View of Tikopia Island with its crater lake from the peak of Mt Reani.
Although little direct archaeological evidence exists to quantify the impacts of human colonization on local ecosystems, commensal animals, which accompany human habitation but are not domesticated, can preserve a record of ecosystem change in the isotopic composition of their remains. Jillian Swift et al. (pp. 6392–6397) analyzed isotope trends in Pacific rats dating between 800 BC and AD 1800 from three Polynesian island systems, covering the period of colonization. The authors report that nitrogen-15 isotope values declined over time in all three systems. The declines may reflect shifts in food sources for both humans and rats that are supported by other evidence, as humans transitioned from slash-and-burn agriculture to agroforestry and from offshore fishing to nearshore and terrestrial food sources. Other shifts include the loss of seabirds from rat diet and loss of seabird guano inputs to terrestrial systems, which may be due to extirpation or extinction. One island did not show a similar decline in nitrogen-15, and evidence suggests that constant human occupation at this site provided rats high-quality diets through continued access to marine foods rich in nitrogen-15. According to the authors, the results suggest that human colonization reshaped nutrient flows and that commensal animal isotopes can document human impacts on natural ecosystems. — P.G.
Protein synthesis triggered by neural activity is required for memory formation in the brain. However, the effects of neural activity-induced synthesis of specific proteins on memory formation, as …
*UPDATE: On June 18, 2018, after this article went to press, the Supreme Court of the United States ruled on two high-profile cases related to partisan gerrymandering. In effect, the rulings sidestepped the issue of when partisan gerrymandering is unconstitutional. Both cases—one concerning ... mehr
It is not known whether the fossil content of amber accurately represents the arthropod biodiversity of past forests, and if and how those fossils can be compared with recent fauna for studies and predictions of biodiversity change through time. Our study of arthropods (mainly insects and s ... mehr
The existence of a chemosynthetic subseafloor biosphere was immediately recognized when deep-sea hot springs were discovered in 1977. However, quantifying how much new carbon is fixed in this environment has remained elusive. In this study, we incubated natural subseafloor communities under ... mehr