Publications by authors named "Jeannette Whitton"

12 Publications

  • Page 1 of 1

Phylogenetic history of vascular plant metabolism revealed using a macroevolutionary common garden.

Proc Biol Sci 2021 06 2;288(1952):20210605. Epub 2021 Jun 2.

Biodiversity Research Centre, University of British Columbia, Vancouver, Canada.

While the fundamental biophysics of C photosynthesis is highly conserved across plants, substantial leaf structural and enzymatic variation translates into variability in rates of carbon assimilation. Although this variation is well documented, it remains poorly understood how photosynthetic rates evolve, and whether macroevolutionary changes are related to the evolution of leaf morphology and biochemistry. A substantial challenge in large-scale comparative studies is disentangling evolutionary adaptation from environmental acclimation. We overcome this by using a 'macroevolutionary common garden' approach in which we measured metabolic traits ( and ) from 111 phylogenetically diverse species in a shared environment. We find substantial phylogenetic signal in these traits at moderate phylogenetic timescales, but this signal dissipates quickly at deeper scales. Morphological traits exhibit phylogenetic signal over much deeper timescales, suggesting that these are less evolutionarily constrained than metabolic traits. Furthermore, while morphological and biochemical traits (LMA, and ) are weakly predictive of and , evolutionary changes in these traits are mostly decoupled from changes in metabolic traits. This lack of tight evolutionary coupling implies that it may be incorrect to use changes in these functional traits in response to global change to infer that photosynthetic strategy is also evolving.
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http://dx.doi.org/10.1098/rspb.2021.0605DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8170189PMC
June 2021

Macroevolutionary history predicts flowering time but not phenological sensitivity to temperature in grasses.

Am J Bot 2021 05 4;108(5):893-902. Epub 2021 May 4.

Biodiversity Research Centre, University of British Columbia, Vancouver, V6T 1Z4, Canada.

Premise: Long-term observations show that flowering phenology has shifted in many lineages in response to climate change. However, it remains unclear whether these results can be generalized to predict the presence, direction, or magnitude of responses in lineages for which we lack long time-series data. If phenological responses are phylogenetically conserved, we can extrapolate from species for which we have data to predict the responses of close relatives. While several studies have found that closely related species flower at similar times, fewer have evaluated whether phylogenetically proximal species respond to environmental change similarly.

Methods: We paired flowering time data from 3161 manually scored herbarium specimens of 72 species of grasses (Poaceae) with historical climate data and analyzed the phylogenetic signal and phylogenetic half-life of phenological sensitivity. We also ran these analyses on a subset of species showing statistically significant sensitivities, in order to assess the role of sampling bias on phylogenetic signal.

Results: Closely related grass species tend to flower at similar times, but flowering times respond to temperature changes in species-specific ways. We also show that only including species for which there is strong evidence of phenological shifts results in overestimating phylogenetic signal.

Conclusions: In agreement with other recent studies, our results suggest caution in extrapolating from evidence of phylogenetic similarity to predicting shared responses in this ecologically relevant trait. Future work is needed to better understand the discrepancy between the phylogenetic signal in observed phenological shifts and absence of such signal in sensitivity.
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http://dx.doi.org/10.1002/ajb2.1647DOI Listing
May 2021

Phylogenetic analysis of the distribution of deadly amatoxins among the little brown mushrooms of the genus Galerina.

PLoS One 2021 10;16(2):e0246575. Epub 2021 Feb 10.

Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada.

Some but not all of the species of 'little brown mushrooms' in the genus Galerina contain deadly amatoxins at concentrations equaling those in the death cap, Amanita phalloides. However, Galerina's ~300 species are notoriously difficult to identify by morphology, and the identity of toxin-containing specimens has not been verified with DNA barcode sequencing. This left open the question of which Galerina species contain toxins and which do not. We selected specimens for toxin analysis using a preliminary phylogeny of the fungal DNA barcode region, the ribosomal internal transcribed spacer (ITS) region. Using liquid chromatography/mass spectrometry, we analyzed amatoxins from 70 samples of Galerina and close relatives, collected in western British Columbia, Canada. To put the presence of toxins into a phylogenetic context, we included the 70 samples in maximum likelihood analyses of 438 taxa, using ITS, RNA polymerase II second largest subunit gene (RPB2), and nuclear large subunit ribosomal RNA (LSU) gene sequences. We sequenced barcode DNA from types where possible to aid with applications of names. We detected amatoxins only in the 24 samples of the G. marginata s.l. complex in the Naucoriopsis clade. We delimited 56 putative Galerina species using Automatic Barcode Gap Detection software. Phylogenetic analysis showed moderate to strong support for Galerina infrageneric clades Naucoriopsis, Galerina, Tubariopsis, and Sideroides. Mycenopsis appeared paraphyletic and included Gymnopilus. Amatoxins were not detected in 46 samples from Galerina clades outside of Naucoriopsis or from outgroups. Our data show significant quantities of toxin in all mushrooms tested from the G. marginata s.l. complex. DNA barcoding revealed consistent accuracy in morphology-based identification of specimens to G. marginata s.l. complex. Prompt and careful morphological identification of ingested G. marginata s.l. has the potential to improve patient outcomes by leading to fast and appropriate treatment.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0246575PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7875387PMC
July 2021

Using herbarium-derived DNAs to assemble a large-scale DNA barcode library for the vascular plants of Canada.

Appl Plant Sci 2017 Dec 22;5(12). Epub 2017 Dec 22.

Centre for Biodiversity Genomics, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada.

Premise Of The Study: Constructing complete, accurate plant DNA barcode reference libraries can be logistically challenging for large-scale floras. Here we demonstrate the promise and challenges of using herbarium collections for building a DNA barcode reference library for the vascular plant flora of Canada.

Methods: Our study examined 20,816 specimens representing 5076 of 5190 vascular plant species in Canada (98%). For 98% of the specimens, at least one of the DNA barcode regions was recovered from the plastid loci and and from the nuclear ITS2 region. We used beta regression to quantify the effects of age, type of preservation, and taxonomic affiliation (family) on DNA sequence recovery.

Results: Specimen age and method of preservation had significant effects on sequence recovery for all markers, but influenced some families more (e.g., Boraginaceae) than others (e.g., Asteraceae).

Discussion: Our DNA barcode library represents an unparalleled resource for metagenomic and ecological genetic research working on temperate and arctic biomes. An observed decline in sequence recovery with specimen age may be associated with poor primer matches, intragenomic variation (for ITS2), or inhibitory secondary compounds in some taxa.
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http://dx.doi.org/10.3732/apps.1700079DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5749818PMC
December 2017

Co-occurrence of related asexual, but not sexual, lineages suggests that reproductive interference limits coexistence.

Proc Biol Sci 2017 Dec;284(1868)

Department of Botany and Biodiversity Research Centre, The University of British Columbia, Vancouver, British Columbia, Canada.

We used randomizations to analyse patterns of co-occurrence of sexual and apomictic (asexual) members of the North American agamic complex (Asteraceae). We expect strong asymmetry in reproductive interactions in : apomicts produce clonal seeds with no need for pollination and are not subject to reproductive interference from co-occurring relatives. However, because they still produce some viable pollen, apomicts can reduce reproductive success of nearby sexual relatives, potentially leading to eventual local exclusion of sexuals. Consistent with this, randomizations reveal that sexuals are over-represented in isolated sites, while apomicts freely co-occur. Incorporation of taxonomic and phylogenetic evidence indicates that this pattern is not driven by local origins of asexuals. Our evidence that patterns of local co-occurrence are structured by reproductive interference suggests an underappreciated role for these interactions in community assembly, and highlights the need for explicit tests of the relative contributions of ecological and reproductive interactions in generating patterns of limiting similarity.
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http://dx.doi.org/10.1098/rspb.2017.1579DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5740271PMC
December 2017

Attack of the clones: reproductive interference between sexuals and asexuals in the agamic complex.

Ecol Evol 2016 09 18;6(18):6473-6483. Epub 2016 Aug 18.

Department of Botany and Biodiversity Research Centre The University of British Columbia 6270 University Boulevard Vancouver British Columbia Canada V6T 1Z4.

Negative reproductive interactions are likely to be strongest between close relatives and may be important in limiting local coexistence. In plants, interspecific pollen flow is common between co-occurring close relatives and may serve as the key mechanism of reproductive interference. Agamic complexes, systems in which some populations reproduce through asexual seeds (apomixis), while others reproduce sexually, provide an opportunity to examine effects of reproductive interference in limiting coexistence. Apomictic populations experience little or no reproductive interference, because apomictic ovules cannot receive pollen from nearby sexuals. Oppositely, apomicts produce some viable pollen and can exert reproductive interference on sexuals by siring hybrids. In the agamic complex, sexuals co-occur less often with other members of the complex, but apomicts appear to freely co-occur with one another. We identified a mixed population and conducted a crossing experiment between sexual diploid and apomictic polyploid using pollen from sexual diploids and apomictic polyploids. Seed set was high for all treatments, and as predicted, diploid-diploid crosses produced all diploid offspring. Diploid-polyploid crosses, however, produced mainly polyploidy offspring, suggesting that non-diploid hybrids can be formed when the two taxa meet. Furthermore, a small proportion of seeds produced in open-pollinated flowers was also polyploid, indicating that polyploid hybrids are produced under natural conditions. Our results provide evidence for asymmetric reproductive interference, with pollen from polyploid apomicts contributing to reduce the recruitment of sexual diploids in subsequent generations. Existing models suggest that these mixed sexual-asexual populations are likely to be transient, eventually leading to eradication of sexual individuals from the population.
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http://dx.doi.org/10.1002/ece3.2353DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5058521PMC
September 2016

A reexamination of the North American Crepis agamic complex and comparison with the findings of Babcock and Stebbins' classic biosystematic monograph.

Am J Bot 2016 07 16;103(7):1289-99. Epub 2016 Jun 16.

Department of Botany and Biodiversity Research Centre, The University of British Columbia, 3529-6270 University Boulevard, Vancouver, British Columbia V6T 1Z4 Canada.

Premise Of The Study: Babcock and Stebbins coined the term agamic complex in their 1938 monograph of the North American Crepis agamic complex. Despite the historical role that this complex holds in the evolutionary literature, it has not been reexamined in over 75 years. We present a thorough reevaluation of the complex to test hypotheses proposed by Babcock and Stebbins about its origins and spread, the relationships of diploids, and the nature and origins of polyploids.

Methods: We used flow cytometry to infer ploidy of roughly 600 samples spanning the morphological and taxonomic diversity of the complex and a phylogenetic analysis of plastid DNA variation to infer maternal relationships among diploids and to infer maternal origins of polyploids.

Key Results: We identified populations of all seven recognized diploids plus one new lineage. Phylogenetic analysis of plastid DNA variation in diploids revealed a well-resolved, but moderately supported phylogeny, with evidence for monophyly of the North America Crepis agamic complex and no evidence of widespread homoploid hybridization. Polyploids showed evidence of multiple origins and a pattern of frequent local co-occurrence consistent with repeated colonization of suitable sites.

Conclusions: Our findings agree broadly with the distribution and variation of ploidy within and among species described by Babcock and Stebbins. One key difference is finding support for monophyly of North American species, and refuting their hypothesis of polyphyly. Our results provide an explicit phylogenetic framework for further study of this classic agamic complex.
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http://dx.doi.org/10.3732/ajb.1600057DOI Listing
July 2016

Can we stop transgenes from taking a walk on the wild side?

Mol Ecol 2008 Mar;17(5):1167-9

Department of Botany, University of British Columbia, Vancouver, BC, Canada V6T 2K8.

Whether the potential costs associated with broad-scale use of genetically modified organisms (GMOs) outweigh possible benefits is highly contentious, including within the scientific community. Even among those generally in favour of commercialization of GM crops, there is nonetheless broad recognition that transgene escape into the wild should be minimized. But is it possible to achieve containment of engineered genetic elements in the context of large scale agricultural production? In a previous study, Warwick et al. (2003) documented transgene escape via gene flow from herbicide resistant (HR) canola (Brassica napus) into neighbouring weedy B. rapa populations (Fig. 1) in two agricultural fields in Quebec, Canada. In a follow-up study in this issue of Molecular Ecology, Warwick et al. (2008) show that the transgene has persisted and spread within the weedy population in the absence of selection for herbicide resistance. Certainly a trait like herbicide resistance is expected to spread when selected through the use of the herbicide, despite potentially negative epistatic effects on fitness. However, Warwick et al.'s findings suggest that direct selection favouring the transgene is not required for its persistence. So is there any hope of preventing transgene escape into the wild?
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http://dx.doi.org/10.1111/j.1365-294X.2008.03663.xDOI Listing
March 2008

Patterns of recurrent evolution and geographic parthenogenesis within apomictic polyploid Easter daises (Townsendia hookeri).

Mol Ecol 2006 Oct;15(11):3389-400

Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada V6T 1Z4.

Geographic patterns of parthenogenesis and the number of transitions from sexual diploidy to asexual (apomictic) autopolyploidy were examined for 40 populations of the Easter daisy, Townsendia hookeri. Analyses of pollen diameter and stainability characterized 15 sexual diploid and 25 apomictic polyploid populations from throughout the plant's western North American range. Sexual diploids were restricted to two Wisconsin refugia: Colorado/Wyoming, south of the ice sheets, and northern Yukon/Beringia. Chloroplast DNA sequencing uncovered 17 polymorphisms within the ndhF gene and trnK intron, yielding 10 haplotypes. Phylogenetic analyses indicated that five exclusively polyploid haplotypes were derived from four haplotypes that are shared among ploidies, conservatively inferring a minimum of four origins of apomictic polyploidy. Three of these apomictic polyploid origins were derived from southern sexual diploids, while the fourth origin was derived from northern sexual diploids. Analyses of regional diversity were suggestive of a formerly broad distribution for sexual diploids that has become subsequently fragmented, possibly due to the last round of glaciation. As sexual diploids were exclusively found north and south of the glacial maximum, while formerly glaciated areas were exclusively inhabited by asexual polyploids derived from both northern and southern sexual lineages, it is more likely that patterns of glaciation, as opposed to a particular latitudinal trend, played a causal role in the establishment of the observed pattern of geographic parthenogenesis in Easter daisies.
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http://dx.doi.org/10.1111/j.1365-294X.2006.03020.xDOI Listing
October 2006

One down and thousands to go - dissecting polyploid speciation.

New Phytol 2004 Mar;161(3):610-612

Department of Botany and Biodiversity Research Centre, The University of British Columbia, Vancouver, BC V6T 1Z4 Canada (tel +1 604 8228863; fax +1 604 8226089; email

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http://dx.doi.org/10.1111/j.1469-8137.2003.01017.xDOI Listing
March 2004

Edaphic races and phylogenetic taxa in the Lasthenia californica complex (Asteraceae: Heliantheae): an hypothesis of parallel evolution.

Mol Ecol 2003 Jun;12(6):1675-9

Department of Botany, University of British Columbia, 3529-6270 University Boulevard, Vancouver, BC, Canada V6T 1Z4.

Lasthenia californica sensu Ornduff consists of two races that differ in their flavonoid pigments and edaphic tolerances. Recent phylogenetic studies of Lasthenia have revealed that members of L. californica sensu Ornduff belong to two phylogenetic species. The relationship of the edaphic races to these new species and to each other is the focus of this study. Characterization of flavonoid profiles and phylogenetic placement of 33 populations demonstrates that races and phylogenetic taxa are not concordant, suggesting that one or both edaphic races evolved in parallel in the two clades. We hypothesize an edaphically linked ecological role for flavonoid differences that first revealed the existence of two races.
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http://dx.doi.org/10.1046/j.1365-294x.2003.01843.xDOI Listing
June 2003

Differential responses to Na /K and Ca /Mg in two edaphic races of the Lasthenia californica (Asteraceae) complex: A case for parallel evolution of physiological traits.

New Phytol 2003 Jan;157(1):93-103

Department of Botany, University of British Columbia, 3529-6270 University Boulevard, Vancouver BC Canada V6T 1Z4.

•  Sodium, potassium, calcium, and magnesium ion uptake physiology and tolerance to sodium and magnesium were characterized in two edaphic races (A and C) of two closely related species in the Lasthenia californica complex. •  Uptake rates of race A plants were 20-fold higher for Na , and 2-fold higher for Ca and Mg than those of race C plants. Race A translocated c.  50% of absorbed Na to the shoot compared with < 30% in race C. For Ca and Mg corresponding values for the two races were > 95% and ≤ 50%, respectively. •  Germination, root growth and survivorship estimates indicated greater tolerance by race A to Na and Mg . Significant genotype treatment interactions were observed, suggesting that these races are genetically differentiated in their tolerance responses. •  The study suggests parallel evolution of physiological traits in populations belonging to the two species and points to intriguing correlations between the presence of sulfated flavonoids and the capacities for the uptake of and tolerance to specific ions.
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http://dx.doi.org/10.1046/j.1469-8137.2003.00648.xDOI Listing
January 2003
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