Acknowledgements:
This study was supported by a grant from the National Natural Science
Foundation of China (42371054, 41871041), Fund for young scholars of
Hainan Natural Science Foundation (422QN269), Hainan Postdoctoral
Research Project (2022-BH-22), Hainan Provincial Innovative Research
Projects of Postgraduates (No. Qhys2022-74).
Abstract
Anthropogenic disturbances have long been acknowledged to be one of the
primary threats to biodiversity worldwide, while little is still
understood about how human-built infrastructure affects the gene flows
and phylogeographic structure of plants. Such information is helpful for
the conservation and restoration of human-disturbed ecosystems. Here we
studied effects of a big river with a huge reservoir and two expressways
on an island-endemic Primulina
heterotricha (Gesneriaceae) on Hainan Island, China, one of the key
parts of the glob ally important Indo-Burma biodiversity hotspot. By
applying comparative phylogeography using one nuclear ribosomal DNA and
two chloroplast DNA sequences, we estimated the levels of genetic
diversity and differentiation in 176 and 117 individuals collected,
respectively, before (in 2016) and after (in 2022) the construction of
two expressways in Hainan Island, from the same eight populations ofP. heterotricha . We found that Primulina heterotrichasignificantly increased nuclear genetic differentiation during the
period 2016–2022, which coincides with the opening of the two
expressways. Also notably, the sharing of ribotypes among the three
groups of populations separated by the expressway network almost
disappeared for the same period. Moreover, the changes in the
significance of genetic barriers before and after road construction
suggest that geographic isolation caused by both the reservoir and the
expressways is key for understanding the present phylogeographical
patterns of P. heterotricha . We provide direct evidence that
anthropogenic infrastructures such as reservoirs and expressways have
been capable of increasing genetic differentiation and, thus, modifying
the phylogeographical pattern of P. heterotricha , in just a
six-year period (or two generations of the study plant). To mitigate
such negative pressure, we suggest establishing ecological corridors to
enhance gene exchange between the two sides of the anthropogenic
barriers.