Phylogeographic analysis of the mid-Holocene Mammoth from Qagnaxˆ Cave, St. Paul Island, Alaska

https://doi.org/10.1016/j.palaeo.2008.12.019Get rights and content

Abstract

Remains of a woolly mammoth (Mammuthus primigenius) were found in Qagnaxˆ Cave, a lava tube cave on St. Paul Island in the Pribilof Islands, 500 km west of the Alaskan mainland in the Bering Sea. Several dates converge on 5725 14C yr BP, making these the youngest mammoth remains discovered in North America, and among the few Holocene mammoths known. Genetic analysis of the cytochrome b gene and adjacent regions of the mitochondrial genome demonstrates that the Qagnaxˆ mammoth is highly derived, possessing several unique polymorphisms not found in other mammoths. However, while this is consistent with a recent insular isolation scenario, phylogenetic analysis suggests that the specimen represents a population whose isolation from other mammoths occurred at or well before the terminal Pleistocene submergence of the Bering Land Bridge. It is possible that it represents a member of a “land bridge subclade” of woolly mammoths that remained distinct from mainland Alaskan populations, but was not restricted to highland areas until the land bridge was submerged. Additional eastern Beringian, and particularly insular, mammoth DNA sequences are required to explore this possibility.

Introduction

A mid-Holocene vertebrate faunal assemblage including woolly mammoth [Mammuthus primigenius (Blumenbach, 1799)] has recently been obtained from Qagnaxˆ Cave, a lava tube cave on St. Paul Island in the Pribilof Islands. Approximately 90 km2 in area, St. Paul Island is one of two smaller and three larger islands comprising the Pribilof Islands group in the eastern Bering Sea (Fig. 1). The islands are among the most isolated places in North America, lying some 500 km WSW from the nearest point on the Alaskan mainland and 400 km NW of the eastern Aleutian Islands. Like the eastern Aleutian Islands, the Pribilofs were separated from the Alaskan mainland by at least 13,000 14C yr BP, gradually shrinking in size, achieving their present size of ~ 90 km2 by around 5000 14C yr BP, when sea level rose to within 4 m of its current position before stabilizing (Manley, 2002, Guthrie, 2004). Since no prehistoric archaeological sites have been found on the islands, it is likely that their isolation resulted in an absence of human occupation prior to their 1786 discovery by Russian sailors and the subsequent transport there of Aleut (Unangan) people.

Mammoth remains have occasionally been documented from St. Paul Island over the past 100 years. Initial discoveries of mammoth remains were detritally derived from coastal erosion; Stanley-Brown (1892), Preble (1923), and Ray (1971), for example, all reported the discovery of mammoth tusks or molar teeth from Northeast Point on St. Paul Island. Among all of the Bering Sea islands, however, St. Paul Island in the Pribilofs is unique in possessing lava tube caves from which animal bones have been collected. An 1897 expedition under R.E. Snodgrass and D.S. Jordan obtained two mammoth teeth from Bogoslof Cave (Stanley-Brown, 1892, Preble, 1923), but they were lost in transit to the Smithsonian Institution in 1904 and never recovered (Ray, 1971). Qagnaxˆ Cave, in the central highlands of the island, was discovered by hunters in August 1999. The cave was initially tested in 2000 as a part of an archaeological project conducted by Veltre and McCartney (2002), and was followed by more intensive collection during 2003 (Crossen et al., 2003). Hundreds of animal bones and mammoth tooth plates were collected from the floor of the cave, which had apparently served as a natural trap for local animal populations. Seven mammoth bones were recovered, including four molar teeth (two partial and two nearly complete) and three postcranial bones, at least one of which is a proximal scapula fragment, including the glenoid facet. Hundreds of additional mammoth molar plate fragments were spread among 24 collection units.

Dates of bones and mammoth teeth, using both AMS and conventional methods, yielded nearly identical results ranging from 5630 to 5800 14C yr BP, with most dates falling between 5710 and 5740 yr 14C yr BP (Crossen et al., 2003, Guthrie, 2004, Veltre et al., 2004, Crossen et al., 2005, Yesner et al., 2005a, Yesner et al., 2005b). The high degree of similarity in both tooth and bone dates suggests that all of the specimens may have derived from a single individual mammoth, with a pooled mean age of 5725 yr BP. Slightly older dates have been obtained by Guthrie (2004) and Grover and Tedor (2006) on detrital mammoth specimens from the Pribilofs; these are the youngest mammoth dates ever produced in North America. Morphological characters of the molar teeth of the Qagnaxˆ mammoth (Maglio, 1973, Haynes, 1991, Veltre et al., 2008) suggest that this individual is consistent with other terminal Pleistocene specimens, sometimes considered at the small end of the size range for woolly mammoth (Lister, 1996, Stuart et al., 2002), but not a truly dwarfed individual in the sense of the California Channel Island mammoths (Mammuthus exilis) (Agenbroad, 2003).

The Qagnaxˆ mammoth offers a unique case study for research in woolly mammoth phylogeography, due to both its insular context and very recent date. Accordingly, we isolated mtDNA from the Qagnaxˆ mammoth to help elucidate its evolutionary and taxonomic status. Our primary research goal was to determine the degree and depth of isolation of the Qagnaxˆ mammoth relative to both eastern and western Beringian mammoths, as well as whether the presence of mammoths on St. Paul might be related to human-induced population displacement from mainland areas during the LGM.

Section snippets

Results

We targeted a continuous sequence of the mitochondrial genome including the cytochrome b gene, two adjacent tRNA genes, and the first portion of the control region. We designed 30 primer pairs using all available definitive M. primigenius mitochondrial sequences (Yang et al., 1996, Ozawa et al., 1997, Noro et al., 1998, Greenwood et al., 1999, Debruyne et al., 2003, Krause et al., 2006, Rogaev et al., 2006, Barnes et al., 2007, Gilbert et al., 2007; see recently Gilbert et al., 2008, Debruyne

Discussion

Based solely on topological features, its relatively ancient common ancestry with other mammoths suggests that the Qagnaxˆ mammoth was isolated from mainland Alaskan mammoths long before its arrival on St. Paul Island (peri- to pre-Last Glacial Maximum), and likely before 13,000 14C yr BP, when the island became separated from the Alaskan mainland (Guthrie, 2004). This does not suggest that the Qagnaxˆ mammoth was displaced from mainland Alaskan populations by Pleistocene humans. If this had

DNA extraction

An enamel plate from one maxillary molar of woolly mammoth specimen number SPC-03-102D from Qagnaxˆ Cave was selected for mtDNA extraction. This specimen was stored at room temperature until our experiments began, shortly after which it was kept frozen. A fragment of the enamel plate was used for the extraction. We performed all ancient nucleic acid extractions using the ancient DNA-dedicated facilities in the Molecular Anthropology Laboratory of the Department of Anthropology, University of

Acknowledgments

We thank Joan Coltrain, Chandler Gatenbee, Alan Rogers, Silvia Smith and Susan Spencer for assistance and insightful discussion. M.T.P. Gilbert and H. Poinar provided helpful reviews. Elizabeth Marchani performed pilot work on this specimen. Funding for the mtDNA analysis was provided by National Science Foundation Grants OPP-0327641 and OPP-0637246 to O'Rourke, and an NSF Graduate Fellowship to Enk. Funding for fieldwork at Qagnaxˆ Cave was provided by a University of Alaska Anchorage Faculty

References (42)

  • CrossenK.J. et al.
  • CrossenK.J. et al.
  • DebruyneR. et al.

    Mitochondrial cytochrome b of the Lyakhov mammoth (Proboscidea, Mammalia): new data and phylogenetic analyses of Elephantidae

    Mol. Phylogenet. Evol.

    (2003)
  • Drummond, A.J., Rambaut, A., 2006. BEAST v1.4, avail. fr....
  • DrummondA.J. et al.

    Relaxed phylogenetics and dating with confidence

    PLoS Biol.

    (2006)
  • GilbertM.T.P. et al.

    Whole-genome shotgun sequencing of mitochondria from ancient hair shafts

    Nucl. Acids Res.

    (2007)
  • GilbertM.T.P. et al.

    Intraspecific phylogenetic analysis of Siberian woolly mammoths using complete mitochondrial genomes

    PNAS

    (2008)
  • GreenwoodA.D. et al.

    Nuclear DNA sequences from late Pleistocene megafauna

    Mol. Biol. Evol.

    (1999)
  • GreenwoodA.D. et al.

    Evolution of Endogenous Retrovirus-like Elements of the Woolly Mammoth (Mammuthus primigenius) and its Relatives

    Mol. Biol. Evol.

    (2001)
  • GroverM.A. et al.

    A mid-Holocene mammoth tusk from St. Paul Island

    Alaska Anthrop. Ass. Prog. Abstr.

    (2006)
  • GuthrieR.D.

    Radiocarbon evidence of mid-Holocene mammoths stranded on an Alaskan Bering Sea island

    Nature

    (2004)
  • Cited by (8)

    • Ecological Change, Range Fluctuations and Population Dynamics during the Pleistocene

      2009, Current Biology
      Citation Excerpt :

      Thus, the giant deer (Megaloceros giganteus) should perhaps be removed from the list of Pleistocene extinctions as it has been shown that they survived in the Urals up to 7,700 years B.P. [22]. Likewise, the mammoth survived on Wrangel Island until about 4,000 years B.P. [20] and on St. Paul Island in the Northern Pacific until 6,000 years B.P. [21,69]. Thus, Wrangel Island did not represent a unique situation, and more Holocene refugia for the mammoth, and possibly other taxa, may await discovery.

    • Recovering a Late-Antique Edition of Pliny's Natural History

      2020, Recovering a Late-Antique Edition of Pliny's Natural History
    • Giant sloths and sabertooth cats: Extinct mammals and the archaeology of the ice age great basin

      2016, Giant Sloths and Sabertooth Cats: Extinct Mammals and the Archaeology of the Ice Age Great Basin
    View all citing articles on Scopus
    View full text