DOI: 10.5061/dryad.f7m0cfxx7
title: Rapid morphological change in a small mammal species after habitat fragmentation over the past half-century

description: 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. Moreover,
 populations on small and more isolated islands had larger body size than
 their relatives on big islands. The relative absence of predators
 (large-bodied mammals, snakes, and raptors) on islands was most strongly
 associated with shifts in the body size of rodents. The documented changes
 occurred after only a half-century of fragmentation. Main conclusions: The
 observed rapid body enlargement of rodents after habitat fragmentation is
 consistent with a release from predation pressure. SEM indicated that
 island area, rather than island isolation, had positive effects on the
 richness of predators, interspecific competitors and food resources, which
 then had an indirect impact on body size of the rodents. In this study, we
 report a remarkably rapid case of mammal morphological shifts in a small
 mammal in response to habitat fragmentation. Given the omnipresence of
 dams and other anthropogenic disturbances, our findings suggest that a
 wave of rapid phenotypic shifts in terrestrial vertebrates is taking place
 in the Anthropocene.
description: <strong>How was this dataset
 collected? </strong> We gathered these data from
 our field survey. We collected the data on body size by live-trapping
 rodents along transects from July to September in 2016 and 2017. The
 primary predators of <i>N. confucianus</i> in the region are
 snakes, owls, and large carnivorous mammals such as wild boars and leopard
 cats. We surveyed the bird community (with an emphasis on the rodent
 predators like <i>Otus bakkamoena</i>) on mainland and island
 sites during 2015–2018. To assess species composition and abundance of
 carnivore mammals that are predators of rodents, we set camera traps on
 study islands and mainland sites from 2015 to 2017. We conducted surveys
 of all vascular plant species occurring on each mainland and island site
 during the growing seasons (April to November) in 2017. 
 All aspects of this study were approved by Chun'an Forestry
 Bureau, Thousand Island Lake National Forest Park and Zhejiang
 University. <strong>How has it been
 processed</strong>?   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.
description: The document  "data-DDi.csv" is about body length and
 body mass data of the rodents on different sites.   In
 this dataset:<br> "area" is island area (h)<br>
 "length" is body length of the rodents (mm)<br>
 "weight" is body mass of the study rodents (h)<br>
 "apredator" is abundance data of rodent predators<br>
 "rpredator" is richness data of rodent predators<br>
 "acompetitor" is abundance data of rodent competitors<br>
 "rcompetitor" is richness data of rodent competitors<br>
 "aqiaodou" is abundance data of rodent food,
 "rqiaodou" is richness data of rodent food<br>
 "intra" is intraspecific data of the study rodents<br>
 "density" is rodent density data of the study rodents
 The above data are of the body size shifts of a small mammal in
 the Thousand Island Lake of China.