Abstract
Chromosome traits may differ between closely related ferns growing in different geological landscapes. Adiantum series Gravesiana (Pteridaceae) includes six species, of which, five species are exclusively distributed in Karst landforms, and one, Adiantum juxtapositum, grows on Danxia landform. Additionally, there are some populations or individuals whose morphology are between different species, which may be the results of polyploidization or hybridization. Here we studied chromosome numbers of species in series Gravesiana primarily using crosiers. Results are: A. longzhouensis and A. juxtapositum were diploids with 2n = 60 and 2n = 64, respectively; A. dentatum was deduced to be diploids with 2n = ca. 60; A. mariesii had two cytotypes, 2n = 60 (diploid) and 2n = ca. 120 (tetraploid), respectively; A. gravesii had four cytotypes including 2n = ca. 60 (diploid), ca. 120 (tetraploid), ca. 150 (pentaploid), and ca. 180 (hexaploid). All these different cytotypes suggest polyploidization and hybridization have occurred in A. gravesii and A. mariesii, so we treated these two species as two “complex group”. All chromosome numbers in this study are the first record.
References
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<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Cheng, X. & Zhang, S.Z. (2010) Index to chromosome numbers of Chinese pteridophyta (1969–2009). Journal of Fairylake Botanical Garden 9: 1–58.</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Dong, S.Y. (2011) Taxonomic Studies on Asplenium sect. Thamnopteris (Aspleniaceae) I: Cytological Observations. American Fern Journal 101: 156–171. https://doi.org/10.1640/0002-8444-101.3.156</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Glick, L. & Mayrose, I. (2014) ChromEvol: assessing the pattern of chromosome number evolution and the inference of polyploidy along a phylogeny. Molecular Biology and Evolution 31: 1914–1922. https://doi.org/10.1093/molbev/msu122</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Guerra, M. (2008) Chromosome numbers in plant cytotaxonomy: concepts and implications. Cytogenetic and Genome Research 120: 339–350. https://doi.org/10.1159/000121083</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">He, Z., Yan, Y., Ma, Q. & Lu, Q. (2012) The bryophyte diversity of the Danxia landform in Hunan, China. Biodiversity Science 20: 522–526. https://doi.org/10.3724/SP.J.1003.2012.05216</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Hsieh, T.H., Chang, Y.H., Chiou, W.L. & Huang, Y.M. (2008) Chromosome Numbers of Five Species of the Marattiaceae in Taiwan. Taiwan Journal of Forest Science 23: 377–381.</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Irudayaraj, V. & Manickam, V.S. (1987) SOCGI plant chromosome number reports—V. Journal of Cytology and Genetics 22: 156–163.</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Kato, M., Nakato, N., Cheng, X. & Iwatsuki, K. (1992) Cytotaxonomic Study of Ferns of Yunnan, Southwestern China. The Botanical Magazine, Tokyo 105: 105–124. https://doi.org/10.1007/BF02489407</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Li, Y.B., Wang, S.J. & Li, R.L. (2004) Some soil features of karst ecosystem. Ecology and Environment 13: 434–438.</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Liu, C.C., Liu, Y.G., Guo, K., Fan, D.Y., Li, G.W., Zheng, Y.R., Yu, L.F. & Yang, R. (2011) Effect of drought on pigments, osmotic adjustment and antioxidant enzymes in six woody plant species in karst habitats of southwestern China. Environment and Experimental Botany 71: 174–183. https://doi.org/10.1016/j.envexpbot.2010.11.012</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Liu, Y., Liu, C., Rubinato, M., Guo, K., Zhou, J. & Cui, M. (2020) An Assessment of Soil’s Nutrient Deficiencies and Their Influence on the Restoration of Degraded Karst Vegetation in Southwest China. Forests 11: 797. https://doi.org/10.3390/f11080797</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Liu, Y.G., Liu, C.C., Wang, S.J., Guo, K., Yang, J., Zhang, X.S. & Li, G.Q. (2013) Organic carbon storage in four ecosystem types in the karst region of southwestern China. PLoS ONE 8:e56443. https://doi.org/10.1371/journal.pone.0056443</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Manickam, V.S. & Irudayaraj, V. (1988) Cytology of ferns of the Western Ghats (South India). Today and Tomorrow’s Printers and Publishers, New Delhi, pp. 81.</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Manton, I., Sinha, B.M.B. & Vida, G. (1970) Cytotaxonomic studies in the Adiantum caudatum complex of Africa and Asia II. Autoploidy and alloploidy in African representaties of A. incisum. Botanical Journal of the Linnean Society 63: 1–21. [With 3 plates and 7 figures] https://doi.org/10.1111/j.1095-8339.1970.tb02299.x</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Mehra, P.N. & Verma, S.C. (1960) Cytotaxonomic Observations on Some West Himalayan Pteridaceae. Caryologia 13: 619–650. https://doi.org/10.1080/00087114.1960.10797101</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Nakato, N. & Kato, M. (2005) Cytogeography of the Adiantum pedatum complex (Pteridaceae, subfamily Adiantoideae). Acta Phytotaxonomica et Geobotanica 56: 85–96.</span></span></span>
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