Nature ecology & evolution最新文献

Global ecosystems are rapidly approaching tipping points, where minute shifts can lead to drastic ecological changes. Theory predicts that evolution can shape a system’s tipping point behaviour, but direct experimental support is lacking. Here we investigate the power of evolutionary processes to alter these critical thresholds and protect an ecological community from collapse. To do this, we propagate a two-species microbial system composed of Escherichia coli and baker’s yeast, Saccharomyces cerevisiae, for over 4,000 generations, and map ecological stability before and after coevolution. Our results reveal that tipping points—and other geometric properties of ecological communities—can evolve to alter the range of conditions under which our microbial community can flourish. We develop a mathematical model to illustrate how evolutionary changes in parameters such as growth rate, carrying capacity and resistance to environmental change affect ecological resilience. Our study shows that adaptation of key species can shift an ecological community’s tipping point, potentially promoting ecological stability or accelerating collapse.

Seasonal bird migration may provide energy benefits associated with moving to areas with less physiologically challenging climates or increased food availability, but migratory movements themselves may carry high costs. However, time-dynamic energy profiles of free-living migrants—especially small-bodied songbirds—are challenging to measure. Here we quantify energy output and thermoregulatory costs in partially migratory common blackbirds using implanted heart rate and temperature loggers paired with automated radio telemetry and energetic modelling. Our results show that blackbirds save considerable energy in preparation for migration by decreasing heart rate and body temperature 28 days before departure, potentially dwarfing the energy costs of migratory flights. Yet, in warmer wintering areas, migrants do not appear to decrease total daily energy expenditure despite a substantially reduced cost of thermoregulation. These findings indicate differential metabolic programmes across different wintering strategies despite equivalent overall energy expenditure, suggesting that the maintenance of migration is associated with differences in energy allocation rather than with total energy expenditure.

The onset of sedentism on the Tibetan Plateau is often presumed to be associated with the dispersal of agriculture or farmers from archaeological sites located in the low elevation margins of the plateau. Previous studies of the plateau assumed that all foragers were probably mobile, but few systematic excavations at forager sites have been conducted to inform us about their settlement patterns. Here we report the world’s highest elevation sedentary way of living exhibited by the Mabu Co site at 4,446 metres above sea level, deep in the interior of the Tibetan Plateau 4,400–4,000 years ago. Our interdisciplinary study indicates that the site was occupied by Indigenous inhabitants of the plateau, representing the earliest known DNA evidence of foragers who predominantly harbour the southern plateau ancestry. The evidence shows that they had a sedentary lifestyle primarily supported by fishing at nearby lakes, supplemented by mammal and bird hunting, as well as small-scale exchanges of millet and rice crops.