42
fragmented populations in ecologically distinct habitats (Vidal-Russell et al. 2011),
from warm- to cold-temperate rainforest, or in the ecotone with the steppe. A low
genetic diversity (He = 0.170) and moderate differentiation between populations
(F ST = 0.202) were detected through isozyme markers (Souto and Premoli 2007),
while a phylogeographic study with chloroplast DNA markers suggests the existence of multiple glacial refugia for this species (Vidal-Russell et al. 2011). Maytenus
boaria is also noteworthy, particularly in the ecotone with the steppe, being a source
of shade and fodder for livestock (its evergreen leaves are palatable). It can reach
20 m in height, and its wood is usually used as firewood (Santos Biloni 1990).
Along Patagonian rivers occurs the only native willow species, Salix humboldtiana, a species that was decimated in Patagonia and just few remnant populations
and isolated individuals exist. A domestication program is starting, and details are
described in Chap. 7B. Another well-known tree species of the Andean Patagonian
forest is Luma apiculata (Fig. 2.5), from the Myrtaceae family. It grows in riparian
areas, and its ornamental value due to its bright and cinnamon bark, notable among
the usual colors of the forest, is highly appreciated. A pure old-growth forest of
L. apiculata, unusually large, was the main reason for the creation of Los Arrayanes
National Park, near San Carlos de Bariloche, which is a site of particular interest for
tourism. Seedlings of this species can be bought in almost every commercial nursery of northwest Argentine Patagonia. Genetic diversity in some Argentinean populations showed a low diversity (He = 0.129) with evidences of inbreeding (Caldiz
and Premoli 2005).
2.4 Shared Patterns in the Distribution of the Genetic
Variation
Many of the abovementioned species grow along the environmental gradients that
characterized the Patagonian region, and their genetic variation is, in some cases,
associated with these gradients (e.g., Pastorino and Gallo 2002; Soliani et al. 2020).
In addition, all of them were affected by the Neogene climatic changes that generated shifts in their distributions. The retractions and expansions of the forests after
these disturbs are still imprinted in the genetic structure of the populations. Moreover,
different genetic studies have analyzed the distribution of the genetic variation and
shared patterns between distant taxa became evident (see review in Sérsic et al. 2011).
The first studies used biochemical markers (i.e., isozymes) to find the more
diverse populations and infer cryptic refugia. For example in Austrocedrus chilensis
(Gallo and Geburek 1994; Pastorino and Gallo 2002; Pastorino et al. 2004),
Nothofagus obliqua (Azpilicueta and Gallo 2009), N. alpina (Marchelli and Gallo
2001, 2004), N. antarctica (Pastorino et al. 2009), Fitzroya cupressoides (Premoli
et al. 2000b), Pilgerodendron uviferum (Premoli et al. 2002), Podocarpus nubigenus
(Quiroga and Premoli 2010), and Embothrium coccineum (Souto and Premoli
2007). The development of new and more specific molecular markers, able to trace
P. Marchelli et al.
fragmented populations in ecologically distinct habitats (Vidal-Russell et al. 2011),
from warm- to cold-temperate rainforest, or in the ecotone with the steppe. A low
genetic diversity (He = 0.170) and moderate differentiation between populations
(F ST = 0.202) were detected through isozyme markers (Souto and Premoli 2007),
while a phylogeographic study with chloroplast DNA markers suggests the existence of multiple glacial refugia for this species (Vidal-Russell et al. 2011). Maytenus
boaria is also noteworthy, particularly in the ecotone with the steppe, being a source
of shade and fodder for livestock (its evergreen leaves are palatable). It can reach
20 m in height, and its wood is usually used as firewood (Santos Biloni 1990).
Along Patagonian rivers occurs the only native willow species, Salix humboldtiana, a species that was decimated in Patagonia and just few remnant populations
and isolated individuals exist. A domestication program is starting, and details are
described in Chap. 7B. Another well-known tree species of the Andean Patagonian
forest is Luma apiculata (Fig. 2.5), from the Myrtaceae family. It grows in riparian
areas, and its ornamental value due to its bright and cinnamon bark, notable among
the usual colors of the forest, is highly appreciated. A pure old-growth forest of
L. apiculata, unusually large, was the main reason for the creation of Los Arrayanes
National Park, near San Carlos de Bariloche, which is a site of particular interest for
tourism. Seedlings of this species can be bought in almost every commercial nursery of northwest Argentine Patagonia. Genetic diversity in some Argentinean populations showed a low diversity (He = 0.129) with evidences of inbreeding (Caldiz
and Premoli 2005).
2.4 Shared Patterns in the Distribution of the Genetic
Variation
Many of the abovementioned species grow along the environmental gradients that
characterized the Patagonian region, and their genetic variation is, in some cases,
associated with these gradients (e.g., Pastorino and Gallo 2002; Soliani et al. 2020).
In addition, all of them were affected by the Neogene climatic changes that generated shifts in their distributions. The retractions and expansions of the forests after
these disturbs are still imprinted in the genetic structure of the populations. Moreover,
different genetic studies have analyzed the distribution of the genetic variation and
shared patterns between distant taxa became evident (see review in Sérsic et al. 2011).
The first studies used biochemical markers (i.e., isozymes) to find the more
diverse populations and infer cryptic refugia. For example in Austrocedrus chilensis
(Gallo and Geburek 1994; Pastorino and Gallo 2002; Pastorino et al. 2004),
Nothofagus obliqua (Azpilicueta and Gallo 2009), N. alpina (Marchelli and Gallo
2001, 2004), N. antarctica (Pastorino et al. 2009), Fitzroya cupressoides (Premoli
et al. 2000b), Pilgerodendron uviferum (Premoli et al. 2002), Podocarpus nubigenus
(Quiroga and Premoli 2010), and Embothrium coccineum (Souto and Premoli
2007). The development of new and more specific molecular markers, able to trace
P. Marchelli et al.