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- Phenotypic trait variation can be linked to genomic sequence variation. These differences range from a single nucleotide to larger insertion and deletion (indel) of chromosomal segments. Indels can change the copy number of affected genes, which can create complex phenotypic trait variation through effects on gene expression. For example, gene dosage variation has been associated with various human chronic diseases. Here we systematically explored the effect of induced gene dosage variation on quantitative trait variation in Populus. We show that gene dosage variation at specific chromosoma...AuthorsHéloïse Bastiaanse, Matthew Zinkgraf, Courtney A. Canning, Helen Tsai, Meric Lieberman, Luca Comai, Isabelle Henry, Andrew T. GrooverKeywordsSourceProceedings of the National Academy of SciencesYear2019
- Adventitious roots occur naturally in many species and can also be induced from explants of some tree species including Populus, providing an important means of clonal propagation. Auxin has been identified as playing a crucial role in adventitious root formation, but the associated molecular regulatory mechanisms need to be elucidated. In this study, we examined the role of PagFBL1, the hybrid poplar (Populus alba× P. glandulosa clone 84K) homolog of Arabidopsis auxin receptor TIR1, in adventitious root formation in poplar. Similar to the distribution pattern of auxin during initiation of...AuthorsWenbo Shu, Houjun Zhou, Cheng Jiang, Shutang Zhao, Liuqiang Wang, Quanzi Li, Zhangqi Yang, Andrew T. Groover, Meng-Zhu LuKeywordsSourcePlant Biotechnology JournalYear2019
- Secondary growth from a vascular cambium, present today only in seed plants and isoetalean lycophytes, has a 400‐million‐yr evolutionary history that involves considerably broader taxonomic diversity, most of it hidden in the fossil record. Approaching vascular cambial growth as a complex developmental process, we review data from living plants and fossils that reveal diverse modes of secondary growth. These are consistent with a modular nature of secondary growth, when considered as a tracheophyte‐wide structural feature. This modular perspective identifies putative constituent development...AuthorsAlexandru M. F. Tomescu, Andrew T. GrooverKeywordsSourceNew PhytologistYear2019
- Societal Impact Statement Drought plays a conspicuous role in forest mortality, and is expected to become more severe in future climate scenarios. Recent surges in drought‐associated forest tree mortality have been documented worldwide. For example, recent droughts in California and Texas killed approximately 129 million and 300 million trees, respectively. Drought has also induced acute pine tree mortality across east‐central China, and across extensive areas in southwest China. Understanding the biological processes that enable trees to modify wood development to mitigate the adverse...AuthorsF. Daniela Rodriguez‐Zaccaro, Andrew T. GrooverKeywordsSourcePlants, People, Planet. 1(4): 346-355.Year2019
- Barred owls (Strix varia) are forest‐dwelling owls, native to eastern North America, with populations that expanded westward into the range of the spotted owl (Strix occidentalis). Barred owls exert an overwhelmingly negative influence on spotted owls, thereby threatening spotted owl population viability where the species co‐occur. In this review, we provide an overview of the barred owl’s range expansion and detail and synthesize previously published literature on spotted and barred owls within the range of the spotted owl as related to potential future outcomes for the northern spotted...AuthorsLinda L. Long, Jared WolfeKeywordsSourceThe Journal of Wildlife Management. 83(6): 1281-1296Year2019
- Forest restoration treatments seek to increase resilience to wildfire and a changing climate while avoiding negative impacts to the ecosystem. The extent and intensity of treatments are often constrained by operational considerations and concerns over uncertainty in the trade-offs of addressing different management goals. The recent (2012–15) extreme drought in California, USA, resulted in widespread tree mortality, particularly in the southern Sierra Nevada, and provided an opportunity to assess the effects of restoration treatments on forest resilience to drought. We assessed changes in...AuthorsJamie Lydersen, Brandon M. Collins, Carolyn T. HunsakerKeywordsSourceInternational Journal of Wildland Fire. 28(7): 495-511Year2019
- Tributary creeks of the southern Sierra Nevada have pronounced knickpoints that separate the landscape into an alternating sequence of gently sloped treads and steeply sloped risers. These knickpoints and the surrounding “stepped topography” suggest that the landscape is still responding to Pleistocene changes in base level on main-stem rivers. We tested this hypothesis using cosmogenic nuclides and uranium isotopes measured in stream sediment from widely distributed locations. Catchment-scale erosion rates from the cosmogenic nuclides suggest that the treads are relict surfaces that have...AuthorsRussell P. Callahan, Ken L. Ferrier, Jean Dixon, Anthony Dosseto, W. Jesse Hahm, Barbara S. Jessup, Scott N. Miller, Carolyn T. Hunsaker, Dale W. Johnson, Leonard S. Sklar, Clifford S. RiebeSourceGSA Bulletin. 131(7-8): 1179-1202Year2019
- Restoration of fire-dependent forests is often guided by reference conditions from forests with an active fire regime, thought to be resilient to current and future disturbances and stresses. Reference conditions are usually based on historical data or reconstruction, which greatly limits the scale and completeness of data that can be collected. In the Sierra Nevada of California, large areas with reintroduced active fire regimes coupled with extensive lidar data coverage provide the unique opportunity to develop a contemporary regional reference condition dataset across a wide gradient of...AuthorsSean M.A. Jeronimo, Van R. Kane, Derek J. Churchill, James A. Lutz, Malcolm P. North, Gregory P. Asner, Jerry F. FranklinSourceForest Ecology and Management. 437: 70-86Year2019
- Frameworks for limiting ecosystem exposure to excess nutrients and acidity require accurate and complete deposition budgets of reactive nitrogen (Nr). While much progress has been made in developing total Nr deposition budgets for the U.S., current budgets remain limited by key data and knowledge gaps. Analysis of National Atmospheric Deposition Program Total Deposition (NADP/TDep) data illustrates several aspects of current Nr deposition that motivate additional research. Averaged across the continental U.S., dry deposition contributes slightly more (55%) to total deposition than wet...AuthorsR.V. Pouyat, M. Puchalski, H.O.T. Pye, A.W. Rea, M.F. Rhodes, C.M. Rogers, R. Saylor, R. Scheffe, B.A. Schichtel, D.B. Schwede, G.A. Sexstone, B.C. Sive, R. Sosa, P.H. Templer, T. Thompson, D. Tong, G.A. Wetherbee, T.H. Whitlow, Z. Wu, Z. Yu, L. Zhang, J.T. Walker, G. Beachley, H.M. Amos, J.S. Baron, J. Bash, R. Baumgardner, M.D. Bell, K.B. Benedict, X. Chen, D.W. Clow, A. Cole, J.G. Coughlin, K. Cruz, R.W. Daly, S.M. Decina, E.M. Elliott, Mark E. Fenn, L. Ganzeveld, K. Gebhart, S.S. Isil, B.M. Kerschner, R.S. Larson, T. Lavery, G.G. Lear, T. Macy, M.A. Mast, K. Mishoe, K.H. Morris, Pamela E. PadgettKeywordsSourceScience of The Total Environment. 691: 1328-1352Year2019
- Premise of the Study Over one‐third of the native flowering plant species in the Hawaiian Islands are listed as federally threatened or endangered. Lack of sufficient pollination could contribute to reductions in populations, reproduction, and genetic diversity among these species but has been little studied. Methods We used systematic observations and manual flower treatments to quantify flower visitation and outcrossing dependency of eight native (including four endangered) plant species in a dryland ecosystem in Hawaii: Argemone glauca, Bidens menziesii, Dubautia linearis, Haplostachys...AuthorsClare E. Aslan, Aaron B. Shiels, William Haines, Christina LiangKeywordsSourceAmerican Journal of Botany. 106(2): 313-324Year2019