Chromosome numbers and DNA content in B romeliaceae: additional data and critical review

For the large N eotropical plant family B romeliaceae, we provide new data on chromosome numbers, cytological features and genome size estimations, and combine them with data available in the literature. Root‐tip chromosome counts for 46 species representing four subfamilies and a literature review of previously published data were carried out. Propidium iodide staining and flow cytometry were used to estimate absolute genome sizes in five subfamilies of B romeliaceae, sampling 28 species. Most species were diploid with 2 n  = 50 in B romelioideae, P uyoideae and P itcairnioideae, followed by 2 n  = 48 observed mainly in Tillandsioideae. Individual chromosome sizes varied more than tenfold, with the largest chromosomes observed in Tillandsioideae and the smallest in B romelioideae. Genome sizes (2 C ‐values) varied from 0.85 to 2.23 pg, with the largest genomes in Tillandsioideae. Genome evolution in B romeliaceae relies on two main mechanisms: polyploidy and dysploidy. With the exception of Tillandsioideae, polyploidy is positively correlated with genome size. Dysploidy is suggested as the mechanism responsible for the generation of the derived chromosome numbers, such as 2 n  = 32/34 or 2 n  = 48. The occurrence of B chromosomes in the dysploid genus C ryptanthus suggests ongoing speciation processes closely associated with chromosome rearrangements. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society , 2014, 176 , 349–368.