![]() ![]() Rock outcrops are considered to be islands (inselbergs) as a result of their irregular distribution and isolation, being surrounded by other forest types or agricultural land. The phytogeography and ecology of rock outcrop vegetation in Brazil are still poorly understood (Scarano, 2007). One such unit is the ‘rock outcrop caatinga’, of which limestone karst outcrops are the most common. The boundaries, nomenclature and classification of caatinga vegetation have been thoroughly examined elsewhere (Queiroz, 2006 Rodal, Barbosa & Thomas, 2008) and it can be divided into eight floristic units (Santos et al., 2012). Caatinga also occurs as remnants and enclaves in the cerrado biome, mainly in limestone outcrop regions. It has been hypothesized that, during dry periods in the Last Glacial Maximum (LGM), the caatinga biome in Brazil was probably part of a continuous SDTF range, linked to Misiones and Piedmont nuclei (Prado, 2000), known as the Pleistocenic Arc (Prado & Gibbs, 1993). 10% of the total territory of the country. 800 000 km 2 in north-eastern Brazil, corresponding to c. The current caatinga biome covers an area of c. The caatinga is amongst the least understood and most degraded forest types in Brazil (Santos et al., 2011), and this ecosystem has been severely affected by an extensive loss of trees as a result of livestock grazing and fire (Leal et al., 2005 Santos et al., 2011). One of the largest areas of South American SDTFs is the caatinga domain: a thorny and xeric woodland with several months of severe drought and a complex mosaic of soil types, usually with high fertility (Queiroz, 2006 Werneck, 2011). Although there is a wide distribution of SDTFs in South America, most occur as isolated patches or nuclei. Recently, SDTFs have been proposed as one of the major biomes (Pennington, Lavin & Oliveira-Filho, 2009), with a large number of deciduous tree species (Pennington et al., 2009 Santos et al., 2012). Seasonally dry tropical forest (SDTF) occurs in seasonally dry regions with annual rainfall of < 1600 mm and at least 5–6 months with < 100 mm of precipitation (Graham & Dilcher, 1998). bonijesulapensis, which are consistent with arboreal caatinga and rock outcrop floristic units, were potential refugia during Quaternary climatic fluctuations.Ĭaatinga, eastern Tropical South America, fig tree, habitat stability, limestone outcrops, Quaternary history Introduction The central and northern regions of the current distribution of F. The low genetic diversity, unimodal mismatch distribution and unfavourable climatic conditions in the southern region suggest a recent southward expansion of the range of the species during the Holocene, supporting the hypothesis of the southward expansion of SDTFs during this period. The phylogeographical groups showed concordance with the floristic units described for SDTFs. Ecological niche modelling suggested that, since the Last Interglacial (130 kyr bp), the central and north regions have been relatively stable, whereas the southern region of the species distribution has been less stable. The central groups had higher total haplotype and nucleotide diversities than the scattered group. Three phylogeographical groups were identified by the median-joining algorithm network and spatial analysis of molecular variance (SAMOVA) ( F CT = 0.591): a central-west, a central-east and a scattered group. The trnQ–5′ rps16 region of plastid DNA was sequenced from 15 populations. We conducted a phylogeographical and niche modelling study of the tree Ficus bonijesulapensis, endemic to Brazilian seasonally dry tropical forests (SDTFs), in order to evaluate the effects of Quaternary climatic fluctuations on population dynamics. ![]()
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