31
(Premoli 2003; Premoli et al. 2007; Mondino et al. 2019; Soliani and Aparicio,
2020; see Chap. 5).
The distribution of species in mountainous areas is typically restricted to narrow
and well- delimited altitudinal zones (Jump et al. 2009). In the Andes, the decrease
in temperature toward higher elevations determines specific niches for the main
three species that characterize the temperate Nothofagus mixed forest of the Lanín
National Park in Argentina, at 40° S. Thus, although some overlap in their altitudinal distributions exists, N. obliqua dominates the lower altitudes between 650 and
800 m asl, N. alpina does so between 800 and 1000 m asl, and N. pumilio is found
from 1000 m till 1700 m asl usually forming the tree line (Donoso 2006).
These particular settings of the Subantarctic forests, occupying different environments along temperature, precipitation, and day length gradients, suggest the
occurrence of local adaptations of populations to their home environmental conditions. Thus, these gradients represent a kind of “natural laboratory” since the same
species can be found living under contrasting environmental conditions (Fig. 2.2).
Furthermore, in some of these gradients, sharp contrasts occur in a matter of few
kilometers (i.e., precipitation) or even meters (i.e., altitude, slope aspect), and consequently, populations not geographically isolated (i.e., within possible gene flow
distances) may, nevertheless, show signs of local adaptation.
Several recent studies are taken advantage of this “natural laboratory” condition
of the Andean-Patagonian forests to shade light about adaptive behavior of different
species. For example, adaptation processes along elevation gradients were studied
in different Nothofagus species (e.g., in N. pumilio (Premoli 2003; Premoli et al.
2007; Mondino et al. 2019), in N. pumilio, N. alpina, and N. obliqua (Arana et al.
2016)). While the effect of the sharp precipitation regime on genetic patterns was
evaluated, for example, in A. chilensis (Pastorino et al. 2010, 2012), and in N. pumilio, N. alpina, and N. obliqua (Soliani et al. 2020). Finally, genetic differences in
morphological and phenological traits at contrasting latitudes (e.g., changing photoperiod) was investigated in N. obliqua (e.g., Barbero 2014), in N. alpina (e.g.,
Duboscq-Carra et al. 2018), and in N. pumilio (e.g., Torres et al. 2017). Recently, the
current extent and bases of local adaptation in N. pumilio along the Andes are under
study to disentangle the interactions between genotype, phenotype, and environmental conditions (Sekely et al. 2020).
Disturbances of different origins and at different scales have influenced and still
do so in the persistence of the Subantarctic forests. The main influencing factors are
those of geological origin given the huge volcanic and tectonic activity of the region.
The tectonic history of the Patagonian region is exposed by very active and extensive volcanism, almost recurrently from the Late Permian (ca. 250 My ago) until
today, with hundreds of active volcanoes along the Andes (Rabassa 2008). Denuded
sites are suitable for the establishment of shade-intolerant species such as some
Nothofagus spp. (e.g., N. dombeyi and N. antarctica) and Fitzroya cupressoides
(Veblen et al. 1981). Also moraines are usually colonized by Nothofagus spp.
(Veblen et al. 1989; Garibotti and Villalba 2017). Actually, coarse-scale disturbance
is required for Nothofagus regeneration, particularly at lower elevations (Pollmann
and Veblen 2004). In addition, the strong winds frequent in Patagonia play a role in
2 Temperate Subantarctic Forests: A Huge Natural Laboratory
(Premoli 2003; Premoli et al. 2007; Mondino et al. 2019; Soliani and Aparicio,
2020; see Chap. 5).
The distribution of species in mountainous areas is typically restricted to narrow
and well- delimited altitudinal zones (Jump et al. 2009). In the Andes, the decrease
in temperature toward higher elevations determines specific niches for the main
three species that characterize the temperate Nothofagus mixed forest of the Lanín
National Park in Argentina, at 40° S. Thus, although some overlap in their altitudinal distributions exists, N. obliqua dominates the lower altitudes between 650 and
800 m asl, N. alpina does so between 800 and 1000 m asl, and N. pumilio is found
from 1000 m till 1700 m asl usually forming the tree line (Donoso 2006).
These particular settings of the Subantarctic forests, occupying different environments along temperature, precipitation, and day length gradients, suggest the
occurrence of local adaptations of populations to their home environmental conditions. Thus, these gradients represent a kind of “natural laboratory” since the same
species can be found living under contrasting environmental conditions (Fig. 2.2).
Furthermore, in some of these gradients, sharp contrasts occur in a matter of few
kilometers (i.e., precipitation) or even meters (i.e., altitude, slope aspect), and consequently, populations not geographically isolated (i.e., within possible gene flow
distances) may, nevertheless, show signs of local adaptation.
Several recent studies are taken advantage of this “natural laboratory” condition
of the Andean-Patagonian forests to shade light about adaptive behavior of different
species. For example, adaptation processes along elevation gradients were studied
in different Nothofagus species (e.g., in N. pumilio (Premoli 2003; Premoli et al.
2007; Mondino et al. 2019), in N. pumilio, N. alpina, and N. obliqua (Arana et al.
2016)). While the effect of the sharp precipitation regime on genetic patterns was
evaluated, for example, in A. chilensis (Pastorino et al. 2010, 2012), and in N. pumilio, N. alpina, and N. obliqua (Soliani et al. 2020). Finally, genetic differences in
morphological and phenological traits at contrasting latitudes (e.g., changing photoperiod) was investigated in N. obliqua (e.g., Barbero 2014), in N. alpina (e.g.,
Duboscq-Carra et al. 2018), and in N. pumilio (e.g., Torres et al. 2017). Recently, the
current extent and bases of local adaptation in N. pumilio along the Andes are under
study to disentangle the interactions between genotype, phenotype, and environmental conditions (Sekely et al. 2020).
Disturbances of different origins and at different scales have influenced and still
do so in the persistence of the Subantarctic forests. The main influencing factors are
those of geological origin given the huge volcanic and tectonic activity of the region.
The tectonic history of the Patagonian region is exposed by very active and extensive volcanism, almost recurrently from the Late Permian (ca. 250 My ago) until
today, with hundreds of active volcanoes along the Andes (Rabassa 2008). Denuded
sites are suitable for the establishment of shade-intolerant species such as some
Nothofagus spp. (e.g., N. dombeyi and N. antarctica) and Fitzroya cupressoides
(Veblen et al. 1981). Also moraines are usually colonized by Nothofagus spp.
(Veblen et al. 1989; Garibotti and Villalba 2017). Actually, coarse-scale disturbance
is required for Nothofagus regeneration, particularly at lower elevations (Pollmann
and Veblen 2004). In addition, the strong winds frequent in Patagonia play a role in
2 Temperate Subantarctic Forests: A Huge Natural Laboratory