Contrasting patterns of genetic diversity across the ranges of Pinus monticola and P. strobus: a comparison between eastern and western North American postglacial colonization histories.
• Premises of the study: Understanding the influence of recent glacial and postglacial periods on species' distributions is key for predicting the effects of future environmental changes. We investigated the influence of two physiographic landscapes on population structure and postglacial colonization of two white pine species of contrasting habitats: P. monticola, which occurs in the highly mountainous region of western North America, and P. strobus, which occurs in a much less mountainous area in eastern North America.•


METHODS
To characterize the patterns of genetic diversity and population structure across the ranges of both species, 158 and 153 single nucleotide polymorphism (SNP) markers derived from expressed genes were genotyped on range-wide samples of 61 P. monticola and 133 P. strobus populations, respectively.•


RESULTS
In P. monticola, a steep latitudinal decrease in genetic diversity likely resulted from postglacial colonization involving rare long-distance dispersal (LDD) events. In contrast, no geographic patterns of diversity were detected in P. strobus, suggesting recolonization via a gradually advancing front or frequent LDD events. For each species, structure analyses identified two distinct southern and northern genetic groups that likely originated from two different glacial lineages. At a finer scale, and for the two species, smaller subgroups were detected that could be remnants of cryptic refugia.•


CONCLUSIONS
During postglacial colonization, the western and eastern North American landscapes had different impacts on genetic signatures in P. monticola compared with P. strobus. We discuss the importance of our findings for conservation programs and predictions of species' response to climate change.
The University of British Columbia, Department of Forest and Conservation Sciences, Forest Science Centre, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du P.E.P.S., P.O. Box 10380 Stn., Sainte-Foy, Québec, QC, G1V 4C7, Canada.
Simon
S
Nadeau
Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du P.E.P.S., P.O. Box 10380 Stn., Sainte-Foy, Québec, QC, G1V 4C7, Canada.
Julie
J
Godbout
Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du P.E.P.S., P.O. Box 10380 Stn., Sainte-Foy, Québec, QC, G1V 4C7, Canada.
Manuel
M
Lamothe
Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du P.E.P.S., P.O. Box 10380 Stn., Sainte-Foy, Québec, QC, G1V 4C7, Canada.
Marie-Claude
MC
Gros-Louis
Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du P.E.P.S., P.O. Box 10380 Stn., Sainte-Foy, Québec, QC, G1V 4C7, Canada.
Nathalie
N
Isabel
The University of British Columbia, Department of Forest and Conservation Sciences, Forest Science Centre, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada.
Kermit
K
Ritland
D002170:Canada; D057231:Climate Change; D014644:Genetic Variation; D028223:Pinus / Q000235:genetics / Q000502:physiology*; D063148:Plant Dispersal; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide; D014481:United States
D010940:Plant Proteins
Pinaceae; Pinus monticola; Pinus strobus; cryptic refugium; glacial refugium; landscape genetics; long-distance dispersal; phylogeography; population structure; postglacial colonization