1 It has been proposed that habitats with low productivity, and hence low resource availability, may favour individuals with lower rates of resource use and energy expenditure. In birds, some studies have shown that basal metabolic rate (BMR) and total evaporative water loss (TEWL) are reduced in desert bird species compared to those that live in more mesic areas. However, the contribution of the phenotypic plasticity of birds to this pattern has been poorly studied. 2 We evaluated the phenotypic flexibility of BMR, TEWL and organ size in sparrows (Zonotrichia capensis) from three populations along an aridity gradient that differ in environmental temperature, rainfall and seasonality. We also tested the hypothesis that populations from variable environments exhibit more physiological flexibility than populations from stable environments. 3 BMR and TEWL in Z. capensis exhibited a positive association with latitude. Additionally, the population from the more stable environment was unaffected by thermal acclimation, but birds from seasonal environments were affected. 4 Our results support the hypothesis of the existence of a correspondence between environmental variability and phenotypic flexibility; that is, birds from localities with a drastic climatic seasonality have a greater response in BMR to thermal acclimation than birds from a more stable environment.

Developmental effects of exposure to endocrine disruptors can influence adult characters in mammals, but could also have evolutionary consequences. The aim of this study was to simulate an environmental exposure of an experimental population of mice to high amounts of nutritional phytoestrogens and to evaluate parameters of relevance for evolutionary change in the offspring. The effect of a continuous pre- and post-natal exposure to high levels of dietary isoflavones was evaluated on sexual maturity, morphometric parameters and DNA methylation status in mice. Adult mice male/female couples were fed ad libitum either with control diet (standard laboratory chow) or ISF diet (control diet plus a soy isoflavone extract at 2% (w/w) that contained the phytoestrogens genistein and daidzein). In the offspring we measured: i) the onset of vaginal opening (sexual maturation) in females, ii) weight and size in all pups at 7, 14, 21 and 42 days post-natal (dpn) and iii) DNA methylation patterns in skeletal α-actin (Acta1), estrogen receptor-α and c-fos in adults (42 dpn).

The arboreal marsupial monito del monte (genus Dromiciops, with two recognized species) is a paradigmatic mammal. It is the sole living representative of the order Microbiotheria, the ancestor lineage of Australian marsupials. Also, this marsupial is the unique frugivorous mammal in the temperate rainforest, being the main seed disperser of several endemic plants of this ecosystem, thus acting as keystone species. Dromiciops is also one of the few hibernating mammals in South America, spending half of the year in a physiological dormancy where metabolism is reduced to 10% of normal levels. This capacity to reduce energy expenditure in winter contrasts with the enormous energy turnover rate they experience in spring and summer. The unique life history strategies of this living Microbiotheria, characterized by an alternation of life in the slow and fast lanes, putatively represent ancestral traits that permitted these cold‐adapted mammals to survive in this environment. Here, we describe the ecological role of this emblematic marsupial, summarizing the ecophysiology of hibernation and sociality, updated phylogeographic relationships, reproductive cycle, trophic relationships, mutualisms, conservation, and threats. This marsupial shows high densities, despite presenting slow reproductive rates, a paradox explained by the unique characteristics of its three‐dimensional habitat. We finally suggest immediate actions to protect these species that may be threatened in the near future due to habitat destruction and climate change.