Glacial cycles have played a dominant role in shaping the genetic structure and distribution of biota in northwestern North America. The two major ice age refugia of Beringia and the Pacific Northwest were connected by major mountain chains and bordered by the Pacific Ocean. As a result, numerous refugial options were available for the regions taxa during glacial advances. We reviewed the importance of glaciations and refugia in shaping northwestern North America’s phylogeographic history. We also tested whether ecological variables were associated with refugial history. The recurrent phylogeographic patterns that emerged were the following: (i) additional complexity, i.e. refugia within refugia, in both Beringia and the Pacific Northwest; and (ii) strong evidence for cryptic refugia in the Alexander Archipelago and Haida Gwaii, the Canadian Arctic and within the ice-sheets. Species with contemporary ranges that covered multiple refugia, or those with high dispersal ability, were significantly more likely to have resided in multiple refugia. Most of the shared phylogeographic patterns can be attributed to multiple refugial locales during the last glacial maximum or major physiographic barriers like rivers and glaciers. However, some of the observed patterns are much older and appear connected to the orogeny of the Cascade-Sierra chain or allopatric differentiation during historic glacial advances. The emergent patterns from this review suggest we should refine the classic Beringian-southern refugial paradigm for northwestern North American biota and highlight the ecological and evolutionary consequences of colonization from multiple refugia.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-294X.2010.04828.x

Of glaciers and refugia: a decade of study sheds new light on the phylogeography of northwestern North America.

ContentsPreface, by M. O. WoodburneList of ContributorsDefinitionsIntroduction, by M. O. WoodburnePrinciples and Procedures, by M. O. WoodburneMammalian Biochronology of the Latest Cretaceous, by R. L. Cifelli,* J. J. Eberle, D. L. Lofgren, J. A. Lillegraven, and W. A. ClemenPaleocene Biochronology: The Puercan Through Clarkforkian Land Mammal Ages, by D. L. Lofgren,* J. A. Lillegraven, W. A. Clemens, P. D. Gingerich, and T. E. WilWasatchian Through Duchesnean Biochronology, by P. Robinson,* G. F. Gunnell, S. L. Walsh, W. C. Clyde, J. E. Storer, R. K. StuckThe Chadronian, Orellan, and Whitneyan North American Land Mammal Ages, by D. R. Prothero and R. J. EmryMammalian Biochronology of the Arikareean Through Hemphillian Interval (Late Oligocene Through Early Pliocene Epochs), by R. H. Tedford,* J. E. Storer, L. B. Albright III, C. C. Swisher III, A. T. BarnoThe Blancan, Irvingtonian, and Rancholabrean Mammal Ages, by E. L. Lundelius Jr. and C. R. Bell,* A. D. Barnosky, R. W. Graham, E. H. LindsayGlobal Events and the North American Mammalian Biochronology, by M. O. WoodburneIndexesSystematic IndexSubject Index

Late Cretaceous and Cenozoic mammals of North America : biostratigraphy and geochronology

Human colonization of the Americas: timing, technology and process

Late Quaternary paleoenvironments of Northwestern North America: implications for inland versus coastal migration routes

Aim Within the past few decades, seven of the 25 historically described populations of American pikas (Ochotona princeps) in the Great Basin of arid western North America appear to have become extinct. In this paper, the prehistoric record for pikas in the Great Basin is used to place these losses in deeper historical context.



Location  The Great Basin, or area of internal drainage, of the western United States.



Methods  The location, elevation, and age of all reported prehistoric Great Basin specimens of American pikas were extracted from the literature. Elevations of extinct pika populations were arrayed through time, and latitudes and longitudes of those populations used to determine changing distances of those populations from the nearest extant populations.



Results  The average elevation of now-extinct Great Basin pika populations during the late Wisconsinan (c. 40,000–10,000 radiocarbon years ago) and early Holocene (c. 10,000–7500 years ago) was 1750 m. During the hot and dry middle Holocene (c. 7500–4500 years ago), the average elevation of these populations rose 435 m, to 2168 m. All prehistorically known late Holocene (c. 4500–200 years ago) populations in the Great Basin are from mountain ranges that currently support populations of this animal, but historic period losses have caused the average elevation of pika populations to rise an additional 152 m. The total elevational increase, from the late Wisconsinan and early Holocene to today, has been 783 m. As lower elevation pika populations were lost, their distribution increasingly came to resemble its modern form. During the late Wisconsinan, now-extinct pika populations were located an average of 170 km from the nearest extant population. By the late Holocene, this distance had declined to 30 km.



Main conclusions  Prehistoric alterations in the distribution of pika population in the Great Basin were driven by climate change and attendant impacts on vegetation. Today, Great Basin pikas contend with both climate change and anthropogenic impacts and thus may be on the brink of extinction.

https://faculty.washington.edu/grayson/grayson-pikas.pdf

A brief history of Great Basin pikas

Ochotona(Lagomorpha) from Late Quaternary Cave Deposits in Eastern North America

New records of Atopomys salvelinus from West Virginia and Florida, and additional remains of A. texensis from Texas are reported. A partial mandible of A. salvelinus with M1–2 from Alachua County, Florida, is the first record of the genus from that state, and the most complete specimen of Atopomys known. Although M3s of A. texensis have not been recovered, three M3s of A. salvelinus are now known from Hamilton Cave, West Virginia. These teeth, as well as the others, are similar to those of the Blancan arvicoline genus Nebraskomys. These similarities support Hibbard's (1970) suggestion that Nebraskomys was ancestral to Atopomys.

The middle Pleistocene rodent Atopomys (Cricetidae: Arvicolinae) from the eastern and south-central United States

Karst systems, sea caves, and rock shelters within the coastal temperate rain forest of Alaska's Alexander Archipelago preserve important records of regional archaeology, sea level history, glacial and climatic history, and vertebrate paleontology. Two 14C AMS dates on human bone discovered in a remote cave (49-PET-408) on Prince of Wales Island document the oldest reliably dated human in Alaska to ca. 9800 B.P. A series of 14C AMS dates from cave deposits span the past 40,000 years and provide the first evidence of Pleistocene faunas from the northwest coast of North America. Other discoveries include sea caves and marine beach deposits elevated above modern sea level, extensive solution caves, and mammalian remains of species previously undocumented within the region. Records of human activity, including cave art, artifacts, and habitation sites may provide new insights into the early human colonization of the Americas. © 1997 John Wiley & Sons, Inc.

Late quaternary regional geoarchaeology of Southeast Alaska karst: A progress report

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Ochotona(Lagomorpha) from Late Quaternary Cave Deposits in Eastern North America

The middle Pleistocene rodent Atopomys (Cricetidae: Arvicolinae) from the eastern and south-central United States

Late quaternary regional geoarchaeology of Southeast Alaska karst: A progress report