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significant in only one population located at 42° 50′ S (5%, F RT = 0.048; p = 0.001).
Spatial autocorrelation and heterogeneity tests between management treatments
were non-significant in the populations, making inviable to assess the true impact of
management on spatial variation. The effects of management varied widely
according to the type of treatment, having multiple effects (positive, negative, or
neutral) on the genetic diversity and the mating system. Additional factors might be
playing a role in the final determination of genetic variation, i.e., intensity of
management, time elapsed since the last intervention, recent practices, and presence
of livestock.
5.4 Genetic Zones: On How Molecular Tools Can Contribute
to the Conservation and Management
of Forest Resources
In widely distributed species conformed by hundreds of natural populations, as
many tree species, it is unfeasible the management from a genetic perspective of
each population separately. The definition of operational genetic management units
(OGMU) overcomes the limitation of making decisions at the level of single populations. Knowledge on the genetic pool of a species gained by sampling Mendelian
populations can contribute to the application of specific management actions to
groups of populations. Those management decisions are commonly related to the
conservation and use of genetic resources and involve actions such as the planning
of reforestation or restoration programs. Properly designed strategies will focus on
the preservation of the local provenance in order to avoid maladaptation and genetic
contamination. In this regard, genetic zones’ (GZs) delineation is the first step
toward OGMUs’ definition. GZs are known as genetically homogeneous regions
(Bucci and Vendramin 2000) within which genetic material can be moved with minimum risk of altering the genetic constitution of the local and nearby populations
(McKay et al. 2005). At the same time, GZs would represent discernible genetic
pools that are desired to be conserved because of its distinctive genetic attributes. To
accomplish this purpose, both a genetic inventory and a representation of the natural
distributional range (mapped geographic area) of the species are crucial requirements. In order to classify the genetic information, a hierarchical clustering of sampled populations is useful to group populations sharing the same genetic background.
Among the available methods, Bayesian clustering represents the most accurate and
reliable.
Genetic analyses using molecular markers provide information based on the neutral evolution of the populations (i.e., not affected by selection) for identifying GZs.
This type of markers could offer information about demographic history of a population and allow identifying the genetic structure of a set of populations modeled by
historical processes. Still, adaptive traits could be evaluated by quantitative genetic
studies and, combined with neutral marker analyses, might provide a complete
assessment of the genetic resources. Thus, GZs constitute a first step toward the
5 Nothofagus pumilio and N. antarctica: The Most Widely Distributed…
significant in only one population located at 42° 50′ S (5%, F RT = 0.048; p = 0.001).
Spatial autocorrelation and heterogeneity tests between management treatments
were non-significant in the populations, making inviable to assess the true impact of
management on spatial variation. The effects of management varied widely
according to the type of treatment, having multiple effects (positive, negative, or
neutral) on the genetic diversity and the mating system. Additional factors might be
playing a role in the final determination of genetic variation, i.e., intensity of
management, time elapsed since the last intervention, recent practices, and presence
of livestock.
5.4 Genetic Zones: On How Molecular Tools Can Contribute
to the Conservation and Management
of Forest Resources
In widely distributed species conformed by hundreds of natural populations, as
many tree species, it is unfeasible the management from a genetic perspective of
each population separately. The definition of operational genetic management units
(OGMU) overcomes the limitation of making decisions at the level of single populations. Knowledge on the genetic pool of a species gained by sampling Mendelian
populations can contribute to the application of specific management actions to
groups of populations. Those management decisions are commonly related to the
conservation and use of genetic resources and involve actions such as the planning
of reforestation or restoration programs. Properly designed strategies will focus on
the preservation of the local provenance in order to avoid maladaptation and genetic
contamination. In this regard, genetic zones’ (GZs) delineation is the first step
toward OGMUs’ definition. GZs are known as genetically homogeneous regions
(Bucci and Vendramin 2000) within which genetic material can be moved with minimum risk of altering the genetic constitution of the local and nearby populations
(McKay et al. 2005). At the same time, GZs would represent discernible genetic
pools that are desired to be conserved because of its distinctive genetic attributes. To
accomplish this purpose, both a genetic inventory and a representation of the natural
distributional range (mapped geographic area) of the species are crucial requirements. In order to classify the genetic information, a hierarchical clustering of sampled populations is useful to group populations sharing the same genetic background.
Among the available methods, Bayesian clustering represents the most accurate and
reliable.
Genetic analyses using molecular markers provide information based on the neutral evolution of the populations (i.e., not affected by selection) for identifying GZs.
This type of markers could offer information about demographic history of a population and allow identifying the genetic structure of a set of populations modeled by
historical processes. Still, adaptive traits could be evaluated by quantitative genetic
studies and, combined with neutral marker analyses, might provide a complete
assessment of the genetic resources. Thus, GZs constitute a first step toward the
5 Nothofagus pumilio and N. antarctica: The Most Widely Distributed…