Biogeography of the Lost World (Pantepui region, northeastern South America): Insights from bryophytes

Abstract

The 'Pantepui' region of northern South America comprises about 50 topographic islands above a lowland/upland rainforest matrix and constitutes a model of choice for testing island theory hypotheses in a continental setting. Although the Guiana Highlands are considered as the second most important center of endemism in the Neotropics for hepatics, the 10% endemism rates at the species level in liverworts, and probably even less in mosses, pale in comparison of the 42% of endemic angiosperm species. While about 60% of angiosperm endemics are distributed on a single tepui, single-tepui endemics represent only 1/3 of endemic liverworts and only one single-tepui endemic moss species has been described to date. These observations point to a higher dispersal ability of bryophytes as compared to angiosperms and may account for the contrasting rates of endemism between the two groups. In contrast to the vertical displacement hypothesis, which proposes that endemic tepui species originated from niche diversification and local adaptation during vertical migrations in the course of glacial/interglacial cycles, the Amazonian element represents only about 10% of the liverwort flora. By contrast, 1/2-2/3 of the species belong to the montane Neotropical element. The recurrent disjunctions observed between the Andes and the Pantepui region suggest that the bulk of endemic species in the Pantepui area might have originated by dispersal from cold-adapted Andean ancestors.

First genome‐wide analysis of the endangered, endemic lichen Cetradonia linearis reveals isolation by distance and strong population structure

“…). This finding is consistent with hypotheses that ranges of present‐day high‐elevation endemics expanded downslope during Pleistocene glaciation (Bruhl, ; Crespi et al., ; Premoli et al., ; Desamore et al., ). While this downslope expansion might have been expected to connect populations and diminish the signal of IBD, the data generated for the present study still show a strong geographic signal of increasing structure with distance.…”

First genome-wide analysis of an endangered lichen reveals isolation by distance and strong population structure

“…5). This finding is consistent with hypotheses that ranges of present-day high-elevation endemics expanded downslope during Pleistocene glaciation (Crespi et al 2003; Bruhl 1997; Premoli et al 2007; Desamore et al 2010). While this downslope expansion might have been expected to connect populations and diminish the signal of IBD, the data generated for this study still show a strong geographic signal of increasing structure with distance.…”

Evolutionary affinities of the ‘Lost World’ mouse suggest a late Pliocene connection between the Guiana and Brazilian shields

“…Necromys, on the other hand, has at least six currently recognized species broadly distributed across open habitats from Venezuela and Trinidad and Tobago in northern South America to central Argentina in the south, and from the Atlantic coast in Brazil, Uruguay and Argentina to Andean elevations of about 5000 m above sea level (D'El ıa et al, 2008). This simple model dichotomy may not be easily applicable, however, especially considering the unique topography of the Pantepui region (Rull, 2005;Kok, 2013), and the two models are not necessarily mutually exclusive (see also D esamor e et al, 2010;Kok, 2013). For example, Patton et al (1990) rejected the gradient or parapatric model of diversification for eastern Andean small mammals, including Akodontini, favouring the vicariant or allopatric model.…”

“…For example, Patton et al (1990) rejected the gradient or parapatric model of diversification for eastern Andean small mammals, including Akodontini, favouring the vicariant or allopatric model. This simple model dichotomy may not be easily applicable, however, especially considering the unique topography of the Pantepui region (Rull, 2005;Kok, 2013), and the two models are not necessarily mutually exclusive (see also D esamor e et al, 2010;Kok, 2013). The divergence of some vertebrates, such as the Pantepui-endemic treefrog genus Tepuihyla, for example, may have involved elements of both the habitat shift hypothesis and Pleistocene climatic fluctuations (Salerno et al, 2012).…”