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Polyploidy does not control all: Lineage‐specific average chromosome length constrains genome size evolution in ferns

First Author: Liu HM
Recent studies investigating the evolution of genome size diversity in ferns have shown that they have a distinctive genome profile compared with other land plants. Ferns are typically characterized by possessing mediumsized genomes, although a few lineages have evolved very large genomes. Ferns are different from other vascular plant lineages as they are the only group to show evidence for a correlation between genome size and chromosome number. In this study, we aim to explore whether the evolution of fern genome sizes is not only shaped by chromosome number changes arising from polyploidy but also by constraints on the average amount of DNA per chromosome. We selected the genus Asplenium L. as a model genus to study the question because of the unique combination of a highly conserved base chromosome number and a high frequency of polyploidy. New genome size data for Asplenium taxa were combined with existing data and analyzed within a phylogenetic framework. Genome size varied substantially between diploid species, resulting in overlapping genome sizes among diploid and tetraploid spleenworts. The observed additive pattern indicates the absence of genome downsizing following polyploidy. The genome size of diploids varied nonrandomly and we found evidence for cladespecific trends towards larger or smaller genomes. The 578fold range of fern genome sizes have arisen not only from repeated cycles of polyploidy but also through cladespecific constraints governing accumulation and/or elimination of DNA.
Contact the author: Schneider H
Page Number: 418-430
Issue: 4
Impact Factor: 4.04
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PubYear: Jul 2019
Volume: 57
Publication Name: Journal of Systematics and Evolution
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