Roads and railways are among the most conspicuous man-made landscape features and they impose major ecological impacts on the ecosystem (Forman and Alexander, 1998; Trombulak and Frissell, 2000). Various effects have been proposed and examined, including large numbers of fatalities (Gibbs and Shriver, 2005), altering individual movement patterns and abundance , and more importantly the “barrier effect” that subdivides populations with significant demographic and genetic consequences

Using data from nine microsatellite DNA loci and a population genetic approach, researchers from Chengdu Institute of Biology evaluate the barrier effect of the Qinghai-Tibet Railway on toad-headed lizard, Phrynocephalus vlangalii. The study area is along a 20 km stretch of the railway on northern Qinghai-Tibet Plateau, and this section of the railway was constructed between 1958–1979. Both assignment tests and analysis of molecular variance (AMOVA) were used for data analysis.

Researchers from Chengdu Institute of Biology found significant genetic differentiation between the populations from the study area and those from a further southeastern area, which are separated by a 20 km gap. This suggests the existence of population substructure at a fine-scale. However, we did not detect any difference between samples from the western and eastern sides of the railway within the study area, and concluded that the railway may not impose a significant barrier effect on these lizard populations at the present time.

Available suitable habitat alongside the railway and bridge underpasses may have facilitated the gene exchange between the sides. The relatively short time since the completion of the railway may not allow the differentiation to accumulate to a detectable level. Since the Qinghai-Tibet Plateau maintains a unique and fragile ecosystem, long-term monitoring of such man-made landscape features is imperative for protecting this ecosystem.