Genetic structure of Dicksonia sellowiana Hook. (Dicksoniaceae) reveals clinal distribution along the latitudinal gradient of the Atlantic Forest

Diversity and Genetic Structure of Dicksonia navarrensis (Dicksoniaceae) Populations in the Mexican Sierra Madre Oriental

“…This study provides the first results on the structure and genetic diversity of Dicksonia navarrensis (sensu Noben et al, 2017) populations in Mexico; 100% of the specific loci included in the work were successfully amplified, and 81.81% were polymorphic, although it is possible that other alleles are masked (Izuno et al, 2012). Here, the polymorphism percentage obtained through the use of microsatellites, is similar to that estimated in D. sellowiana in Brazil, the values range between 72.73% (Nazareno et al, 2013) and 100% (Fagundes et al, 2020), with a total number of alleles similar to that of Mexican populations of D. navarrensis, 38 and 32, respectively (versus 33 in the present work). In Alsophila spinulosa populations of China, polymorphism estimated with SSR markers was 21.43% (Zhou et al, 2008), and in Sphaeropteris brunoniana populations of China, polymorphism was 80.6%, estimated using AFLP (Wang & Guan, 2011).…”

“…Even though the dispersal capacity of the spores of this species is very high, the probability that they will find suitable conditions for germination, gametophyte production and sporophyte formation is low, but studies are required to confirm that argument. In contrast, populations of D. sellowiana are distributed over a larger geographic area in the Atlantic Forest of South America (Mallman et al, 2019), have a high density of individuals, and have a continuous influx of gametophytes into populations (Schmitz et al, 2006;Fagundes et al, 2020); these three characteristics could be related to the corresponding values of H E , higher than those estimated for D. navarrensis in the present study.…”

“…Here, the polymorphism percentage obtained through the use of microsatellites, is similar to that estimated in D . sellowiana in Brazil, the values range between 72.73% (Nazareno et al, 2013) and 100% (Fagundes et al, 2020), with a total number of alleles similar to that of Mexican populations of D . navarrensis , 38 and 32, respectively (versus 33 in the present work).…”

“…Dicksonia navarrensis presented low genetic diversity (mean H E = 0.36) compared to other species of the same genera, such as D . sellowiana (mean H E = 0.50, Fagundes et al, 2020), or with respect to Alsophila spinulosa (mean H E = 0.45, Zhou et al, 2008), probably as a result of the high degree of fragmentation and loss of its habitat, the montane cloud forest of Mexico (INEGI, 2017), which affects the connectivity between its populations (Graignic et al, 2018). However, it must be considered that habitat loss and fragmentation in other fern species ( Pleopeltis crassinervata and Polypodium rhodopleuron ) did not have a strong influence on genetic diversity because it remained high; mean H E = 0.257 and 0.223, respectively (Winkler et al, 2011).…”

“…Alsophila firma, for example, has developed a post-zygotic mechanism that enables it to promote outcrossing in its populations (Ramírez-Barahona & Eguiarte, 2015); therefore, it is necessary to analyze the mating system of D. navarrensis, to find whether the specific cause of the deficiency in heterozygotes is attributable to natural selection or self-crossing (Wang et al, 2014). Fagundes et al (2020) note that the spores of D. sellowiana are very small, so they are easily dispersed by wind and rain, which facilitates the movement of individuals and interbreeding. This is plausible for this species, but the environmental conditions in which D. navarrensis grows are somewhat different.…”