Abstract In poison frogs (Dendrobatoidea), usually the males are territorial, care for terrestrial nests and later transport their offspring to waterbodies where they complete larval development. In some species, mothers care for their offspring or may exhibit flexible care to compensate for father absence. We conducted a multi-season field experiment with the Amazonian species Allobates paleovarzensis, in which it was possible to study the joint impact of paternal care and the El Niño climatic anomaly on offspring survival. The experiment consisted of two treatments: non-removal, and removal of the father from their territories. We observed that parental care was performed exclusively by the father, and none of the mothers of the 21 monitored nests transported the tadpoles. We also observed that the severe drought in a year under the influence of the El Niño event caused such a high mortality in all pre-metamorphic stages, that the role of parental care became irrelevant for offspring survival during that season. We found that pre-metamorphic Allobates paleovarzensis are highly vulnerable to the loss of paternal care. In addition, we showed that paternal care, when present, does not prevent offspring death under these increasingly frequent climatic anomalies.

Amphibians are one of the most threatened groups of vertebrates whose populations are declining due to many reasons including, among others, the presence of chemicals associated with human intervention and in particular, with agriculture. These chemicals are deposited where amphibian larvae develop provoking morphological abnormalities in different organs, such as the gonads, which have been used as biological indicators of these substances in the environment. Therefore, descriptions of normal gonadal development among anurans are important not only to increase our knowledge about the reproductive biology of species but also to identify the type of gonadal abnormalities. The main objective of this work was to describe the morphological changes that occur during gonadal differentiation in the Neotropical high Andean frog Dendropsophus labialis, an endemic species from the Eastern Andes of Colombia. We analyzed 211 individuals including larvae and adults. This species has a differentiated pattern of gonadal development and accelerated rates of ovary and testis differentiation since mature oocytes and seminiferous tubules are present during pre-metamorphic larval stages. In comparison with other phylogenetically related species, D. labialis has one of the most accelerated rates of gonadal differentiation described so far. We confirmed that the gonadal development is to some degree independent of somatic development and we described a case of a gonadal abnormality.

Los anfibios constituyen uno de los grupos de vertebrados más amenazados, y sus poblaciones están declinando debido a diferentes factores que incluyen, entre otros, productos químicos provenientes de la actividad antrópica, en particular, la agricultura. Estos químicos se depositan en los cuerpos de agua donde se desarrollan las larvas de anfibios, generando malformaciones en diferentes órganos, como las gónadas, las cuales han sido usadas como indicadores biológicos del impacto de estas sustancias en el ambiente. Por lo tanto, las descripciones del desarrollo gonadal normal en anfibios son relevantes, ya que no solo nos permite conocer acerca de la biología reproductiva de las especies, sino que también es fundamental para identificar anormalidades gonadales. El objetivo de este trabajo es describir los cambios que ocurren durante la diferenciación gonadal en la rana neotropical altoandina Dendropsophus labialis, endémica de la cordillera oriental de Colombia. Analizamos 211 individuos incluyendo larvas y adultos. Esta especie presenta un patrón de desarrollo gonadal diferenciado; además presenta un desarrollo acelerado del ovario y el testículo, con ovocitos maduros y túbulos seminíferos presentes en estados pre metamórficos. Es así que respecto a otras especies relacionadas filogenéticamente, D. labialis exhibe una de las tasas más acelerada del desarrollo gonadal hasta ahora descritas. Finalmente, confirmamos que el desarrollo gonadal es en algún grado independiente del desarrollo somático, y describimos un caso de anormalidad gonadal.

The presence of Mytilus galloprovincialis, widely known as the Mediterranean mussel, have been genetically certified from Coliumo Bay to the Magellan Strait, in central and southern Chile, respectively. To correlate the geographic distribution of this species along the Chilean coast with its physiological tolerance to upper temperatures, experiments were carried out with adults and larval stages. Trochophore, umbonate veliger, and pre-metamorphic larvae were submitted to experimental temperatures from 17-33°C, during 24 h to determine the upper temperature limit. Meanwhile, adult experiments were carried with specimens having different previous physiological background: spring-summer acclimation (November-January), and fall-winter acclimation (August-October) and exposed to temperature range of 17-33°C for period of 24, 48, 72 and 96 h, to verify mortality and byssus formation. Results showed that at larvae stages, the 50% of mortality occurred at 27°C, with 100% mortality at 30°C. Adult stages reached the 55% mortality exposed for 48 h at 30°C and 100% mortality in 72 h at the same temperature. The byssus secretion become failing at 27°C and ceased at 30°C.

La presencia de Mytilus galloprovincialis, conocido mundialmente como mejillón del mediterráneo, ha sido verificada genéticamente desde bahía Coliumo hasta el Estrecho de Magallanes, en la costa central y sur de Chile respectivamente. Para relacionar la distribución geográfica de esta especie con su tolerancia fisiológica a temperaturas altas, se realizaron experimentos con estados larvarios y adultos. Trocóforas y estados larvales velígera umbonada y premetamórficas fueron sometidas a temperaturas entre 17 y 33°C, durante 24 h para determinar el límite termal letal superior. Los experimentos de mejillones adultos fueron realizados con individuos de diferentes condiciones fisiológicas previas: aclimatados a primavera-verano (noviembre-enero) y otoño-invierno (agosto-octubre), y expuestos a un rango termal de 17-33°C por un período de 24, 48, 72 y 96 h para verificar mortalidad y presencia de biso. Los resultados indicaron que la mortalidad de larvas pre-metamórficas fue de 50% a 27°C y de 100% a 30°C. En adultos, el 55% mortalidad ocurrió en individuos expuestos por 48 h a 30°C y el 100% a 72 h a la misma temperatura. La formación del biso se debilitó sobre 27°C y cesa a 30°C.