Abstract
Comparing gene expression patterns and genetic polymorphisms between populations is of central importance for understanding the origin and maintenance of biodiversity. Based on population-specific gene expression levels and allele frequency differences, we sought to identify population divergence (PD) genes across the introgression-resistant genomic regions of Populus trichocarpa. Genes containing highly diverged loci [i.e., genetic divergence (GD)] or showing expression divergence (ED) between populations were widely distributed in the genome and substantially enriched in functional categories related to stress responses, disease resistance, timing of flowering, cell cycle regulation, plant growth, and development. Nine genomic regions showing evidence of strong positive selection were overlapped with GD genes, which had significant differences between Oregon (a southernmost peripheral deme) and the other demes. However, we did not find evidence that genes under positive selection show an enrichment for ED. PD genes and genes under selection pertained to the same gene classes, such as SERINE/CYSTEINE PROTEASE, ABC TRANSPORTER, GLYCOSYLTRANSFERASE and other transferases. Our analysis also revealed that GD genes were polymorphic within the species (41.9 ± 3.66 biallelic variants per gene), as previously reported in herbaceous plants. By contrast, ED genes contained less genetic variants (10.73 ± 1.14) and were likely highly expressed. In addition, we found that trans- rather than cis-acting variants considerably contribute to the evolution of >90% PD genes. Overall, this study elucidates that cohorts of PD genes agree with the general attributes of known speciation genes and GD genes will provide substrates for positive selection to operate on.
Access options
Subscribe to Journal
Get full journal access for 1 year
$499.00
only $41.58 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
from$8.99
All prices are NET prices.






Data availability
The original genotyping data have been deposited on SRA under the accession PRJNA276056. The RNA-sequencing data have been deposited on SRA under the accession PRJNA300564. All the intermediate data supporting the findings of this study are available upon reasonable request.
Code availability
Custom Python scripts have been made available as a notebook appendix in the Supporting Information.
References
Abbott R, Albach D, Ansell S, Arntzen JW, Baird SJE, Bierne N et al. (2013) Hybridization and speciation. J Evol Biol 26(2):229–246
Abzhanov A, Kuo WP, Hartmann C, Grant BR, Grant PR, Tabin CJ (2006) The calmodulin pathway and evolution of elongated beak morphology in Darwin’s finches. Nature 442(7102):563–567
Alachiotis N, Stamatakis A, Pavlidis P (2012) OmegaPlus: A scalable tool for rapid detection of selective sweeps in whole-genome datasets. Bioinformatics 28(17):2274–2275
Albanese D, Filosi M, Visintainer R, Riccadonna S, Jurman G, Furlanello C (2013) minerva and minepy: A C engine for the MINE suite and its R, Python and MATLAB wrappers. Bioinformatics 29(3):407–408
Alcázar R, García AV, Kronholm I, de Meaux J, Koornneef M, Parker JE et al. (2010) Natural variation at strubbelig receptor kinase 3 drives immune-triggered incompatibilities between Arabidopsis thaliana accessions. Nat Genet 42:1135
Alexa A, Rahnenführer J (2010) topGO: enrichment analysis for gene ontology. R package version 2.28.0. https://bioconductor.org/packages/topGO/
Anderson E (1953) Introgressive hybridization. Biol Rev Camb Philos Soc 28(3):280–307
Anderson E, Hubricht L (1938) Hybridization in Tradescantia. III The evidence for introgressive hybridization. Am J Bot 25(6):396–402
Avise J (2000) Phylogeography: The history and formation of species. Harvard University Press, Cambridge, MA
Barton N (1979) The dynamics of hybrid zones. Heredity 43:341–359
Barton NH (2001) The role of hybridization in evolution. Mol Ecol 10(3):551–568
Bass AJ, Dabney A, Robinson D (2015). qvalue: Q-value estimation for false discovery rate control. R package version 2.10.0. http://github.com/jdstorey/qvalue.
Baum LE, Petrie T, Soules G, Weiss N (1970) A maximization technique occurring in statistical analysis of probabilistic functions of markov chains. Ann Math Stat 41(1):164–171
Bell GDM, Kane NC, Rieseberg LH, Adams KL (2013) RNA-seq analysis of allele-specific expression, hybrid effects, and regulatory divergence in hybrids compared with their parents from natural populations. Genome Biol Evol 5(7):1309–1323
Benjamini Y, Hochberg Y (1995) Controlling the false discovery rate: A practical and powerful approach to multiple testing. J R Stat Soc B Met 57(1):289–300
Bikard D, Patel D, Le Mette C, Giorgi V, Camilleri C, Bennett MJ et al. (2009) Divergent evolution of duplicate genes leads to genetic incompatibilities within A. thaliana. Science 323(5914):623–626
Blevins T, Wang J, Pflieger D, Pontvianne F, Pikaard CS (2017) Hybrid incompatibility caused by an epiallele. Proc Natl Acad Sci USA 114(14):3702–3707
Bolger AM, Lohse M, Usadel B (2014) Trimmomatic: A flexible trimmer for Illumina sequence data. Bioinformatics 30(15):2114–2120
Bomblies K, Lempe J, Epple P, Warthmann N, Lanz C, Dangl JL et al. (2007) Autoimmune response as a mechanism for a Dobzhansky-Muller-type incompatibility syndrome in plants. PLoS Biol 5:1962–1972
Bomblies K, Weigel D (2007) Hybrid necrosis: autoimmunity as a potential gene-flow barrier in plant species. Nat Rev Genet 8:382
Bouckaert R, Vaughan TG, Barido-Sottani J, Duchêne S, Fourment M, Gavryushkina A et al. (2019) BEAST 2.5: an advanced software platform for Bayesian evolutionary analysis. PLoS Comp Biol 15(4):e1006650
Bouckaert RR (2010) DensiTree: Making sense of sets of phylogenetic trees. Bioinformatics 26(10):1372–1373
Britten RJ, Davidson EH (1971) Repetitive and non-repetitive DNA sequences and a speculation on the origins of evolutionary novelty. Q Rev Biol 46(2):111–138
Bryant D, Bouckaert R, Felsenstein J, Rosenberg NA, RoyChoudhury A (2012) Inferring species trees directly from biallelic genetic markers: Bypassing gene trees in a full coalescent analysis. Mol Biol Evol 29(8):1917–1932
Caseys C, Stritt C, Glauser G, Blanchard T, Lexer C (2015) Effects of hybridization and evolutionary constraints on secondary metabolites: The genetic architecture of phenylpropanoids in European populus species. PLoS ONE 10(5):e0128200
Chan YF, Marks ME, Jones FC, Villarreal G, Shapiro MD, Brady SD et al. (2010) Adaptive evolution of pelvic reduction in sticklebacks by recurrent deletion of a Pitx1 enhancer. Science 327(5963):302–305
Chen JJ, Ding JH, Ouyang YD, Du HY, Yang JY, Cheng K et al. (2008) A triallelic system of S5 is a major regulator of the reproductive barrier and compatibility of indica-japonica hybrids in rice. Proc Natl Acad Sci USA 105(32):11436–11441
Chhatre VE, Evans LM, DiFazio SP, Keller SR (2018) Adaptive introgression and maintenance of a trispecies hybrid complex in range-edge populations of Populus. Mol Ecol 27(23):4820–4838
Christie P, Macnair MR (1987) The distribution of postmating reproductive isolating genes in populations of the yellow monkey flower, Mimulus guttatus. Evolution 41(3):571–578
Chung H, Loehlin DW, Dufour HD, Vaccarro K, Millar JG, Carroll SB (2014) A single gene affects both ecological divergence and mate choice in. Drosoph Sci 343(6175):1148–1151
Cingolani P, Platts A, Wang le L, Coon M, Nguyen T, Wang L et al. (2012) A program for annotating and predicting the effects of single nucleotide polymorphisms, SnpEff: SNPs in the genome of Drosophila melanogaster strain w1118; iso-2; iso-3. Fly (Austin) 6(2):80–92
Clausen J (1951) Stages in the evolution of plant species Cornell University Press, Ithaca, New York
de Meaux J (2018) Cis-regulatory variation in plant genomes and the impact of natural selection. Am J Bot 105(11):1788–1791
de Tayrac M, Lê S, Aubry M, Mosser J, Husson F (2009) Simultaneous analysis of distinct Omics data sets with integration of biological knowledge: multiple Factor Analysis approach. BMC Genomics 10(1):32
DeBell DS (1990) Populus trichocarpa Torr. & Gray, black cottonwood, vol 2. US Department of Agriculture, Forest Service, Agriculture Handbook, Washington, D.C., USA
DeGiorgio M, Huber CD, Hubisz MJ, Hellmann I, Nielsen R (2016) SweepFinder2: Increased sensitivity, robustness and flexibility. Bioinformatics 32(12):1895–1897
DiFazio SP, Slavov GT, Joshi CP (2011) Populus: A premier pioneer system for plant genomics. In: Joshi C, Difazio SP, Kole C (eds). Genetics, genomics and breeding of poplar. Science Publishers, Enfield, NH
Dion-Côté A-M, Renaut S, Normandeau E, Bernatchez L (2014) RNA-seq reveals transcriptomic shock involving transposable elements reactivation in hybrids of young lake whitefish species. Mol Biol Evol 31(5):1188–1199
Dixon MS, Jones DA, Keddie JS, Thomas CM, Harrison K, Jones JDG (1996) The tomato Cf-2 disease resistance locus comprises two functional genes encoding leucine-rich repeat proteins. Cell 84(3):451–459
Durst F, Benveniste I (1993) Cytochrome P450 in plants, vol 105. Springer, Berlin, Heidelberg
Geraldes A, Farzaneh N, Grassa CJ, McKown AD, Guy RD, Mansfield SD et al. (2014) Landscape genomics of Populus trichocarpa: the role of hybridization, limited gene flow, and natural selection in shaping patterns of population structure. Evolution 68(11):3260–3280
Gilad Y (2012) Using genomic tools to study regulatory evolution. Humana Press, New York
Hadfield JD (2010) MCMC methods for multi-response generalized linear mixed models: The MCMCglmm R package. J Stat Softw 1:2
Haerty W, Singh RS (2006) Gene regulation divergence is a major contributor to the evolution of Dobzhansky-Muller incompatibilities between species of Drosophila. Mol Biol Evol 23(9):1707–1714
Han F, Lamichhaney S, Grant BR, Grant PR, Andersson L, Webster MT (2017) Gene flow, ancient polymorphism, and ecological adaptation shape the genomic landscape of divergence among Darwin’s finches. Genome Res 27(6):1004–1015
Hofer T, Foll M, Excoffier L (2012) Evolutionary forces shaping genomic islands of population differentiation in humans. BMC Genomics 13(1):107
Karasov TL, Kniskern JM, Gao LP, DeYoung BJ, Ding J, Dubiella U et al. (2014) The long-term maintenance of a resistance polymorphism through diffuse interactions. Nature 512(7515):436–440
Klein J, Sato A, Nikolaidis N (2007) MHC, TSP, and the origin of species: From immunogenetics to evolutionary genetics. Annu Rev Genet 41:281–304
Kradolfer D, Wolff P, Jiang H, Siretskiy A, Kohler C (2013) An imprinted gene underlies postzygotic reproductive isolation in Arabidopsis thaliana. Dev Cell 26(5):525–535
Kruger J, Thomas CM, Golstein C, Dixon MS, Smoker M, Tang SK et al. (2002) A tomato cysteine protease required for Cf-2-dependent disease resistance and suppression of autonecrosis. Science 296(5568):744–747
Kruijer W, Boer MP, Malosetti M, Flood PJ, Engel B, Kooke R et al. (2015) Marker-based estimation of heritability in immortal populations. Genetics 199(2):379–398
Lȇ S, Josse J, Husson F (2008) FactoMineR: an R package for multivariate analysis. J Stat Softw 25(1):1–18
Leffler EM, Gao Z, Pfeifer S, Ségurel L, Auton A, Venn O et al. (2013) Multiple instances of ancient balancing selection shared between humans and chimpanzees. Science 339(6127):1578–1582
Leinonen T, McCairns RJ, O’Hara RB, Merilä J (2013) QST-FST comparisons: evolutionary and ecological insights from genomic heterogeneity. Nat Rev Genet 14(3):179–190
Lexer C, Joseph JA, van Loo M, Barbará T, Heinze B, Bartha D et al. (2010) Genomic admixture analysis in European Populus spp. reveals unexpected patterns of reproductive isolation and mating. Genetics 186(2):699–712
Lindtke D, Gompert Z, Lexer C, Buerkle CA (2014) Unexpected ancestry of Populus seedlings from a hybrid zone implies a large role for postzygotic selection in the maintenance of species. Mol Ecol 23(17):4316–4330
Long YM, Zhao LF, Niu BX, Su J, Wu H, Chen YL et al. (2008) Hybrid male sterility in rice controlled by interaction between divergent alleles of two adjacent genes. Proc Natl Acad Sci USA 105(48):18871–18876
Lowry DB, Modliszewski JL, Wright KM, Wu CA, Willis JH (2008) The strength and genetic basis of reproductive isolating barriers in flowering plants. Philos T R Soc B 363(1506):3009–3021
Ma T, Wang K, Hu Q, Xi Z, Wan D, Wang Q et al. (2018) Ancient polymorphisms and divergence hitchhiking contribute to genomic islands of divergence within a poplar species complex. Proc Natl Acad Sci USA 115(2):E236–43
Mallet J (1995) A species definition for the modern synthesis. Trends Ecol Evol 10(7):294–299
Mallet J (2005) Hybridization as an invasion of the genome. Trends Ecol Evol 20(5):229–237
Mallet J (2007) Hybrid speciation. Nature 446(7133):279–283
Marques DA, Lucek K, Meier JI, Mwaiko S, Wagner CE, Excoffier L et al. (2016) Genomics of rapid incipient speciation in sympatric threespine stickleback. PLoS Genet 12(2):e1005887
McBride CS, Baier F, Omondi AB, Spitzer SA, Lutomiah J, Sang R et al. (2014) Evolution of mosquito preference for humans linked to an odorant receptor. Nature 515(7526):222–227
McKay JK, Latta RG (2002) Adaptive population divergence: Markers, QTL and traits. Trends Ecol Evol 17(6):285–291
McKown AD, Guy RD, Azam MS, Drewes EC, Quamme LK (2013) Seasonality and phenology alter functional leaf traits. Oecologia 172(3):653–665
Metzger BPH, Duveau F, Yuan DC, Tryban S, Yang B, Wittkopp PJ (2016) Contrasting frequencies and effects of cis- and trans-regulatory mutations affecting gene expression. Mol Biol Evol 33(5):1131–1146
Mizuno N, Shitsukawa N, Hosogi N, Park P, Takumi S (2011) Autoimmune response and repression of mitotic cell division occur in inter-specific crosses between tetraploid wheat and Aegilops tauschii Coss. that show low temperature-induced hybrid necrosis. Plant J 68(1):114–128
Nielsen R, Williamson S, Kim Y, Hubisz MJ, Clark AG, Bustamante C (2005) Genomic scans for selective sweeps using SNP data. Genome Res 15(11):1566–1575
Nosil P, Feder JL, Flaxman SM, Gompert Z (2017) Tipping points in the dynamics of speciation. Nat Ecol Evol 1(2):0001
Nosil P, Funk DJ, Ortiz-Barrientos D (2009) Divergent selection and heterogeneous genomic divergence. Mol Ecol 18(3):375–402
Orr HA, Masly JP, Presgraves DC (2004) Speciation genes. Curr Opin Genet Dev 14(6):675–679
Orr HA, Presgraves DC (2000) Speciation by postzygotic isolation: Forces, genes and molecules. Bioessays 22(12):1085–1094
Pagès J (2002) Analyse factorielle multiple appliquée aux variables qualitatives et aux données mixtes. Rev Statistique Appliquée 4:5–37
Pfeifer B, Wittelsbürger U, Ramos-Onsins SE, Lercher MJ (2014) PopGenome: an efficient Swiss army knife for population genomic analyses in R. Mol Biol Evol 31(7):1929–1936
Purcell S, Neale B, Todd-Brown K, Thomas L, Ferreira MAR, Bender D et al. (2007) PLINK: A tool set for whole-genome association and population-based linkage analyses. Am J Hum Genet 81(3):559–575
Qvarnstrom A, Bailey RI (2009) Speciation through evolution of sex-linked genes. Heredity 102(1):4–15
Rambaut A, Drummond AJ, Xie D, Baele G, Suchard MA (2018) Posterior summarization in Bayesian phylogenetics using Tracer 1.7. Syst Biol 67(5):901–904
Ravinet M, Faria R, Butlin RK, Galindo J, Bierne N, Rafajlović M et al. (2017) Interpreting the genomic landscape of speciation: a road map for finding barriers to gene flow. J Evol Biol 30(8):1450–1477
Ren Z-H, Gao J-P, Li L-G, Cai X-L, Huang W, Chao D-Y et al. (2005) A rice quantitative trait locus for salt tolerance encodes a sodium transporter. Nat Genet 37(10):1141–1146
Renaut S, Owens GL, Rieseberg LH (2014) Shared selective pressure and local genomic landscape lead to repeatable patterns of genomic divergence in sunflowers. Mol Ecol 23(2):311–324
Ridley M (2004) Evolution. Blackwell Publishing, Oxford, UK
Rieseberg L, Wendel J (1993) Introgression and its consequences in plants. Oxford University Press, New York, NY
Rieseberg LH, Archer MA, Wayne RK (1999) Transgressive segregation, adaptation and speciation. Heredity 83:363–372
Robinson MD, McCarthy DJ, Smyth GK (2010) edgeR: A Bioconductor package for differential expression analysis of digital gene expression data. Bioinformatics 26(1):139–140
Rockman MV, Kruglyak L (2006) Genetics of global gene expression. Nat Rev Genet 7(11):862–872
Romero IG, Ruvinsky I, Gilad Y (2012) Comparative studies of gene expression and the evolution of gene regulation. Nat Rev Genet 13(7):505–516
Rooney HCE, van’t Klooster JW, van der Hoorn RAL, Joosten MHAJ, Jones JDG, de Wit PJGM (2005) Cladosporium Avr2 inhibits tomato Rcr3 protease required for Cf-2-dependent disease resistance. Science 308(5729):1783–1786
Roux C, Pauwels M, Ruggiero MV, Charlesworth D, Castric V, Vekemans X (2013) Recent and ancient signature of balancing selection around the S-locus in Arabidopsis halleri and A. lyrata. Mol Biol Evol 30(2):435–447
Schluttenhofer C, Yuan L (2015) Regulation of specialized metabolism by WRKY transcription factors. Plant Physiol 167(2):295–306
Seehausen O, Butlin RK, Keller I, Wagner CE, Boughman JW, Hohenlohe PA et al. (2014) Genomics and the origin of species. Nat Rev Genet 15:176
Shabalin AA (2012) Matrix eQTL: Ultra fast eQTL analysis via large matrix operations. Bioinformatics 28(10):1353–1358
Soria-Carrasco V, Gompert Z, Comeault AA, Farkas TE, Parchman TL, Johnston JS et al. (2014) Stick insect genomes reveal natural selection’s role in parallel speciation. Science 344(6185):738–742
Spitze K (1993) Population structure in Daphnia obtusa: quantitative genetic and allozymic variation. Genetics 135(2):367–374
Stern DL (2000) Evolutionary developmental biology and the problem of variation. Evolution 54(4):1079–1091
Stölting KN, Nipper R, Lindtke D, Caseys C, Waeber S, Castiglione S et al. (2013) Genomic scan for single nucleotide polymorphisms reveals patterns of divergence and gene flow between ecologically divergent species. Mol Ecol 22(3):842–855
Suarez-Gonzalez A, Hefer CA, Christe C, Corea O, Lexer C, Cronk QC et al. (2016) Genomic and functional approaches reveal a case of adaptive introgression from Populus balsamifera (balsam poplar) in P. trichocarpa (black cottonwood). Mol Ecol 25(11):2427–2442
Suarez-Gonzalez A, Hefer CA, Lexer C, Cronk QCB, Douglas CJ (2018a) Scale and direction of adaptive introgression between black cottonwood (Populus trichocarpa) and balsam poplar (P.balsamifera). Mol Ecol 27(7):1667–1680
Suarez-Gonzalez A, Hefer CA, Lexer C, Douglas CJ, Cronk QCB (2018b) Introgression from Populus balsamifera underlies adaptively significant variation and range boundaries in P. trichocarpa. N Phytol 217(1):416–427
Supek F, Bošnjak M, Škunca N, Šmuc T (2011) REVIGO summarizes and visualizes long lists of gene ontology terms. PLoS ONE 6(7):e21800
Sweigart AL, Mason AR, Willis JH (2007) Natural variation for a hybrid incompatibility between two species of Mimulus. Evolution 61(1):141–151
Świadek M, Proost S, Sieh D, Yu J, Todesco M, Jorzig C et al. (2017) Novel allelic variants in ACD6 cause hybrid necrosis in local collection of Arabidopsis thaliana. N Phytol 213(2):900–915
Thomae AW, Schade GOM, Padeken J, Borath M, Vetter I, Kremmer E et al. (2013) A pair of centromeric proteins mediates reproductive isolation in Drosophila species. Dev Cell 27(4):412–424
Trapnell C, Roberts A, Goff L, Pertea G, Kim D, Kelley DR et al. (2012) Differential gene and transcript expression analysis of RNA-seq experiments with TopHat and Cufflinks. Nat Protoc 7(3):562–578
Viterbi AJ (1967) Error bounds for convolutional codes and an asymptotically optimum decoding algorithm. IEEE Trans Inf Theory 13(2):260–269
Wang JL, Tian L, Lee HS, Chen ZJ (2006) Nonadditive regulation of FRI and FLC loci mediates flowering-time variation in Arabidopsis allopolyploids. Genetics 173(2):965–974
Wang M, Zhang L, Zhang Z, Li M, Wang D, Zhang X et al. (2020) Phylogenomics of the genus Populus reveals extensive interspecific gene flow and balancing selection. N Phytol 225(3):1370–1382
Wang P, Li Z, Wei J, Zhao Z, Sun D, Cui S (2012) A Na+/Ca2+ exchanger-like protein (AtNCL) involved in salt stress in Arabidopsis. J Biol Chem 287(53):44062–44070
Whitehead A, Crawford DL (2006) Neutral and adaptive variation in gene expression. Proc Natl Acad Sci USA 103(14):5425–5430
Whitlock MC, Lotterhos KE (2015) Reliable detection of loci responsible for local adaptation: inference of a null model through trimming the distribution of FST. Am Nat 186:S24–S36
Wittkopp PJ (2005) Genomic sources of regulatory variation in cis and in trans. Cell Mol Life Sci 62(16):1779–1783
Wittkopp PJ, Haerum BK, Clark AG (2004) Evolutionary changes in cis and trans gene regulation. Nature 430(6995):85–88
Wolf JBW, Ellegren H (2017) Making sense of genomic islands of differentiation in light of speciation. Nat Rev Genet 18(2):87–100
Wray GA (2007) The evolutionary significance of cis-regulatory mutations. Nat Rev Genet 8(3):206–216
Wright KM, Lloyd D, Lowry DB, Macnair MR, Willis JH (2013). Indirect evolution of hybrid lethality due to linkage with selected locus in Mimulus guttatus. PLoS Biol 11(2):e1001497
Wu CI (2001) The genic view of the process of speciation. J Evol Biol 14(6):851–865
Wu CI, Ting CT (2004) Genes and speciation. Nat Rev Genet 5(2):114–122
Wu Q, Han TS, Chen X, Chen JF, Zou YP, Li ZW et al. (2017) Long-term balancing selection contributes to adaptation in Arabidopsis and its relatives. Genome Biol 18(1):217
Xie C-Y, Ying CC, Yanchuk AD, Holowachuk DL (2009) Ecotypic mode of regional differentiation caused by restricted gene migration: A case in black cottonwood (Populus trichocarpa) along the Pacific Northwest coast. Can J For Res 39(3):519–525
Xie CY, Carlson MR, Ying CC (2012) Ecotypic mode of regional differentiation of black cottonwood (Populus trichocarpa) due to restricted gene migration: Further evidence from a field test on the northern coast of British Columbia. Can J For Res 42(2):400–405
Yamagata Y, Yamamoto E, Aya K, Win KT, Doi K, Sobrizal et al. (2010) Mitochondrial gene in the nuclear genome induces reproductive barrier in rice. Proc Natl Acad Sci USA 107(4):1494–1499
Yamaguchi-Shinozaki K, Shinozaki K (2005) Organization of cis-acting regulatory elements in osmotic- and cold-stress-responsive promoters. Trends Plant Sci 10(2):88–94
Yamamoto E, Takashi T, Morinaka Y, Lin SY, Wu JZ, Matsumoto T et al. (2010) Gain of deleterious function causes an autoimmune response and Bateson-Dobzhansky-Muller incompatibility in rice. Mol Genet Genomics 283(4):305–315
Acknowledgements
This work was supported by funds of the Genome Canada Large-Scale Applied Research Program (POPCAN; project 168BIO) to YAE (and other leading PIs of the project team: C. J. Douglas, R. D. Guy, S. D. Mansfield, and Q. C. B. Cronk), and by a National Sciences and Engineering Research Council of Canada Discovery Grant to YAE. We thank Q. C. B. Cronk (UBC) for assistance in RNA-seq data pre-processing. We are equally grateful for Compute Canada (Cedar system) to afford part of computational simulations. Finally, we thank the Editor and anonymous referees for their helpful comments after thorough reading and granting an extended time for revision due to the COVID pandemic.
Author information
Affiliations
Contributions
YAE led and coordinated the project (experimental design and data collection); YL conceived of this study, performed data analyses, and wrote the manuscript with supportive inputs from YAE. All authors read and approved the final version.
Corresponding author
Ethics declarations
Conflict of interest
The authors declare that they have no conflict of interest.
Additional information
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary information
Rights and permissions
About this article
Cite this article
Liu, Y., El-Kassaby, Y.A. Transcriptome-wide analysis of introgression-resistant regions reveals genetic divergence genes under positive selection in Populus trichocarpa. Heredity (2020). https://doi.org/10.1038/s41437-020-00388-4
Received:
Revised:
Accepted:
Published: