Data from: Evaluating the impact of historical climate and early human groups in the Araucaria Forest of Eastern South America

It has been hypothesized that the Araucaria Forest in Southern Brazil
underwent expansions in the past, driven either by human groups or by
climate fluctuations of the Holocene and Pleistocene. Fossil pollen
records of the Paraná Pine (Araucaria angustifolia), a dominant tree in
that forest, provide some insights into when those may have occurred.
Still, the timing of those expansions has never been estimated. To infer
past range shifts and shed light on their main drivers, we employed
next-generation DNA sequencing (ddRADseq), machine learning, and a
comprehensive database of fossil pollen records in a study of historical
demographic inference and paleo-distribution modeling of the Paraná Pine.
We found that A. angustifolia comprises two populations expanding at
different times: one in the Mantiqueira mountain chain, and the other in
the southern Brazilian plateau. The Southern population began to expand
during the Last Glacial Period ~70kya, long before human arrival in South
America. Still, genetic analyses support that humans later impacted this
population, resulting in lower genetic diversity, higher inbreeding, and
high levels of gene flow over large distances with a weak pattern of
isolation by distance. It is possible this resulted from human influence
on seed dispersal and germination on the Southern Brazilian plateau. The
Mantiqueira population, in contrast, expanded only recently (~3kya). This
timing coincides with Holocene climatic changes and human settlements
established further south, although, to date, there is little
archeological evidence of human impact in the Mantiqueira. In addition,
multitemporal species distribution models built from a combination of
present-day and pollen records infer range expansion of the Araucaria
Forest during glacial times until the cold humid HS1 event (~16kya), when
the forest was most widespread, with no evidence of glacial refugia. The
combination of genomic and spatial analyses suggests that both human and
climatic controls played a role in the dynamics of the Araucaria Forest.