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Life and extinction of megafauna in the ice-age Arctic (free pdf)

Ben Creisler

A new paper that may be of interest:

Daniel H. Mann, Pamela Groves, Richard E. Reanier, Benjamin V.
Gaglioti, Michael L. Kunz, and Beth Shapiro (2015)
Life and extinction of megafauna in the ice-age Arctic.
Proceedings of the National Academy of Sciences (advance online publication)
doi: 10.1073/pnas.1516573112



Understanding species extinction is a major concern today, and past
extinctions provide valuable lessons. Numerous mammal species became
extinct in the Arctic at the end of the ice age, but it is unclear
why. By comparing numbers of dated bones with climate records, we find
that megafaunal species, like mammoth, horse, and bison, experienced
boom and bust cycles during the ice age as they tracked rapid climate
changes. For these species to persist, long-distance dispersal was
necessary. Their extinction on the North Slope occurred as the ice age
ended, because rising sea level severed dispersal routes and spreading
peat simultaneously degraded range quality. This finding suggests that
arctic mammals can be resilient to environmental changes but only if
their habitats remain widely interconnected.


Understanding the population dynamics of megafauna that inhabited the
mammoth steppe provides insights into the causes of extinctions during
both the terminal Pleistocene and today. Our study area is Alaska's
North Slope, a place where humans were rare when these extinctions
occurred. After developing a statistical approach to remove the age
artifacts caused by radiocarbon calibration from a large series of
dated megafaunal bones, we compare the temporal patterns of bone
abundance with climate records. Megafaunal abundance tracked ice age
climate, peaking during transitions from cold to warm periods. These
results suggest that a defining characteristic of the mammoth steppe
was its temporal instability and imply that regional extinctions
followed by population reestablishment from distant refugia were
characteristic features of ice-age biogeography at high latitudes. It
follows that long-distance dispersal was crucial for the long-term
persistence of megafaunal species living in the Arctic. Such dispersal
was only possible when their rapidly shifting range lands were
geographically interconnected. The end of the last ice age was fatally
unique because the geographic ranges of arctic megafauna became
permanently fragmented after stable, interglacial climate engendered
the spread of peatlands at the same time that rising sea level severed
former dispersal routes.