Egg burying behaviour in Pristimantis highlights the link between direct development and specialised parental care.

One of the most extreme adaptations to terrestriality in anurans is direct development, where eggs from terrestrial clutches entirely circumvent an aquatic tadpole stage and directly develop into small froglets. We here report the first case of egg-burying behaviour in a neotropical direct-developing frog with subsequent short-term maternal care. An amplectant pair of Pristimantis chocoensis was found at the Reserva Canandé in Esmeraldas, Ecuador, and we recorded oviposition and the later rotation and active burying of the clutch by the female. Both parents remained close to the nest area the following day. This rare observation sheds light on the complex but often cryptic reproductive behaviours of terrestrial amphibians and suggests that the evolution of direct development has selected for highly specialized forms of parental care.

Una de las adaptaciones más extremas a la terrestreidad en los anuros es el desarrollo directo, donde los huevos de puestas terrestres evitan por completo la etapa de renacuajo acuático y se desarrollan directamente en versiones miniatura de los adultos. Aquí informamos el primer caso de comportamiento de enterrar huevos en una rana neotropical de desarrollo directo con posterior cuidado materno a corto plazo. Una pareja amplectante de Pristimantis chocoensis fue encontrada en la Reserva Canandé en Esmeraldas­Ecuador, y registramos la oviposición y la posterior rotación y enterramiento activo de la puesta por parte de la hembra. Ambos padres permanecieron cerca del área del nido durante el día siguiente. Esta rara observación arroja luz sobre los complejos, pero a menudo crípticos, comportamientos reproductivos de los anfibios terrestres y sugiere que la evolución del desarrollo directo ha seleccionado formas altamente especializadas de cuidado parental.

Growing in the womb: The effect of seismic activity on fetal growth.

We study whether exposure to earthquake affects health at birth. A mother-fixed-effect model together with the spatiotemporal variation of earthquakes in Chile allow us to better estimate the impacts on birth outcomes. Our findings show that exposure to earthquakes affects fetal growth. Infants born to mothers exposed to earthquakes in the second trimester are 1.8% more likely to be large for gestational age (LGA), which is a large effect from a baseline of 7% of LGA newborns. The reported impact varies across mothers' socioeconomic status, with relatively poorer Chilean mothers being more vulnerable to earthquakes. A possible mechanism that explains these results could work through changes in the incidence of women with diabetes. We provide indirect evidence in this regard. Mothers with diabetes are more likely to have large-for-gestational-age babies. Exposure to earthquakes increases the incidence of diabetes among the affected population, with the observed impact on diabetes being relatively higher among women of lower socioeconomic status.

Natural disasters and indicators of social cohesion.

Do adversarial environmental conditions create social cohesion? We provide new answers to this question by exploiting spatial and temporal variation in exposure to earthquakes across Chile. Using a variety of methods and controlling for a number of socio-economic variables, we find that exposure to earthquakes has a positive effect on several indicators of social cohesion. Social cohesion increases after a big earthquake and slowly erodes in periods where environmental conditions are less adverse. Our results contribute to the current debate on whether and how environmental conditions shape formal and informal institutions.