(NEW PUBLICATION) Small-Mammal Genomics Highlights Viaducts as Potential Dispersal Conduits for Fragmented Populations

Can viaducts truly bridge the gap created by highways, fostering genetic connectivity among fragmented populations?

A recent scientific study delves into this inquiry, examining the effectiveness of wildlife crossings in mitigating the barrier effects of roads on four small mammal species—Tupaia glis, Maxomys rajah, M. whiteheadi, and Niviventer cremoriventer.

The study, conducted in two lowland dipterocarp forest areas in peninsular Malaysia, compares three treatment types: viaduct sites, where sampling locations are separated by a highway but connected by a vegetated viaduct; non-viaduct sites, with sampling locations separated by a highway and lacking viaduct connections; and control sites, where no highways fragment the forest. Researchers also employed genome-wide markers to assess genetic diversity, gene flow, and genetic structure across the four species. The results paint a nuanced picture of how different species respond to the challenges posed by roads and viaducts.

The four study species: (a) Maxomys whiteheadi, (b) Maxomys rajah, (c) Niviventer cremoriventer and (d) Tupaia glis. Photos by Tabitha Hui. (Hui et al., 2024, Figure 3)

Surprisingly, viaducts demonstrated their efficacy in facilitating movement, particularly for ground-dwelling species like M. whiteheadi, especially when dealing with wider highways. However, the study reveals a complex reality: while viaducts can enhance genetic connectivity for some species, the genetic distance in populations at viaduct sites remains greater than at control or non-viaduct sites for others.

The findings emphasize the importance of maintaining intact forests, cautioning against overreliance on the construction of viaducts as the sole solution to connect fragmented populations.

Read more about it here: https://www.mdpi.com/2076-2615/14/3/426