Continental-scale characterization of molecular variation in quaking aspen

Quaking aspen (Populus tremuloides) has the largest natural distribution of any tree native to North America, ranging from Alaska through the breadth of Canada and south to mid-Mexico. The Laurentide ice sheet occupied most of the current range of P. tremuloides until the late Pleistocene epoch, so this species has undergone a significant, geologically recent range expansion. Surprisingly, range-wide patterns of genetic variation in P. tremuloides have never been described. Using a sample set representing the full longitudinal and latitudinal extent of the species distribution, I have conducted a phylogeographic analysis for P. tremuloides. Preliminary results comparing both nuclear and chloroplast DNA sequences revealed surprisingly low levels of divergence across the range. Because of this remarkably shallow genetic divergence among aspen populations, I used a set of rapidly-evolving molecular markers (microsatellites) to describe patterns of gene flow and diversity and to correlate those patterns with landscape features and histories. I analyzed eight microsatellite loci in 794 individuals from 30 sampling sites. From this multilocus data set, I identified pronounced genetic structuring across the range. Strikingly, sampling sites representing the southwestern portion of the range, the western United States and Mexico, form a distinct cluster. Sites within this southwestern cluster display dramatically reduced within-site genetic diversity but elevated regional genetic diversity, which suggests that populations in the southwestern portion of the range make up a stable edge persisting through multiple climate oscillations. Based on the uniqueness of the southwestern cluster and the climatic differences between the southwest and northern portions of the range, I propose that the southwestern cluster may represent a distinct ecotype. I also identified hotspots of diversity that correspond with potential refugia during the last glacial maximum but additional work is needed to refine these patterns. Further, my findings provide a solid foundation for a range of future studies on adaptive genetic and trait variation in this species

Establishment of introduced reptiles increases with the presence and richness of native congeners

Darwin proposed two contradictory hypotheses to explain the influence of congeners on the outcomes of invasion: the naturalization hypothesis, which predicts a negative relationship between the presence of congeners and invasion success, and the pre-adaptation hypothesis, which predicts a positive relationship between the presence of congeners and invasion success. Studies testing these hypotheses have shown mixed support. We tested these hypotheses using the establishment success of non-native reptiles and congener presence/absence and richness across the globe. Our results demonstrated support for the pre-adaptation hypothesis. We found that globally, both on islands and continents, establishment success was higher in the presence than in the absence of congeners and that establishment success increased with increasing congener richness. At the life form level, establishment success was higher for lizards, marginally higher for snakes, and not different for turtles in the presence of congeners; data were insufficient to test the hypotheses for crocodiles. There was no relationship between establishment success and congener richness for any life form. We suggest that we found support for the pre-adaptation hypothesis because, at the scale of our analysis, native congeners represent environmental conditions appropriate for the species rather than competition for niche space. Our results imply that areas to target for early detection of non-native reptiles are those that host closely related species

Continental-scale assessment of genetic diversity and population structure in quaking aspen (Populus tremuloides)

Aim: Quaking aspen (Populus tremuloides) has the largest natural distribution of any tree native to North America. The primary objectives of this study were to characterize range-wide genetic diversity and genetic structuring in quaking aspen, and to assess the influence of glacial history and rear-edge dynamics. Location: North America. Methods: Using a sample set representing the full longitudinal and latitudinal extent of the species’ distribution, we examined geographical patterns of genetic diversity and structuring using 8 nuclear microsatellite loci in 794 individuals from 30 sampling sites. Results: Two major genetic clusters were identified across the range: a southwestern cluster and a northern cluster. The south-western cluster, which included two subclusters, was bounded approximately by the Continental Divide to the east and the southern extent of the ice sheet at the Last Glacial Maximum to the north. Subclusters were not detected in the northern cluster, despite its continent-wide distribution. Genetic distance was significantly correlated with geographical distance in the south-western but not the northern cluster, and allelic richness was significantly lower in south-western sampling sites compared with northern sampling sites. Population structuring was low overall, but elevated in the south-western cluster. Main conclusions: Aspen populations in the south-western portion of the range are consistent with expectations for a historically stable edge, with low within-population diversity, significant geographical population structuring, and little evidence of northward expansion. Structuring within the southwestern cluster may result from distinct gene pools separated during the Pleistocene and reunited following glacial retreat, similar to patterns found in other forest tree species in the western USA. In aspen, populations in the southwestern portion of the species range are thought to be at particularly high risk of mortality with climate change. Our findings suggest that these same populations may be disproportionately valuable in terms of both evolutionary potential and conservation value

Mountain hare transcriptome and diagnostic markers as resources to monitor hybridization with European hares

We report the first mountain hare (Lepus timidus) transcriptome, produced by de novo assembly of RNA-sequencing reads. Data were obtained from eight specimens sampled in two localities, Alps and Ireland. The mountain hare tends to be replaced by the invading European hare (Lepus europaeus) in their numerous contact zones where the species hybridize, which affects their gene pool to a yet unquantified degree. We characterize and annotate the mountain hare transcriptome, detect polymorphism in the two analysed populations and use previously published data on the European hare (three specimens, representing the European lineage of the species) to identify 4 672 putative diagnostic sites between the species. A subset of 85 random independent SNPs was successfully validated using PCR and Sanger sequencing. These valuable genomic resources can be used to design tools to assess population status and monitor hybridization between species

Transcriptomic regulation of seasonal coat color change in hares

Color molts from summer brown to winter white coats have evolved in several species to maintain camouflage year-round in environments with seasonal snow. Despite the eco-evolutionary relevance of this key phenological adaptation, its molecular regulation has only recently begun to be addressed. Here, we analyze skin transcription changes during the autumn molt of the mountain hare (Lepus timidus) and integrate the results with an established model of gene regulation across the spring molt of the closely related snowshoe hare (L. americanus). We quantified differences in gene expression among three stages of molt progression-"brown" (early molt), "intermediate," and "white" (late molt). We found 632 differentially expressed genes, with a major pulse of expression early in the molt, followed by a milder one in late molt. The functional makeup of differentially expressed genes anchored the sampled molt stages to the developmental timeline of the hair growth cycle, associating anagen to early molt and the transition to catagen to late molt. The progression of color change was characterized by differential expression of genes involved in pigmentation, circadian, and behavioral regulation. We found significant overlap between differentially expressed genes across the seasonal molts of mountain and snowshoe hares, particularly at molt onset, suggesting conservatism of gene regulation across species and seasons. However, some discrepancies suggest seasonal differences in melanocyte differentiation and the integration of nutritional cues. Our established regulatory model of seasonal coat color molt provides an important mechanistic context to study the functional architecture and evolution of this crucial seasonal adaptation

The Grizzly, February 17, 2011

Over 45 Businesses Visit Career Fair • Alcohol Incidents on Campus Raise Concern for Administration • Dance Organizations Promise Exciting Spring Performances • UITA to Bring W. J. T. Mitchell to Campus Today • Urbano Cheers and Sings Her Way Through Senior Year • Valentine\u27s Day: Memories of Puppies and Passing Out • To Write Love on Her Arms Comes to Ursinus • Internship Profile: Jordan Oliver • Opinions: Like-a-Little Provides a Fun, Flirtatious Environment; Like-a-Little Could be Detrimental to Ursinus; Snow and Ice Cause Problems in Ursinus Parking Lots • UC Baseball Looks to Bounce Back in Season • Men\u27s Lacrosse is Young, Deep, and Hungryhttps://digitalcommons.ursinus.edu/grizzlynews/1830/thumbnail.jp

The Grizzly, January 31, 1995

Hangin\u27 with Mickey! • New Rules for Guys\u27 Pledging • New Faces in Ursinus Security • Chechens Fortify Grozny • O.J. Trial Facing Delays • Kennedy Family Matriarch Dies • Senior Spotlight: Ellen Cosgrove • Baseball Blows • Response to State of the Union • Letter to the Editor • Echoes of an Artist • Ursinus Brought Back to Earth • Ursinus Splits with F&M • Ursinus Women Set School Record at Freedom Classic • Bears Lose Heartbreaker at Muhlenberg • Bears Win Key Conference Matchhttps://digitalcommons.ursinus.edu/grizzlynews/1351/thumbnail.jp

The Grizzly, November 5, 2009

Escape Velocity Performances are Timeless • Dr. William Keim Inspires with Humor • National Deficit May Favor Health Care Reform • Second Annual Greek Activities Fair Held in Wismer Parents Lounge • Sophomores Learn About the ILE • Behind the Scenes: Association for Computing Machinery • Educational Effect of the International Film Festival • Haunted Ursinus: Good ole\u27 Ghost Stories • Opinion: Where Did the Lounges Go? The Cramped UC Community; Texting and Facebook IM: Our Generation Conversation; Drop the Natural Light and Expand Your Beverage Horizons • UC Athletics Spotlight: Alyssa Thren of Field Hockeyhttps://digitalcommons.ursinus.edu/grizzlynews/1798/thumbnail.jp

The Grizzly, March 26, 1996

Marijuana Incident Results in Dismissal of Two Students • UC Professors to Participate in AIDS Ride • Ryan Auch: The Gentle Giant • Women\u27s Week • Opinions: Capitalism, Individualism and Responsibility; Scotland Fury • Thoughts on the Honor Code • Senegel Professor Speaks on Africa • Berwyn Tavern & Grill: A Trappe Alternative • Faculty Spotlight: Antoni Castells-Talens • Bears at 10-3 After Winning Streak • Trecroce Named Player of the Week • Lacrosse Starts Season With a Banghttps://digitalcommons.ursinus.edu/grizzlynews/1378/thumbnail.jp

WHAAM: A new online service supporting parents and teachers of children with ADHD

info:eu-repo/semantics/publishedVersio