TY - JOUR
T1 - Geographical barriers and climate influence demographic history in narrowleaf cottonwoods
AU - Evans, L. M.
AU - Allan, G. J.
AU - Difazio, S. P.
AU - Slavov, G. T.
AU - Wilder, J. A.
AU - Floate, K. D.
AU - Rood, S. B.
AU - Whitham, T. G.
N1 - Funding Information:
We thank Deb Ball, Brad Blake, Victor Busov, Karen Gill, Basil Jefferies, Sobadini Kaluthota, Karla Kennedy, Mindie Lipphardt, Tamara Max, Julie Nielsen, Ian Ouwerkerk, Phil Patterson, David Pearce, David Smith, Amy Whipple, Matt Zinkgraf and the Cottonwood Ecology Group for help in the field, laboratory, greenhouse and discussion. We thank the Apache-Sitgreaves, Fishlake and Bridger-Teton National Forests; Monticello BLM; Weber Basin Water Conservancy District; AZ Game & Fish and UT Division of Wildlife Resources. We also thank the anonymous reviewers for many helpful comments on previous versions of the manuscript. Research was supported by NSF-FIBR DEB-0425908 to TGW, GJA and SPD; a Science Foundation Arizona Graduate Student Fellowship, NSF IGERT and Doctoral Dissertation Improvement Grant to LME and Northern Arizona University.
Publisher Copyright:
© 2015 Macmillan Publishers Limited All rights reserved.
PY - 2015/4/12
Y1 - 2015/4/12
N2 - Studies of genetic variation can clarify the role of geography and spatio-temporal variation of climate in shaping demography, particularly in temperate zone tree species with large latitudinal ranges. Here, we examined genetic variation in narrowleaf cottonwood, Populus angustifolia, a dominant riparian tree. Using multi-locus surveys of polymorphism in 363 individuals across the species' 1800 km latitudinal range, we found that, first, P. angustifolia has stronger neutral genetic structure than many forest trees (simple sequence repeat (SSR) F ST =0.21), with major genetic groups corresponding to large apparent geographical barriers to gene flow. Second, using SSRs and putatively neutral sequenced loci, coalescent simulations indicated that populations diverged before the last glacial maximum (LGM), suggesting the presence of population structure before the LGM. Third, the LGM and subsequent warming appear to have had different influences on each of these distinct populations, with effective population size reduction in the southern extent of the range but major expansion in the north. These results are consistent with the hypothesis that climate and geographic barriers have jointly affected the demographic history of P. angustifolia, and point the importance of both factors as being instrumental in shaping genetic variation and structure in widespread forest trees.
AB - Studies of genetic variation can clarify the role of geography and spatio-temporal variation of climate in shaping demography, particularly in temperate zone tree species with large latitudinal ranges. Here, we examined genetic variation in narrowleaf cottonwood, Populus angustifolia, a dominant riparian tree. Using multi-locus surveys of polymorphism in 363 individuals across the species' 1800 km latitudinal range, we found that, first, P. angustifolia has stronger neutral genetic structure than many forest trees (simple sequence repeat (SSR) F ST =0.21), with major genetic groups corresponding to large apparent geographical barriers to gene flow. Second, using SSRs and putatively neutral sequenced loci, coalescent simulations indicated that populations diverged before the last glacial maximum (LGM), suggesting the presence of population structure before the LGM. Third, the LGM and subsequent warming appear to have had different influences on each of these distinct populations, with effective population size reduction in the southern extent of the range but major expansion in the north. These results are consistent with the hypothesis that climate and geographic barriers have jointly affected the demographic history of P. angustifolia, and point the importance of both factors as being instrumental in shaping genetic variation and structure in widespread forest trees.
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U2 - 10.1038/hdy.2014.115
DO - 10.1038/hdy.2014.115
M3 - Article
C2 - 25585921
AN - SCOPUS:84924967652
SN - 0018-067X
VL - 114
SP - 387
EP - 396
JO - Heredity
JF - Heredity
IS - 4
ER -