410
Furthermore, genetic diversity for each population was estimated with He, percentage of polymorphic loci (PPL), and number of exclusive loci (EL) indexes
(Table 15.1; Inza et al. 2018). The results revealed a trend of decreasing genetic
diversity of the Argentinean A. angustifolia populations from east to west, as the
distance to the main area of the species distribution in southern Brazil increases.
Thereby, the most diverse populations, Gramado and Manuel Belgrano natural forest, are those located closest to Brazil, whereas Piñalito Norte and provincial
reserves Cruce Caballero, Caá Yarí, and Araucaria, which show less diversity, are at
the edges of the species range (Inza et al. 2018). This result is consistent with haplotype studies with chloroplast markers (Ferrero Klabunde 2012), which suggested
that Argentinean populations have migrated from glacial refuges in southern Brazil.
This displacement would have led to a genetic drift process, associated with founder
effects or population bottlenecks (Newton et al. 1999), which explains the observed
genetic diversity gradient. Similarly, Marchelli et al. (2010) associated the loss of
genetic diversity in western A. araucana populations of Patagonia (Argentina) to a
recolonization process from the non-glaciated areas in the eastern vicinity.
Logging history of Argentinean A. angustifolia populations could also explain
their current diversity (Mac Donagh and Rivero 2005), since the initial levels of
genetic variability may be modified by fragmented landscapes (Degen et al. 2006).
These effects were observed in A. araucana in Argentina and Chile by Bekessy
et al. (2002) and in A. angustifolia in Brazil by Sousa et al. (2004) and Auler et al.
(2002). In Argentina, A. angustifolia exploitation began and was more intense in
southern Misiones between 1940 and 1970 (Rau 2005), likely affecting its genetic
diversity. Despite some remnant populations from this area are protected, the
reserves are small and/or recently created, showing different intensities of previous
degradation (Bertolini 2000; Inza et al. 2018). Particularly, the fact that Cáa Yarí
Provincial Reserve is within the Yabotí Biosphere Reserve that protects a larger
continuous forest (SAyDS 2007) may explain its higher number of exclusive bands
(EL = 19; Inza et al. 2018). However, lower values of exclusive loci in more disturbed populations of unprotected areas have been observed and could be explained
by direct tree removal or a preliminary genetic drift process. In accordance to this,
Bittencourt and Sebbenn (2009) observed loss of rare alleles in fragmented populations in contrast to continuous A. angustifolia populations, in Brazil. On the other
hand, because of different logging histories, northern populations of the Argentinean
range present more variable diversity levels than southern ones. Populations with
long disturbance history, like Piñalito Norte and Campiñas de Américo, displayed
much lower diversity than those less disturbed, like Manuel Belgrano natural forest,
or historically more diverse due to their original high density of trees, like Gramado
population (Ragonese and Castiglione 1946; Fernández et al. 2005). Nevertheless,
if the valuable gene pool of the populations located in private properties remains
unprotected, their singular genetic variability will drop, increasing the risk of local
population extinction, according to different future scenarios that were predicted for
the Province of Misiones by Izquierdo et al. (2011).
M. E. Gauchat et al.
Furthermore, genetic diversity for each population was estimated with He, percentage of polymorphic loci (PPL), and number of exclusive loci (EL) indexes
(Table 15.1; Inza et al. 2018). The results revealed a trend of decreasing genetic
diversity of the Argentinean A. angustifolia populations from east to west, as the
distance to the main area of the species distribution in southern Brazil increases.
Thereby, the most diverse populations, Gramado and Manuel Belgrano natural forest, are those located closest to Brazil, whereas Piñalito Norte and provincial
reserves Cruce Caballero, Caá Yarí, and Araucaria, which show less diversity, are at
the edges of the species range (Inza et al. 2018). This result is consistent with haplotype studies with chloroplast markers (Ferrero Klabunde 2012), which suggested
that Argentinean populations have migrated from glacial refuges in southern Brazil.
This displacement would have led to a genetic drift process, associated with founder
effects or population bottlenecks (Newton et al. 1999), which explains the observed
genetic diversity gradient. Similarly, Marchelli et al. (2010) associated the loss of
genetic diversity in western A. araucana populations of Patagonia (Argentina) to a
recolonization process from the non-glaciated areas in the eastern vicinity.
Logging history of Argentinean A. angustifolia populations could also explain
their current diversity (Mac Donagh and Rivero 2005), since the initial levels of
genetic variability may be modified by fragmented landscapes (Degen et al. 2006).
These effects were observed in A. araucana in Argentina and Chile by Bekessy
et al. (2002) and in A. angustifolia in Brazil by Sousa et al. (2004) and Auler et al.
(2002). In Argentina, A. angustifolia exploitation began and was more intense in
southern Misiones between 1940 and 1970 (Rau 2005), likely affecting its genetic
diversity. Despite some remnant populations from this area are protected, the
reserves are small and/or recently created, showing different intensities of previous
degradation (Bertolini 2000; Inza et al. 2018). Particularly, the fact that Cáa Yarí
Provincial Reserve is within the Yabotí Biosphere Reserve that protects a larger
continuous forest (SAyDS 2007) may explain its higher number of exclusive bands
(EL = 19; Inza et al. 2018). However, lower values of exclusive loci in more disturbed populations of unprotected areas have been observed and could be explained
by direct tree removal or a preliminary genetic drift process. In accordance to this,
Bittencourt and Sebbenn (2009) observed loss of rare alleles in fragmented populations in contrast to continuous A. angustifolia populations, in Brazil. On the other
hand, because of different logging histories, northern populations of the Argentinean
range present more variable diversity levels than southern ones. Populations with
long disturbance history, like Piñalito Norte and Campiñas de Américo, displayed
much lower diversity than those less disturbed, like Manuel Belgrano natural forest,
or historically more diverse due to their original high density of trees, like Gramado
population (Ragonese and Castiglione 1946; Fernández et al. 2005). Nevertheless,
if the valuable gene pool of the populations located in private properties remains
unprotected, their singular genetic variability will drop, increasing the risk of local
population extinction, according to different future scenarios that were predicted for
the Province of Misiones by Izquierdo et al. (2011).
M. E. Gauchat et al.