Rapid morphological change in a small mammal species after habitat fragmentation over the past half-century

Study Aim: To compare the rapid shifts in body size of mainland and island populations of a native rodent and examine the mechanisms underlying these changes.

Location: Thousand Island Lake, China, which was created in 1959 when the Xin’anjiang Dam was constructed for generating hydroelectricity.

Taxon: The Chinese white-bellied rat, Niviventer confucianus.

Methods: Field surveys were conducted from 2015 to 2018 to collect data on body size of the rodents from a set of islands and nearby mainland sites. We constructed multiple linear models to examine the relationships between body size (length and mass) of rodents and biological variables (predators, interspecific and intraspecific competitors, and food availability). We also conducted structural equation modeling (SEM) by constructing models via confirmatory path analysis.

Results: All island populations of N. confucianus had significantly larger body size (both body mass and body length) than their mainland counterparts. ...