4.2 | Influence of topographic feathers on genetic
structure
Topographic features often act as a physical barrier to gene exchange
between populations of species (Pilot et al., 2006). A previous study of
giant pandas has shown that natural barriers might have decreased gene
flow between the Xiaoxiangling and Daxiangling regions (Zhu, Zhan, Meng,
Zhang, & Wei, 2010). Moreover, using landscape genetic approaches,
researchers investigated the population genetics of American mink, and
found the Cairngorms Mountains may act as a major geographical barrier
to gene flow among populations (Zalewski, Piertney, Zalewska, & Lambin,
2009). A study by Wei et al. (2013) also showed that gene flow ofEuptelea pleiospermum was limited by mountain ridges.
As mentioned before, Orchidaceae is often characterized by relatively
low levels of genetic differentiation among populations because of
long-distance dispersal afforded by minute size of seeds, and
geographical features usually have no impacts on their spatial genetic
structure. For example, Perez-Escobar et al. (2017) noted that the Andes
seem not to have been much of a barrier to the dispersal of lowland
epiphytic orchids. Consistent with the previous result, we also found
the Qinling Mountains do not appear to be a geographic barrier of
genetic exchange for terrestrial orchid C. faberi . However,
another study of an epiphytic orchid found that seed flow among twelve
populations in Costa Rican mountain ranges was comparatively limited
(cpDNA, FST = 0.443), which possibly due to the
directional prevailing winds (Kartzinel, Shefferson, & Trapnell, 2013).