Person: Willis, Charles G.
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Willis
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Charles G.
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Willis, Charles G.
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Publication Phylogenetic conservatism and trait correlates of spring phenological responses to climate change in northeast China(John Wiley and Sons Inc., 2017) Du, Yanjun; Chen, Jingru; Willis, Charles G.; Zhou, Zhiqiang; Liu, Tong; Dai, Wujun; Zhao, Yuan; Ma, KepingAbstract Climate change has resulted in major changes in plant phenology across the globe that includes leaf‐out date and flowering time. The ability of species to respond to climate change, in part, depends on their response to climate as a phenological cue in general. Species that are not phenologically responsive may suffer in the face of continued climate change. Comparative studies of phenology have found phylogeny to be a reliable predictor of mean leaf‐out date and flowering time at both the local and global scales. This is less true for flowering time response (i.e., the correlation between phenological timing and climate factors), while no study to date has explored whether the response of leaf‐out date to climate factors exhibits phylogenetic signal. We used a 52‐year observational phenological dataset for 52 woody species from the Forest Botanical Garden of Heilongjiang Province, China, to test phylogenetic signal in leaf‐out date and flowering time, as well as, the response of these two phenological traits to both temperature and winter precipitation. Leaf‐out date and flowering time were significantly responsive to temperature for most species, advancing, on average, 3.11 and 2.87 day/°C, respectively. Both leaf‐out and flowering, and their responses to temperature exhibited significant phylogenetic signals. The response of leaf‐out date to precipitation exhibited no phylogenetic signal, while flowering time response to precipitation did. Native species tended to have a weaker flowering response to temperature than non‐native species. Earlier leaf‐out species tended to have a greater response to winter precipitation. This study is the first to assess phylogenetic signal of leaf‐out response to climate change, which suggests, that climate change has the potential to shape the plant communities, not only through flowering sensitivity, but also through leaf‐out sensitivity.Publication The establishment of Central American migratory corridors and the biogeographic origins of seasonally dry tropical forests in Mexico(Frontiers Media S.A., 2014) Willis, Charles G.; Franzone, Brian; Xi, Zhenxiang; Davis, CharlesBiogeography and community ecology can mutually illuminate the formation of a regional species pool or biome. Here, we apply phylogenetic methods to a large and diverse plant clade, Malpighiaceae, to characterize the formation of its species pool in Mexico, and its occupancy of the seasonally dry tropical forest (SDTF) biome that occurs there. We find that the ~162 species of Mexican Malpighiaceae represent ~33 dispersals from South America beginning in the Eocene and continuing until the Pliocene (~46.4–3.8 Myr). Furthermore, dispersal rates between South America and Mexico show a significant six-fold increase during the mid-Miocene (~23.9 Myr). We hypothesize that this increase marked the availability of Central America as an important corridor for Neotropical plant migration. We additionally demonstrate that this high rate of dispersal contributed substantially more to the phylogenetic diversity of Malpighiaceae in Mexico than in situ diversification. Finally, we show that most lineages arrived in Mexico pre-adapted with regard to one key SDTF trait, total annual precipitation. In contrast, these lineages adapted to a second key trait, precipitation seasonality, in situ as mountain building in the region gave rise to the abiotic parameters of extant SDTF. The timing of this in situ adaptation to seasonal precipitation suggests that SDTF likely originated its modern characteristics by the late Oligocene, but was geographically more restricted until its expansion in the mid-Miocene. These results highlight the complex interplay of dispersal, adaptation, and in situ diversification in the formation of tropical biomes. Our results additionally demonstrate that these processes are not static, and their relevance can change markedly over evolutionary time. This has important implications for understanding the origin of SDTF in Mexico, but also for understanding the temporal and spatial origin of biomes and regional species pools more broadly.Publication Herbarium records are reliable sources of phenological change driven by climate and provide novel insights into species’ phenological cueing mechanisms(Botanical Society of America, 2015) Davis, Charles; Willis, Charles G.; Connolly, Bryan; Courtland, Kelly; Ellison, AaronPremise of the study: Climate change has resulted in major changes in the phenology of some species but not others. Long-term field observational records provide the best assessment of these changes, but geographic and taxonomic biases limit their utility. Plant specimens in herbaria have been hypothesized to provide a wealth of additional data for studying phenological responses to climatic change. However, no study to our knowledge has comprehensively addressed whether herbarium data are accurate measures of phenological response, and thus applicable to addressing such questions. Methods: We compared flowering phenology determined from field observations (years 1852-1858; 1875; 1878-1908; 2003-2006; 2011-2013) and herbarium records (1852-2013) of 20 species from New England, USA. Key Results: Earliest flowering date estimated from herbarium records faithfully reflected field observations of first flowering date and substantially increased the sampling range across climatic conditions. Additionally, although most species demonstrated a response to inter-annual temperature variation, long-term temporal changes in phenological response were not detectable. Conclusions: Our findings support the use of herbarium records for understanding plant phenological responses to changes in temperature, and also importantly establish a new use of herbarium collections: inferring primary phenological cueing mechanisms of individual species (e.g., temperature, winter chilling, photoperiod). These latter data are lacking from most investigations of phenological change, but are vital for understanding differential responses of individual species to ongoing climate change.Publication Phylogenetic patterns of species loss in Thoreau's woods are driven by climate change(Proceedings of the National Academy of Sciences, 2008) Willis, Charles G.; Ruhfel, B; Primack, R. B.; Miller-Rushing, A. J.; Davis, CharlesClimate change has led to major changes in the phenology (the timing of seasonal activities, such as flowering) of some species but not others. The extent to which flowering-time response to temperature is shared among closely related species might have important consequences for community-wide patterns of species loss under rapid climate change. Henry David Thoreau initiated a dataset of the Concord, Massachusetts, flora that spans ≈150 years and provides information on changes in species abundance and flowering time. When these data are analyzed in a phylogenetic context, they indicate that change in abundance is strongly correlated with flowering-time response. Species that do not respond to temperature have decreased greatly in abundance, and include among others anemones and buttercups [Ranunculaceae pro parte (p.p.)], asters and campanulas (Asterales), bluets (Rubiaceae p.p.), bladderworts (Lentibulariaceae), dogwoods (Cornaceae), lilies (Liliales), mints (Lamiaceae p.p.), orchids (Orchidaceae), roses (Rosaceae p.p.), saxifrages (Saxifragales), and violets (Malpighiales). Because flowering-time response traits are shared among closely related species, our findings suggest that climate change has affected and will likely continue to shape the phylogenetically biased pattern of species loss in Thoreau's woods.Publication Corrigendum to: The establishment of Central American migratory corridors and the biogeographic origins of seasonally dry tropical forests in Mexico(Frontiers Media S.A., 2015) Willis, Charles G.; Franzone, Brian; Xi, Zhenxiang; Davis, CharlesPublication Digitization protocol for scoring reproductive phenology from herbarium specimens of seed plants(John Wiley and Sons Inc., 2018) Yost, Jennifer M.; Sweeney, Patrick W.; Gilbert, Ed; Nelson, Gil; Guralnick, Robert; Gallinat, Amanda S.; Ellwood, Elizabeth R.; Rossington, Natalie; Willis, Charles G.; Blum, Stanley D.; Walls, Ramona L.; Haston, Elspeth M.; Denslow, Michael W.; Zohner, Constantin M.; Morris, Ashley B.; Stucky, Brian J.; Carter, J. Richard; Baxter, David G.; Bolmgren, Kjell; Denny, Ellen G.; Dean, Ellen; Pearson, Katelin D.; Davis, Charles; Mishler, Brent D.; Soltis, Pamela S.; Mazer, Susan J.Premise of the Study Herbarium specimens provide a robust record of historical plant phenology (the timing of seasonal events such as flowering or fruiting). However, the difficulty of aggregating phenological data from specimens arises from a lack of standardized scoring methods and definitions for phenological states across the collections community. Methods and Results: To address this problem, we report on a consensus reached by an iDigBio working group of curators, researchers, and data standards experts regarding an efficient scoring protocol and a data‐sharing protocol for reproductive traits available from herbarium specimens of seed plants. The phenological data sets generated can be shared via Darwin Core Archives using the Extended MeasurementOrFact extension. Conclusions: Our hope is that curators and others interested in collecting phenological trait data from specimens will use the recommendations presented here in current and future scoring efforts. New tools for scoring specimens are reviewed.