Timothy Dickinson

Dr. Timothy Dickinson

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Research Focus & Metrics

Academic Career Length

39Years (1988-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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28 June 2007 in Plant Systematics and Evolution
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Journal Article
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TDTimothy Dickinson
Timothy Dickinson
ELE. Lo
E. Lo
NTN. Talent
N. Talent

31 August 2024 in Nature Communications
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Journal Article
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IEIsaac Eckert
Isaac Eckert
ABAnne Bruneau
Anne Bruneau
DMDeborah A. Metsger
Deborah A. Metsger
SJSimon Joly
Simon Joly
TDTimothy Dickinson
Timothy Dickinson
LPLaura J. Pollock
Laura J. Pollock
The past decade has yielded more biodiversity observations from community science than the past century of traditional scientific collection. This rapid influx of data is promising for overcoming critical biodiversity data shortfalls, but we also have vast untapped resources held in undigitized natural history collections. Yet, the ability of these undigitized collections to fill data gaps, especially compared against the constant accumulation of community science data, remains unclear. Here, we compare how well community science (iNaturalist) observations and digitized herbarium specimens represent the diversity, distributions, and modeling needs of vascular plants in Canada. We find that, despite having only a third as many records, herbarium specimens capture more taxonomic, phylogenetic, and functional diversity and more efficiently capture species’ environmental niches. As such, the digitization of Canada’s 7.3M remaining specimens has the potential to more than quintuple our ability to model biodiversity. In contrast, it would require over 27M more iNaturalist observations to produce similar benefits. Our findings indicate that digitizing Earth’s remaining herbarium specimens is likely an efficient, feasible, and potentially critical investment when it comes to improving our ability to predict and protect biodiversity into the future.


1 January 2015 in AoB Plants
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Journal Article
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MZMehdi Zarrei
Mehdi Zarrei
NTNadia Talent
Nadia Talent
Maria (Masha)  KuzminaMaria (Masha) Kuzmina
Maria (Masha) Kuzmina
JLJeanette Lee
Jeanette Lee
JLJensen Lund
Jensen Lund
TDTimothy Dickinson
Timothy Dickinson
DNA barcodes can facilitate identification of organisms especially when morphological characters are limited or unobservable. To what extent this potential is realized in specific groups of plants remains to be determined. Libraries of barcode sequences from well-studied authoritatively identified plants represented by herbarium voucher specimens are needed in order for DNA barcodes to serve their intended purpose, where this is possible, and to understand the reasons behind their failure to do so, when this occurs. We evaluated four loci, widely regarded as universal DNA barcodes for plants, for their utility in hawthorn species identification. Three plastid regions, matK, rbcLa and psbA-trnH, and the internal transcribed spacer 2 (ITS2) of nuclear ribosomal DNA discriminate only some of the species of Crataegus that can be recognized on the basis of their morphology etc. This is, in part, because in Rosaceae tribe Maleae most individual plastid loci yield relatively little taxonomic resolution and, in part, because the effects of allopolyploidization have not been eliminated by concerted evolution of the ITS regions. Although individual plastid markers provided generally poor resolution of taxonomic groups in Crataegus, a few species were notable exceptions. In contrast, analyses of concatenated sequences of the 3 plastid barcode loci plus 11 additional plastid loci gave a well-resolved maternal phylogeny. In the ITS2 tree, different individuals of some species formed groups with taxonomically unrelated species. This is a sign of lineage sorting due to incomplete concerted evolution in ITS2. Incongruence between the ITS2 and plastid trees is best explained by hybridization between different lineages within the genus. In aggregate, limited between-species variation in plastid loci, hybridization and a lack of concerted evolution in ITS2 all combine to limit the utility of standard barcoding markers in Crataegus. These results have implications for authentication of hawthorn materials in natural health products.

1 February 2013 in Botany
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Journal Article
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ELE.Y.Y. Lo
E.Y.Y. Lo
SSS. Stefanović
S. Stefanović
TDTimothy Dickinson
Timothy Dickinson
We have demonstrated geographical parthenogenesis in Crataegus series Douglasianae, an agamic complex comprising exclusively tetraploid Crataegus douglasii sensu lato and the morphologically distinct Crataegus suksdorfii complex that comprises diploids and polyploids. Here we characterize ploidy level and breeding system by detailed flow cytometric measurements of the 2C nuclear DNA content of leaf, embryo, and endosperm tissues from 282 black-fruited hawthorns (Crataegus series Douglasianae) representing 33 localities in the Pacific Northwest, one in the Cypress Hills, and three more in the upper Great Lakes basin. We use existing climate and molecular data to place our flow cytometry results in an environmental and evolutionary context. Crataegus douglasii occupies more widely distributed sites that experience more extreme temperature and moisture regimes than do the sites occupied by diploid C. suksdorfii.

15 September 2006 in The Journal of ExtraCorporeal Technology
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TDTimothy Dickinson
Timothy Dickinson
JRJeffrey B. Riley
Jeffrey B. Riley
JCJeffrey C. Crowley
Jeffrey C. Crowley
PZPaul M. Zabetakis
Paul M. Zabetakis
Neurologic impairment is a common complication of adult cardiac surgery. Cerebral gaseous microemboli (GME) detected during cardiopulmonary bypass has been associated with cognitive impairment after adult cardiac surgery. Several previous studies have shown that components comprising the extra-corporeal circuit (ECC) can affect the ability of the ECC to eliminate air. The differences in the air separation ability of four manufacturer’s commonly used ECCs were studied. The air-separating ability of Cobe Cardiovascular, Gish Biomedical, Medtronic, and Terumo Cardiovascular Systems Corp. ECCs were studied in vitro under clinically relevant conditions. Bolus and continuous venous air were introduced and output GME patterns by size, time, and count were measured (using an embolus detection device) and statistically analyzed. Graphic representations depicting elapsed time, GME size, and bubble count helped to visually rank the air-handling performance of the ECCs. There are significant air-handling differences between the ECCs tested. Overall, the blinded results reveal that ECC A and ECC C removed significantly (p < 0.001) more suspended GME than ECC B and ECC D. In the 50-mL venous room-air bolus and the 100 mL/min pulsed air challenges, ECC B and ECC D allowed significantly more GME to pass (p < 0.001) compared with ECC A and ECC C. For example, in a 2-hour pump run ECC C would deliver 480 potential high-intensity transient signals (HITS) compared with the 9600 from the ECC B during venous room air entrainment at 100 mL/min. There are substantial and significant air-handling differences between the ECCs from the four different manufacturers. The results from this work allow for objective characterization of ECCs air-separating ability. This additional information provides an opportunity for clinicians to potentially minimize the risks of arterial air embolization and its associated deleterious neurologic effects, while allowing clinicians to make better-informed consumer decisions.