Species delimitation using multiple sources of evidence from the Pinus strobiformis-Pinus ayacahuite Species Complex

keywords: integrative taxonomy, Trans Mexican Volcanic Belt, unified species concept, white pines


Background: The Trans-Mexican Volcanic Belt (TMVB) in central Mexico is characterized by peaks of high altitude and geologic instability. In this zone, Pinus strobiformis and Pinus ayacahuite form a contact zone with Pinus veitchii. The taxonomical circumscription of white pines in Central Mexico has been unstable, especially regarding the status of P. veitchii.

Questions: What are the species boundaries of the montane Mexican white pines species complex? Is Pinus veitchii a hybrid or an independently evolving lineage?

Studied species: Pinus strobiformis, Pinus veitchii and Pinus ayacahuite species complex.

Study site and dates: United States of America and Mexico from 2003 to 2022.

Methods: We performed multivariate analyses on 10 morphological characters and characterized the climatic niche divergence and the genetic differentiation using SNPs.

Results: Our results showed that P. veitchii is morphologically similar to P. strobiformis, but does not have intermediate morphological values with P. ayacahuite. The ecological niche differentiation was not significant.  Genetic analyses showed P. veitchii as an independent lineage with evidence of admixture with P. ayacahuite, suggesting a gene flow but not a hybrid origin.

Conclusions: Two of the three lines of evidence support three independent lineages. Environmental information showed niche conservatism, morphology and genetic structure showed differentiation of all three taxa, with a greater morphological similarity between P. strobiformis and P. veitchii, and genetic analyses recovered evidence of introgression, suggesting a complex demographic history in the Trans Mexican Volcanic Belt.


Download data is not yet available.
Species delimitation using multiple sources of evidence from the <em>Pinus strobiformis</em>-<em>Pinus ayacahuite</em> Species Complex


Abbott JE. 1974. Introgressive hybridization between shortleaf and loblolly pine in southeast Oklahoma. MSc. Thesis Oklahoma University.

Aguirre-Gutiérrez J, Serna-Chavez HM, Villalobos-Arambula AR, Pérez de la Rosa JA, Raes N. 2015. Similar but not equivalent: ecological niche comparison across closely related mexican white pines. Diversity and Distributions 21: 245-257. DOI: https://doi.org/10.1111/ddi.12268

Alexander DH, Novembre J, Lange K. 2009. Fast model-based estimation of ancestry in unrelated individuals. Genome Research 19: 1655-1664. DOI: https://10.1101/gr.094052.109

Aparicio-Rentería A, Viveros-Viveros H, Hernández-Villa J, Sáenz-Romero C, Ruiz-Montiel C, Pineda PJA. 2020. Zonificación altitudinal de Pinus patula a partir de conos y semillas en la sierra de Huayacocotla, Veracruz, México. Madera y Bosques 26: e2621962. DOI: https://doi.org/10.21829/myb.2020.2621962

Barton NH, Hewitt GM. 1985. Analysis of hybrid zones. Annual Review of Ecology and Systematics 16: 113-148. DOI: https://doi.org/10.1146/annurev.es.16.110185.000553

Bisbee J. 2014. Cone morphology of the Pinus ayacahuite-flexilis complex of the southwestern United States and Mexico. Bulletin of the Cupressus conservation project 3: 3-33.

Boluda CG, Christe C, Randriarisoa A, Gautier L, Naciri Y. 2021. Species delimitation and conservation in taxonomically challenging lineages: The case of two clades of capurodendron (Sapotaceae) in madagascar. Plants 10: 1-26. DOI: https://doi.org/10.3390/plants10081702

Borazan A, Babaç MT. 2003. Morphometric leaf variation in oaks (Quercus) of Bolu, Turkey. Annales Botanici Fennici 40: 233-242.

Bradbury PJ, Zhang Z, Kroon DE, Casstevens TM, Ramdoss Y, Buckler ES. 2007. TASSEL: software for association mapping of complex traits in diverse samples. Bioinformatics 23: 2633-5. DOI: https://doi.org/10.1093/bioinformatics/btm308

Brauner N, Shacham M. 1998. Role of range and precision of the independent variable in regression of data. AIChE Journal 44: 603-611. DOI: https://doi.org/10.1002/aic.690440311

Bruce P, Bruce A. 2017. Practical statistics for data scientists. O’Reilly Media.

Businský R. 2008. The Genus Pinus L., Pines. Acta Pruhoniciana 88: 3-126.

Cabrera-Toledo D, Vargas-Ponce O, Ascencio-Ramírez S, Valadez-Sandova LM, Pérez-Alquicira J, Morales-Saavedra J, Huerta-Galván OF. 2020. Morphological and genetic variation in monocultures, forestry systems and wild populations of Agave maximiliana of Western Mexico: implications for its conservation. Frontiers in Plant Science 11: 817. DOI: https://doi.org/10.3389/fpls.2020.00817

Callaham RZ. 2013. Pinus ponderosa: geographic races and subspecies based on morphological variation. Research Paper PSW-RP-265, USDA Forest Service, Pacific Southwest Research Station, California. DOI: https://doi.org/10.2737/PSW-RP-265

Carney SE, Wolfe DE, Rieseberg LH. 2000. Hybridization and Forest conservation. In: Young A, Boshier D, Boyle T, eds. Forest Conservation Genetics: Principles and Practice. Melbourne, Australia: CSIRO Publishing Group: pp. 167-182. ISBN: 0643102574, 9780643102576

Castellanos-Morales G, Gámez N, Castillo-Gámez RA, Eguiarte LE. 2016. Peripatric speciation of an endemic species driven by Pleistocene climate change: The case of the Mexican prairie dog (Cynomys mexicanus). Molecular Phylogenetics and Evolution 94: 171-181. DOI: https://doi.org/10.1016/j.ympev.2015.08.027

Cavender-Bares J, Ramírez-Valiente JA. 2017. Physiological evidence from common garden experiments for local adaptation and adaptive plasticity to climate in American Live Oaks (Quercus Section Virentes): implications for conservation under global change. In: Gil-Peregrin E, Peguero-Pina JJ, Sancho-Knapik D. eds. Oaks Physiological Ecology. Exploring the Functional Diversity of Genus Quercus L. Switzerland: Springer. pp. 107-136. DOI: https://doi.org/10.1007/978-3-319-69099-5_4

Chen J, Tauer CG, Bai G, Huang Y, Payton ME, Holley AG. 2004. Bidirectional introgression between Pinus taeda and Pinus echinata: Evidence from morphological and molecular data. Canadian Journal of Forest Research 34: 2508-2516. DOI: https://doi.org/10.1139/X04-134

Cicero C, Mason NA, Jiménez RA, Wait DR, Wang-Claypool CY, Bowie RCK. 2021. Integrative taxonomy and geographic sampling underlie successful species delimitation. Ornithology 138: 1-15. DOI: https://doi.org/10.1093/ornithology/ukab009

Cronn R, Liston A, Parks M, Gernandt DS, Shen R, Mockler T. 2008. Multiplex sequencing of plant chloroplast genomes using Solexa sequencing-by-synthesis technology. Nucleic acids research 36: e122. DOI: https://doi.org/10.1093/nar/gkn502

Cruz-Nicolás J, Giles-Pérez G, González-Linares E, Múgica-Gallart J, Lira-Noriega A, Gernandt DS, Eguiarte LE, Jaramillo-Correa JP. 2020 Contrasting evolutionary processes drive morphological and genetic differentiation in a subtropical fir (Abies, Pinaceae) species complex. Botanical Journal of the Linnean Society 192: 401-420. DOI: https://doi.org/10.1093/botlinnean/boz077

Danecek P, Auton A, Abecasis G, Albers CA, Banks E, DePristo MA, Handsaker RE, Lunter G, Marth GT, Sherry ST, McVean G, Durbin R, 1000 Genomes Prohect Analysis Group. 2011. The variant call format and VCFtools. Bioinformatics 27: 2156-2158. DOI: https://doi.org/10.1093/bioinformatics/btr330

Dayrat B. 2005. Towards integrative taxonomy. Biological Journal of the Linnean Society 85: 407-415. DOI: https://doi.org/10.1111/j.1095-8312.2005.00503.x

Del Castillo RG, Pérez de la Rosa JA, Vargas-Amado G, Rivera-García R. 2004. Coníferas. In: García-Mendoza A, Ordoñez MJ, Briones-Salas M, eds. Biodiversidad de Oaxaca. México: Instituto de Biología UNAM Fondo Oaxaqueño para la Conservación de la Naturaleza, World Wildlife Foundation. pp. 141-158. https://web.ciidiroaxaca.ipn.mx/fsanchez/sites/web.ciidiroaxaca.ipn.mx.fsanchez/files/pdf/coniferas.pdf (accessed september 13, 2022).

Delgado P, Salas-Lizana R, Vázquez-Lobo A, Wegier A, Anzidei M, Alvarez-Buylla E.R, Vendramin GG, Piñero D. 2007. Introgressive hybridization in Pinus montezumae Lamb and Pinus pseudostrobus Lindl. (Pinaceae): morphological and molecular (cpSSR) evidence. International Journal of Plant Sciences 168: 861-875. DOI: https://doi.org/10.1086/518260

De Queiroz K. 2007. Species concepts and species delimitation. Systematic Biology 56: 879-86. DOI: https://doi.org/10.1080/10635150701701083

Doyle JJ, Doyle JL. 1987. A rapid DNA isolation procedure from small quantities of fresh leaf tissues. Phytochemical Bulletin 19: 11-15.

Eckenwalder JE. 2009. Conifers of the world: the complete reference.Portland, Oregon: Timber Press. ISBN: 0881929743, 9780881929744

Farjon A. 1998. World checklist and bibliography of conifers. San Jose, California: Royal Botanical Gardens, Kew.ISBN: 9781900347549

Farjon A, 2010. A Handbook of the World's Conifers (Vol. 1). Leiden, Boston: Brill Academic Publishers. ISBN: 978-90-04-32451-0

Farjon A, Styles BT. 1997. Pinus (Pinaceae). Flora Neotropica, monograph 75. Bronx, New York: The New York Botanical Garden. ISBN: 0893274119, 9780893274115

Fick SE, Hijmans RJ. 2017. WorldClim 2: new 1-km spatial resolution climate surfaces for global land areas. International Journal of Climatology 37: 4302-4315. DOI: https://doi.org/10.1002/joc.5086

Frankis M. 2009. The high-altitude white pines of Mexico and the adjacent SW USA. International Dendrological Society Year Book 64-72. http://pinetum.org/articles/Pinus/PNstylesiiFrankis2009.pdf (accessed July 15, 2021).

Gailing O, Lind J, Lilleskov E. 2012. Leaf morphological and genetic differentiation between Quercus rubra L. and Q. ellipsoidalis E. J. Hill populations in contrasting environments. Plant Systematics and Evolution 298: 1533-1545. DOI: https://doi.org/10.1007/s00606-012-0656-y

GBIF [Global Biodiversity Information Facility]. 2024. GBIF occurrence download https://doi.org/10.15468/dl.v5vhrj (accessed July 10, 2023)

Gompert Z, Parchman TL, Buerkle CA. 2012. Genomics of isolation in hybrids. Philosophical Transactions of the Royal Society B: Biological Sciences 367: 439-450. DOI: https://doi.org/10.1098/rstb.2011.0196

González-Ibeas D, Martinez-Garcia PJ, Famula RA, Delfino-Mix A, Stevens KA, Loopstra CA, Langley CH, Neale DB, Wegrzyn JL. 2016. Assessing the gene content of the megagenome: Sugar pine (Pinus lambertiana). G3: Genes, Genomes, Genetics 6: 3787-3802. DOI: https://doi.org/10.1534/g3.116.032805

Hamilton JA, Aitken SN. 2013. Genetic and morphological structure of a spruce hybrid (Picea sitchensis x P. glauca) zone along a climatic gradient. American Journal of Botany 100: 1651-1662. DOI: https://doi.org/10.3732/ajb.1200654

Hicks RR Jr. 1973. Evaluation of morphological characters for use in shortleaf hybrids. Castanea 38: 182-189.

James G, Witten D, Hastie T, Tibshirani R. 2014. An introduction to statistical learning: with applications in R. New York: Springer. ISBN: 978-1-4614-7137-0

Janes JK, Hamilton JA. 2017. Mixing it up: the role of hybridization in forest management and conservation under climate change. Forests 8: 237. DOI: https://doi.org/10.3390/f8070237

Kass JM, Vilela B, Aiello-Lammens ME, Muscarella R, Merow C, Anderson RP. 2018. Wallace: a flexible platform for reproducible modeling of species niches and distributions built for community expansion. Methods in Ecology and Evolution 9: 1151-1156. DOI: https://doi.org/10.1111/2041-210X.12945

Kassambara A, Mundt F. 2017. Package factoextra: extract and visualize the results of multivariate data analyses. http://www.sthda.com/english/rpkgs/factoextra (accessed July 18, 2022).

Kendall MG. 1938. A new measure of rank correlation. Biometrica 30: 81-93. DOI: https://doi.org/10.2307/2332226

Kopelman NM, Mayzel J, Jakobsson M, Rosenberg NA, Mayrose I. 2015. CLUMPAK: A program for identifying clustering modes and packaging population structure inferences across K. Molecular Ecology Resources 15: 1179-1191. DOI: https://doi.org/10.1111/1755-0998.12387

Kral R. 1993. Pinus Linnaeus. In: Flora of North America Editorial Committee, eds. Flora of North America North of Mexico, New York: Oxford University Press, pp. 1-17. ISBN: 0195082427, 9780195082425

Lanner RM. 1996. Made for each other: a symbiosis of birds and pines. New York: Oxford University Press. ISBN: 0-19-508902-2

Laughlin DC, Fulé PZ, Huffman DW, Crouse J, Laliberté E. 2011. Climatic constraints on trait-based forest assembly. Journal of Ecology 99: 1489-1499. DOI: https://doi.org/10.1111/j.1365-2745.2011.01885.x

Lê S, Josse J, Husson F. 2008. FactoMineR: an R package for multivariate analysis. International of Statistical Software 25: 1-18. DOI: https://doi.org/10.18637/jss.v025.i01

Leal-Sáenz A, Waring KM, Menon M, Cushman SA, Eckert A, Flores-Rentería L, Hernández-Díaz JC, López-Sánchez CA, Martínez-Guerrero JH, Wehenkel C. 2020. Morphological differences in Pinus strobiformis across latitudinal and elevational gradients. Frontiers in Plant Science 11: 559697. DOI: https://doi.org/10.3389/fpls.2020.559697

Li H, Handsaker B, Wysoker A, Fennell T, Ruan J, Homer N, Marth G, Abecasis G, Durbin R, 1000 Genome Project Data Processing Subgroup. 2009. The sequence alignment/map format and SAMtools. Bioinformatics 25: 2078-2079. DOI: https://doi.org/10.1093/bioinformatics/btp352

López-Reyes A, Pérez de la Rosa J, Ortiz E, Gernandt DS. 2015. Morphological, molecular, and ecological divergence in Pinus douglasiana and P. maximinoi. Systematic Botany 40: 658-670. DOI: https://doi.org/10.1600/036364415X689384

Malusa J. 1992. Phylogeny and biogeography of the pinyon pines (Pinus Subsect. Cembroides). Systematic Botany 17: 42-66. DOI: https://doi.org/10.2307/2419064

Mao JF, Wang XR. 2011. Distinct niche divergence characterizes the homoploid hybrid speciation of Pinus densata on the tibetan plateau. American Naturalist 177: 424-439. https://doi.org/10.1086/658905

Martínez-Méndez N, Aguirre-Planter E, Eguiarte LE, Jaramillo-Correa JP. 2016. Modelado de nicho ecológico de las especies del género Abies (Pinaceae) en México: Algunas implicaciones taxonómicas y para la conservación. Botanical Sciences 94: 5-24. DOI: https://doi.org/10.17129/botsci.508

Mastretta-Yanes A, Moreno‐Letelier A, Piñero D, Jorgensen TH, Emerson BC. 2015. Biodiversity in the Mexican highlands and the interaction of geology, geography and climate within the Trans-Mexican Volcanic Belt. Journal of Biogeography 42: 1586-1600. DOI: https://doi.org/10.1111/jbi.12546

Matos JA. 1995. Pinus hartwegii and P. rudis: a critical assessment. Systematic Botany 20: 6-21. DOI: https://doi.org/10.2307/2419628

Maya ZL. 2006. Patrones de variación química de poblaciones del complejo Pinus ayacahuite-Pinus strobiformis. MsC Thesis. Universidad de Guadalajara.

McCormack JE, Zellmer AJ, Knowles LL. 2009. Does Niche Divergence Accompany Allopatric Divergence in Aphelocoma Jays As Predicted Under Ecological Speciation?: Insights From Tests With Niche Models. Evolution 64: 1231-1244. DOI: https://doi.org/10.1111/j.1558-5646.2009.00900.x

Menon M, Bagley JC, Friedline CJ, Whipple AV, Schoettle AW, Leal-Sáenz A, Wehenkel C, Molina-Freaner F, Flores-Rentería L, Gonzalez-Elizondo MS, Sniezko RA, Cushman SA, Waring KM, Eckert AJ. 2018. The role of hybridization during ecological divergence of southwestern white pine (Pinus strobiformis) and limber pine (P. flexilis). Molecular Ecology 27: 1245-1260. DOI: https://doi.org/10.1111/mec.14505

Montes JR, Peláez P, Moreno-Letelier A, Gernandt DS. 2022. Coalescent-based species delimitation in North American pinyon pines using low-copy nuclear genes and plastomes. American Journal of Botany 109: 706-726. DOI: https://doi.org/10.1002/ajb2.1847

Mergen F, Stairs GR, Snyder EB. 1965. Natural and controlled loblolly-x-shortleaf pine hybrids in Mississippi. Forest Science 11: 306-314. DOI: https://doi.org/10.1093/forestscience/11.3.306

Moreno-Letelier A, Barraclough TG. 2015. Mosaic genetic differentiation along environmental and geographic gradients indicate divergent selection in a white pine species complex. Evolutionary Ecology 29: 733-748. DOI: https://doi.org/10.1007/s10682-015-9785-4

Moreno-Letelier A, Piñero D. 2009. Phylogeographic structure of Pinus strobiformis Engelm. across the Chihuahuan Desert filter-barrier. Journal of Biogeography 36: 121-131. DOI: https://doi.org/10.1111/j.1365-2699.2008.02001.x

Moreno-Letelier A, Ortiz-Medrano A, Piñero D. 2013. Niche divergence versus neutral processes: combined environmental and genetic analyses identify contrasting patterns of differentiation in recently diverged pine species. Plos One 8: e78228. DOI: https://doi.org/10.1371/journal.pone.0078228

Nuzzo V, Gatto A, Montanaro G. 2022. Morphological characterization of some local varieties of fig (Ficus carica L.) cultivated in southern Itlaly. Sustainability 14: 15970. DOI: https://doi.org/10.3390/su142315970

Ornelas JF, Sosa V, Soltis DE, Daza JM, González C, Soltis PS, Gutiérrez-Rodríguez C, Espinosa A, Castoe TA, Bell C, Ruiz-Sanchez E. 2013. Comparative phylogeographic analyses illustrate the complex evolutionary history of threatened cloud forests of Northern Mesoamérica. Plos One 8: e56283. DOI: https://doi.org/10.1371/journal.pone.0056283

Padial JM, Miralles A, De la Riva I, Vences M. 2010. The integrative future of taxonomy. Frontiers in Zoology 7: 1-14. DOI: https://doi.org/10.1186/1742-9994-7-16

Pérez de la Rosa JA. 1993. Taxonomía de Pinus ayacahuite y Pinus strobiformis. MSc Thesis. Colegio de Postgraduados.

Perry JP. 1991. The pines of Mexico and Central America. Portland: Timber Press. ISBN: 9781604691108

Phillips SJ, Anderson RP, Schapire RE. 2006. Maximum entropy modeling of species geographic distributions. Ecological Modelling 190: 231-259. DOI: https://doi.org/10.1016/j.ecolmodel.2005.03.026

Pooler MR, Riedel LGH, Bentz SE, Townsend AM. 2002. Molecular markers used to verify interspecific hybridization between Hemlock (Tsuga) species. Journal of the American Society for Horticultural Science 127: 623-627. DOI: https://doi.org/10.21273/JASHS.127.4.623

Purcell S, Neale K, Todd-Brown L, Thomas MAR, Ferreira D, Bender JM. 2007. PLINK: a tool set for whole-genome association and population-based linkage analyses. American Journal of Human Genetics 81: 559-575. DOI: https://doi.org/10.1086/519795

R Core Team. 2021. R: a language and environment for statistical computing. R foundation for statistical computing, Vienna, Austria. http://www.R-project.org

Rehfeldt GE. 1999. Systematics and genetic structure of Ponderosae taxa (Pinaceae) inhabiting the mountain islands of the Southwest. American Journal of Botany 86: 741-752. DOI: https://doi.org/10.2307/2656584

Savolainen O, Pyhäjärvi T, Knürr T. 2007. Gene flow and local adaptation in trees. Annual Review of Ecology, Evolution, and Systematics 38: 595-619. DOI: https://doi.org/10.1146/annurev.ecolsys.38.091206.095646

Shirk AJ, Cushman SA, Waring KM, Wehenkel CA, Leal-Sáenz A, Toney C, López-Sanchez CA. 2018. Southwestern white pine (Pinus strobiformis) species distribution models project a large range shift and contraction due to regional climatic changes. Forest Ecology and Management 411: 176-186. DOI: https://doi.org/10.1016/j.foreco.2018.01.025

Sokal RR, Michener DC. 1958. A statistical method for evaluating systematic relationships. University of Kansas Science Bulletin 28: 1409-1438.

Stead JW. 1983. Studies of variation in Central American pines V: a numerical study of variation in the Pseudostrobus group. Silvae Genetica 32: 101-115.

Syring J, Farrel K, Busunský R, Cronn R, Liston A. 2007. Widespread genealogical nonmoonophyly in species of Pinus subgenus Strobus. Systematic Biology 56: 163-181. DOI: https://doi.org/10.1080/10635150701258787

Tauer CG, Stewart JF, Will RE, Lilly CJ, Guldin JM, Nelson CD. 2012. Hybridization leads to loss of genetic integrity in shortleaf pine: unexpected consequences of pine management and fire suppression. Journal of Forestry 110: 216-224. DOI: https://doi.org/10.5849/jof.11-044

Uribe-Salas D, Sáenz-Romero C, González-Rodríguez A, Telléz-Valdéz O, Oyama K. 2008. Foliar morphological variation in the white oak Quercus rugosa Née (Fagaceae) along a latitudinal gradient in Mexico: potential implications for management and conservation. Forest Ecology and Management 256: 2121-2126. DOI: https://doi.org/10.1016/j.foreco.2008.08.002

Warren DL, Glor RE, Turelli MM. 2008. Environmental niche equivalency versus conservatism: quantitative approaches to niche evolution. Evolution 62: 2868-2883. DOI: https://doi.org/10.1111/j.1558-5646.2008.00482.x

Warren DL, Glor RE, Turelli M. 2010. ENMTools: a tool-box for comparative studies of environmental niche models. Ecography 33: 607-611. DOI: https://dx.doi.org/10.1111/j.1600-0587.2009.06142.x

Wei T, Simko V. 2021. R package ‘corrplot’: visualization of a correlation matrix. https://github.com/taiyun/corrplot

Xing F, Mao J-F, Meng X, Dai J, Zhao W, Liu H, Xing Z, Zhang H, Wang X-R, Li Y. 2014. Needle morphological evidence of the homoploid hybrid origin of Pinus densata based on analysis of artificial hybrids and the putative parents, Pinus tabuliformis and Pinus yunnanensis. Ecology and Evolution 4: 1890-1902. DOI: https://doi.org/10.1002/ece3.1062

Zheng X, Levine D, Shen J, Gogarten SM, Laurie C, Weir, BS. 2012. A high-performance computing toolset for relatedness and principal component analysis of SNP data. Bioinformatics 28: 3326-3328. DOI: https://doi.org/10.1093/bioinformatics/bts606

Zhou Y, Duvaux L, Ren G, Zhang L, Savolainen O, Liu J. 2016. Importance of incomplete lineage sorting and introgression in the origin of shared genetic variation between two closely related pines with overlapping distributions. Heredity 118: 211-220. DOI: https://doi.org/10.1038/hdy.2016.72

Zúñiga EÁ, Sánchez-González A, Granados SD. 2009. Análisis de la variación morfológica foliar en Quercus laeta Liebm. en el parque nacional Los Mármoles, Hidalgo, México. Revista Chapingo Serie Ciencias Forestales y del Ambiente 15: 87-93.

How to Cite
Ortíz-Martínez, A., Ornelas-García, C. P., Moo-Llanes, D. A., Piñero, D., Pérez de la Rosa, J. A., Peláez, P., & Moreno-Letelier, A. (2024). Species delimitation using multiple sources of evidence from the Pinus strobiformis-Pinus ayacahuite Species Complex. Botanical Sciences, 102(2), 482-498. https://doi.org/10.17129/botsci.3364