Morpho-Colorimetric Characterization of the Sardinian Endemic Taxa of the Genus Anchusa L. by Seed Image Analysis

Abstract

In this work, the seed morpho-colorimetric differentiation of the Sardinian endemic species of Anchusa (Boraginaceae) was evaluated. In Sardinia, the Anchusa genus includes the following seven taxa: A. capellii, A. crispa ssp. crispa, A. crispa ssp. maritima, A. formosa, A. littorea, A. montelinasana, and A. sardoa. Seed images were acquired using a flatbed scanner and analyzed using the free software package ImageJ. A total of 74 seed morpho-colorimetric features of 2692 seed lots of seven taxa of Anchusa belonging to 17 populations were extrapolated and used to build a database of seed size, shape, and color features. The data were statistically elaborated by the stepwise linear discriminant analysis (LDA) to compare and discriminate each accession and taxon. In addition, the seed morpho-colorimetric differences among coastal and mountainous taxa were evaluated. Considering the ecological conditions, the LDA was able to discriminate among the Anchusa taxa with a correct identification of 87.4% and 90.8% of specimens for mountainous and coastal plants, respectively. Moreover, the LDA of the 17 populations of Anchusa showed a low separation among species and populations within the coastal group, highlighting how the long-distance dispersal by flotation on the sea water surface and the pollination network may influence the similarity patterns observed. In addition, a misattribution was observed for A. crispa ssp. crispa, which was misclassified as A. crispa ssp. maritima in 14.1% of cases, while A. crispa ssp. maritima was misidentified as A. crispa ssp. crispa in 21.1% of cases, highlighting a close phenotypic relationship between these two taxa. The statistical results obtained through the seed image analysis showed that the morpho-colorimetric features of the seeds provide important information about the adaptation and evolution of Anchusa taxa in Sardinia.

An Integrated Taxonomic Approach Points towards a Single-Species Hypothesis for Santolina (Asteraceae) in Corsica and Sardinia

“…In order to check for possible differences in external shape, size, and colour of cypselae, a morpho-colorimetric analysis was carried out. This approach is based on image analysis and turned out to be useful to untangle discrimination problems both in cultivated [42,43] and in wild plants [44][45][46]. Digital images of 100 cypselae for each population (99 for S. insularis from Monte Spada) were acquired using a flatbed scanner (Epson Perfection V550) with a digital resolution of 1,200 dpi.…”

Seed Morphology in Species from the Silene mollissima Aggregate (Caryophyllaceae) by Comparison with Geometric Models

“…Variations in the size and shape of the seeds represent an important source of information of high potential in taxonomy, particularly in Silene [ 14 , 15 , 16 , 17 , 18 , 19 ]. The application of image analysis techniques allows to obtain measurements related to the color, size and shape of seeds and to distinguish between different taxa or populations [ 20 , 21 , 22 , 23 , 24 , 25 ].…”

The Endemic Vascular Flora of Sardinia: A Dynamic Checklist with an Overview of Biogeography and Conservation Status

“…Worthy of mention is also the high endemism rate among the Boraginaceae family, especially due to the genus Anchusa , a moderate-sized genus with six of the seven allopatric endemic taxa—out of a total of about 30 taxa of the entire genus—exclusive to coastal or mountain habitats of Sardinia and with a probable common genetic pool of tertiary origin [ 5 , 16 , 82 , 83 ]. The high number of endemic taxa belonging to the family Boraginaceae is, especially if considering the genus Anchusa , exceptional with respect to the other western Mediterranean insular territories and comparable only to the number of endemic Echium in the Canarian Archipelago, with which Sardinia shares a Boraginaceae ancestor of Anatolian origin [ 5 ].…”