Salvia austriaca
Creators: name: Mátis, Attila
name: Malkócs, Tamás
name: Kuhn, Thomas
name: Laczkó, Levente
name: Moysiyenko, Ivan
name: Szabó, Anna
name: Bădărău, Alexandru S.
name: Sramkó, Gábor
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Lamiales
Lamiaceae
Salvia
Salvia austriaca

description: Distribution of the taxa of the Salvia austriaca group. —
Our collection of occurrence data for taxa of the Salvia austriaca group with two different pollen deposition modes (i.e., dorsal and lateral deposition) indicates strong eco-geographical differentiation with an almost complete vicariance of the two forms (Fig. 3). The taxon with lateral pollen deposition (i.e., S. austriaca s.str.) occupies the forest-steppe zone of the Pannonian basin, Transylvanian basin, the Pontic steppe, the SE part of Crimea, and the Balkans, whereas Salvia FDPD is confined to the short-grass steppe zone (or true steppe zone) as defined by Lavrenko & al. (1991) of the Pontic steppe. The westernmost observations of Salvia FDPD are from northern Bulgaria (settlement: Bozhurluka), whereas the easternmost is from the city of Rostov (Russia).
Morphological differentiation between Salvia austriaca and Salvia FDPD. — While processing the collected samples, we noted that several individuals exhibited reduced, shortened staminal levers, indicating that Salvia FDPD might be exhibiting gynodioecy, a dimorphic sexual system where populations are composed of both hermaphroditic and female individuals. Gynodioecy is known in S. austriaca, S. candidissima, S. cyanescens and S. pratensis as well (Kaul, 1988; Zhang & Classen-Bockhoff, 2019). Measurements of quantitative floral traits were performed only on hermaphroditic flowers. Based on the results of the linear mixed-effects models, five of the six investigated floral traits differed significantly between the two taxa: calyx length (χ 2 = 34.70, p <0.0001), corolla height (χ 2 = 6.18, p = 0.0129), corolla length (χ 2 = 107.64, p <0.0001), absolute length of the abaxial lever arm (χ 2 = 269.67, p <0.0001), and absolute length of the adaxial lever arm (χ 2 = 10.25, p = 0.0014) had significantly greater values for Salvia FDPD compared to S. austriaca s.str. (Table 1). In contrast, we only observed a marginally significant difference between the number of stem leaf pairs (χ 2 = 6.11, p = 0.0134), where the higher values also belonged to Salvia FDPD. There was no difference in the other vegetative traits between the two taxa (data not shown).
In the PCA, 74.6% of total variation in flower-traits was explained by the first two PC-axes (PC1 – 54.0%, PC2 – 20.6%). However, the two focal taxa were differentiated only along the first PC-axis (Fig. 4).
Phylogenomics, species delimitation and divergence dating. — Our maximum likelihood (ML) phylogenetic tree reconstruction based on unlinked genome-wide SNPs produced a well-resolved phylogram (Fig. 5A,B), in which samples of the same a priori classified taxa are monophyletic and strongly supported (BS = 100), but some of the tip nodes received moderate support (i.e., 70 ≤ BS ≤ 99). The topology strongly supports the separation of the Salvia austriaca group from the rest of the samples (our a priori outgroup) along the longest branch on the tree (Fig. 5A). Within the latter clade, S. nutans is sister to the crown-clade formed by S. pratensis and S. nemorosa.
Values represent (minimum) mean ± standard error (maximum). * indicates significant differences between measurements (p <0.05).
The species tree reconstruction based on coalescence analysis (Fig. 6) yielded a fully congruent topology to the ML-tree, in which taxa of the Salvia austriaca group are sister to the lineage formed by S. nutans, S. pratensis and S. nemorosa. The next split within this lineage is much younger and is represented by S. nutans, which separated from the other two species during the Middle Pleistocene. The following isolation event is marked by the separation of the two taxa of the Salvia austriaca group, which was followed by the split between S. nemorosa and S. pratensis. All nodes were fully supported in the species tree (posterior probability [PP] = 1.0). The divergence dating analysis indicated that S. austriaca s.str. and Salvia FDPD diverged 0.197 mya (95% confidence interval [CI]: 0.302 –0.087 mya) (Fig. 6).
The DAPC analysis attained the lowest BIC scores to models with 5 and 7 clusters (suppl. Fig. S1). At K = 5, all individuals were assigned into a cluster—according to existing classification and splitting the taxa of the Salvia austriaca group—with full posterior probability (Fig. 5C). Interestingly, models with higher number of clusters assigned individuals from S. nemorosa and S. pratensis into separate clusters, whereas the clusters formed by samples of the taxa of the Salvia austriaca group were not divided (suppl. Fig. S2). Similarly, at K = 4, S. nemorosa and S. pratensis were lumped together, whereas S. austriaca s.str. and Salvia FDPD were still conceived as separate groups (suppl. Fig. S2).
The BFD favored the alternative model, which considered Salvia austriaca s.str. and Salvia FDPD as separate entities. The null model, grouping all individuals into one species within the Salvia austriaca group (i.e., S. austriaca s.l.), performed worse in both repetitions with a mean BF value of 348.67 in favor of the alternative model (Table 2) across the two repetitions. This is considered decisive according to Kass & Raftery (1995). Mean ESS was 336.34 (standard deviation = 200.74) across both models and all steps and repetitions, implying that the chain length was adequate to reach convergence.
description: Published as part of Mátis, Attila, Malkócs, Tamás, Kuhn, Thomas, Laczkó, Levente, Moysiyenko, Ivan, Szabó, Anna, Bădărău, Alexandru S. & Sramkó, Gábor, 2023, Hiding in plain sight: Integrative analyses uncover a cryptic Salvia species in Europe, pp. 78-97 in TAXON 72 (1) on pages 82-84, DOI: 10.1002/tax.12818, http://zenodo.org/record/14047522