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definition of provenance regions (PRs), which ensure not only the conservation of
evolutionary significant variants related to its life history (Crandall et al. 2000; de
Guia and Saitoh 2007) but also the ecological viability and local adaptation of populations. The final goal of OGMUs’ definition is to conserve relevant ecological entities that represent short- and long-term genetic processes (Fraser and
Bernatchez 2001).
Population genetic diversity of a species is shaped in terms of evolutionary time
as the product of the interplay between enhancing forces (i.e., gene flow, generation
of new mutations, hybridization) and erosive forces (i.e., genetic drift, selection).
Highly diverse populations should be prioritized for conservation, since they probably expose a better response to environmental changes that might risk their persistence (e.g., extreme climatic events, biological invasions). Unique variants (i.e.,
infrequent genotypes, private alleles, or haplotypes) or geographically restricted
variants are also relevant to face new and unpredictable environments. It is crucial
to understand the distribution of the genetic diversity along the natural species range
since it reveals the degree of interconnection among them. The variation level of
each population might be related to past evolutionary footprints, the mating system,
or current genetic processes. Whatever the cause, its identification could assist managers when collection of propagation material is needed.
Based on molecular markers, standardize allelic richness SAR (Marchelli et al.
2017) was obtained for Nothofagus pumilio and N. antarctica populations, and the
more diverse were identified (1–5, 8, 12, 14, 16, and 19 and II, IV, IX, XIII, XIV,
XV, and XX, respectively (Table 5.1); Soliani et al. 2017). Considering the emergent patterns of genetic diversity and structure, but also the prevailing topography
and the geographic isolation of the populations, preliminary genetic zones were
proposed for both species. Several GZs include large areas of the natural distribution of the target species, demanding the screening of more and new populations to
refine the divisions. In N. pumilio case, a re-delineation of GZs has being carried out
by adding 14 new populations to the previous set and thus covering almost completely the main distribution range of this species (Mattera et al., in press). As a
result of this, 18 GZs were defined in the species within four main regions along
Patagonia (36–42° S, 42–44° S, 44–51° S, and 55° S corresponding to populations
included in the island of Tierra del Fuego). In N. antarctica, nine GZs were proposed (Fig. 5.4) based on the genetic data from the 21 populations presented in
Table 5.1. From north to south, they are North, Tromen, Central, Chubut, Río
Grande, LGM East, LGM West, South, and Tierra del Fuego.
5.5 Adaptive Genetic Variation of N. pumilio: Assessment
of Juvenile Traits in Common Garden Experiments
Genetic diversity is a population intrinsic property, the basis on which the evolutionary force of natural selection operates. The geographic variation of quantitative
traits displayed by individuals in situ can be associated with their distribution in
environmental gradients and inferred as a result of adaptation processes, thus
C. Soliani et al.
definition of provenance regions (PRs), which ensure not only the conservation of
evolutionary significant variants related to its life history (Crandall et al. 2000; de
Guia and Saitoh 2007) but also the ecological viability and local adaptation of populations. The final goal of OGMUs’ definition is to conserve relevant ecological entities that represent short- and long-term genetic processes (Fraser and
Bernatchez 2001).
Population genetic diversity of a species is shaped in terms of evolutionary time
as the product of the interplay between enhancing forces (i.e., gene flow, generation
of new mutations, hybridization) and erosive forces (i.e., genetic drift, selection).
Highly diverse populations should be prioritized for conservation, since they probably expose a better response to environmental changes that might risk their persistence (e.g., extreme climatic events, biological invasions). Unique variants (i.e.,
infrequent genotypes, private alleles, or haplotypes) or geographically restricted
variants are also relevant to face new and unpredictable environments. It is crucial
to understand the distribution of the genetic diversity along the natural species range
since it reveals the degree of interconnection among them. The variation level of
each population might be related to past evolutionary footprints, the mating system,
or current genetic processes. Whatever the cause, its identification could assist managers when collection of propagation material is needed.
Based on molecular markers, standardize allelic richness SAR (Marchelli et al.
2017) was obtained for Nothofagus pumilio and N. antarctica populations, and the
more diverse were identified (1–5, 8, 12, 14, 16, and 19 and II, IV, IX, XIII, XIV,
XV, and XX, respectively (Table 5.1); Soliani et al. 2017). Considering the emergent patterns of genetic diversity and structure, but also the prevailing topography
and the geographic isolation of the populations, preliminary genetic zones were
proposed for both species. Several GZs include large areas of the natural distribution of the target species, demanding the screening of more and new populations to
refine the divisions. In N. pumilio case, a re-delineation of GZs has being carried out
by adding 14 new populations to the previous set and thus covering almost completely the main distribution range of this species (Mattera et al., in press). As a
result of this, 18 GZs were defined in the species within four main regions along
Patagonia (36–42° S, 42–44° S, 44–51° S, and 55° S corresponding to populations
included in the island of Tierra del Fuego). In N. antarctica, nine GZs were proposed (Fig. 5.4) based on the genetic data from the 21 populations presented in
Table 5.1. From north to south, they are North, Tromen, Central, Chubut, Río
Grande, LGM East, LGM West, South, and Tierra del Fuego.
5.5 Adaptive Genetic Variation of N. pumilio: Assessment
of Juvenile Traits in Common Garden Experiments
Genetic diversity is a population intrinsic property, the basis on which the evolutionary force of natural selection operates. The geographic variation of quantitative
traits displayed by individuals in situ can be associated with their distribution in
environmental gradients and inferred as a result of adaptation processes, thus
C. Soliani et al.