DOI: 10.5061/dryad.931zcrjg6
title: Subspecies variation of Daucus carota coastal (“gummifer”) morphotypes (Apiaceae) using genotyping-by-sequencing

description: The genus Daucus is widely distributed worldwide, but with a concentration
 of diversity in the Mediterranean Region. The D. carota complex presents
 the greatest taxonomic problems in the genus. We focus on a distinctive
 phenotypic group of coastal morphotypes of D. carota, strictly confined to
 the margins to within about 0.5 km of the Mediterranean Sea and the
 Atlantic Ocean, which we here refer to as coastal morphotypes or D. carota
 subsp. “gummifer” complex, the earliest name for taxa in this group. They
 are loosely morphologically coherent, sharing a relatively short stature,
 thick, broad, sometimes highly glossy leaf segments, and usually flat or
 convex fruiting umbels. We analyzed 288 accessions obtained from genebanks
 in England, France, and the USA, and an expedition to Spain in 2016,
 covering the Mediterranean and Atlantic coasts and Balearic Islands, where
 much of the gummifer complex variation occurs. Our study includes 112
 accessions not examined before in this context. Genotyping-by-sequencing
 identified 29,041 filtered SNPs. Based on high bootstrap support from
 Maximum likelihood and Structure analysis we highlight three main clades.
 The gummifer morphotypes are intercalated with members of Daucus carota
 subspecies carota and subspecies maximus in two of these main clades,
 including a clade containing accessions from Tunisia (also including D.
 carota subsp. capillifolius) and a clade containing accessions from
 western Europe (including the British Isles), southern Europe (including
 the Balearic Islands and the Iberian Peninsula) and Morocco. These results
 support five independent selections of the gummifer morphotypes in these
 narrowly restricted maritime environments in the Mediterranean Region and
 nearby Atlantic coasts. Daucus annuus (=Tornabenea annua) and Daucus
 tenuissimus (=Tornabenea tenuissima; Cape Verde) also fall firmly within
 Daucus carota, supporting their classification as morphologically
 well-defined subspecies of D. carota, which are accepted here with new
 combinations. Types are indicated for most of treated names, including
 designation of four new lectotypes and two new epitypes, which contribute
 to fixation of further use of these names.
description: Figure 1. Maximum likelihood reconstruction and structure of the
 genetic diversity of 288 accessions of the <i>Daucus
 carota</i> complex and outgroup, using 29,041 SNPs obtained by
 genotyping-by-sequencing. Each accession is represented by a horizontal
 bar, and each color corresponds to a theoretical population (nine in
 total). Numbers above the branches represent bootstrap values.
 <i>Daucus syrticus</i> is the outgroup. Accessions previously
 studied in Arbizu et al. (2016) and Mezghani et al. (2018) are marked in
 green. Supplemental Table 1. The 288 accessions of
 <i>Daucus</i> included in this study: accession number, clade,
 corresponding number on Fig. 3 map, new identification, and locality
 information. Maximum likelihood file and VCF file that
 was produced before the Maximum likelihood file.