Previous research suggests that Gossypium has undergone a 5‐ to 6‐fold multiplication following its divergence from Theobroma. However, the number of events, or where they occurred in the Malvaceae phylogeny remains unknown. We analyzed transcriptomic and genomic data from representatives of eight of the nine Malvaceae subfamilies. Phylogenetic analysis of nuclear data placed Dombeya (Dombeyoideae) as sister to the rest of Malvadendrina clade, but the plastid DNA tree strongly supported Durio (Helicteroideae) in this position. Intraspecific Ks plots indicated that all sampled taxa, except Theobroma (Byttnerioideae), Corchorus (Grewioideae), and Dombeya (Dombeyoideae), have experienced whole genome multiplications (WGMs). Quartet analysis suggested WGMs were shared by Malvoideae‐Bombacoideae and Sterculioideae‐Tilioideae, but did not resolve whether these are shared with each other or Helicteroideae (Durio). Gene tree reconciliation and Bayesian concordance analysis suggested a complex history. Alternative hypotheses are suggested, each involving two independent autotetraploid and one allopolyploid event. They differ in that one entails an allopolyploid origin for the Durio lineage, whereas the other invokes an allopolyploid origin for Malvoideae‐Bombacoideae. We highlight the need for more genomic information in the Malvaceae and improved methods to resolve complex evolutionary histories that may include allopolyploidy, incomplete lineage sorting, and variable rates of gene and genome evolution.

Newcastle University ePrints -eprint.ncl.ac.uk Logan SA, Phuekvilai P, Wolff K. Ancient woodlands in the limelight: delineation and genetic structure of ancient woodland species Tilia cordata and Tilia platyphyllos (Tiliaceae) in the UK. Abstract Ancient woodlands in Europe are currently subjected to fragmentation, which leads to ecological deterioration and genetic isolation. This is likely to intensify with further climate change and increased land use. Tilia are keystone, ancient woodland indicators, represented in the United Kingdom by two species (Tilia cordata and T. platyphyllos) and their hybrid (T. x europaea). For management of the species we need to investigate genetic differentiation and population genetic structure. Morphology can usually separate the two species but the distinguishing features are not always observable, particularly in less optimum, shady, conditions. Here we test for the first time, 13 microsatellite markers to discriminate the species and hybrid, and to assess the population genetic diversity of the two species. The markers successfully distinguished the species and hybrid. The two species show significant genetic differentiation, indicating two distinct biological units. Sub-structure within both species is loosely related to geographic location. Because Tilia populations in the UK are highly fragmented future conservation should consider provenance issues.

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This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International licence Newcastle University ePrints -eprint.ncl.ac.uk Logan SA, Chytry M, Wolff K. Genetic diversity and demographic history of the Siberian lime (Tilia sibirica)..

No abstract