44
private alleles in some populations of A. chilensis suggested they would be ancient
refugia from pre-Holocene times (Arana et al. 2010).
Concerning the genetic variation in adaptive traits, several species of the
Subantarctic forests have been studied either by traditional provenance and progeny
field tests or under controlled conditions in the nursery. The use of common garden
experiments, where different genetic entities (provenances or progenies) are evaluated in the same environment, allows inferring the genetic bases of the observed
phenotypic variation. These trials can be temporary installed in the nursery (inside
or outside the greenhouse) for evaluating early traits under more or less controlled
conditions, or permanently in the field for long-term evaluation, in this case usually
as networks across environmental gradients. For example, early growth traits were
evaluated in 24 provenances of N. pumilio (Mondino 2014, see Chap. 5) to estimate
geographic and genetic variation, in 116 families from eight provenances of N. obliqua (Barbero 2014; see Chap. 4), and in 177 families from 10 provenances of
Austrocedrus chilensis (Aparicio et al. 2010; Pastorino et al. 2014; see Chap. 6).
Likewise, phenological traits were analyzed in 65 open pollinated families from 8
provenances of N. alpina (Duboscq-Carra et al. 2020) and in 12 provenances of
N. pumilio (Torres et al. 2017).
Field trials are especially important for long-lived, slow-growing species like
forest trees, because they allow evaluating later life history traits, which might show
variation not evident in younger plants (O’Brien et al. 2007). Morphological traits
like growth, branching, tree form, as well as phenological and reproductive traits are
relevant both for breeding programs and for studies of adaptation and can only be
measured in long-establish trials. These trials demand a huge effort for establishing
and maintenance, and, currently, only few species from the Patagonian forests are
being evaluated in this way. The oldest progeny test of a forest tree species of the
Andean-Patagonian forest in Argentina was planted for Nothofagus alpina in 1997,
at Trevelin Forest Station of INTA (Instituto Nacional de Tecnología Agropecuaria),
much further south of its natural distribution. Since then, several trials (both provenance and progeny) were installed (mainly in INTA experimental stations) for the
species with the highest domestication potential, with the aims of analyzing their
genetic variation and evaluating their performance for breeding programs. Thus,
around 20-year-old field trials are already available and under evaluation for
N. alpina, N. obliqua, A. chilensis, and A. araucana, and more recently, long-term
trials for N. pumilio and N. antarctica were also installed.
Several studies attempted to evaluate adaptive responses of populations to ecological gradients, like altitude, where the most important environmental variable is
the temperature (e.g., (Premoli 2003; Premoli and Brewer 2007; Arana et al. 2016),
and longitude, where the precipitation changes drastically (e.g., Pastorino et al.
2012; Soliani et al. 2020). In those studies, natural populations along the particular
gradient are evaluated aiming to find local adaptations to their home environments.
Using reciprocal transplants and/or common garden trials, morphological, ecophysiological, and phenological traits were measured to elucidate genetic vs. plasticity responses.
P. Marchelli et al.
private alleles in some populations of A. chilensis suggested they would be ancient
refugia from pre-Holocene times (Arana et al. 2010).
Concerning the genetic variation in adaptive traits, several species of the
Subantarctic forests have been studied either by traditional provenance and progeny
field tests or under controlled conditions in the nursery. The use of common garden
experiments, where different genetic entities (provenances or progenies) are evaluated in the same environment, allows inferring the genetic bases of the observed
phenotypic variation. These trials can be temporary installed in the nursery (inside
or outside the greenhouse) for evaluating early traits under more or less controlled
conditions, or permanently in the field for long-term evaluation, in this case usually
as networks across environmental gradients. For example, early growth traits were
evaluated in 24 provenances of N. pumilio (Mondino 2014, see Chap. 5) to estimate
geographic and genetic variation, in 116 families from eight provenances of N. obliqua (Barbero 2014; see Chap. 4), and in 177 families from 10 provenances of
Austrocedrus chilensis (Aparicio et al. 2010; Pastorino et al. 2014; see Chap. 6).
Likewise, phenological traits were analyzed in 65 open pollinated families from 8
provenances of N. alpina (Duboscq-Carra et al. 2020) and in 12 provenances of
N. pumilio (Torres et al. 2017).
Field trials are especially important for long-lived, slow-growing species like
forest trees, because they allow evaluating later life history traits, which might show
variation not evident in younger plants (O’Brien et al. 2007). Morphological traits
like growth, branching, tree form, as well as phenological and reproductive traits are
relevant both for breeding programs and for studies of adaptation and can only be
measured in long-establish trials. These trials demand a huge effort for establishing
and maintenance, and, currently, only few species from the Patagonian forests are
being evaluated in this way. The oldest progeny test of a forest tree species of the
Andean-Patagonian forest in Argentina was planted for Nothofagus alpina in 1997,
at Trevelin Forest Station of INTA (Instituto Nacional de Tecnología Agropecuaria),
much further south of its natural distribution. Since then, several trials (both provenance and progeny) were installed (mainly in INTA experimental stations) for the
species with the highest domestication potential, with the aims of analyzing their
genetic variation and evaluating their performance for breeding programs. Thus,
around 20-year-old field trials are already available and under evaluation for
N. alpina, N. obliqua, A. chilensis, and A. araucana, and more recently, long-term
trials for N. pumilio and N. antarctica were also installed.
Several studies attempted to evaluate adaptive responses of populations to ecological gradients, like altitude, where the most important environmental variable is
the temperature (e.g., (Premoli 2003; Premoli and Brewer 2007; Arana et al. 2016),
and longitude, where the precipitation changes drastically (e.g., Pastorino et al.
2012; Soliani et al. 2020). In those studies, natural populations along the particular
gradient are evaluated aiming to find local adaptations to their home environments.
Using reciprocal transplants and/or common garden trials, morphological, ecophysiological, and phenological traits were measured to elucidate genetic vs. plasticity responses.
P. Marchelli et al.