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Blonder BW. Why are triploid quaking aspen (Populus tremuloides) common? AMERICAN JOURNAL OF BOTANY 2024:e16325. [PMID: 38704729 DOI: 10.1002/ajb2.16325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 04/06/2024] [Accepted: 04/07/2024] [Indexed: 05/07/2024]
Abstract
PREMISE Quaking aspen is a clonal tree species that has mixed ploidy, often with high relative abundance of both diploids and triploids but no haploids or tetraploids. Triploids typically have low fertility, leaving their occurrence apparently unlikely from an evolutionary perspective, unless they provide a "triploid bridge" to generating higher-fitness tetraploids-which are not observed in this species. This study focused on how triploidy can be maintained in quaking aspen. METHODS A computational model was used to simulate gamete production, sexual reproduction, asexual reproduction, parent survival, and offspring survival in a population. All parameters were assumed to be cytotype-dependent and environment-independent. Sampling methods were used to identify parameter combinations consistent with observed cytotype frequencies. RESULTS Many processes and parameter values were sufficient to yield a moderate frequency of triploids, and very few were necessary. The most plausible route involved higher triploid survival at the parent or offspring stage and limited unreduced gamete production by either diploid or triploid parents. Triploid fertility was helpful but not necessary. CONCLUSIONS The coexistence of diploids and triploids in quaking aspen is statistically likely and promoted by the existence of commonly observed, long-lived triploid clones. However, other mechanisms not captured by the model related to environmental variation could also occur. Further empirical data or more complex but difficult-to-parameterize models are needed to gain further insight.
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Affiliation(s)
- Benjamin Wong Blonder
- Department of Environmental Science, Policy, and Management, University of California at Berkeley, Berkeley, 94720 USA, CA
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Blonder BW, Brodrick PG, Chadwick KD, Carroll E, Cruz-de Hoyos RM, Expósito-Alonso M, Hateley S, Moon M, Ray CA, Tran H, Walton JA. Climate lags and genetics determine phenology in quaking aspen (Populus tremuloides). THE NEW PHYTOLOGIST 2023; 238:2313-2328. [PMID: 36856334 DOI: 10.1111/nph.18850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 02/19/2023] [Indexed: 05/19/2023]
Abstract
Spatiotemporal patterns of phenology may be affected by mosaics of environmental and genetic variation. Environmental drivers may have temporally lagged impacts, but patterns and mechanisms remain poorly known. We combine multiple genomic, remotely sensed, and physically modeled datasets to determine the spatiotemporal patterns and drivers of canopy phenology in quaking aspen, a widespread clonal dioecious tree species with diploid and triploid cytotypes. We show that over 391 km2 of southwestern Colorado: greenup date, greendown date, and growing season length vary by weeks and differ across sexes, cytotypes, and genotypes; phenology has high phenotypic plasticity and heritabilities of 31-61% (interquartile range); and snowmelt date, soil moisture, and air temperature predict phenology, at temporal lags of up to 3 yr. Our study shows that lagged environmental effects are needed to explain phenological variation and that the effect of cytotype on phenology is obscured by its correlation with topography. Phenological patterns are consistent with responses to multiyear accumulation of carbon deficit or hydraulic damage.
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Affiliation(s)
- Benjamin W Blonder
- Department of Environmental Science, Policy, and Management, University of California - Berkeley, Berkeley, CA, 94720, USA
- Rocky Mountain Biological Laboratory, Crested Butte, CO, 81224, USA
| | - Philip G Brodrick
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91109, USA
| | - K Dana Chadwick
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91109, USA
| | - Erin Carroll
- Department of Environmental Science, Policy, and Management, University of California - Berkeley, Berkeley, CA, 94720, USA
- Rocky Mountain Biological Laboratory, Crested Butte, CO, 81224, USA
| | - Roxanne M Cruz-de Hoyos
- Department of Environmental Science, Policy, and Management, University of California - Berkeley, Berkeley, CA, 94720, USA
- Rocky Mountain Biological Laboratory, Crested Butte, CO, 81224, USA
| | | | - Shannon Hateley
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
| | - Minkyu Moon
- Department of Earth & Environment, Boston University, Boston, MA, 02215, USA
| | - Courtenay A Ray
- Department of Environmental Science, Policy, and Management, University of California - Berkeley, Berkeley, CA, 94720, USA
- Rocky Mountain Biological Laboratory, Crested Butte, CO, 81224, USA
| | - Hoang Tran
- Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, 08540, USA
- Atmospheric Sciences & Global Change Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - James A Walton
- Molecular Ecology Laboratory, Department of Wildland Resources, Utah State University, Logan, UT, 84322, USA
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Eisenring M, Lindroth RL, Flansburg A, Giezendanner N, Mock KE, Kruger EL. Genotypic variation rather than ploidy level determines functional trait expression in a foundation tree species in the presence and absence of environmental stress. ANNALS OF BOTANY 2023; 131:229-242. [PMID: 35641114 PMCID: PMC9904343 DOI: 10.1093/aob/mcac071] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 05/28/2022] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS At the population level, genetic diversity is a key determinant of a tree species' capacity to cope with stress. However, little is known about the relative importance of the different components of genetic diversity for tree stress responses. We compared how two sources of genetic diversity, genotype and cytotype (i.e. differences in ploidy levels), influence growth, phytochemical and physiological traits of Populus tremuloides in the presence and absence of environmental stress. METHODS In a series of field studies, we first assessed variation in traits across diploid and triploid aspen genotypes from Utah and Wisconsin under non-stressed conditions. In two follow-up experiments, we exposed diploid and triploid aspen genotypes from Wisconsin to individual and interactive drought stress and defoliation treatments and quantified trait variations under stress. KEY RESULTS We found that (1) tree growth and associated traits did not differ significantly between ploidy levels under non-stressed conditions. Instead, variation in tree growth and most other traits was driven by genotypic and population differences. (2) Genotypic differences were critical for explaining variation of most functional traits and their responses to stress. (3) Ploidy level played a subtle role in shaping traits and trait stress responses, as its influence was typically obscured by genotypic differences. (4) As an exception to the third conclusion, we showed that triploid trees expressed 17 % higher foliar defence (tremulacin) levels, 11 % higher photosynthesis levels and 23 % higher rubisco activity under well-watered conditions. Moreover, triploid trees displayed greater drought resilience than diploids as they produced 35 % more new tissue than diploids when recovering from drought stress. CONCLUSION Although ploidy level can strongly influence the ecology of tree species, those effects may be relatively small in contrast to the effects of genotypic variation in highly diverse species.
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Affiliation(s)
| | - Richard L Lindroth
- Department of Entomology, University of Wisconsin-Madison, 1630 Linden Dr., Madison, WI, USA
| | - Amy Flansburg
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, 1630 Linden Dr., Madison, WIUSA
| | - Noreen Giezendanner
- Department of Entomology, University of Wisconsin-Madison, 1630 Linden Dr., Madison, WI, USA
| | - Karen E Mock
- Department of Wildland Resources and Ecology Center, 5230 Old Main Hill, Utah State University, Logan, UT, USA
| | - Eric L Kruger
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, 1630 Linden Dr., Madison, WIUSA
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Blonder B, Brodrick PG, Walton JA, Chadwick KD, Breckheimer IK, Marchetti S, Ray CA, Mock KE. Remote sensing of cytotype and its consequences for canopy damage in quaking aspen. GLOBAL CHANGE BIOLOGY 2022; 28:2491-2504. [PMID: 34962013 DOI: 10.1111/gcb.16064] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 12/19/2021] [Accepted: 12/19/2021] [Indexed: 06/14/2023]
Abstract
Mapping geographic mosaics of genetic variation and their consequences via genotype x environment interactions at large extents and high resolution has been limited by the scalability of DNA sequencing. Here, we address this challenge for cytotype (chromosome copy number) variation in quaking aspen, a drought-impacted foundation tree species. We integrate airborne imaging spectroscopy data with ground-based DNA sequencing data and canopy damage data in 391 km2 of southwestern Colorado. We show that (1) aspen cover and cytotype can be remotely sensed at 1 m spatial resolution, (2) the geographic mosaic of cytotypes is heterogeneous and interdigitated, (3) triploids have higher leaf nitrogen, canopy water content, and carbon isotope shifts (δ13 C) than diploids, and (4) canopy damage varies among cytotypes and depends on interactions with topography, canopy height, and trait variables. Triploids are at higher risk in hotter and drier conditions.
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Affiliation(s)
- Benjamin Blonder
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, California, USA
- Rocky Mountain Biological Laboratory, Crested Butte, Colorado, USA
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Philip G Brodrick
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - James A Walton
- Department of Wildland Resources, Utah State University, Logan, Utah, USA
| | - Katherine Dana Chadwick
- Department of Earth System Science, Stanford University, Stanford, California, USA
- Climate and Ecosystems Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | | | - Suzanne Marchetti
- Forest Health Protection, United States Forest Service, Gunnison, Colorado, USA
| | - Courtenay A Ray
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, California, USA
- Rocky Mountain Biological Laboratory, Crested Butte, Colorado, USA
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Karen E Mock
- Department of Wildland Resources, Utah State University, Logan, Utah, USA
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