Uncovering the genetic basis of adaptation hinges on the ability to detect loci under selection. However, population genomics outlier approaches to detect selected loci may be inappropriate for clinal populations or those with unclear population structure because they require that individuals be clustered into populations. An alternate approach, landscape genomics, uses individualbased approaches to detect loci under selection and reveal potential environmental drivers of selection. We tested four landscape genomics methods on a simulated clinal population to determine their effectiveness at identifying a locus under varying selection strengths along an environmental gradient. We found all methods produced very low type I error rates across all selection strengths, but elevated type II error rates under "weak" selection. We then applied these methods to an AFLP genome scan of an alpine plant, Campanula barbata, and identified five highly supported candidate loci associated with precipitation variables. These loci * These authors contributed equally to this work.

Investigations of vegetation stress along non-paved roads treated with a range of magnesium chloride (MgCl 2 ) application rates utilized 60 roadside and 79 drainage plots on 15 and 18 roads, respectively. Evaluations were completed of foliar damage, plant health, biotic and abiotic damage incidence and severity, soil and foliar chemistry and other common site and stand characteristics of Pinus contorta, Populus tremuloides, Picea engelmannii, Abies lasiocarpa, and lower elevation plots dominated by shrubs and grasses. High concentrations of soil magnesium and chloride (400-500 ppm), high foliar chloride (2,000-16,000 ppm depending on species) and high incidence of foliar damage were measured in roadside plots along straight road segments in the first 3 to 6.1 m adjacent to treated roads. In drainage plots, where water is channeled off roads, high concentrations of both magnesium and chloride ions and associated foliar damage were measured between 3 and 98 m from the road. High incidence of foliar damage and elevated ion concentrations were not apparent in control plots along non-treated roads. Lodgepole pine appeared to be the most sensitive species, while aspen accumulated the most chloride and exhibited the least amount of damage. Foliar chloride concentrations strongly correlated with percent foliar damage for all species (r=0.53 to 0.74, p< 0.0001) while the incidence of biotic damages did not correlate well. Positive relationships between foliar chloride and magnesium chloride application rates were strong and can be used to predict foliar concentrations and subsequent damage to roadside trees.

Pinus aristata Engelm., Rocky Mountain bristlecone pine, has a narrow core geographic and elevational distribution, occurs in disjunct populations, and is threatened by rapid climate change, white pine blister rust, and bark beetles. Knowledge of genetic diversity and population structure will help guide gene conservation strategies for this species. Sixteen sites across four mountain ranges in the core distribution of P. aristata were sampled and genetic diversity was assessed with 21 isozyme loci. Low species and population level genetic diversity (He = 0.070 and 0.062, respectively) occurred with moderate among-population differentiation (FST = 0.131). Genetic diversity correlated with longitude, latitude, and elevation and a strong mountain island effect may contribute to substructuring and isolation. Using multiple complementary analyses, sampled trees were assigned to three genetic lineages that varied in diversity and admixture and were associated with different climatic factors. The distribution of genetic diversity and substructuring of P. aristata may be an outcome of a combination of restricted gene flow due to geographic and phenological isolation, random processes of genetic drift, life history traits, natural selection, and postglacial migrations. The combination of low genetic diversity, moderate population isolation, and a protracted regeneration dynamic puts populations at risk for extirpation by novel stresses.Résumé : Pinus aristata Engelm., le pin aristé, possède une distribution centrale restreinte, tant géographique qu'altitudinale. L'espèce se retrouve en populations isolées et est menacée par la rapidité des changements climatiques, la rouille vési-culeuse du pin blanc et les scolytes. La connaissance de la diversité génétique et de la structure de populations aidera à orienter les stratégies de conservation des ressources génétiques chez cette espèce. Les auteurs ont échantillonné 16 populations réparties dans les quatre chaînes de montagnes se retrouvant au coeur de la distribution centrale de P. aristata. La diversité génétique a été évaluée pour 21 loci d'isoenzymes. Une diversité génétique faible fut remarquée, tant pour l'espèce que dans les populations (He = 0,070 et 0,062, respectivement). La différenciation de populations était modérée (FST = 0,131). La diversité génétique était corrélée avec la longitude, la latitude et l'altitude, et un fort effet insulaire dû aux montagnes pourrait contribuer à la sous-structuration et à l'isolement. En recourant à des analyses multiples complémentaires, les arbres échantillonnés pouvaient être assignés à trois lignées génétiques qui variaient quant à leur diversité et leur composition et qui étaient associées à différents facteurs climatiques. La distribution de la diversité génétique et la sous-structuration de P. aristata pourraient être la résultante d'une combinaison de facteurs incluant le flux génique restreint en raison de l'isolement géographique ou phénologique, les processus aléatoires découlant de la dérive génétique, les caractéris...

Untreated firewood can harbor destructive insects and pathogens and transport them to uninfested areas. In a national survey of retail locations selling firewood in 18 states, over half (52%) of the firewood was from sources out of the purchase state and 50% showed evidence of insect infestation. In a three state survey of southern Rocky Mountain retailers, the most common retailer types carrying firewood were grocery stores and department or big box stores followed by gas stations or convenience stores. In 2007-2009, we purchased 419 firewood bundles from retailers in Colorado, New Mexico, Utah, and Wyoming and caged the firewood to quantify insect emergence. Live insects emerged from 47% of firewood bundles over 18 mo of rearing time. Approximately 11 insects emerged on average from each infested bundle (1-520 per bundle). Pine, fir, and mixed-conifer bundles yielded the greatest number of insects. Beetles (Coleoptera) were prominent and made up the majority of individuals (3-60 individuals in each of 24 families). Most Coleoptera were bark and ambrosia beetles (subfamily Scolytinae) while wood borers (Buprestidae, Cerambycidae, Siricidae) occurred in lower numbers. Firewood with evidence of previous or current insect infestation was more likely to have insects emerge than firewood without such evidence. The risk of moving live native or nonindigenous insects in untreated firewood is high because insects emerged up to 558 d from purchase date. Retail firewood should be heat treated in a manner to eliminate insects that is uniformly accepted across North America.

The persistence of some tree species is threatened by combinations of novel abiotic and biotic stressors. To examine the hypothesis that Pinus strobiformis Engelm., a tree threatened by an invasive forest pathogen and a changing climate, exhibits intraspecific genetic variation in adaptive traits, we conducted a common garden study of seedlings at one location with two watering regimes using 24 populations. Four key findings emerged: (i) growth and physiological traits were low to moderately differentiated among populations but differentiation was high for some traits in water-stressed populations; (ii) seedlings from warmer climates grew larger, had higher stomatal density and were more water-use efficient (as measured by the carbon isotope ratio) than populations from colder climates; (iii) seedlings from the northern edge of the species' distribution had lower water-use efficiency, higher stomatal conductance, slower growth and longer survival in a lethal drought experiment compared with seedlings from more southern populations; and (iv) based on non-metric multidimensional scaling analyses, populations clustered into southern and northern groups, which did not correspond to current seed transfer zones. Our discovery of a clinal geographic pattern of genetic variation in adaptive traits of P. strobiformis seedlings will be useful in developing strategies to maintain the species during ongoing climate change and in the face of an invasive pathogen.