Revisiting the historical distribution of Seasonally Dry Tropical Forests: new insights based on palaeodistribution modelling and palynological evidencegeb

摘要: Aim  To investigate the potential distribution of Seasonally Dry Tropical Forests (SDTFs) during Quaternary climatic fluctuations; to reassess formerly proposed ‘Pleistocenic arc hypothesis’ (PAH); and identify historically stable unstable areas SDTF distributions in light palaeodistribution modelling. Location  SDTFs lowland cis-Andean eastern-central South America. Methods  We first developed georeferenced maps depicting current distributional extent under two distinct definitions (narrow broad). then generated occurrence datasets, which were used with past bioclimatic variables predict by implementing maximum entropy machine-learning algorithm. obtained historical stability overlapping presence/absence projections each three scenarios [current, 6 kyr bp Holocene, 21 kyr Last Glacial Maximum (LGM)]. Finally, we checked consistencies model prediction qualitative comparisons vegetation types inferred from available fossil pollen records. Results  The present-day is disjunct, but provide evidence that it was even more disjunct LGM. Reconstructions support a progressive southward eastward expansion on continental scale since No significant into Amazon Basin detected. Areas presumed long-term are identified confirmed (the nuclear regions, Caatinga, Misiones Piedmont, plus Chiquitano region), these possibly acted as refugial areas. Main conclusions  LGM climate probably too dry cold large tracts SDTF, restricted climatically favourable relative present day (in contrast PAH, originally conceived). Expansions have occupied southern portion Caatinga nucleus recently early–middle Holocene transition. propose an alternative scenario amenable further testing earlier (either at Lower Pleistocene or Tertiary), followed fragmentation secondary Holocene. generate specific genetic predictions both regional scales (stable expected higher diversity endemism levels than adjacent areas) can be direct field sampling cover (predicted refugia) (recently colonized) areas. Lastly, discuss possibility may experience future changing should prioritized conservation initiatives.