Tao Fujiwara1,2, Hongmei Liu3, Esteban I Meza-Torres4, Rita E Morero5, Alvaro J Vega4, Zhenlong Liang1, Atsushi Ebihara6, Ilia J Leitch7, Harald Schneider1. 1. Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Yunnan, China. 2. Makino Herbarium, Tokyo Metropolitan University, Minami-osawa, Hachioji, Tokyo, Japan. 3. Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Yunnan, China. 4. Instituto de Botánica del Nordeste, Universidad Nacional del Nordeste, Consejo Nacional de Investigaciones Científicas y Técnicas, Corrientes, Argentina. 5. Instituto Multidiscipinario de Biologia Vegetal, Universidad Nacional de Cordoba, Consejo Nacional de Investigaciones Científicas y Tecnicas, Cordoba, Argentina. 6. Department of Botany, National Museum of Nature and Sciences, Tsukuba, Japan. 7. Jodrell Laboratory, Royal Botanic Gardens, Kew, London, UK.
Abstract
BACKGROUND AND AIMS: The dynamics of genome evolution caused by whole genome duplications and other processes are hypothesized to shape the diversification of plants and thus contribute to the astonishing variation in species richness among the main lineages of land plants. Ferns, the second most species rich lineages of land plants are highly suitable to test this hypothesis because of several unique features that distinguish fern genomes from those of seed plants. In this study, we tested the hypothesis that genome diversity and disparity shape fern species diversity by recording several parameters related to genome size and chromosome number. METHODS: We conducted de novo measurement of DNA C-values across the fern phylogeny to reconstruct the phylogenetic history of the genome space occupation in ferns by integrating genomic parameters such as genome size, chromosome number, and average DNA amount per chromosome into a time-scaled phylogenetic framework. Using phylogenetic generalized least square methods, we determined correlations between chromosome number and genome size, species diversity and evolutionary rates of their transformation. KEY RESULTS: The measurements of DNA C-values for 233 species more than doubled the taxon coverage from ca. 2.2% in previous studies to 5.3% of extant diversity. The dataset documented not only substantial differences in the accumulation of genomic diversity and disparity among the major lineages of ferns but also recovered support the predicted correlation between species diversity and the dynamics of genome evolution. CONCLUSIONS: Our results demonstrated substantial genome disparity among different groups in ferns and supported the prediction that alterations of reproductive modes alter trends of genome evolution. Finally, we recovered evidence for a close link between the dynamics of genome evolution and species diversity in ferns for the first time.
BACKGROUND AND AIMS: The dynamics of genome evolution caused by whole genome duplications and other processes are hypothesized to shape the diversification of plants and thus contribute to the astonishing variation in species richness among the main lineages of land plants. Ferns, the second most species rich lineages of land plants are highly suitable to test this hypothesis because of several unique features that distinguish fern genomes from those of seed plants. In this study, we tested the hypothesis that genome diversity and disparity shape fern species diversity by recording several parameters related to genome size and chromosome number. METHODS: We conducted de novo measurement of DNA C-values across the fern phylogeny to reconstruct the phylogenetic history of the genome space occupation in ferns by integrating genomic parameters such as genome size, chromosome number, and average DNA amount per chromosome into a time-scaled phylogenetic framework. Using phylogenetic generalized least square methods, we determined correlations between chromosome number and genome size, species diversity and evolutionary rates of their transformation. KEY RESULTS: The measurements of DNA C-values for 233 species more than doubled the taxon coverage from ca. 2.2% in previous studies to 5.3% of extant diversity. The dataset documented not only substantial differences in the accumulation of genomic diversity and disparity among the major lineages of ferns but also recovered support the predicted correlation between species diversity and the dynamics of genome evolution. CONCLUSIONS: Our results demonstrated substantial genome disparity among different groups in ferns and supported the prediction that alterations of reproductive modes alter trends of genome evolution. Finally, we recovered evidence for a close link between the dynamics of genome evolution and species diversity in ferns for the first time.