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scientific papers, and unpublished compiled databases that review in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):
- Haploid/Diploid (D), species having solely haploid or diploid
(or both) populations;
- Polyploid (P), species exhibiting various levels and forms of
polyploidy; and
- 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).