Assessment of the Genetic Diversity in Forest Tree Populations Using Molecular Markers

Abstract

Molecular markers have proven to be invaluable tools for assessing plants' genetic resources by improving our understanding with regards to the distribution and the extent of genetic variation within and among species. Recently developed marker technologies allow the uncovering of the extent of the genetic variation in an unprecedented way through increased coverage of the genome. Markers have diverse applications in plant sciences, but certain marker types, due to their inherent characteristics, have also shown their limitations. A combination of diverse marker types is usually recommended to provide an accurate assessment of the extent of intra-and inter-population genetic diversity of naturally distributed plant species on which proper conservation directives for species that are at risk of decline can be issued. Here, specifically, natural populations of forest trees are reviewed by summarizing published reports in terms of the status of genetic variation in the pure species. In general, for outbred forest tree species, the genetic diversity within populations is larger than among populations of the same species, indicative of a negligible local spatial structure. Additionally, as is the case for plants in general, the diversity at the phenotypic level is also much larger than at the marker level, as selectively neutral markers are commonly used to capture the extent of genetic variation. However, more and more, nucleotide diversity within candidate genes underlying adaptive traits are studied for signatures of selection at single sites. This adaptive genetic diversity constitutes important potential for future forest management and conservation purposes.

Genetic diversity in African nutmeg (Monodora myristica) accessions from South Eastern Nigeria

“…An average of 0.31 was reported for Anonna crassiflora (Cota et al, 2011). The high values obtained in our study are quite encouraging and conform to that expected for tree species which generally present greater genetic variation within populations (Porth and El-Kassaby, 2014). The genetic similarity indices usually range from zero to one, with values closer to one indicating greater genetic diversity.…”

“…Apart from maintaining food and health security, a rich genetic diversity is a basic resource for improvement programs. It also helps the species to withstand different biotic and abiotic stresses under changing environmental conditions (Porth and El-Kassaby, 2014).…”

Morphological and Molecular Differentiation in Populations of Persian Oak (Quercus Brantii Lindl.) in Southwestern Iran

“…This pattern has been explained to be the result of long generation times, woody life forms, out-crossing mating system, high fecundity, mechanism of pollination (anemophily), long age and dispersal of seeds by animals. These are responsible for the low levels of differentiation between populations, which Shiran et al, 2011;QIN et al, 2012;Zhang et al, 2013;Alfonso-Corrado et al, 2014;Porth & El-Kassaby, 2014;ValenciaCuevas et al, 2014 andWang et al, 2014).…”

Assessment of Genetic Diversity and Population Genetic Structure of Norway Spruce (Picea abies (L.) Karsten) at Its Southern Lineage in Europe. Implications for Conservation of Forest Genetic Resources

“…Furthermore, mean H e across five common loci (WS00716.F13, WS0022.B15, WS0073.H08, WS00111.K13, WS0023.B03) was slightly higher (0.89) in Serbian populations in comparison to those observed in Tyrol (0.87) and the Czech republic (0.86) [47,48]. Numerous studies using SSRs evidenced that geographically widespread tree species showed significantly higher intra-population genetic diversity than variation among populations (e.g., [51,52]). Also here, the major proportion of gene diversity was harbored within populations, with only minor share partitioning among them.…”

“…Reed and Frankham [63] documented a strong positive correlation between heterozygosity and population fitness, which is important for the long-term adaptation of populations to novel environmental conditions. Besides heterozygosity, certain authors identified allelic richness as a more suitable parameter for conservation purposes [52,64,65]. Discussing selection of candidate populations for conservation based on molecular marker studies, Petit et al [54] stated that allelic richness should get priority over heterozygosity because it is highly dependent on effective population size and provides better information concerning past evolutionary history.…”