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Denney DA, Patel P, Anderson JT. Elevated [CO 2] and temperature augment gas exchange and shift the fitness landscape in a montane forb. THE NEW PHYTOLOGIST 2024; 243:58-71. [PMID: 38655662 DOI: 10.1111/nph.19765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 03/29/2024] [Indexed: 04/26/2024]
Abstract
Climate change is simultaneously increasing carbon dioxide concentrations ([CO2]) and temperature. These factors could interact to influence plant physiology and performance. Alternatively, increased [CO2] may offset costs associated with elevated temperatures. Furthermore, the interaction between elevated temperature and [CO2] may differentially affect populations from along an elevational gradient and disrupt local adaptation. We conducted a multifactorial growth chamber experiment to examine the interactive effects of temperature and [CO2] on fitness and ecophysiology of diverse accessions of Boechera stricta (Brassicaceae) sourced from a broad elevational gradient in Colorado. We tested whether increased [CO2] would enhance photosynthesis across accessions, and whether warmer conditions would depress the fitness of high-elevation accessions owing to steep reductions in temperature with increasing elevation in this system. Elevational clines in [CO2] are not as evident, making it challenging to predict how locally adapted ecotypes will respond to elevated [CO2]. This experiment revealed that elevated [CO2] increased photosynthesis and intrinsic water use efficiency across all accessions. However, these instantaneous responses to treatments did not translate to changes in fitness. Instead, increased temperatures reduced the probability of reproduction for all accessions. Elevated [CO2] and increased temperatures interacted to shift the adaptive landscape, favoring lower elevation accessions for the probability of survival and fecundity. Our results suggest that elevated temperatures and [CO2] associated with climate change could have severe negative consequences, especially for high-elevation populations.
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Affiliation(s)
- Derek A Denney
- Department of Plant Biology, University of Georgia, Athens, GA, 30602, USA
| | - Pratik Patel
- Department of Genetics, University of Georgia, Athens, GA, 30602, USA
| | - Jill T Anderson
- Department of Genetics, University of Georgia, Athens, GA, 30602, USA
- Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
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2
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Hay NM, Windham MD, Mandáková T, Lysak MA, Hendriks KP, Mummenhoff K, Lens F, Pryer KM, Bailey CD. A Hyb-Seq phylogeny of Boechera and related genera using a combination of Angiosperms353 and Brassicaceae-specific bait sets. AMERICAN JOURNAL OF BOTANY 2023; 110:e16226. [PMID: 37561651 DOI: 10.1002/ajb2.16226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 07/21/2023] [Accepted: 07/21/2023] [Indexed: 08/12/2023]
Abstract
PREMISE Although Boechera (Boechereae, Brassicaceae) has become a plant model system for both ecological genomics and evolutionary biology, all previous phylogenetic studies have had limited success in resolving species relationships within the genus. The recent effective application of sequence data from target enrichment approaches to resolve the evolutionary relationships of several other challenging plant groups prompted us to investigate their usefulness in Boechera and Boechereae. METHODS To resolve the phylogeny of Boechera and closely related genera, we utilized the Hybpiper pipeline to analyze two combined bait sets: Angiosperms353, with broad applicability across flowering plants; and a Brassicaceae-specific bait set designed for use in the mustard family. Relationships for 101 samples representing 81 currently recognized species were inferred from a total of 1114 low-copy nuclear genes using both supermatrix and species coalescence methods. RESULTS Our analyses resulted in a well-resolved and highly supported phylogeny of the tribe Boechereae. Boechereae is divided into two major clades, one comprising all western North American species of Boechera, the other encompassing the eight other genera of the tribe. Our understanding of relationships within Boechera is enhanced by the recognition of three core clades that are further subdivided into robust regional species complexes. CONCLUSIONS This study presents the first broadly sampled, well-resolved phylogeny for most known sexual diploid Boechera. This effort provides the foundation for a new phylogenetically informed taxonomy of Boechera that is crucial for its continued use as a model system.
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Affiliation(s)
- Nikolai M Hay
- Department of Biology, Duke University, Durham, 27708, North Carolina, USA
| | - Michael D Windham
- Department of Biology, Duke University, Durham, 27708, North Carolina, USA
| | - Terezie Mandáková
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 5, Brno, 625 00, Czech Republic
- Department of Experimental Biology, Faculty of Science, Masaryk University, Kamenice 5, Brno, 625 00, Czech Republic
| | - Martin A Lysak
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 5, Brno, 625 00, Czech Republic
- National Centre for Biomolecular Research (NCBR), Faculty of Science, Masaryk University, Kamenice 5, Brno, 625 00, Czech Republic
| | - Kasper P Hendriks
- Department of Biology/Botany, University of Osnabrück, Barbarastraße 11, Osnabrück, D-49076, Germany
- Naturalis Biodiversity Center, P.O. Box 9517, Leiden, 2300 RA, The Netherlands
| | - Klaus Mummenhoff
- Department of Biology/Botany, University of Osnabrück, Barbarastraße 11, Osnabrück, D-49076, Germany
| | - Frederic Lens
- Naturalis Biodiversity Center, P.O. Box 9517, Leiden, 2300 RA, The Netherlands
- Institute of Biology Leiden, Plant Sciences, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands
| | - Kathleen M Pryer
- Department of Biology, Duke University, Durham, 27708, North Carolina, USA
| | - C Donovan Bailey
- Department of Biology, New Mexico State University, Las Cruces, New Mexico, USA
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3
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MacTavish R, Anderson JT. Water and nutrient availability exert selection on reproductive phenology. AMERICAN JOURNAL OF BOTANY 2022; 109:1702-1716. [PMID: 36031862 DOI: 10.1002/ajb2.16057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 07/22/2022] [Accepted: 07/22/2022] [Indexed: 06/15/2023]
Abstract
PREMISE Global change has changed resource availability to plants, which could shift the adaptive landscape. We hypothesize that novel water and nutrient availability combinations alter patterns of natural selection on reproductive phenology in Boechera stricta (Brassicaceae) and influence the evolution of local adaptation. METHODS We conducted a multifactorial greenhouse study using 35 accessions of B. stricta sourced from a broad elevational gradient in the Rocky Mountains. We exposed full siblings to three soil water and two nutrient availability treatment levels, reflecting current and projected future conditions. In addition, we quantified fitness (seed count) and four phenological traits: the timing of first flowering, the duration of flowering, and height and leaf number at flowering. RESULTS Selection favored early flowering and longer duration of flowering, and the genetic correlation between these traits accorded with the direction of selection. In most treatments, we found selection for increased height, but selection on leaf number depended on water availability, with selection favoring more leaves in well-watered conditions and fewer leaves under severe drought. Low-elevation genotypes had the greatest fitness under drought stress, consistent with local adaptation. CONCLUSIONS We found evidence of strong selection on these heritable traits. Furthermore, the direction and strength of selection on size at flowering depended on the variable measured (height vs. leaf number). Finally, selection often favored both early flowering and a longer duration of flowering. Selection on these two components of phenology can be difficult to disentangle due to tight genetic correlations.
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Affiliation(s)
- Rachel MacTavish
- Department of Genetics and Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
| | - Jill T Anderson
- Department of Genetics and Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
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4
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Rushworth CA, Wagner MR, Mitchell-Olds T, Anderson JT. The Boechera model system for evolutionary ecology. AMERICAN JOURNAL OF BOTANY 2022; 109:1939-1961. [PMID: 36371714 DOI: 10.1002/ajb2.16090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 08/27/2022] [Accepted: 08/30/2022] [Indexed: 06/16/2023]
Abstract
Model systems in biology expand the research capacity of individuals and the community. Closely related to Arabidopsis, the genus Boechera has emerged as an important ecological model owing to the ability to integrate across molecular, functional, and eco-evolutionary approaches. Boechera species are broadly distributed in relatively undisturbed habitats predominantly in western North America and provide one of the few experimental systems for identification of ecologically important genes through genome-wide association studies and investigations of selection with plants in their native habitats. The ecologically, evolutionarily, and agriculturally important trait of apomixis (asexual reproduction via seeds) is common in the genus, and field experiments suggest that abiotic and biotic environments shape the evolution of sex. To date, population genetic studies have focused on the widespread species B. stricta, detailing population divergence and demographic history. Molecular and ecological studies show that balancing selection maintains genetic variation in ~10% of the genome, and ecological trade-offs contribute to complex trait variation for herbivore resistance, flowering phenology, and drought tolerance. Microbiome analyses have shown that host genotypes influence leaf and root microbiome composition, and the soil microbiome influences flowering phenology and natural selection. Furthermore, Boechera offers numerous opportunities for investigating biological responses to global change. In B. stricta, climate change has induced a shift of >2 weeks in the timing of first flowering since the 1970s, altered patterns of natural selection, generated maladaptation in previously locally-adapted populations, and disrupted life history trade-offs. Here we review resources and results for this eco-evolutionary model system and discuss future research directions.
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Affiliation(s)
| | - Maggie R Wagner
- Department of Ecology and Evolutionary Biology, Kansas Biological Survey and Center for Ecological Research, University of Kansas, Lawrence, KS, 66045, USA
| | | | - Jill T Anderson
- Department of Genetics and Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
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5
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McMinn R, Salmela MJ, Weinig C. Naturally segregating genetic variation in circadian period exhibits a regional elevational and climatic cline. PLANT, CELL & ENVIRONMENT 2022; 45:2696-2707. [PMID: 35686466 DOI: 10.1111/pce.14377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 05/15/2022] [Accepted: 05/21/2022] [Indexed: 06/15/2023]
Abstract
Circadian clocks confer adaptation to predictable 24-h fluctuations in the exogenous environment, but it has yet to be determined what ecological factors maintain natural genetic variation in endogenous circadian period outside of the hypothesized optimum of 24 h. We estimated quantitative genetic variation in circadian period in leaf movement in 30 natural populations of the Arabidopsis relative Boechera stricta sampled within only 1° of latitude but across an elevation gradient spanning 2460-3300 m in the Rocky Mountains. Measuring ~3800 plants from 473 maternal families (7-20 per population), we found that genetic variation was of similar magnitude among versus within populations, with population means varying between 21.9 and 24.9 h and maternal family means within populations varying by up to ~6 h. After statistically accounting for spatial autocorrelation at a habitat extreme, we found that elevation explained a significant proportion of genetic variation in the circadian period, such that higher-elevation populations had shorter mean period lengths and reduced intrapopulation ranges. Environmental data indicate that these spatial trends could be related to steep regional climatic gradients in temperature, precipitation, and their intra-annual variability. Our findings suggest that spatially fine-grained environmental heterogeneity contributes to naturally occurring genetic variation in circadian traits in wild populations.
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Affiliation(s)
- Rob McMinn
- Department of Botany, University of Wyoming, Laramie, Wyoming, USA
- Program in Ecology, University of Wyoming, Laramie, Wyoming, USA
| | | | - Cynthia Weinig
- Department of Botany, University of Wyoming, Laramie, Wyoming, USA
- Program in Ecology, University of Wyoming, Laramie, Wyoming, USA
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, USA
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6
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Liang YY, Chen XY, Zhou BF, Mitchell-Olds T, Wang B. Globally Relaxed Selection and Local Adaptation in Boechera stricta. Genome Biol Evol 2022; 14:evac043. [PMID: 35349686 PMCID: PMC9011030 DOI: 10.1093/gbe/evac043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/23/2022] [Indexed: 11/25/2022] Open
Abstract
The strength of selection varies among populations and across the genome, but the determinants of efficacy of selection remain unclear. In this study, we used whole-genome sequencing data from 467 Boechera stricta accessions to quantify the strength of selection and characterize the pattern of local adaptation. We found low genetic diversity on 0-fold degenerate sites and conserved non-coding sites, indicating functional constraints on these regions. The estimated distribution of fitness effects and the proportion of fixed substitutions suggest relaxed negative and positive selection in B. stricta. Among the four population groups, the NOR and WES groups have smaller effective population size (Ne), higher proportions of effectively neutral sites, and lower rates of adaptive evolution compared with UTA and COL groups, reflecting the effect of Ne on the efficacy of natural selection. We also found weaker selection on GC-biased sites compared with GC-conservative (unbiased) sites, suggested that GC-biased gene conversion has affected the strength of selection in B. stricta. We found mixed evidence for the role of the recombination rate on the efficacy of selection. The positive and negative selection was stronger in high-recombination regions compared with low-recombination regions in COL but not in other groups. By scanning the genome, we found different subsets of selected genes suggesting differential adaptation among B. stricta groups. These results show that differences in effective population size, nucleotide composition, and recombination rate are important determinants of the efficacy of selection. This study enriches our understanding of the roles of natural selection and local adaptation in shaping genomic variation.
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Affiliation(s)
- Yi-Ye Liang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences,
Guangzhou, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Xue-Yan Chen
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences,
Guangzhou, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Biao-Feng Zhou
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences,
Guangzhou, China
- University of the Chinese Academy of Sciences, Beijing, China
| | | | - Baosheng Wang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences,
Guangzhou, China
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China
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7
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Yan W, Wang B, Chan E, Mitchell-Olds T. Genetic architecture and adaptation of flowering time among environments. THE NEW PHYTOLOGIST 2021; 230:1214-1227. [PMID: 33484593 PMCID: PMC8193995 DOI: 10.1111/nph.17229] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 01/07/2021] [Indexed: 05/17/2023]
Abstract
The genetic basis of flowering time changes across environments, and pleiotropy may limit adaptive evolution of populations in response to local conditions. However, little information is known about how genetic architecture changes among environments. We used genome-wide association studies (GWAS) in Boechera stricta (Graham) Al-Shehbaz, a relative of Arabidopsis, to examine flowering variation among environments and associations with climate conditions in home environments. Also, we used molecular population genetics to search for evidence of historical natural selection. GWAS found 47 significant quantitative trait loci (QTLs) that influence flowering time in one or more environments, control plastic changes in phenology between experiments, or show associations with climate in sites of origin. Genetic architecture of flowering varied substantially among environments. We found that some pairs of QTLs showed similar patterns of pleiotropy across environments. A large-effect QTL showed molecular signatures of adaptive evolution and is associated with climate in home environments. The derived allele at this locus causes later flowering and predominates in sites with greater water availability. This work shows that GWAS of climate associations and ecologically important traits across diverse environments can be combined with molecular signatures of natural selection to elucidate ecological genetics of adaptive evolution.
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Affiliation(s)
- Wenjie Yan
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
- Department of Biology, Duke University, Box 90338, Durham, NC 27708, USA
| | - Baosheng Wang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, 510650 China
| | - Emily Chan
- Department of Biology, Duke University, Box 90338, Durham, NC 27708, USA
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8
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Hamann E, Wadgymar SM, Anderson JT. Costs of reproduction under experimental climate change across elevations in the perennial forb Boechera stricta. Proc Biol Sci 2021; 288:20203134. [PMID: 33849323 PMCID: PMC8059524 DOI: 10.1098/rspb.2020.3134] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 03/17/2021] [Indexed: 01/13/2023] Open
Abstract
Investment in current reproduction can reduce future fitness by depleting resources needed for maintenance, particularly under environmental stress. These trade-offs influence life-history evolution. We tested whether climate change alters the future-fitness costs of current reproduction in a large-scale field experiment of Boechera stricta (Brassicaceae). Over 6 years, we simulated climate change along an elevational gradient in the Rocky Mountains through snow removal, which accelerates snowmelt and reduces soil water availability. Costs of reproduction were greatest in arid, lower elevations, where high initial reproductive effort depressed future fitness. At mid-elevations, initial reproduction augmented subsequent fitness in benign conditions, but pronounced costs emerged under snow removal. At high elevation, snow removal dampened costs of reproduction by prolonging the growing season. In most scenarios, failed reproduction in response to resource limitation depressed lifetime fecundity. Indeed, fruit abortion only benefited high-fitness individuals under benign conditions. We propose that climate change could shift life-history trade-offs in an environment-dependent fashion, possibly favouring early reproduction and short lifespans in stressful conditions.
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Affiliation(s)
- Elena Hamann
- Department of Genetics and the Odum School of Ecology, University of Georgia, Athens, GA 30602, USA
| | | | - Jill T. Anderson
- Department of Genetics and the Odum School of Ecology, University of Georgia, Athens, GA 30602, USA
- The Rocky Mountain Biological Laboratory, Crested Butte, CO 81224, USA
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9
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Rushworth CA, Brandvain Y, Mitchell‐Olds T. Identifying the fitness consequences of sex in complex natural environments. Evol Lett 2020; 4:516-529. [PMID: 33312687 PMCID: PMC7719549 DOI: 10.1002/evl3.194] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/14/2020] [Accepted: 08/24/2020] [Indexed: 02/06/2023] Open
Abstract
In the natural world, sex prevails, despite its costs. Although much effort has been dedicated to identifying the intrinsic costs of sex (e.g., the cost of males), few studies have identified the ecological fitness consequences of sex. Furthermore, correlated biological traits that differ between sexuals and asexuals may alter these costs, or even render the typical costs of sex irrelevant. We conducted a large-scale, multisite, reciprocal transplant using multiple sexual and asexual genotypes of a native North American wildflower to show that sexual genotypes have reduced lifetime fitness, despite lower herbivory. We separated the effects of sex from those of hybridity, finding that overwinter survival is elevated in asexuals regardless of hybridity, but herbivores target hybrid asexuals more than nonhybrid asexual or sexual genotypes. Survival is lowest in homozygous sexual lineages, implicating inbreeding depression as a cost of sex. Our results show that the consequences of sex are shaped not just by sex itself, but by complex natural environments, correlated traits, and the identity and availability of mates.
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Affiliation(s)
- Catherine A. Rushworth
- Department of Evolution and EcologyUniversity of California, DavisDavisCalifornia95616
- University and Jepson HerbariaUniversity of California, BerkeleyBerkeleyCalifornia94720
- Department of Plant and Microbial BiologyUniversity of MinnesotaSt. PaulMinnesota55108
- Department of BiologyDuke UniversityDurhamNorth Carolina27708
| | - Yaniv Brandvain
- Department of Plant and Microbial BiologyUniversity of MinnesotaSt. PaulMinnesota55108
| | - Tom Mitchell‐Olds
- Department of BiologyDuke UniversityDurhamNorth Carolina27708
- Center for Genomic and Computational BiologyDuke UniversityDurhamNorth Carolina27708
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10
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Rushworth CA, Mitchell-Olds T. The Evolution of Sex is Tempered by Costly Hybridization in Boechera (Rock Cress). J Hered 2020; 112:67-77. [PMID: 33211850 DOI: 10.1093/jhered/esaa041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 10/03/2020] [Indexed: 12/17/2022] Open
Abstract
Despite decades of research, the evolution of sex remains an enigma in evolutionary biology. Typically, research addresses the costs of sex and asexuality to characterize the circumstances favoring one reproductive mode. Surprisingly few studies address the influence of common traits that are, in many organisms, obligately correlated with asexuality, including hybridization and polyploidy. These characteristics have substantial impacts on traits under selection. In particular, the fitness consequences of hybridization (i.e., reduced fitness due to interspecific reproductive isolation) will influence the evolution of sex. This may comprise a cost of either sex or asexuality due to the link between hybridity and asexuality. We examined reproductive isolation in the formation of de novo hybrid lineages between 2 widespread species in the ecological model system Boechera. Seventeen percent of 664 crosses produced F1 fruits, and only 10% of these were viable, suggesting that postmating prezygotic and postzygotic barriers inhibit hybrid success in this system. The postmating prezygotic barrier was asymmetrical, with 110 of 115 total F1 fruits produced when Boechera stricta acted as maternal parent. This asymmetry was confirmed in wild-collected lineages, using a chloroplast phylogeny of wild-collected B. stricta, Boechera retrofracta, and hybrids. We next compared fitness of F2 hybrids and selfed parental B. stricta lines, finding that F2 fitness was reduced by substantial hybrid sterility. Multiple reproductively isolating barriers influence the formation and fitness of hybrid lineages in the wild, and the costs of hybridization likely have profound impacts on the evolution of sex in the natural environment.
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Affiliation(s)
- Catherine A Rushworth
- Department of Evolution and Ecology, Storer Hall, University of California Davis, Davis, CA.,Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN.,University and Jepson Herbaria, University of California Berkeley, Berkeley, CA.,Department of Biology and Center for Genomic and Computational Biology, Duke University, Box, Durham, NC
| | - Tom Mitchell-Olds
- Department of Biology and Center for Genomic and Computational Biology, Duke University, Box, Durham, NC
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11
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MacTavish R, Anderson JT. Resource availability alters fitness trade-offs: implications for evolution in stressful environments. AMERICAN JOURNAL OF BOTANY 2020; 107:308-318. [PMID: 31943133 DOI: 10.1002/ajb2.1417] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 09/16/2019] [Indexed: 05/22/2023]
Abstract
PREMISE Industrialization and human activities have elevated temperatures and caused novel precipitation patterns, altering soil moisture and nutrient availability. Predicting evolutionary responses to climate change requires information on the agents of selection that drive local adaptation and influence resource acquisition and allocation. Here, we examined the contribution of nutrient and drought stress to local adaptation, and we tested whether trade-offs across fitness components constrain or facilitate adaptation under resource stress. METHODS We exposed 35 families of Boechera stricta (Brassicaceae) to three levels of water and two levels of nutrient supply in a factorial design in the greenhouse. We sourced maternal families from a broad elevational gradient (2499-3530 m a.s.l.), representing disparate soil moisture and nutrient availability. RESULTS Concordant with local adaptation, maternal families from arid, low-elevation populations had enhanced fecundity under severe drought over those from more mesic, high-elevation sites. Furthermore, fitness trade-offs between growth and reproductive success depended on the environmental context. Under high, but not low, nutrient levels, we found a negative phenotypic relationship between the probability of reproduction and growth rate. Similarly, a negative phenotypic association only emerged between fecundity and growth under severe drought stress, not the benign water treatment levels, indicating that stressful resource environments alter the direction of trait correlations. Genetic covariances were broadly concordant with these phenotypic patterns. CONCLUSIONS Despite high heritabilities in all fitness components across treatments, trade-offs between growth and reproduction could constrain adaptation to increasing drought stress and novel nutrient levels.
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Affiliation(s)
- Rachel MacTavish
- Department of Genetics and Odum School of Ecology, University of Georgia, Athens, GA, USA
| | - Jill T Anderson
- Department of Genetics and Odum School of Ecology, University of Georgia, Athens, GA, USA
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12
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Comparative studies on population genetic structure of two closely related selfing and outcrossing Zingiber species in Hainan Island. Sci Rep 2019; 9:17997. [PMID: 31784623 PMCID: PMC6884562 DOI: 10.1038/s41598-019-54526-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Accepted: 11/15/2019] [Indexed: 02/04/2023] Open
Abstract
How mating system impacts the genetic diversity of plants has long fascinated and puzzled evolutionary biologists. Numerous studies have shown that self-fertilising plants have less genetic diversity at both the population and species levels than outcrossers. However, the phylogenetic relationships between species and correlated ecological traits have not been accounted for in these previous studies. Here, we conduct a comparative population genetic study of two closely related selfing and outcrossing Zingiber species, with sympatric distribution in Hainan Island, and obtain a result contrary to previous studies. The results indicate that selfing Z. corallinum can maintain high genetic diversity through differentiation intensified by local adaptation in populations across the species’ range. In contrast, outcrossing Z. nudicarpum preserves high genetic diversity through gene exchange by frequent export of pollen within or among populations. Contrary to expectations, the major portion of genetic variation of outcrossing Z. nudicarpum may exist among populations, depending on the dispersal ability of pollen and seed. Our results also reveal that the main factor affecting population structure of selfing Z. corallinum is mountain ranges, followed by a moist climate, while that of outcrossing Z. nudicarpum is likely moisture, but not mountain ranges, due to gene flow via pollen.
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13
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Anderson JT, Wadgymar SM. Climate change disrupts local adaptation and favours upslope migration. Ecol Lett 2019; 23:181-192. [DOI: 10.1111/ele.13427] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 07/19/2019] [Accepted: 10/19/2019] [Indexed: 12/30/2022]
Affiliation(s)
- Jill T. Anderson
- Department of Genetics and Odum School of Ecology University of Georgia Athens GA 30602 USA
- The Rocky Mountain Biological Laboratory Crested Butte CO 81224 USA
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14
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Bemmels JB, Anderson JT. Climate change shifts natural selection and the adaptive potential of the perennial forb Boechera stricta in the Rocky Mountains. Evolution 2019; 73:2247-2262. [PMID: 31584183 DOI: 10.1111/evo.13854] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 09/03/2019] [Accepted: 09/05/2019] [Indexed: 12/14/2022]
Abstract
Heritable genetic variation is necessary for populations to evolve in response to anthropogenic climate change. However, antagonistic genetic correlations among traits may constrain the rate of adaptation, even if substantial genetic variation exists. We examine potential genetic responses to selection by comparing multivariate genetic variance-covariances of traits and fitness (multivariate Robertson-Price identities) across different environments in a reciprocal transplant experiment of the forb Boechera stricta in the Rocky Mountains. By transplanting populations into four common gardens arrayed along an elevational gradient, and exposing populations to control and snow removal treatments, we simulated future and current climates and snowmelt regimes. Genetic variation in flowering and germination phenology declined in plants moved downslope to warmer, drier sites, suggesting that these traits may have a limited ability to evolve under future climates. Simulated climate change via snow removal altered the strength of selection on flowering traits, but we found little evidence that genetic correlations among traits are likely to affect the rate of adaptation to climate change. Overall, our results suggest that climate change may alter the evolutionary potential of B. stricta, but reduced expression of genetic variation may be a larger impediment to adaptation than constraints imposed by antagonistic genetic correlations.
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Affiliation(s)
- Jordan B Bemmels
- Department of Genetics, University of Georgia, Athens, Georgia, 30602.,Current Address: Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, M1C 1A4, Canada
| | - Jill T Anderson
- Department of Genetics, University of Georgia, Athens, Georgia, 30602.,Rocky Mountain Biological Laboratory, PO Box 519, Crested Butte, Colorado, 81224
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15
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Olsen J, Singh Gill G, Haugen R, Matzner SL, Alsdurf J, Siemens DH. Evolutionary constraint on low elevation range expansion: Defense-abiotic stress-tolerance trade-off in crosses of the ecological model Boechera stricta. Ecol Evol 2019; 9:11532-11544. [PMID: 31695866 PMCID: PMC6822064 DOI: 10.1002/ece3.5499] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 09/08/2018] [Accepted: 09/13/2018] [Indexed: 01/27/2023] Open
Abstract
Most transplant experiments across species geographic range boundaries indicate that adaptation to stressful environments outside the range is often constrained. However, the mechanisms of these constraints remain poorly understood. We used extended generation crosses from diverged high and low elevation populations. In experiments across low elevation range boundaries, there was selection on the parental lines for abiotic stress-tolerance and resistance to herbivores. However, in support of a defense-tolerance trade-off, extended generation crosses showed nonindependent segregation of these traits in the laboratory across a drought-stress gradient and in the field across the low elevation range boundary. Genotypic variation in a marker from a region of the genome containing a candidate gene (MYC2) was associated with change in the genetic trade-off. Thus, using crosses and forward genetics, we found experimental genetic and molecular evidence for a pleiotropic trade-off that could constrain the evolution of range expansion.
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Affiliation(s)
- Jason Olsen
- Integrative Genomics ProgramBlack Hills State UniversitySpearfishSDUSA
- Present address:
500 W Fort Street 111RBoiseID83702USA
| | - Gunbharpur Singh Gill
- Integrative Genomics ProgramBlack Hills State UniversitySpearfishSDUSA
- Present address:
Department of BiologyUtah State UniversityLoganUTUSA
| | - Riston Haugen
- Integrative Genomics ProgramBlack Hills State UniversitySpearfishSDUSA
| | | | - Jake Alsdurf
- Integrative Genomics ProgramBlack Hills State UniversitySpearfishSDUSA
- Present address:
Division of BiologyKansas State UniversityManhattanKSUSA
| | - David H. Siemens
- Integrative Genomics ProgramBlack Hills State UniversitySpearfishSDUSA
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16
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Wang B, Mojica JP, Perera N, Lee CR, Lovell JT, Sharma A, Adam C, Lipzen A, Barry K, Rokhsar DS, Schmutz J, Mitchell-Olds T. Ancient polymorphisms contribute to genome-wide variation by long-term balancing selection and divergent sorting in Boechera stricta. Genome Biol 2019; 20:126. [PMID: 31227026 PMCID: PMC6587263 DOI: 10.1186/s13059-019-1729-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Accepted: 06/04/2019] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Genomic variation is widespread, and both neutral and selective processes can generate similar patterns in the genome. These processes are not mutually exclusive, so it is difficult to infer the evolutionary mechanisms that govern population and species divergence. Boechera stricta is a perennial relative of Arabidopsis thaliana native to largely undisturbed habitats with two geographic and ecologically divergent subspecies. Here, we delineate the evolutionary processes driving the genetic diversity and population differentiation in this species. RESULTS Using whole-genome re-sequencing data from 517 B. stricta accessions, we identify four genetic groups that diverged around 30-180 thousand years ago, with long-term small effective population sizes and recent population expansion after the Last Glacial Maximum. We find three genomic regions with elevated nucleotide diversity, totaling about 10% of the genome. These three regions of elevated nucleotide diversity show excess of intermediate-frequency alleles, higher absolute divergence (dXY), and lower relative divergence (FST) than genomic background, and significant enrichment in immune-related genes, reflecting long-term balancing selection. Scattered across the genome, we also find regions with both high FST and dXY among the groups, termed FST-islands. Population genetic signatures indicate that FST-islands with elevated divergence, which have experienced directional selection, are derived from divergent sorting of ancient polymorphisms. CONCLUSIONS Our results suggest that long-term balancing selection on disease resistance genes may have maintained ancestral haplotypes across different geographical lineages, and unequal sorting of balanced polymorphisms may have generated genomic regions with elevated divergence. This study highlights the importance of ancestral balanced polymorphisms as crucial components of genome-wide variation.
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Affiliation(s)
- Baosheng Wang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
- Department of Biology, Duke University, Box 90338, Durham, NC, 27708, USA.
| | - Julius P Mojica
- Department of Biology, Duke University, Box 90338, Durham, NC, 27708, USA
| | - Nadeesha Perera
- Department of Biology, Duke University, Box 90338, Durham, NC, 27708, USA
| | - Cheng-Ruei Lee
- Institute of Ecology and Evolutionary Biology and Institute of Plant Biology, National Taiwan University, Taipei, 10617, Taiwan, ROC
| | - John T Lovell
- HudsonAlpha Institute for Biotechnology, Huntsville, AL, 35806, USA
| | - Aditi Sharma
- Department of Energy Joint Genome Institute, Walnut Creek, CA, 94598, USA
| | - Catherine Adam
- Department of Energy Joint Genome Institute, Walnut Creek, CA, 94598, USA
| | - Anna Lipzen
- Department of Energy Joint Genome Institute, Walnut Creek, CA, 94598, USA
| | - Kerrie Barry
- Department of Energy Joint Genome Institute, Walnut Creek, CA, 94598, USA
| | - Daniel S Rokhsar
- Department of Energy Joint Genome Institute, Walnut Creek, CA, 94598, USA
| | - Jeremy Schmutz
- HudsonAlpha Institute for Biotechnology, Huntsville, AL, 35806, USA
- Department of Energy Joint Genome Institute, Walnut Creek, CA, 94598, USA
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17
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Fuller RS, McGlaughlin ME. Calochortus gunnisonii furthers evidence for the complex genetic legacy of historical climate change in the southern Rocky Mountains. AMERICAN JOURNAL OF BOTANY 2019; 106:477-488. [PMID: 30901490 DOI: 10.1002/ajb2.1259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 12/27/2018] [Indexed: 06/09/2023]
Abstract
PREMISE OF THE STUDY Climate cycles of the Quaternary have impacted plants at a global scale, leaving behind a complex genetic legacy. Species of the northern Rocky Mountains of North America were exposed to more uniform glacial patterns than the central and southern ranges, where synergistic relationships between temperature and precipitation caused differences in the timing and extent of glacier onset. We examined the genetic impacts of climate oscillations on Calochortus gunnisonii (Liliaceae) in the central and southern Rocky Mountains. METHODS Populations were sampled from disjunct mountain ranges across the basins of Wyoming and northern and central Colorado. Allelic data from nuclear microsatellites and plastid sequences (trnV-ndhC, petA-psbJ, and rpl16) were used to examine patterns of genetic structure between and among populations along the southern Rocky Mountain corridor. KEY RESULTS We infer considerable population structure concordant with mountain range of origin. Clustering analysis supports separate north and south genetic clusters on either side of major basins in Wyoming, suggesting that populations were maintained in two distinct refugia. Additionally, populations within the Sierra Madre Range of southern Wyoming show localized, divergent genetic signal indicative of a third potential glacial refugium. By contrast, recent genetic admixture is observed in the Laramie, Medicine Bow, and Front ranges, where population expansion from glacial refugia has likely occurred. CONCLUSIONS We conclude that during climate cycles of the Quaternary, C. gunnisonii experienced periods of population expansion and reduction, habitat fragmentation, isolation in three or more refugia, and admixture mirroring genetic impacts of other southern Rocky Mountains organisms.
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Affiliation(s)
- Ryan S Fuller
- School of Biological Sciences, University of Northern Colorado, 501 20th Street, Greeley, Colorado, 80639, USA
- Committee on Evolutionary Biology, University of Chicago, 1025 E. 57th Street, Chicago, Illinois, 60637, USA
| | - Mitchell E McGlaughlin
- School of Biological Sciences, University of Northern Colorado, 501 20th Street, Greeley, Colorado, 80639, USA
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18
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Rushworth CA, Windham MD, Keith RA, Mitchell-Olds T. Ecological differentiation facilitates fine-scale coexistence of sexual and asexual Boechera. AMERICAN JOURNAL OF BOTANY 2018; 105:2051-2064. [PMID: 30548985 PMCID: PMC6685206 DOI: 10.1002/ajb2.1201] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 09/10/2018] [Indexed: 05/28/2023]
Abstract
PREMISE OF THE STUDY Ecological differentiation (ED) between sexual and asexual organisms may permit the maintenance of reproductive polymorphism. Several studies of sexual/asexual ED in plants have shown that the geographic ranges of asexuals extend beyond those of sexuals, often in areas of higher latitude or elevation. But very little is known about ED at fine scales, wherein coexistence of sexuals and asexuals may be permitted by differential niche occupation. METHODS We used 149 populations of sexual and apomictic lineages in the genus Boechera (rock cress) collected across a portion of this mustard's vast range. We characterized reproductive mode, ploidy, and species identity or hybrid parentage of each individual, and then used a multipronged statistical approach to (1) identify ED between sexuals and asexuals; (2) investigate the impacts of two confounding factors, polyploidy and hybridization, on ED; and (3) determine the environmental variables underlying ED. KEY RESULTS We found that sexuals and asexuals are significantly ecologically differentiated across the landscape, despite fine-scale interdigitation of these two reproductive forms. Asexual reproduction was strongly associated with greater disturbance, reduced slope, and greater environmental variability. Although ploidy had little effect on the patterns observed, hybridization has a unique impact on the relationships between asexual reproduction and specific environmental variables. CONCLUSIONS Ecological differentiation along the axes of disturbance, slope, and climatic variability, as well as the effects of heterozygosity, may contribute to the maintenance of sexuality and asexuality across the landscape, ultimately impacting the establishment and spread of asexual lineages.
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Affiliation(s)
- Catherine A. Rushworth
- Department of Biology, Box 90338, Duke University, Durham, NC 27708, USA
- University and Jepson Herbaria and Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
| | - Michael D. Windham
- Department of Biology, Box 90338, Duke University, Durham, NC 27708, USA
| | - Rose A. Keith
- Program in Genetics and Genomics, Duke University, Durham, NC 27708, USA
| | - Tom Mitchell-Olds
- Department of Biology, Box 90338, Duke University, Durham, NC 27708, USA
- Program in Genetics and Genomics, Duke University, Durham, NC 27708, USA
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19
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Wadgymar SM, Mactavish RM, Anderson JT. Transgenerational and Within-Generation Plasticity in Response to Climate Change: Insights from a Manipulative Field Experiment across an Elevational Gradient. Am Nat 2018; 192:698-714. [DOI: 10.1086/700097] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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20
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Morin DP, Alexander PJ, Beck JB, Windham MD, Bailey CD. Deciphering the sexual diploid members of the Boechera suffrutescens complex (Brassicaceae, Boechereae). PHYTOKEYS 2018; 98:15-50. [PMID: 29750070 PMCID: PMC5943444 DOI: 10.3897/phytokeys.98.24296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Accepted: 04/05/2018] [Indexed: 06/08/2023]
Abstract
Boechera is a model genus that is of particular interest for understanding apomixis due to the presence of numerous apomictic diploid lineages that are tightly correlated with hybridisation events. Boechera includes many narrowly distributed endemics and apomictic hybrid lineages that obscure morphological boundaries amongst taxa. In this study, we focus on the Boechera suffrutescens complex, a phylogenetically well-supported but taxonomically complex north-western United States clade whose diploid species currently include the widespread B. suffrutescens and two narrowly distributed serpentine endemics, B. constancei and B. rollei. Using a 15-locus microsatellite dataset, we infer ploidy and sexual vs. apomictic reproduction for all individuals and then assess species limits for all sexual diploid samples. Our results support the recognition of B. rollei and B. constancei as distinct species and reveal three divergent sexual diploid lineages within B. suffrutescens sensu lato. The latter three lineages exhibit geographic, genetic and morphological coherence and consequently warrant recognition at the species rank. These include Boechera suffrutescens s.s., which is restricted to Idaho and eastern Oregon, Boechera botulifructa, a newly described species distributed along the Cascade Mountain Province from Lassen County, California north to Deschutes County, Oregon and the heretofore dismissed species Boechera duriuscula (basionym ≡ Arabis duriuscula), which occurs along the Sierra Nevada Province from Plumas County southwards to Fresno County, California. Our data also reveal substructure in B. constancei that is likely attributable to the highly fragmented distribution of its serpentine habitat. This refined taxonomic framework for the B. suffrutescens complex enhances Boechera as a model system, adds to our knowledge of speciation in edaphically extreme environments and provides information on ongoing conservation efforts for these taxa.
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Affiliation(s)
- David P. Morin
- Biology Department, New Mexico State University, P.O. Box 30001 – MSC 3AF, Las Cruces, New Mexico 88003, USA
| | - Patrick J. Alexander
- Biology Department, New Mexico State University, P.O. Box 30001 – MSC 3AF, Las Cruces, New Mexico 88003, USA
| | - James B. Beck
- Department of Biological Sciences, Wichita State University, 1845 Fairmount, Wichita, Kansas 67260, USA
- Botanical Research Institute of Texas, 1700 University Drive, Fort Worth, TX 76107, USA
| | - Michael D. Windham
- Department of Biology, Duke University, 139 Biological Sciences (Box 90338), Durham, North Carolina 27708, USA
| | - C. Donovan Bailey
- Biology Department, New Mexico State University, P.O. Box 30001 – MSC 3AF, Las Cruces, New Mexico 88003, USA
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21
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Schilling MP, Gompert Z, Li FW, Windham MD, Wolf PG. Admixture, evolution, and variation in reproductive isolation in the Boechera puberula clade. BMC Evol Biol 2018; 18:61. [PMID: 29699502 PMCID: PMC5921550 DOI: 10.1186/s12862-018-1173-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 04/04/2018] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Hybridization is very common in plants, and the incorporation of new alleles into existing lineages (i.e. admixture) can blur species boundaries. However, admixture also has the potential to increase standing genetic variation. With new sequencing methods, we can now study admixture and reproductive isolation at a much finer scale than in the past. The genus Boechera is an extraordinary example of admixture, with over 400 hybrid derivates of varying ploidy levels. Yet, few studies have assessed admixture in this genus on a genomic scale. RESULTS In this study, we used Genotyping-by-Sequencing (GBS) to clarify the evolution of the Boechera puberula clade, whose six members are scattered across the western United States. We further assessed patterns of admixture and reproductive isolation within the group, including two additional species (B. stricta and B. retrofracta) that are widespread across North America. Based on 14,815 common genetic variants, we found evidence for some cases of hybridization. We find evidence of both recent and more ancient admixture, and that levels of admixture vary across species. CONCLUSIONS We present evidence for a monophyletic origin of the B. puberula group, and a split of B. puberula into two subspecies. Further, when inferring reproductive isolation on the basis of presence and absence of admixture, we found that the accumulation of reproductive isolation between species does not seem to occur linearly with time since divergence in this system. We discuss our results in the context of sexuality and asexuality in Boechera.
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Affiliation(s)
- Martin P Schilling
- Biology Department, Utah State University, 5305 Old Main Hill, Logan, UT, 84322, USA.,Ecology Center, Utah State University, 5205 Old Main Hill, Logan, UT, 84322, USA.,present address: Department of Ecology and Evolutionary Biology, University of Colorado, N211 Ramaley Hall, Boulder, CO, 80309, USA
| | - Zachariah Gompert
- Biology Department, Utah State University, 5305 Old Main Hill, Logan, UT, 84322, USA.,Ecology Center, Utah State University, 5205 Old Main Hill, Logan, UT, 84322, USA
| | - Fay-Wei Li
- Boyce Thompson Institute, 533 Tower Rd, Ithaca, New York, 14853, USA.,Plant Biology Section, Cornell University, 237 Mann Dr, Ithaca, New York, 14853, USA
| | - Michael D Windham
- Department of Biology, Duke University, 266 Biological Sciences, Durham, NC, 27708, USA
| | - Paul G Wolf
- Biology Department, Utah State University, 5305 Old Main Hill, Logan, UT, 84322, USA. .,Ecology Center, Utah State University, 5205 Old Main Hill, Logan, UT, 84322, USA.
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22
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Wagner MR, Mitchell-Olds T. Plasticity of plant defense and its evolutionary implications in wild populations of Boechera stricta. Evolution 2018. [PMID: 29522254 DOI: 10.1111/evo.13469] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Phenotypic plasticity is thought to impact evolutionary trajectories by shifting trait values in a direction that is either favored by natural selection ("adaptive" plasticity) or disfavored ("nonadaptive" plasticity). However, it is unclear how commonly each of these types of plasticity occurs in natural populations. To answer this question, we measured glucosinolate defensive chemistry and reproductive fitness in over 1500 individuals of the wild perennial mustard Boechera stricta, planted in four common gardens across central Idaho, United States. Glucosinolate profiles-including total glucosinolate concentration as well as the relative abundances and overall diversity of different compounds-were strongly plastic both among habitats and within habitats. Patterns of glucosinolate plasticity varied greatly among genotypes. Plasticity among sites was predicted to affect fitness in 27.1% of cases; more often than expected by chance, glucosinolate plasticity increased rather than decreased relative fitness. In contrast, we found no evidence for within-habitat selection on glucosinolate reaction norm slopes (i.e., plasticity along a continuous environmental gradient). Together, our results indicate that glucosinolate plasticity may improve the ability of B. stricta populations to persist after migration to new habitats.
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Affiliation(s)
- Maggie R Wagner
- Program in Genetics and Genomics, Department of Biology, Duke University, Durham, North Carolina 27708.,Current Address: Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, North Carolina 27695
| | - Thomas Mitchell-Olds
- Program in Genetics and Genomics, Department of Biology, Duke University, Durham, North Carolina 27708
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23
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Wadgymar SM, Ogilvie JE, Inouye DW, Weis AE, Anderson JT. Phenological responses to multiple environmental drivers under climate change: insights from a long-term observational study and a manipulative field experiment. THE NEW PHYTOLOGIST 2018; 218:517-529. [PMID: 29451307 DOI: 10.1111/nph.15029] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Accepted: 01/03/2018] [Indexed: 06/08/2023]
Abstract
Climate change has induced pronounced shifts in the reproductive phenology of plants, yet we know little about which environmental factors contribute to interspecific variation in responses and their effects on fitness. We integrate data from a 43 yr record of first flowering for six species in subalpine Colorado meadows with a 3 yr snow manipulation experiment on the perennial forb Boechera stricta (Brassicaceae) from the same site. We analyze shifts in the onset of flowering in relation to environmental drivers known to influence phenology: the timing of snowmelt, the accumulation of growing degree days, and photoperiod. Variation in responses to climate change depended on the sequence in which species flowered, with early-flowering species reproducing faster, at a lower heat sum, and under increasingly disparate photoperiods relative to later-flowering species. Early snow-removal treatments confirm that the timing of snowmelt governs observed trends in flowering phenology of B. stricta and that climate change can reduce the probability of flowering, thereby depressing fitness. Our findings suggest that climate change is decoupling historical combinations of photoperiod and temperature and outpacing phenological changes for our focal species. Accurate predictions of biological responses to climate change require a thorough understanding of the factors driving shifts in phenology.
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Affiliation(s)
- Susana M Wadgymar
- Department of Genetics and Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
- The Rocky Mountain Biological Laboratory, Crested Butte, CO, 81224, USA
| | - Jane E Ogilvie
- The Rocky Mountain Biological Laboratory, Crested Butte, CO, 81224, USA
- Department of Biological Science, Florida State University, Tallahassee, FL, 32306, USA
| | - David W Inouye
- The Rocky Mountain Biological Laboratory, Crested Butte, CO, 81224, USA
- Department of Biology, University of Maryland, College Park, MD, 20742, USA
| | - Arthur E Weis
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
| | - Jill T Anderson
- Department of Genetics and Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
- The Rocky Mountain Biological Laboratory, Crested Butte, CO, 81224, USA
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24
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Vaidya P, McDurmon A, Mattoon E, Keefe M, Carley L, Lee CR, Bingham R, Anderson JT. Ecological causes and consequences of flower color polymorphism in a self-pollinating plant (Boechera stricta). THE NEW PHYTOLOGIST 2018; 218:380-392. [PMID: 29369384 DOI: 10.1111/nph.14998] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 12/12/2017] [Indexed: 05/21/2023]
Abstract
Intraspecific variation in flower color is often attributed to pollinator-mediated selection, yet this mechanism cannot explain flower color polymorphisms in self-pollinating species. Indirect selection mediated via biotic and abiotic stresses could maintain flower color variation in these systems. The selfing forb, Boechera stricta, typically displays white flowers, but some individuals produce purple flowers. We quantified environmental correlates of flower color in natural populations. To disentangle plasticity from genotypic variation, we performed a multiyear field experiment in five gardens. In controlled conditions, we evaluated herbivore preferences and the effects of drought stress and soil pH on flower color expression. In natural populations, purple-flowered individuals experienced lower foliar herbivory than did their white-flowered counterparts. This pattern also held in the common gardens. Additionally, low-elevation environments induced pigmented flowers (plasticity), and the likelihood of floral pigmentation decreased with source elevation of maternal families (genetic cline). Viability selection favored families with pigmented flowers. In the laboratory, herbivores exerted greater damage on tissue derived from white- vs purple-flowered individuals. Furthermore, drought induced pigmentation in white-flowered lineages, and white-flowered plants had a fecundity advantage in the well-watered control. Flower color variation in selfing species is probably maintained by herbivory, drought stress, and other abiotic factors that vary spatially.
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Affiliation(s)
- Priya Vaidya
- The Rocky Mountain Biological Laboratory, Crested Butte, CO, 81224, USA
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
| | - Ansley McDurmon
- The Rocky Mountain Biological Laboratory, Crested Butte, CO, 81224, USA
| | - Emily Mattoon
- Department of Biology, Duke University, Durham, NC, 27708, USA
| | - Michaela Keefe
- The Rocky Mountain Biological Laboratory, Crested Butte, CO, 81224, USA
- Department of Natural and Environmental Sciences, Western State Colorado University, Gunnison, CO, 81231, USA
| | - Lauren Carley
- The Rocky Mountain Biological Laboratory, Crested Butte, CO, 81224, USA
- Department of Biology, Duke University, Durham, NC, 27708, USA
- University Program in Ecology, Duke University, Durham, NC, 27708, USA
| | - Cheng-Ruei Lee
- Institute of Ecology and Evolutionary Biology & Institute of Plant Biology, National Taiwan University, Taipei, Taiwan
| | - Robin Bingham
- The Rocky Mountain Biological Laboratory, Crested Butte, CO, 81224, USA
- Department of Natural and Environmental Sciences, Western State Colorado University, Gunnison, CO, 81231, USA
| | - Jill T Anderson
- The Rocky Mountain Biological Laboratory, Crested Butte, CO, 81224, USA
- Department of Genetics and Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
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25
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Salmela MJ, McMinn RL, Guadagno CR, Ewers BE, Weinig C. Circadian Rhythms and Reproductive Phenology Covary in a Natural Plant Population. J Biol Rhythms 2018; 33:245-254. [DOI: 10.1177/0748730418764525] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
| | - Robby L. McMinn
- Department of Botany, University of Wyoming, Laramie, Wyoming
- Program in Ecology, University of Wyoming, Laramie, Wyoming
| | | | - Brent E. Ewers
- Department of Botany, University of Wyoming, Laramie, Wyoming
- Program in Ecology, University of Wyoming, Laramie, Wyoming
| | - Cynthia Weinig
- Department of Botany, University of Wyoming, Laramie, Wyoming
- Program in Ecology, University of Wyoming, Laramie, Wyoming
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming
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26
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The Tanggula Mountains enhance population divergence in Carex moorcroftii: a dominant sedge on the Qinghai-Tibetan Plateau. Sci Rep 2018; 8:2741. [PMID: 29426823 PMCID: PMC5807306 DOI: 10.1038/s41598-018-21129-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 01/30/2018] [Indexed: 11/08/2022] Open
Abstract
High-altitude mountains are often geographic barriers to gene flow and play important roles in shaping population divergence. The central Qinghai-Tibetan Plateau (QTP) stands the location of the Tanggula Mountains (TM). We use the TM as a case, using Carex moorcroftii, a dominant species on the QTP to test the effects of geographic barriers on plant population divergence. We sampled 18 C. moorcroftii populations along a north-south transect crossing the TM to investigate the correlations of genetic variation and morphological traits with climate variables. The results showed this species holds high genetic diversity (He = 0.58) and the surveyed populations can be genetically clustered into two groups: populations from the north face of TM, and the other from the south. Gene flow between populations within groups is higher than those between groups. The traits, number and mass of seeds, mass of root and infructescence significantly varied among populations. Mantel-tests detected a weak but significantly positive correlation between genetic and geographic (R2 = 0.107, p = 0.032) and climatic distance (R2 = 0.162, p = 0.005), indicating both isolation by distance and isolation by environment. These findings together suggest high-altitude mountains of TM interrupt habitat continuity, result in distinct climatic conditions on both sides, increasing population divergence of plant species.
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27
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Schmidt L, Fischer M, Oja T. Two closely related species differ in their regional genetic differentiation despite admixing. AOB PLANTS 2018; 10:ply007. [PMID: 29479408 PMCID: PMC5817946 DOI: 10.1093/aobpla/ply007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 01/09/2018] [Indexed: 06/08/2023]
Abstract
Regional genetic differentiation within species is often addressed in evolutionary ecology and conservation biology. Here, we address regional differentiation in two closely related hybridizing taxa, the perennial sedges Carex flava and C. viridula and their hybrid C. × subviridula in 37 populations in the north and centre of their distribution range in Europe (Estonia, Lowland (<1000 m a.s.l.) and Highland Switzerland) using 10 putative microsatellite loci. We ask whether regional differentiation was larger in the less common taxon C. viridula or whether, possibly due to hybridization, it was similar between taxa. Our results showed similar, low to moderate genetic diversity for the three studied taxa. In total, we found 12 regional species-specific alleles. Analysis of molecular variance (AMOVA), STRUCTURE and multidimensional scaling analysis showed regional structure in genetic variation, where intraspecific differentiation between regions was lower for C. flava (AMOVA: 6.84 %) than for C. viridula (20.77 %) or C. × subviridula (18.27 %) populations. Hybrids differed from the parental taxa in the two regions where they occurred, i.e. in Estonia and Lowland Switzerland. We conclude that C. flava and C. viridula clearly differ from each other genetically, that there is pronounced regional differentiation and that, despite hybridization, this regional differentiation is more pronounced in the less common taxon, C. viridula. We encourage future studies on hybridizing taxa to work with plant populations from more than one region.
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Affiliation(s)
- Lisanna Schmidt
- Institute of Ecology and Earth Sciences, Department of Botany, University of Tartu, Tartu, Estonia
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
| | - Markus Fischer
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
- Botanical Garden, University of Bern, Bern, Switzerland
- Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - Tatjana Oja
- Institute of Ecology and Earth Sciences, Department of Botany, University of Tartu, Tartu, Estonia
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Colautti RI, Ågren J, Anderson JT. Phenological shifts of native and invasive species under climate change: insights from the Boechera-Lythrum model. Philos Trans R Soc Lond B Biol Sci 2017; 372:rstb.2016.0032. [PMID: 27920377 DOI: 10.1098/rstb.2016.0032] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2016] [Indexed: 01/22/2023] Open
Abstract
Warmer and drier climates have shifted phenologies of many species. However, the magnitude and direction of phenological shifts vary widely among taxa, and it is often unclear when shifts are adaptive or how they affect long-term viability. Here, we model evolution of flowering phenology based on our long-term research of two species exhibiting opposite shifts in floral phenology: Lythrum salicaria, which is invasive in North America, and the sparse Rocky Mountain native Boechera stricta Genetic constraints are similar in both species, but differences in the timing of environmental conditions that favour growth lead to opposite phenological shifts under climate change. As temperatures increase, selection is predicted to favour earlier flowering in native B. stricta while reducing population viability, even if populations adapt rapidly to changing environmental conditions. By contrast, warming is predicted to favour delayed flowering in both native and introduced L. salicaria populations while increasing long-term viability. Relaxed selection from natural enemies in invasive L. salicaria is predicted to have little effect on flowering time but a large effect on reproductive fitness. Our approach highlights the importance of understanding ecological and genetic constraints to predict the ecological consequences of evolutionary responses to climate change on contemporary timescales.This article is part of the themed issue 'Human influences on evolution, and the ecological and societal consequences'.
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Affiliation(s)
- Robert I Colautti
- Department of Biology, Queen's University, 116 Barrie Street, Kingston, Ontario, Canada K7L 3N6
| | - Jon Ågren
- Plant Ecology and Evolution, Department of Ecology and Genetics, EBC, Uppsala University, Norbyvägen 18 D, 752 36 Uppsala, Sweden
| | - Jill T Anderson
- Department of Genetics and Odum School of Ecology, University of Georgia, 120 Green Street, Athens, GA 30602, USA
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29
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Li FW, Rushworth CA, Beck JB, Windham MD. Boechera microsatellite website: an online portal for species identification and determination of hybrid parentage. DATABASE-THE JOURNAL OF BIOLOGICAL DATABASES AND CURATION 2017; 2017:3057076. [PMID: 28365726 PMCID: PMC5467466 DOI: 10.1093/database/baw169] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Accepted: 12/13/2016] [Indexed: 11/14/2022]
Abstract
Boechera (Brassicaceae) has many features to recommend it as a model genus for ecological and evolutionary research, including species richness, ecological diversity, experimental tractability and close phylogenetic proximity to Arabidopsis . However, efforts to realize the full potential of this model system have been thwarted by the frequent inability of researchers to identify their samples and place them in a broader evolutionary context. Here we present the Boechera Microsatellite Website (BMW), a portal that archives over 55 000 microsatellite allele calls from 4471 specimens (including 133 nomenclatural types). The portal includes analytical tools that utilize data from 15 microsatellite loci as a highly effective DNA barcoding system. The BMW facilitates the accurate identification of Boechera samples and the investigation of reticulate evolution among the ±83 sexual diploid taxa in the genus, thereby greatly enhancing Boechera 's potential as a model system. Database URL http://sites.biology.duke.edu/windhamlab/.
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Affiliation(s)
- Fay-Wei Li
- Department of Biology, Duke University, Durham, NC 27708, USA.,University and Jepson Herbaria and Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
| | - Catherine A Rushworth
- Department of Biology, Duke University, Durham, NC 27708, USA.,University and Jepson Herbaria and Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
| | - James B Beck
- Department of Biological Sciences, Wichita State University, Wichita, KS 67260, USA.,Botanical Research Institute of Texas, 1700 University Drive, Fort Worth, TX 76107, USA
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30
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The Spread of an Inversion with Migration and Selection. Genetics 2017; 208:377-382. [PMID: 29158424 DOI: 10.1534/genetics.117.300426] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 11/14/2017] [Indexed: 11/18/2022] Open
Abstract
We re-examine the model of Kirkpatrick and Barton for the spread of an inversion into a local population. This model assumes that local selection maintains alleles at two or more loci, despite immigration of alternative alleles at these loci from another population. We show that an inversion is favored because it prevents the breakdown of linkage disequilibrium generated by migration; the selective advantage of an inversion is dependent on the amount of recombination between the loci involved, as in other cases where inversions are selected for as a result of their effects on recombination. We derive expressions for the rate of spread of an inversion; when the loci covered by the inversion are tightly linked, these conditions deviate substantially from those proposed previously, and imply that an inversion can then have only a small advantage.
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31
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Wadgymar SM, Daws SC, Anderson JT. Integrating viability and fecundity selection to illuminate the adaptive nature of genetic clines. Evol Lett 2017; 1:26-39. [PMID: 30283636 PMCID: PMC6121800 DOI: 10.1002/evl3.3] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 03/15/2017] [Accepted: 03/20/2017] [Indexed: 12/18/2022] Open
Abstract
Genetically based trait variation across environmental gradients can reflect adaptation to local environments. However, natural populations that appear well-adapted often exhibit directional, not stabilizing, selection on ecologically relevant traits. Temporal variation in the direction of selection could lead to stabilizing selection across multiple episodes of selection, which might be overlooked in short-term studies that evaluate relationships of traits and fitness under only one set of conditions. Furthermore, nonrandom mortality prior to trait expression can bias inferences about trait evolution if viability selection opposes fecundity selection. Here, we leveraged fitness and trait data to test whether phenotypic clines are genetically based and adaptive, whether temporal variation in climate imposes stabilizing selection, and whether viability selection acts on adult phenotypes. We monitored transplants of the subalpine perennial forb, Boechera stricta (Brassicaceae), in common gardens at two elevations over 2-3 years that differed in drought intensity. We quantified viability, and fecundity fitness components for four heritable traits: specific leaf area, integrated water-use efficiency, height at first flower, and flowering phenology. Our results indicate that genetic clines are maintained by selection, but their expression is context dependent, as they do not emerge in all environments. Moreover, selection varied spatially and temporally. Stabilizing selection was most pronounced when we integrated data across years. Finally, viability selection prior to trait expression targeted adult phenotypes (age and size at flowering). Indeed, viability selection for delayed flowering opposed fecundity selection for accelerated flowering; this result demonstrates that neglecting to account for viability selection could lead to inaccurate conclusions that populations are maladapted. Our results suggest that reconciling clinal trait variation with selection requires data collected across multiple spatial scales, time frames, and life-history stages.
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Affiliation(s)
- Susana M Wadgymar
- Department of Genetics and Odum School of Ecology University of Georgia Athens Georgia 30602
| | - S Caroline Daws
- Department of Ecology, Evolution and Behavior University of Minnesota St. Paul Minnesota 55108
| | - Jill T Anderson
- Department of Genetics and Odum School of Ecology University of Georgia Athens Georgia 30602
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32
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Salmela MJ, Ewers BE, Weinig C. Natural quantitative genetic variance in plant growth differs in response to ecologically relevant temperature heterogeneity. Ecol Evol 2016; 6:7574-7585. [PMID: 30128112 PMCID: PMC6093144 DOI: 10.1002/ece3.2482] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 07/22/2016] [Accepted: 08/28/2016] [Indexed: 01/06/2023] Open
Abstract
Adaptation to large‐scale spatial heterogeneity in the environment accounts for a major proportion of genetic diversity within species. Theory predicts the erosion of adaptive genetic variation on a within‐population level, but considerable genetic diversity is often found locally. Genetic diversity could be expected to be maintained within populations in temporally or spatially variable conditions if genotypic rank orders vary across contrasting microenvironmental settings. Taking advantage of fine‐resolution environmental data, we tested the hypothesis that temperature heterogeneity among years could be one factor maintaining quantitative genetic diversity within a natural and genetically diverse plant population. We sampled maternal families of Boechera stricta, an Arabidopsis thaliana relative, at one location in the central Rocky Mountains and grew them in three treatments that, based on records from an adjacent weather station, simulated hourly temperature changes at the native site during three summers with differing mean temperatures. Treatment had a significant effect on all traits, with 2–3‐fold increase in above‐ and belowground biomass and the highest allocation to roots observed in the treatment simulating the warmest summer on record at the site. Treatment affected bivariate associations between traits, with the weakest correlation between above‐ and belowground biomass in the warmest treatment. The magnitude of quantitative genetic variation for all traits differed across treatments: Genetic variance of biomass was 0 in the warmest treatment, while highly significant diversity was found in average conditions, resulting in broad‐sense heritability of 0.31. Significant genotype × environment interactions across all treatments were found only in root‐to‐shoot ratio. Therefore, temperature variation among summers appears unlikely to account for the observed levels of local genetic variation in size in this perennial species, but may influence family rank order in growth allocation. Our results indicate that natural environmental fluctuations can have a large impact on the magnitude of within‐population quantitative genetic variance.
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Affiliation(s)
- Matti J Salmela
- Department of Botany University of Wyoming Laramie WY USA.,Present address: Natural Resources Institute Finland Vantaa Finland
| | - Brent E Ewers
- Department of Botany University of Wyoming Laramie WY USA.,Program in Ecology University of Wyoming Laramie WY USA
| | - Cynthia Weinig
- Department of Botany University of Wyoming Laramie WY USA.,Program in Ecology University of Wyoming Laramie WY USA.,Department of Molecular Biology University of Wyoming Laramie WY USA
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33
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Wagner MR, Lundberg DS, del Rio TG, Tringe SG, Dangl JL, Mitchell-Olds T. Host genotype and age shape the leaf and root microbiomes of a wild perennial plant. Nat Commun 2016; 7:12151. [PMID: 27402057 PMCID: PMC4945892 DOI: 10.1038/ncomms12151] [Citation(s) in RCA: 416] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 06/06/2016] [Indexed: 01/01/2023] Open
Abstract
Bacteria living on and in leaves and roots influence many aspects of plant health, so the extent of a plant's genetic control over its microbiota is of great interest to crop breeders and evolutionary biologists. Laboratory-based studies, because they poorly simulate true environmental heterogeneity, may misestimate or totally miss the influence of certain host genes on the microbiome. Here we report a large-scale field experiment to disentangle the effects of genotype, environment, age and year of harvest on bacterial communities associated with leaves and roots of Boechera stricta (Brassicaceae), a perennial wild mustard. Host genetic control of the microbiome is evident in leaves but not roots, and varies substantially among sites. Microbiome composition also shifts as plants age. Furthermore, a large proportion of leaf bacterial groups are shared with roots, suggesting inoculation from soil. Our results demonstrate how genotype-by-environment interactions contribute to the complexity of microbiome assembly in natural environments.
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Affiliation(s)
- Maggie R. Wagner
- Program in Genetics and Genomics, Department of Biology, Duke University, Durham, North Carolina 27708, USA
| | - Derek S Lundberg
- Department of Biology, Curriculum in Genetics and Molecular Biology, Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Tijana G. del Rio
- Department of Energy Joint Genome Institute, Walnut Creek, California 94598, USA
| | - Susannah G. Tringe
- Department of Energy Joint Genome Institute, Walnut Creek, California 94598, USA
| | - Jeffery L. Dangl
- Department of Biology, Curriculum in Genetics and Molecular Biology, Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, North Carolina 27599, USA
- Howard Hughes Medical Institute, Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Thomas Mitchell-Olds
- Program in Genetics and Genomics, Department of Biology, Duke University, Durham, North Carolina 27708, USA
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34
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Salmela MJ, Greenham K, Lou P, McClung CR, Ewers BE, Weinig C. Variation in circadian rhythms is maintained among and within populations in Boechera stricta. PLANT, CELL & ENVIRONMENT 2016; 39:1293-303. [PMID: 26514754 DOI: 10.1111/pce.12670] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 10/19/2015] [Accepted: 10/20/2015] [Indexed: 05/13/2023]
Abstract
Circadian clocks have evolved independently in all three domains of life, and fitness benefits of a functional clock have been demonstrated in experimental genotypes in controlled conditions. Still, little is known about genetic variation in the clock and its fitness consequences in natural populations from heterogeneous environments. Using Wyoming populations of the Arabidopsis relative Boechera stricta as our study system, we demonstrate that genetic variation in the clock can occur at multiple levels: means of circadian period among populations sampled at different elevations differed by less than 1 h, but means among families sampled within populations varied by as much as 3.5 h. Growth traits also varied among and within populations. Within the population with the most circadian variation, we observed evidence for a positive correlation between period and growth and a negative correlation between period and root-to-shoot ratio. We then tested whether performance tradeoffs existed among families of this population across simulated seasonal settings. Growth rankings of families were similar across seasonal environments, but for root-to-shoot ratio, genotype × environment interactions contributed significantly to total variation. Therefore, further experiments are needed to identify evolutionary mechanisms that preserve substantial quantitative genetic diversity in the clock in this and other species.
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Affiliation(s)
- Matti J Salmela
- Department of Botany, University of Wyoming, Laramie, WY, 82071, USA
| | - Kathleen Greenham
- Department of Biological Sciences, Dartmouth College, Hanover, NH, 03755, USA
| | - Ping Lou
- Department of Biological Sciences, Dartmouth College, Hanover, NH, 03755, USA
| | - C Robertson McClung
- Department of Biological Sciences, Dartmouth College, Hanover, NH, 03755, USA
| | - Brent E Ewers
- Department of Botany, University of Wyoming, Laramie, WY, 82071, USA
- Program in Ecology, University of Wyoming
| | - Cynthia Weinig
- Department of Botany, University of Wyoming, Laramie, WY, 82071, USA
- Program in Ecology, University of Wyoming
- Department of Molecular Biology, University of Wyoming
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35
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Effect of Drought on Herbivore-Induced Plant Gene Expression: Population Comparison for Range Limit Inferences. PLANTS 2016; 5:plants5010013. [PMID: 27135233 PMCID: PMC4844423 DOI: 10.3390/plants5010013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 02/04/2016] [Accepted: 02/23/2016] [Indexed: 11/25/2022]
Abstract
Low elevation “trailing edge” range margin populations typically face increases in both abiotic and biotic stressors that may contribute to range limit development. We hypothesize that selection may act on ABA and JA signaling pathways for more stable expression needed for range expansion, but that antagonistic crosstalk prevents their simultaneous co-option. To test this hypothesis, we compared high and low elevation populations of Boechera stricta that have diverged with respect to constitutive levels of glucosinolate defenses and root:shoot ratios; neither population has high levels of both traits. If constraints imposed by antagonistic signaling underlie this divergence, one would predict that high constitutive levels of traits would coincide with lower plasticity. To test this prediction, we compared the genetically diverged populations in a double challenge drought-herbivory growth chamber experiment. Although a glucosinolate defense response to the generalist insect herbivore Spodoptera exigua was attenuated under drought conditions, the plastic defense response did not differ significantly between populations. Similarly, although several potential drought tolerance traits were measured, only stomatal aperture behavior, as measured by carbon isotope ratios, was less plastic as predicted in the high elevation population. However, RNAseq results on a small subset of plants indicated differential expression of relevant genes between populations as predicted. We suggest that the ambiguity in our results stems from a weaker link between the pathways and the functional traits compared to transcripts.
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36
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Alsdurf J, Anderson C, Siemens DH. Epigenetics of drought-induced trans-generational plasticity: consequences for range limit development. AOB PLANTS 2015; 8:plv146. [PMID: 26685218 PMCID: PMC4722181 DOI: 10.1093/aobpla/plv146] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 11/19/2015] [Indexed: 05/26/2023]
Abstract
Genetic variation gives plants the potential to adapt to stressful environments that often exist beyond their geographic range limits. However, various genetic, physiological or developmental constraints might prevent the process of adaptation. Alternatively, environmentally induced epigenetic changes might sustain populations for several generations in stressful areas across range boundaries, but previous work on Boechera stricta, an upland mustard closely related to Arabidopsis, documented a drought-induced trans-generational plastic trade-off that could contribute to range limit development. Offspring of parents who were drought treated had higher drought tolerance, but lower levels of glucosinolate toxins. Both drought tolerance and defence are thought to be needed to expand the range to lower elevations. Here, we used methylation-sensitive amplified fragment length polymorphisms to determine whether environmentally induced DNA methylation and thus epigenetics could be a mechanism involved in the observed trans-generational plastic trade-off. We compared 110 offspring from the same self-fertilizing lineages whose parents were exposed to experimental drought stress treatments in the laboratory. Using three primer combinations, 643 polymorphic epi-loci were detected. Discriminant function analysis (DFA) on the amount of methylation detected resulted in significant combinations of epi-loci that distinguished the parent drought treatments in the offspring. Principal component (PC) and univariate association analyses also detected the significant differences, even after controlling for lineage, planting flat, developmental differences and multiple testing. Univariate tests also indicated significant associations between the amount of methylation and drought tolerance or glucosinolate toxin concentration. One epi-locus that was implicated in DFA, PC and univariate association analysis may be directly involved in the trade-off because increased methylation at this site on the genome decreased drought tolerance, but increased glucosinolate concentration.
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Affiliation(s)
- Jacob Alsdurf
- Integrative Genomics Program, Black Hills State University, Spearfish, SD 77799, USA Present address: Division of Biology, Kansas State University, Ackert Hall, Room 315, Manhattan, KS 66506-4901, USA
| | - Cynthia Anderson
- Integrative Genomics Program, Black Hills State University, Spearfish, SD 77799, USA
| | - David H Siemens
- Integrative Genomics Program, Black Hills State University, Spearfish, SD 77799, USA
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37
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Lovell JT, McKay JK. Ecological genetics of range size variation in Boechera spp. (Brassicaceae). Ecol Evol 2015; 5:4962-75. [PMID: 26640674 PMCID: PMC4662302 DOI: 10.1002/ece3.1746] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 08/10/2015] [Accepted: 08/22/2015] [Indexed: 11/18/2022] Open
Abstract
Many taxonomic groups contain both rare and widespread species, which indicates that range size can evolve quickly. Many studies have compared molecular genetic diversity, plasticity, or phenotypic traits between rare and widespread species; however, a suite of genetic attributes that unites rare species remains elusive. Here, using two rare and two widespread Boechera (Brassicaceae) species, we conduct a simultaneous comparison of quantitative trait diversity, genetic diversity, and population structure among species with highly divergent range sizes. Consistent with previous studies, we do not find strong associations between range size and within-population genetic diversity. In contrast, we find that both the degree of phenotypic plasticity and quantitative trait structure (Q ST) were positively correlated with range size. We also found higher F ST: Q ST ratios in rare species, indicative of either a greater response to stabilizing selection or a lack of additive genetic variation. While widespread species occupy more ecological and climactic space and have diverged at both traits and markers, rare species display constrained levels of population differentiation and phenotypic plasticity. Combined, our results provide evidence for a specialization-generalization trade-off across three orders of magnitude of range size variation in the ecological model genus, Boechera.
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Affiliation(s)
- John T. Lovell
- Graduate Degree Program in EcologyC129 Plant SciencesColorado State UniversityFort CollinsCO80523‐1177USA
- Department of Integrative BiologyUniversity of Texas1 University Station, C0930AustinTX78712USA
| | - John K. McKay
- Graduate Degree Program in EcologyC129 Plant SciencesColorado State UniversityFort CollinsCO80523‐1177USA
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38
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Anderson JT, Perera N, Chowdhury B, Mitchell-Olds T. Microgeographic Patterns of Genetic Divergence and Adaptation across Environmental Gradients in Boechera stricta (Brassicaceae). Am Nat 2015; 186 Suppl 1:S60-73. [PMID: 26656218 DOI: 10.1086/682404] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Abiotic and biotic conditions often vary continuously across the landscape, imposing divergent selection on local populations. We used a provenance trial approach to examine microgeographic variation in local adaptation in Boechera stricta (Brassicaceae), a perennial forb native to the Rocky Mountains. In montane ecosystems, environmental conditions change considerably over short spatial scales, such that neighboring populations can be subject to different selective pressures. Using accessions from southern (Colorado) and northern (Idaho) populations, we characterized spatial variation in genetic similarity via microsatellite markers. We then transplanted genotypes from multiple local populations into common gardens in both regions. Continuous variation in local adaptation emerged for several components of fitness. In Idaho, genotypes from warmer environments (low-elevation or south-facing sites) were poorly adapted to the north-facing garden. In high- and low-elevation Colorado gardens, susceptibility to insect herbivory increased with source elevation. In the high-elevation Colorado garden, germination success peaked for genotypes that evolved at elevations similar to that of the garden and decreased for genotypes from higher and lower elevations. We also found evidence for local maladaptation in survival and fecundity components of fitness in the low-elevation Colorado garden. This approach is a first step in predicting how global change could affect evolutionary dynamics.
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Affiliation(s)
- Jill T Anderson
- Department of Genetics and Odum School of Ecology, University of Georgia, Athens, Georgia 30602
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39
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Boechera species exhibit species-specific responses to combined heat and high light stress. PLoS One 2015; 10:e0129041. [PMID: 26030823 PMCID: PMC4452622 DOI: 10.1371/journal.pone.0129041] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 05/04/2015] [Indexed: 12/22/2022] Open
Abstract
As sessile organisms, plants must be able to complete their life cycle in place and therefore tolerance to abiotic stress has had a major role in shaping biogeographical patterns. However, much of what we know about plant tolerance to abiotic stresses is based on studies of just a few plant species, most notably the model species Arabidopsis thaliana. In this study we examine natural variation in the stress responses of five diverse Boechera (Brassicaceae) species. Boechera plants were exposed to basal and acquired combined heat and high light stress. Plant response to these stresses was evaluated based on chlorophyll fluorescence measurements, induction of leaf chlorosis, and gene expression. Many of the Boechera species were more tolerant to heat and high light stress than A. thaliana. Gene expression data indicates that two important marker genes for stress responses: APX2 (Ascorbate peroxidase 2) and HsfA2 (Heat shock transcription factor A2) have distinct species-specific expression patterns. The findings of species-specific responses and tolerance to stress indicate that stress pathways are evolutionarily labile even among closely related species.
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40
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Anderson JT, Gezon ZJ. Plasticity in functional traits in the context of climate change: a case study of the subalpine forb Boechera stricta (Brassicaceae). GLOBAL CHANGE BIOLOGY 2015; 21:1689-703. [PMID: 25470363 DOI: 10.1111/gcb.12770] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Accepted: 10/06/2014] [Indexed: 05/27/2023]
Abstract
Environmental variation often induces shifts in functional traits, yet we know little about whether plasticity will reduce extinction risks under climate change. As climate change proceeds, phenotypic plasticity could enable species with limited dispersal capacity to persist in situ, and migrating populations of other species to establish in new sites at higher elevations or latitudes. Alternatively, climate change could induce maladaptive plasticity, reducing fitness, and potentially stalling adaptation and migration. Here, we quantified plasticity in life history, foliar morphology, and ecophysiology in Boechera stricta (Brassicaceae), a perennial forb native to the Rocky Mountains. In this region, warming winters are reducing snowpack and warming springs are advancing the timing of snow melt. We hypothesized that traits that were historically advantageous in hot and dry, low-elevation locations will be favored at higher elevation sites due to climate change. To test this hypothesis, we quantified trait variation in natural populations across an elevational gradient. We then estimated plasticity and genetic variation in common gardens at two elevations. Finally, we tested whether climatic manipulations induce plasticity, with the prediction that plants exposed to early snow removal would resemble individuals from lower elevation populations. In natural populations, foliar morphology and ecophysiology varied with elevation in the predicted directions. In the common gardens, trait plasticity was generally concordant with phenotypic clines from the natural populations. Experimental snow removal advanced flowering phenology by 7 days, which is similar in magnitude to flowering time shifts over 2-3 decades of climate change. Therefore, snow manipulations in this system can be used to predict eco-evolutionary responses to global change. Snow removal also altered foliar morphology, but in unexpected ways. Extensive plasticity could buffer against immediate fitness declines due to changing climates.
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Affiliation(s)
- Jill T Anderson
- Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA
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41
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Naithani KJ, Ewers BE, Adelman JD, Siemens DH. Abiotic and biotic controls on local spatial distribution and performance of Boechera stricta. FRONTIERS IN PLANT SCIENCE 2014; 5:348. [PMID: 25101102 PMCID: PMC4106276 DOI: 10.3389/fpls.2014.00348] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 06/28/2014] [Indexed: 06/03/2023]
Abstract
This study investigates the relative influence of biotic and abiotic factors on community dynamics using an integrated approach and highlights the influence of space on genotypic and phenotypic traits in plant community structure. We examined the relative influence of topography, environment, spatial distance, and intra- and interspecific interactions on spatial distribution and performance of Boechera stricta (rockcress), a close perennial relative of model plant Arabidopsis. First, using Bayesian kriging, we mapped the topography and environmental gradients and explored the spatial distribution of naturally occurring rockcress plants and two neighbors, Taraxacum officinale (dandelion) and Solidago missouriensis (goldenrod) found in close proximity within a typical diverse meadow community across topographic and environmental gradients. We then evaluated direct and indirect relationships among variables using Mantel path analysis and developed a network displaying abiotic and biotic interactions in this community. We found significant spatial autocorrelation among rockcress individuals, either because of common microhabitats as displayed by high density of individuals at lower elevation and high soil moisture area, or limited dispersal as shown by significant spatial autocorrelation of naturally occurring inbred lines, or a combination of both. Goldenrod and dandelion density around rockcress does not show any direct relationship with rockcress fecundity, possibly due to spatial segregation of resources. However, dandelion density around rockcress shows an indirect negative influence on rockcress fecundity via herbivory, indicating interspecific competition. Overall, we suggest that common microhabitat preference and limited dispersal are the main drivers for spatial distribution. However, intra-specific interactions and insect herbivory are the main drivers of rockcress performance in the meadow community.
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Affiliation(s)
- Kusum J. Naithani
- Program in Ecology, University of WyomingLaramie, WY, USA
- Department of Botany, University of WyomingLaramie, WY, USA
| | - Brent E. Ewers
- Program in Ecology, University of WyomingLaramie, WY, USA
- Department of Botany, University of WyomingLaramie, WY, USA
| | | | - David H. Siemens
- Department of Biology, Black Hills State UniversitySpearfish, SD, USA
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Wagner MR, Lundberg DS, Coleman-Derr D, Tringe SG, Dangl JL, Mitchell-Olds T. Natural soil microbes alter flowering phenology and the intensity of selection on flowering time in a wild Arabidopsis relative. Ecol Lett 2014; 17:717-26. [PMID: 24698177 DOI: 10.1111/ele.12276] [Citation(s) in RCA: 168] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 02/09/2014] [Accepted: 02/28/2014] [Indexed: 02/03/2023]
Abstract
Plant phenology is known to depend on many different environmental variables, but soil microbial communities have rarely been acknowledged as possible drivers of flowering time. Here, we tested separately the effects of four naturally occurring soil microbiomes and their constituent soil chemistries on flowering phenology and reproductive fitness of Boechera stricta, a wild relative of Arabidopsis. Flowering time was sensitive to both microbes and the abiotic properties of different soils; varying soil microbiota also altered patterns of selection on flowering time. Thus, soil microbes potentially contribute to phenotypic plasticity of flowering time and to differential selection observed between habitats. We also describe a method to dissect the microbiome into single axes of variation that can help identify candidate organisms whose abundance in soil correlates with flowering time. This approach is broadly applicable to search for microbial community members that alter biological characteristics of interest.
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Affiliation(s)
- Maggie R Wagner
- Duke University Program in Genetics and Genomics, Department of Biology, Duke University, Durham, NC, 27708, USA
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Anderson JT, Lee CR, Mitchell-Olds T. Strong selection genome-wide enhances fitness trade-offs across environments and episodes of selection. Evolution 2014; 68:16-31. [PMID: 24102539 PMCID: PMC3928097 DOI: 10.1111/evo.12259] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 08/16/2013] [Indexed: 12/12/2022]
Abstract
Fitness trade-offs across episodes of selection and environments influence life-history evolution and adaptive population divergence. Documenting these trade-offs remains challenging as selection can vary in magnitude and direction through time and space. Here, we evaluate fitness trade-offs at the levels of the whole organism and the quantitative trait locus (QTL) in a multiyear field study of Boechera stricta (Brassicaceae), a genetically tractable mustard native to the Rocky Mountains. Reciprocal local adaptation was pronounced for viability, but not for reproductive components of fitness. Instead, local genomes had a fecundity advantage only in the high latitude garden. By estimating realized selection coefficients from individual-level data on viability and reproductive success and permuting the data to infer significance, we examined the genetic basis of fitness trade-offs. This analytical approach (Conditional Neutrality-Antagonistic Pleiotropy, CNAP) identified genetic trade-offs at a flowering phenology QTL (costs of adaptation) and revealed genetic trade-offs across fitness components (costs of reproduction). These patterns would not have emerged from traditional ANOVA-based QTL mapping. Our analytical framework can be applied to other systems to investigate fitness trade-offs. This task is becoming increasingly important as climate change may alter fitness landscapes, potentially disrupting fitness trade-offs that took many generations to evolve.
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Affiliation(s)
- Jill T Anderson
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, 29208.
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Siemens DH, Haugen R. Plant chemical defense allocation constrains evolution of tolerance to community change across a range boundary. Ecol Evol 2013; 3:4339-47. [PMID: 24340176 PMCID: PMC3856735 DOI: 10.1002/ece3.657] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 05/24/2013] [Accepted: 05/31/2013] [Indexed: 11/07/2022] Open
Abstract
Because transplant experiments show that performance usually decreases across species range boundaries, some range limits might develop from factors and processes that prevent adaptation to stressful environments. Here, we determined whether an ecological cost of plant defense involving stress associated with changes in the local plant community may contribute to range limit development in the upland mustard species Boechera stricta. In a common garden experiment of 499 B. stricta plants, performance decreased and a multivariate axis of community structure increased across the boundary, indicating increased stress associated with the community change. There was also significant genetic variation (evolutionary potential) among marker-inferred inbred lines of B. stricta for tolerance to the stress; however, lines with high basal levels of glucosinolate toxins had lower tolerance to the change in community structure. We suggest that defense allocation, which is also needed across the range, may impede adaptation to the stress associated with the community change and thus contribute to range limit development.
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Affiliation(s)
- David H Siemens
- Biology, Integrative Genomics Program, Black Hills State University Spearfish, South Dakota, 57799
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Baskauf CJ, Jinks NC, Mandel JR, McCauley DE. Population genetics of Braun's Rockcress (Boechera perstellata, Brassicaceae), an endangered plant with a disjunct distribution. J Hered 2013; 105:265-75. [PMID: 24163403 DOI: 10.1093/jhered/est074] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Boechera perstellata is an endangered plant found only in middle Tennessee and north central Kentucky. After sampling 4 Tennessee and 3 Kentucky populations, genetic variability and population structure were examined for this species using isozymes, chloroplast DNA, and microsatellites (averaging 35, 29, and 27 individuals per population per class of marker, respectively). The only genetic variability detected for 23 isozymes was a fixed difference between Tennessee and Kentucky populations at 1 locus. Fixed differences between populations of the 2 states were also observed for 3 chloroplast markers. Polymorphism at 19 nuclear microsatellites was 74% at the species level and averaged 21% at the population level. However, observed heterozygosity was extremely low in all populations, ranging from 0.000 to 0.005. High F IS values (0.93) suggest that Boechera perstellata is a primarily selfing species. Tennessee populations have more genetic diversity than Kentucky populations of B. perstellata. Microsatellite markers revealed substantial genetic divergence between the states and genetic differences among populations within each state. Analysis of molecular variance indicates that most variability in this species occurs between the 2 states (49%) and among populations within each state (42%), with relatively little variation found within populations (9%). These data indicate that there is very little gene flow among populations of B. perstellata and that it is important to protect as many populations as possible in order to conserve the genetic diversity of this rare species.
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Affiliation(s)
- Carol J Baskauf
- Department of Biology, Austin Peay State University, PO Box 4718, Clarksville, TN 37044
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Lee CR, Mitchell-Olds T. Complex trait divergence contributes to environmental niche differentiation in ecological speciation of Boechera stricta. Mol Ecol 2013; 22:2204-17. [PMID: 23432437 PMCID: PMC3618598 DOI: 10.1111/mec.12250] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 01/10/2013] [Accepted: 01/12/2013] [Indexed: 01/22/2023]
Abstract
Ecological factors may contribute to reproductive isolation if differential local adaptation causes immigrant or hybrid fitness reduction. Because local adaptation results from the interaction between natural selection and adaptive traits, it is crucial to investigate both to understand ecological speciation. Previously, we used niche modelling to identify local water availability as an environmental correlate of incipient ecological speciation between two subspecies in Boechera stricta, a close relative of Arabidopsis. Here, we performed several large-scale glasshouse experiments to investigate the divergence of various physiological, phenological and morphological traits. Although we found no significant difference in physiological traits, the Western subspecies has significantly faster growth rate, larger leaf area, less succulent leaves, delayed reproductive time and longer flowering duration. These trait differences are concordant with previous results that habitats of the Western genotypes have more consistent water availability, while Eastern genotypes inhabit locations with more ephemeral water supplies. In addition, by comparing univariate and multivariate divergence of complex traits (Q(ST)) to the genomewide distribution of SNP FST , we conclude that the aspects of phenology and morphology (but not physiology) are under divergent selection. In addition, we also identified several highly diverged traits without obvious water-related functions.
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Affiliation(s)
- Cheng-Ruei Lee
- Department of Biology, Institute for Genome Sciences and Policy, Duke University, Durham, NC 27708, USA.
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Alsdurf JD, Ripley TJ, Matzner SL, Siemens DH. Drought-induced trans-generational tradeoff between stress tolerance and defence: consequences for range limits? AOB PLANTS 2013; 5:plt038. [PMID: 24307931 PMCID: PMC3849778 DOI: 10.1093/aobpla/plt038] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2013] [Accepted: 08/13/2013] [Indexed: 05/19/2023]
Abstract
Areas just across species range boundaries are often stressful, but even with ample genetic variation within and among range-margin populations, adaptation towards stress tolerance across range boundaries often does not occur. Adaptive trans-generational plasticity should allow organisms to circumvent these problems for temporary range expansion; however, range boundaries often persist. To investigate this dilemma, we drought stressed a parent generation of Boechera stricta (A.Gray) A. Löve & D. Löve, a perennial wild relative of Arabidopsis, representing genetic variation within and among several low-elevation range margin populations. Boechera stricta is restricted to higher, moister elevations in temperate regions where generalist herbivores are often less common. Previous reports indicate a negative genetic correlation (genetic tradeoff) between chemical defence allocation and abiotic stress tolerance that may prevent the simultaneous evolution of defence and drought tolerance that would be needed for range expansion. In growth chamber experiments, the genetic tradeoff became undetectable among offspring sib-families whose parents had been drought treated, suggesting that the stress-induced trans-generational plasticity may circumvent the genetic tradeoff and thus enable range expansion. However, the trans-generational effects also included a conflict between plastic responses (environmental tradeoff); offspring whose parents were drought treated were more drought tolerant, but had lower levels of glucosinolate toxins that function in defence against generalist herbivores. We suggest that either the genetic or environmental tradeoff between defence allocation and stress tolerance has the potential to contribute to range limit development in upland mustards.
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Affiliation(s)
- Jacob D. Alsdurf
- Department of Biology, Black Hills State University, Spearfish, SD, USA
- Integrative Genomics Program, Black Hills State University, Spearfish, SD, USA
| | - Tayler J. Ripley
- Integrative Genomics Program, Black Hills State University, Spearfish, SD, USA
| | | | - David H. Siemens
- Department of Biology, Black Hills State University, Spearfish, SD, USA
- Integrative Genomics Program, Black Hills State University, Spearfish, SD, USA
- Corresponding author's e-mail address:
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Prasad KVSK, Song BH, Olson-Manning C, Anderson JT, Lee CR, Schranz ME, Windsor AJ, Clauss MJ, Manzaneda AJ, Naqvi I, Reichelt M, Gershenzon J, Rupasinghe SG, Schuler MA, Mitchell-Olds T. A gain-of-function polymorphism controlling complex traits and fitness in nature. Science 2012; 337:1081-4. [PMID: 22936775 DOI: 10.1126/science.1221636] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Identification of the causal genes that control complex trait variation remains challenging, limiting our appreciation of the evolutionary processes that influence polymorphisms in nature. We cloned a quantitative trait locus that controls plant defensive chemistry, damage by insect herbivores, survival, and reproduction in the natural environments where this polymorphism evolved. These ecological effects are driven by duplications in the BCMA (branched-chain methionine allocation) loci controlling this variation and by two selectively favored amino acid changes in the glucosinolate-biosynthetic cytochrome P450 proteins that they encode. These changes cause a gain of novel enzyme function, modulated by allelic differences in catalytic rate and gene copy number. Ecological interactions in diverse environments likely contribute to the widespread polymorphism of this biochemical function.
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Affiliation(s)
- Kasavajhala V S K Prasad
- Department of Biology, Institute for Genome Sciences and Policy, Duke University, Durham, NC 27708, USA
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Anderson JT, Inouye DW, McKinney AM, Colautti RI, Mitchell-Olds T. Phenotypic plasticity and adaptive evolution contribute to advancing flowering phenology in response to climate change. Proc Biol Sci 2012; 279:3843-52. [PMID: 22787021 DOI: 10.1098/rspb.2012.1051] [Citation(s) in RCA: 268] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Anthropogenic climate change has already altered the timing of major life-history transitions, such as the initiation of reproduction. Both phenotypic plasticity and adaptive evolution can underlie rapid phenological shifts in response to climate change, but their relative contributions are poorly understood. Here, we combine a continuous 38 year field survey with quantitative genetic field experiments to assess adaptation in the context of climate change. We focused on Boechera stricta (Brassicaeae), a mustard native to the US Rocky Mountains. Flowering phenology advanced significantly from 1973 to 2011, and was strongly associated with warmer temperatures and earlier snowmelt dates. Strong directional selection favoured earlier flowering in contemporary environments (2010-2011). Climate change could drive this directional selection, and promote even earlier flowering as temperatures continue to increase. Our quantitative genetic analyses predict a response to selection of 0.2 to 0.5 days acceleration in flowering per generation, which could account for more than 20 per cent of the phenological change observed in the long-term dataset. However, the strength of directional selection and the predicted evolutionary response are likely much greater now than even 30 years ago because of rapidly changing climatic conditions. We predict that adaptation will likely be necessary for long-term in situ persistence in the context of climate change.
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Affiliation(s)
- Jill T Anderson
- Institute for Genome Sciences and Policy, Department of Biology, Duke University, Durham, NC 27708, USA.
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50
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Anderson JT, Lee CR, Rushworth CA, Colautti RI, Mitchell-Olds T. Genetic trade-offs and conditional neutrality contribute to local adaptation. Mol Ecol 2012; 22:699-708. [PMID: 22420446 DOI: 10.1111/j.1365-294x.2012.05522.x] [Citation(s) in RCA: 175] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Divergent natural selection promotes local adaptation and can lead to reproductive isolation of populations in contrasting environments; however, the genetic basis of local adaptation remains largely unresolved in natural populations. Local adaptation might result from antagonistic pleiotropy, where alternate alleles are favoured in distinct habitats, and polymorphism is maintained by selection. Alternatively, under conditional neutrality some alleles may be favoured in one environment but neutral at other locations. Antagonistic pleiotropy maintains genetic variation across the landscape; however, there is a systematic bias against discovery of antagonistic pleiotropy because the fitness benefits of local alleles need to be significant in at least two environments. Here, we develop a generally applicable method to investigate polygenic local adaptation and identify loci that are the targets of selection. This approach evaluates allele frequency changes after selection at loci across the genome to distinguish antagonistic pleiotropy from conditional neutrality and deleterious variation. We investigate local adaptation at the qualitative trait loci (QTL) level in field experiments, in which we expose 177 F(6) recombinant inbred lines and parental lines of Boechera stricta (Brassicaceae) to their parental environments over two seasons. We demonstrate polygenic selection for native alleles in both environments, with 2.8% of the genome exhibiting antagonistic pleiotropy and 8% displaying conditional neutrality. Our study strongly supports antagonistic pleiotropy at one large-effect flowering phenology QTL (nFT): native homozygotes had significantly greater probabilities of flowering than foreign homozygotes in both parental environments. Such large-scale field studies are essential to elucidate the genetic basis of adaptation in natural populations.
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Affiliation(s)
- Jill T Anderson
- Department of Biology, Institute for Genome Sciences and Policy, Duke University, Durham, NC 27708, USA
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