RESUMO
RESUMEN Analizamos el uso de microhábitat para las diferentes clases etarias entre épocas climáticas y comparamos la diversidad de presas consumidas por los machos y hembras adultas de Craugastor berkenbuschii en un arroyo tropical del sureste de México. Los datos fueron colectados en diez transectos de 100 x 15 m, separados entre sí por 25 m de distancia entre ellos. Los muestreos diurnos y nocturnos se realizaron mensualmente entre septiembre 2017 y agosto 2018. A cada individuo observado le registramos el sexo, la clase etaria y el microhábitat utilizado al momento del avistamiento. Las presas consumidas fueron extraídas mediante lavados estomacales in situ. Registramos un total de 437 individuos; 165 fueron adultos, 162 juveniles y 110 crías. Los microhábitats utilizados fueron roca, hojarasca, suelo, tronco, rama, hojas y raíz, de los cuales roca fue el más utilizado independientemente de la época del año y clases etarias. Se identificaron 21 órdenes de presas, 19 órdenes en hembras y 11 en machos. El índice de diversidad verdadera (1D), mostró valores similares para machos y hembras, con 9,67 y 9,08 respectivamente. El índice de distintividad taxonómica promedio (A+) determinó que las hembras consumen una mayor diversidad de presas que los machos, con 5,12 y 4,25, respectivamente. Los resultados muestran que las diferentes clases etarias de C. berkenbuschii aprovechan una gran variedad de microhábitats entre épocas climáticas y que existen diferencias entre las presas consumidas entre machos y hembras adultas.
ABSTRACT We analyzed microhabitat use for different age classes between climatic seasons and compared the diversity of prey consumed by adult males and females of Craugastor berkenbuschii in a tropical stream in southeastern Mexico. The data was collected in ten transects of 100 x 15 m, separated from each other by 25 m of the distance between them. Day and night sampling was carried out monthly between September 2017 and august 2018. For each observed individual, we recorded the sex, age class, and microhabitat used at the time of the sighting. The consumed prey was extracted by means of in situ stomach washings. We registered a total of 437 individuals; 165 were adults, 162 were juveniles, and 110 were young. The microhabitats used were rock, litter, soil, trunk, branch, leaves, and root, of which rock was the most used regardless of the time of year and age classes. Twenty-one orders of prey were identified, 19 orders in females and 11 in males. The true diversity index (1D) showed similar values for males and females, with 9.67 and 9.08 respectively. The average taxonomic distinctness index (A+) determined that females consume a greater diversity of prey than males, with 5.12 and 4.25, respectively. The results show that the different age classes of C. berkenbuschii take advantage of a wide variety of microhabitats between climatic seasons and that there are differences between the prey consumed between adult males and females.
RESUMO
The Mesoamerican slider Trachemysvenusta is endemic to Central America and Southern Mexico. Several human-mediated disturbances, including habitat degradation and illegal hunting for food, have impacted its populations along the Usumacinta river basin. The extent to which these disturbances have affected the genetic diversity and population structure of T. venusta inhabiting the basin remains unresolved. To this end, we analyzed eight microsatellite markers in five wild populations of T. venusta from the middle and lower reaches of the basin as well as one captive population. Our results show high levels of genetic diversity for all analyzed populations, low F ST values, high gene flow and no genetic structure, indicating an absence of genetic differentiation across sites and, thus, a single panmictic population for the basin. Evidence of a genetic bottleneck was observed in two of the wild populations (and the captive one), indicating some impact from disturbances, whether from poaching or habitat fragmentation, despite the seemingly high connectivity of most populations. Results are discussed in terms of the relative importance of genetic parameters for the conservation of T. venusta, particularly in light of the importance of demographic stochasticity in local conditions undergoing rapid changes.
Assuntos
Distribuição Animal , Variação Genética , Repetições de Microssatélites , Tartarugas/genética , Animais , Animais Selvagens , Animais de Zoológico , Teorema de Bayes , DNA/genética , México , Rios , Tartarugas/fisiologiaRESUMO
Presence and spatio-temporal habitat characterization of Dermatemys mawii (Testudines: Dermatemydidae) in the Grijalva-Usumacinta watershed, Tabasco, Mexico. The Central American River Turtle (Dermatemys mawii) is an endangered species that has been poorly studied. There are no reports on their population status, habitat condition, and the species distribution area is still unknown. This study analyzes the seasonal and spatial variations of their habitat and the presence/absence of D. mawii in three rivers within the Pantanos de Centla Biosphere Reserve (Tabasco, Mexico). For habitat characterization, natural segmentation of rivers was used and three sites per segment were identified, 9 in each rivers (Grijalva and Usumacinta) and 6 in Tabasquillo. Additionally, the evaluation of 11 environmental variables such as water hydrological, physicochemical characteristics and riparian and hydrophytic vegetation were carried out during two different seasons (dry and rainy). The presence/absence of species was assessed with eight fike nets that were set per segment, with a capture effort of 384 hours per trap. The capture per unit effort (CPUE) was used as an indicator of relative abundance. The results indicated spatio-temporal variations in habitat characteristics and the presence of environmental gradients. The principal components analysis (PCA) applied allowed us to determine that the first three components explained 67.8% of the environmental variability. The species presence was confirmed in all rivers, however significant differences exists in their relative abundance: the highest was registered in the Tabasquillo River where the species was present in both seasons and in all segments. Of the 11 environmental variables analyzed, the gradient, shelter and depth were the most indicative of species presence. The obtained results evidenced the importance of riparian vegetation as habitat for Dermatemys. This represents the first approach towards an action plan for a species and its habitat protection within the Pantanos de Centla Biosphere Reserve. Rev. Biol. Trop. 58 (4): 1247-1260. Epub 2010 December 01.
La tortuga centroamericana (Dermatemys mawii) es una especie en peligro de extinción pobremente estudiada. En el presente trabajo se analizaron las variaciones estacionales y espaciales del hábitat y se relacionaron con la presencia/ausencia de D. mawii en tres ríos de la Reserva de la Biosfera Pantanos de Centla (Tabasco, México). Para caracterizar el hábitat se evaluaron 11 variables (hidrológicas, fisicoquímicas del agua y de la vegetación) en dos temporadas (seca y lluviosa). Para determinar la presencia/ ausencia de la especie se colocaron 8 trampas de desvío acuáticas, empleando la captura por unidad de esfuerzo (CPUE) como indicador de la abundancia relativa. Los resultados indicaron variaciones espacio-temporales. El análisis de componentes principales (ACP) permitió determinar la variabilidad ambiental. La presencia de la especie se confirmó en los tres ríos, sin embargo la mayor abundancia relativa se registró en el Río Tabasquillo. Cuatro variables tuvieron el mayor peso como variables predictoras de la presencia de la especie. Con los resultados obtenidos, es evidente la importancia que tiene el ambiente ribereño como hábitat para Dermatemys, asimismo es posible hacer el primer acercamiento a un plan de acción para la protección de la especie y su hábitat en esta reserva.
Assuntos
Animais , Ecossistema , Tartarugas/classificação , Conservação dos Recursos Naturais , México , Densidade Demográfica , Dinâmica Populacional , Análise de Componente Principal , Estações do Ano , Conglomerados Espaço-Temporais , Tartarugas/fisiologiaRESUMO
The Central American River Turtle (Dermatemys mawii) is an endangered species that has been poorly studied. There are no reports on their population status, habitat condition, and the species distribution area is still unknown. This study analyzes the seasonal and spatial variations of their habitat and the presence/absence of D. mawii in three rivers within the Pantanos de Centla Biosphere Reserve (Tabasco, Mexico). For habitat characterization, natural segmentation of rivers was used and three sites per segment were identified, 9 in each rivers (Grijalva and Usumacinta) and 6 in Tabasquillo. Additionally, the evaluation of 11 environmental variables such as water hydrological, physicochemical characteristics and riparian and hydrophytic vegetation were carried out during two different seasons (dry and rainy). The presence/absence of species was assessed with eight fike nets that were set per segment, with a capture effort of 384 hours per trap. The capture per unit effort (CPUE) was used as an indicator of relative abundance. The results indicated spatio-temporal variations in habitat characteristics and the presence of environmental gradients. The principal components analysis (PCA) applied allowed us to determine that the first three components explained 67.8% of the environmental variability. The species presence was confirmed in all rivers, however significant differences exists in their relative abundance: the highest was registered in the Tabasquillo River where the species was present in both seasons and in all segments. Of the 11 environmental variables analyzed, the gradient, shelter and depth were the most indicative of species presence. The obtained results evidenced the importance of riparian vegetation as habitat for Dermatemys. This represents the first approach towards an action plan for a species and its habitat protection within the Pantanos de Centla Biosphere Reserve.