A Geophysical and Climatological Assessment of New Guinea — Implications for the Origins ofSaccharum

Abstract

Any assessment of whether or not Saccharum species are native or introduced in New Guinea require an evolutionary (in a geological sense), geophysical and climatological assessment of the island. Like many of the land masses circling the Pacific (in the volcanically active region known as the 'ring of fire') New Guinea is geologically young, with the island in its modern form not pre-dating 2 Ma. Novel modelling of the 74 ka youngest Toba supereruption indicates a potential extinction level tsunami and loss of habitat. The late Pleistocene megafaunal mass extinction and the last glacial maximum (33-16 ka) are two global effects that would have significantly altered the flora on New Guinea; though the implications of these events on New Guinea have not previously been studied. Even if the genus Saccharum was established on the island during pre-historic times the consequences of Toba and other global climate change events means that it would have been eliminated from New Guinea and would have had to be re-introduced during the period of human colonization. Indeed, given the evolution of Saccharum's immediate ancestors in Africa and Indochina it is most parsimonious to conclude that it was never native to New Guinea, but was introduced by humans relatively recently.Little work has been done on palaeotsunami evidence and ancient tsunami modelling in New Guinea. However, the recent recognition that the Aitape skull (dating to about 6 ka) may have been the victim of a tsunami (Goff et al. 2017) show that, in the past, tsunami have penetrated significantly (about 10 km in this case) into the interior of the island to have a profound effect on biodiversity. This tsunami would have left the north coast of the island impoverished of plant life for several decades after.

Wild to domesticates: genomes of edible diploid bananas hold traces of several undefined genepools

“…Bottleneck can be due to the establishment of selfing (Foxe et al 2009;Guo et al 2009) but it could also jointly be resulting from the last glacial period during which the climate was cooler and drier (Bowler et al 1976;Hope et al 2004), inducing conditions less favourable for M. acuminata in NG. The northern coast lowlands were likely the only rainforest refugee of the island at the time (Evans 2020). Stabilization in climate, estimated 9,000 years ago, interestingly roughly coincided with the moment when humans of the region were on their way to domesticate local crops, with clear evidence of established agricultural activities in NG highlands dated back at 7,000 years ago (Denham et al 2003).…”