Global aquatic macrophyte ploidy database
Collation of ploidy information was undertaken from a total of 468 sources, commencing with the database underpinning the study (Rice et al., 2019; who included >800 macrophyte species in their world dataset), and complemented by information derived from Floras, scientific papers, and unpublished compiled databases that review in detail data for chromosome number and ploidy level of each species. A substantial part of the relevant ploidy information was found in local journals, dissertations, and books, as well as in non-English language publications (source data are available: see Data Accessibility section below). Ploidy state was characterized in three classes, following Wani et al. (2018) and Dar et al. (2020):
  1. Haploid/Diploid (D), species having solely haploid or diploid (or both) populations;
  2. Polyploid (P), species exhibiting various levels and forms of polyploidy; and
  3. Mixed ploidy (D&P), species showing “other” ploidy, i.e., with both haploid/ diploid, and polyploid populations (or variants showing, for example, agmatoploidy or dysploidy) occurring in different parts of their range.
In allocating percentage occurrence for species showing each ploidy state per global gridcell and ecozone: (i) we used the definition of “aquatic macrophyte” originally proposed by Chambers et al. (2008) and subsequently extended by Murphy et al. (2019), to set up a global pool of 3496 vascular macrophyte species; (ii) we note that polyploidy is an ongoing process and most polyploids are allopolyploids (Tippery et al., 2018; Levin, 2019), so we did not separate our database into autopolyploid and allopolyploid species; (iii) we also note that complete agmatoploidy, complete symploidy, and polyagmatoploidy are considered a “misinterpretation of polyploidy” by many authors (e.g., Guerra, 2016); and (iv) there is a general lack of appropriate data for species of tropical regions (Ramsey & Ramsey, 2014).