Population genetic diversity and structure within and among disjunct populations of Alnus maritima (seaside alder) using microsatellites

Abstract

Small, isolated populations are prone to genetic drift and high levels of inbreeding that can threaten their long-term survival. Alnus maritima persists exclusively in three groups of small, highly disjunct, regional populations in the Delmarva Peninsula, Georgia, and Oklahoma. Trees in the three regions are recognized as separate subspecies. Microsatellite markers were used to measure fine-scale population genetic diversity and structure (1) within and among regions and (2) within and among populations in each region. Compared to a previous study utilizing allozymes, microsatellite data show higher levels of variation, lower levels of inbreeding, but similar levels of genetic differentiation among regions. Significant genetic differentiation was detected among regions and among distinct populations within regions. Genetic differentiation was significantly correlated with geographic distance among regional populations, but not among populations within regions. Populations, therefore, likely represent fragments of formerly extensive networks of populations that have decayed and retracted due to competition with other species better adapted to the shadier habitats of late-succession environments. The unique genetic features of populations within different regions should be considered as part of future conservation efforts.

Genetic Diversity and Population Structure of Alnus cremastogyne as Revealed by Microsatellite Markers

“…The genetic differentiation among A. cremastogyne populations was very low (Fst = 0.021), lower than that of A. maritima (Fst = 0.107) [11] and A. incana (Fst = 0.0836) [41] populations, but similar to that of A. glutinosa populations at the border of Belgium, Luxembourg, and France (Fst = 0.015) [35]. Wright [43] considered values of Fst in the ranges of 0-0.05, 0.05-0.15, 0.15-0.25, or > 0.25, which represented low, moderate, high, and very high genetic variation among populations, respectively.…”

“…Overall, the 14 A. cremastogyne populations all have relatively high levels of genetic diversity (Na = 5.83, Ht = 0.630), with the Liangshan Prefecture populations (Meigu, Mianning) and Ganzi population (Luding) having the highest level of genetic diversity. Based on the SSR data, the genetic diversity of A. cremastogyne is higher than that of A. maritima (Na = 4.70, He = 0.45) [11] and A. incana (Na = 3.31, He = 0.386) [41]. Meanwhile, the genetic diversity of A. cremastogyne is similar to that of the whole European population (Na = 6.70, He = 0.643) [35], the Irish, Scottish, and French population (Na = 6.61, He = 0.64) [17], as well as that of A. glutinosa population located at the border of Belgium, Luxembourg, and France (Na = 7.34, He = 0.64) [41].…”

Genetic structure of the endangered Leucomeris decora (Asteraceae) in China inferred from chloroplast and nuclear DNA markers

“…Although the genetic data obtained here for L. decora based on differentially inherited genetic markers of cpDNA and nDNA are neutral (nearly neutral) and may not reflect adaptive genetic diversity directly it provides useful data to inform the unique genetic information of each population so that the greatest amount of genetic variation in L. decora is preserved. Low levels of genetic diversity at neutral loci may reflect losses of genetic diversity at loci that influence fitness and preserving such variation may help to inhibit the dissolution of locally well-adapted phenotypes (Godt et al 1996;Jones and Gibson 2011;Ueno et al 2005). While it is worth to remark that a species should be definitely maintained within its ecological community, therefore, more genetic diversity work related to adaptive traits and knowledge on ecosystem functions and species interactions will be helpful for understanding how the species adapt to the changing conditions.…”

Development of polymorphic microsatellite markers and the population genetic structure of the half-fin anchovy, Setipinna taty

“…Low levels of genetic diversity at loci might reflect the losses of genetic diversity that could influence the fitness. Preserving variation might help to inhibit the dissolution of locally well-adapted phenotypes (Godt et al, 1996;Ueno et al, 2005;Jones and Gibson, 2011). It is important to note that a species should be maintained within its ecological community, and more genetic diversity research related to adaptive traits and the knowledge about ecosystem functions and species interactions would be helpful to understand how the species could adapt to changing conditions.…”