Pleistocene refugia and recolonization routes in the southern Andes: insights from Hypochaeris palustris (Asteraceae, Lactuceae)

Abstract

Hypochaeris palustris (Phil.) De Wild. is a species growing in the southern Andean chain. To elucidate potential Pleistocene refugia and recolonization routes in the southern Andes, we analysed amplified fragment length polymorphisms (AFLPs) in 206 individuals in 21 populations of H. palustris from the coastal Cordillera, the central, northern, and eastern ranges of the southern Andes, and Patagonia. Populations from the coastal Cordillera harboured more private AFLP fragments, and exhibited a higher frequency of polymorphic fragments as well as higher Shannon diversity than all other areas investigated. The comparison among pooled AFLP profiles of each region revealed that the central Andean ranges shared most fragments with populations from the margins of the distributional area in the Andes, in the N, E, and S (Patagonia). Phenetic analysis indicated close relationships among populations of the central ranges. Populations of the coastal Cordillera were shown to be highly differentiated from the Andean populations. It is very likely therefore that (1) H. palustris recolonized the central ranges of the southern Andes from nearby refugia, possibly unglaciated areas N, E, and/or S of its present distributional area; (2) the postglacial spread of H. palustris in the central ranges of the southern Andes occurred rapidly; and (3) the coastal Cordillera served as a refugium for H. palustris, but these populations did not contribute to the recolonization of the central Andean ranges.

The effects of Quaternary glaciations in Patagonia as evidenced by chloroplast DNA phylogeography of Southern beech Nothofagus obliqua

“…The patchy distribution of the coastal haplotypes and the lack of phylogeographical structure suggest a strong historical fragmentation process, probably associated with the Early Pleistocene glaciation, (Kodama et al 1986). Similar results were reported for N. nervosa (Marchelli and Gallo 2006) and for Hypochaeris palustris, an herbaceous species of the region, in which Pacific Coastal populations were the most diverse and distinct based on amplified fragment length polymorphism genetic analyses (Muellner et al 2005).…”

“…Alternatively, sporadic events of long-distance seed dispersal could also be responsible of the disjunct distribution of some haplotypes. However, we consider the isolation and local survival at coastal populations more plausible, a situation that is also suggested for other species with disjunctive distribution (Muellner et al 2005;Marchelli and Gallo 2006). Similarly, paleobotanical, palynological, and molecular data showed that none of the three European peninsulas (Iberian, Italian, and Balkan) identified as main refuge areas (Demesure et al 1996;Comps et al 2001;Petit et al 2003) were the source for Fagus sylvatica in central and northern Europe (Magri et al 2006); moreover, they found that Mediterranean populations did not spread into central Europe after ice retraction.…”

Population genetic structure and historical population dynamics of the South American sea lion, Otaria flavescens, in north-central Patagonia

“…If such expansions occurred too recently for mtDNA to accumulate point mutations, low genetic diversity and weak phylogeographical patterns would be observed today, as appears to occur in O. flavescens in north-central Patagonia. Other evidences in favour of habitat contractions and reduced genetic diversity caused by Pleistocene glacial cycles came from studies in different species that inhabits the southern hemisphere, which include several species of plants (Allnutt et al 1999(Allnutt et al , 2003Premoli et al 2002;Muellner et al 2005) and fishes (Zattara and Premoli 2005;Ruzzante et al 2006); the rock shags, Stictocarbo magellanicus, (Siegel-Causey 1997) and the saxicolous mice, Phyllotis xanthopygus (Kim et al 2002). Another member of the Family Otariidae, Arctocephalus pusillus pusillus, also show a population dynamics associated with the dynamics of glaciations, but in a inverse way.…”

Andean Land Use and Biodiversity: Humanized Landscapes in a Time of Change

“…Hughes and Eastwood (2006) suggest that resulting rapid speciation is behind high diversity in a variety of Andean plant genera. Muellner et al (2005) begin to sort the details explaining current genetic structure of an Andean composite, Hypochaeris palustris (Phil.) Wildeman, as caused by differential colonization and survival in refugia.…”