentemente utiliza a mesma rocha para oviposição.