Evidences of delayed size recovery in Araucaria angustifolia populations after post-glacial colonization of highlands in Southeastern Brazil

Abstract

Up to date, little is known about the relationship between historical demography and the current genetic structure of A. angustifolia. As a first effort towards overcoming this lack, microsatellite data scored in six populations and isozyme allele frequencies published for 11 natural stands of this species were analysed in order to assess molecular signatures of populations' demographic history. Signatures of genetic bottlenecks were captured in all analysed populations of southeastern Brazil. Among southern populations, signatures of small effective population size were observed in only three out of 13 populations. Southern populations likely experienced faster recovery of population size after migration onto highlands. Accordingly, current genetic diversity of the southern populations gives evidence of fast population size recovery. In general, demographic history of A. angustifolia matches climatic dynamics of southern and southeastern Brazil during the Pleistocene and Holocene. Palynological records and reconstruction of the past climatic dynamics of southeastern and southern Brazil support the hypothesis of different population size recovery dynamics for populations from these regions.

Landscapes with Araucaria in South America: evidence for a cultural dimension

“…One additional piece of evidence in this context is the lack of isolation by distance in all the genetic studies in both species (Auller et al 2002, Bekessy et al 2002, Ruiz et al 2007, Stefenon et al 2008, Machielli et al 2009, Klabunde 2012). In addition, the genetic studies show elevated values of the fixation index (F or F IS ) for several populations (Auller et al 2002, Gallo et al 2004, Ruiz et al 2007, Ferreira et al 2011, unexpected in diocious species.…”

Evidences of genetic bottleneck and fitness decline in <i>Luehea divaricata</i> populations from southern Brazil

“…Large ice sheets or permafrost were not commonly observed in South America during the Quaternary ice ages (Hewitt 2000). However, the colder and drier climate (Behling 2002;Behling et al 2005) likely led many plant species to experience significant reduction in effective population size, as suggested for Araucaria angustifolia populations from southern Brazil (Stefenon et al 2008), and for a small isolated population of Pinus taeda in North America (AlRabab'ah and Williams 2004). In addition, ancient anthropic interference may not be discarded, since the earlier human inhabitants of this region are dated from this period (Behling et al 2005;Schmitz 2006).…”

“…The action of indigenous people modifying the environment (e.g. cleaning the forest understory in the plantation of crops and dispersing seeds) was considered an important factor in shaping the current occurrence area and genetic structure of A. angustifolia in Southern Brazil (Stefenon et al 2008).…”

“…Ledig et al 1999;Al-Rabab'ah and Williams 2004;Stefenon et al 2008). Such reductions of effective population size may result in very negative outcomes to these populations, guiding them to a decline in adaptive and reproductive potentials, and to increased risk of extinction (Nei et al 1975) as effect of demographic, genetic, and environmental stochasticity (Luijten et al 2000).…”

Late Holocene Vegetation History and Early Evidence of Araucaria angustifolia in Caçapava do Sul in the Lowland Region of Rio Grande do Sul State, Southern Brazil

“…The São Francisco de Assis record indicates no evidence of Araucaria angustifolia in that area. Genetic studies on Araucaria angustifolia on southeastern and southern Brazilian highland indicate evidences of genetic bottlenecks (Stefenon et al 2008 …”