RESUMO
AbstractIn the world's highest mountain ranges, uncertainty about the upper elevational range limits of alpine animals represents a critical knowledge gap regarding the environmental limits of life and presents a problem for detecting range shifts in response to climate change. Here we report results of mountaineering mammal surveys in the Central Andes, which led to the discovery of multiple species of mice living at extreme elevations that far surpass previously assumed range limits for mammals. We livetrapped small mammals from ecologically diverse sites spanning >6,700 m of vertical relief, from the desert coast of northern Chile to the summits of the highest volcanoes in the Andes. We used molecular sequence data and whole-genome sequence data to confirm the identities of species that represent new elevational records and to test hypotheses regarding species limits. These discoveries contribute to a new appreciation of the environmental limits of vertebrate life.
Assuntos
Altitude , Animais , Camundongos/genética , Camundongos/fisiologia , Chile , Filogenia , Distribuição AnimalRESUMO
Seaweeds living at their temperature limits of distribution are naturally exposed to physiological stressors, facing additional stress when exposed to coastal pollution. The physiological responses of seaweeds to environmental conditions combining natural and anthropogenic stressors provide important information on their vulnerability. We assessed the physiological effects and ultrastructural alterations of trace metals enrichment at concentrations observed in polluted regions within the temperature ranges of distribution of the endemic seaweed Halimeda jolyana, an important component of tropical southwestern Atlantic reefs. Biomass yield and photosynthetic performance declined substantially in samples exposed to metal, although photosynthesis recovered partially at the highest temperature when metal enrichment was ceased. Metal enrichment caused substantial ultrastructural alterations to chloroplasts regardless of temperatures. The lack of photosynthetic recovery at the lower temperatures indicates a higher vulnerability of the species at its temperature limits of distribution in the southwestern Atlantic.