4. Discussion
4.1Genetic
diversity of P. villosa
Genetic
diversity refers to intraspecific genetic variation and is closely
linked to the evolutionary potential of a species to adapt to adverse
environments (Ma & Qian, 1994). The study of genetic diversity can
facilitate understanding of spatial genetic patterns of a species, and
elucidate its evolutionary processes and adaptive mechanisms (Hao,
2005).
In
the present study, we observed high genetic diversity at species-level
in P. villosa (P =95.72%, I = 0.3316) and the
population-level
(P= 32.02%, I =
0.1640)
(Table 2 & Table S1). Compared to genetic diversity in other species of
Poaceae assessed using AFLPs, genetic diversity in P. villosa was
slightly lower than that ofChascolytrum
bulbosum (P = 98.2%, h = 0.1500; Silva, Essi, Welker, &
de, Souza-Chies, 2016), and was higher than that of Leymus
chinensis (P = 16.53%, I = 0.0890),Leymus
racemosus (P = 16.53%, I = 0.0890), andDactylis
glomerata (P = 61.70%, I = 0.2664) (Gong et al., 2007;
Cai, 2016; Zhang, He, Zhao, Zhang, & Xu, 2017).
The underlying drivers of genetic diversity within species are generally
a combination of biological properties, such as dispersal abilities and
life history, and environmental factors, such as climate and
anthropogenic activities (Loveless & Hamrick, 1984; Hamrick & Godt,
1996; Wang & Hu, 1996; Wen, Han, & Wu, 2010). The life history ofP. villosa frequently involves clonal reproduction via its
rhizomes under harsh environmental conditions, although the species
reproduces sexually by seed following wind pollination (Wang, Ge, &
Dong, 1999; Li & Ge, 2001). In comparison with L. chinensis ,L. racemosus , and D. glomerata , the relatively high
genetic diversity of P. villosa might be explained by one or more
of several factors. Among these, our study design comprised more
populations, which might lead to greater accuracy. However, biological
explanations are more likely and include possible higher clonal fitness
due to P. villosa having extremely robust, hardy rhizomes; high
rates of seed production; and seedling regeneration, while rare within
any one growing season, occurring often over the long lifetime of the
species (Eriksson & Bremer, 1993; Helena & Mikko, 1996; Shimizu et
al., 1998).