title: Life and extinction of megafauna in the ice-age Arctic.
abstract: 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.
authors.affiliation: Geosciences Department, University of Alaska, Fairbanks, AK 99775; bashapir@ucsc.edu dhmann@alaska.edu.
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Mann
authors.affiliation: Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775;
authors.forename: Pamela
authors.initials: P
authors.lastname: Groves
authors.affiliation: Reanier & Associates, Inc., Seattle, WA 98166;
authors.forename: Richard E
authors.initials: RE
authors.lastname: Reanier
authors.affiliation: Water and Environmental Research Center, University of Alaska, Fairbanks, AK 99775;
authors.forename: Benjamin V
authors.initials: BV
authors.lastname: Gaglioti
authors.affiliation: Cooperative Extension and Resources, University of Alaska, Fairbanks, AK 99775;
authors.forename: Michael L
authors.initials: ML
authors.lastname: Kunz
authors.affiliation: Department of Ecology and Evolutionary Biology and University of California, Santa Cruz Genomics Institute, University of California, Santa Cruz, CA 95064 bashapir@ucsc.edu dhmann@alaska.edu.
authors.forename: Beth
authors.initials: B
authors.lastname: Shapiro
mesh_terms: D000818:Animals; D001110:Arctic Regions; D057231:Climate Change; D053476:Extinction, Biological; D005580:Fossils
keywords: extinction; ice age; mammoth steppe; megafauna; paleoecology