Out in the cold: genetic variation of Nothofagus pumilio (Nothofagaceae) provides evidence for latitudinally distinct evolutionary histories in austral South America

Abstract

Nothofagus pumilio is the dominant and almost ubiquitous tree species in mountainous environments of temperate South America. We used two types of molecular markers (cpDNA and isozymes) to evaluate the effects of the Paleogene paleogeography of Patagonia and more recent climatic oscillations of the Neogene on such cold-tolerant species' genetic makeup. Phylogeographic analysis on sequences of three cpDNA non-coding regions at 85 populations yielded two latitudinally disjunct monophyletic clades north and south of c. 42 degrees S containing 11 and three haplotypes, respectively. This indicates a long-lasting vicariant event due to the presence of an extended open paleobasin at mid latitudes of Patagonia. Also distribution patterns of cpDNA haplotypes suggest regional spread following stepping-stone models using pre-Cenozoic mountains as corridors. Comparable genetic diversity measured along 41 sampled populations using seven polymorphic isozyme loci provides evidence of local persistence and spread from multiple ice-free locations. In addition, significantly higher heterozygosity and allelic richness at high latitudes, i.e. in areas of larger glacial extent, suggest survival in large and isolated refugia. While, higher cpDNA diversity in lower latitudes reflects the complex orogeny that historically isolated northern populations, lower isozyme diversity and reduced F(ST) values provide evidence of local glacial survival in numerous small locales. Therefore, current genetic structure of N. pumilio is the result of regional processes which took place during the Tertiary that were enhanced by contemporary local effects of drift and isolation in response to Quaternary climatic cycles.

A Gondwanan imprint on global diversity and domestication of wine and cider yeast Saccharomyces uvarum

“…Favorable climatic and geologic conditions prevailing since 25.000 years ago seem to have facilitated secondary contact. In mid-latitudes, northward migration of Nothofagus appears to have been more efficient than southward migration 49 , which is concordant with what we have observed for S. uvarum (Fig. 1c).…”

“…1d) suggest that the two populations are presently in contact and that there is little or no relevant reproductive isolation between them, which could be experimentally confirmed. The geographic distribution of the two Patagonian populations can be related to the phylogeography of Nothofagus whose species tend to have latitudinally disjunct populations as a consequence of long-lasting vicariance events related to past glaciations and to the presence of an ancient paleobasin at mid-latitudes in Patagonia 47-49 . Our results fit this model of two, historically isolated clades, one in the north and one in the south.…”

Glaciation Effects on the Phylogeographic Structure of Oligoryzomys longicaudatus (Rodentia: Sigmodontinae) in the Southern Andes

“…Pollen records suggest the southern coastal range of lowland Chile and the Chiloé island, as well as the southern central depression, as the most likely locations of refugia between 40–42°S [18], [21], [24], [55]. The latter areas served as refugia to diverse taxa such as the long-lived conifer Fitzroya cuppresoides [56], the Andean Asteraceae Hypochaeris palustris [57], the Nothofagaceae tree Nothofagus pumilio [58], some lizards of the genus Liolaemus [4], the fresh water shrimp Samastacus spinifrons (Castro et al , unpublished), and the sigmodontine mice Abrothrix olivaceus [59], [60], [61] and A. longipilis [62]. The latter two species are commonly found coexisting with O. longicaudatus along its distribution in Chile and adjacent Argentina.…”

Phylogeography and palaeodistribution modelling in the Patagonian steppe: the case of Mulinum spinosum (Apiaceae)

“…, 2009; Xu et al. , 2009; Acosta & Premoli, 2010; Mathiasen & Premoli, 2010), with only a few studies addressing patterns in the vast area of the Patagonian steppe (Kim et al. ,1998; Morando et al.…”