Phylogeography of Aegean green toads (Bufo viridis subgroup): continental hybrid swarm vs. insular diversification with discovery of a new island endemic

BACKGROUND: Debated aspects in speciation research concern the amount of gene flow between incipient species under secondary contact and the modes by which post-zygotic isolation accumulates. Secondary contact zones of allopatric lineages, involving varying levels of divergence, provide natural settings for comparative studies, for which the Aegean (Eastern Mediterranean) geography offers unique scenarios. In Palearctic green toads (Bufo viridis subgroup or Bufotes), Plio-Pleistocene (~ 2.6 Mya) diverged species show a sharp transition without contemporary gene flow, while younger lineages, diverged in the Lower-Pleistocene (~ 1.9 Mya), admix over tens of kilometers. Here, we conducted a fine-scale multilocus phylogeographic analysis of continental and insular green toads from the Aegean, where a third pair of taxa, involving Mid-Pleistocene diverged (~ 1.5 Mya) mitochondrial lineages, earlier tentatively named viridis and variabilis, (co-)occurs. RESULTS: We discovered a new lineage, endemic to Naxos (Central Cyclades), while coastal islands and Crete feature weak genetic differentiation from the continent. In continental Greece, both lineages, viridis and variabilis, form a hybrid swarm, involving massive mitochondrial and nuclear admixture over hundreds of kilometers, without obvious selection against hybrids. CONCLUSIONS: The genetic signatures of insular Aegean toads appear governed by bathymetry and Quaternary sea level changes, resulting in long-term isolation (Central Cyclades: Naxos) and recent land-bridges (coastal islands). Conversely, Crete has been isolated since the end of the Messinian salinity crisis (5.3 My) and Cretan populations thus likely result from human-mediated colonization, at least since Antiquity, from Peloponnese and Anatolia. Comparisons of green toad hybrid zones support the idea that post-zygotic hybrid incompatibilities accumulate gradually over the genome. In this radiation, only one million years of divergence separate a scenario of complete reproductive isolation, from a secondary contact resulting in near panmixia

Contribution to the vascular flora of Chalki Island (East Aegean, Greece) and biomonitoring of a local endemic taxon

The island of Chalki, located W of Rhodos, belongs to the East Aegean Islands and is situated at the E part of the South Aegean Island Arc. The flora of Chalki consists of 519 vascular plant taxa, 29 of which are under statutory protection, 22 are Greek endemics and 109 are reported here for the first time. We show that Chalki has the second highest percentage of Greek endemics in the phytogeographical region of the East Aegean Islands. The known distribution of Limonium ocymifolium, L. sitiacum and Phoenix theophrasti is expanded, being reported for the first time for the phytogeographical region of the East Aegean Islands. Finally, we assess for the first time the conservation status of Allium chalkii, a single-island endemic, by biomonitoring its populations. © 2016 The Authors

Multivariate morphometric analysis and taxa delimitation in two narrow greek endemics: Astragalus maniaticus and Aethionema saxatile subsp. corinthiacum

Astragalus maniaticus and Aethionema saxatile subsp. corinthiacum have vague taxonomic relationships. Astragalus maniaticus was placed in sect. Hypoglottis but shows affinities to A. suberosus subsp. haarbachii of sect. Platyglottis. The Aethionema saxatile complex is an intriguing group due to the wide distribution and morphological variability of its taxa. In order to elucidate the variation patterns of these two taxa and to test their morphological identity, we carried out several multivariate morphometric (stepwise canonical and classificatory) analyses. They revealed that Astragalus maniaticus cannot be distinguished from A. suberosus subsp. haarbachii on morphological grounds. Therefore, it is transferred to sect. Platyglottis and regarded a heterotypic synonym of A. suberosus subsp. haarbachii. The taxonomic interpretation of Aethionema saxatile subsp. corinthiacum necessitated a broad revision of the Ae. saxatile group in Greece and detection of its relations with Ae. rhodopaeum, a Bulgarian endemic. The analyses showed that Ae. saxatile subsp. corinthiacum represents a distinct taxon; likewise, three additional subspecies receive support of similar strength: subsp. creticum, subsp. graecum and subsp. oreophilum. Intermediate forms between subsp. oreophilum and subsp. saxatile were detected in NW Greece. Ae. rhodopaeum is more variable than its original circumscription and is considered as another subspecies of Ae. saxatile. © 2016 Società Botanica Italiana

The rediscovery of silene guicciardii (Caryophyllaceae) on Mt. Parnassos (Greece) after 160 years: Taxonomic re-evaluation and conservation

Silene guicciardii (Caryophyllaceae) was rediscovered after field surveys carried out on Mt. Parnassos (Sterea Ellas, Greece), 160 years after the type collection made by J.B. Samaritani and J. Guicciardi in 1857. Since its first collection, it has been considered either as a distinct species, a variety or a mere synonym of the SW-Asiatic S. marschallii. We provide a revised description of the species and we re-evaluate its taxonomic position and that of the related species. We propose to treat the taxon guicciardii at the subspecific rank of S. marschallii. A color plate of S. marshallii subsp. guicciardii and a distribution map for all subspecies of S. marschallii are also provided. The name Silene guicciardii was lectotypified on a specimen preserved at G-BOIS, while isolectotypes are at G-BOIS, B, BR, C, GOET, JE, K and WU. © 2017 Magnolia Press

The rediscovery of stachys virgata (Lamiaceae), a rare endemic of peloponnisos,greece: taxonomy, distribution, karyology and conservation

Stachys virgata, a rare Greek member of S. subsect. Rectae, was hitherto known from historical collections made in the north-eastern and southern parts of Peloponnisos, the last one dated in 1844. Its only recent record, on Poros Island in 1940, is not supported by a herbarium specimen. The species was rediscovered in 2005, 161 years after its last collection, and subsequently documented in 18 populations (1 of them now extinct) distributed along the eastern slopes of Mt. Parnonas and Mt. Madara in east Peloponnisos. We review the species’ description and distribution based on both historical records and recent collections, select a specimen deposited in the Natural History Museum, Paris (P) as a lectotype, and count its chromosome number, 2n = 34, for the first time. We evaluate the species’ taxonomic relationships and consider its threats and conservation status based on our own field work and several years of monitoring. S. virgata totals 355 mature plants and 12 out of its 18 populations comprise 20 plants or fewer. Based on the IUCN criteria, S. virgata falls under the Endangered (EN) category and specific conservation measures are proposed. Finally, we provide a key distinguishing S. virgata from the other Greek members of S. subsect. Rectae. © 2015 Magnolia Pres

An orchid in retrograde: Climate-driven range shift patterns of ophrys helenae in Greece

Climate change is regarded as one of the most important threats to plants. Already species around the globe are showing considerable latitudinal and altitudinal shifts. Helen’s bee orchid (Ophrys helenae), a Balkan endemic with a distribution center in northwestern Greece, is reported to be expanding east and southwards. Since this southeastern movement goes against the usual expectations, we investigated via Species Distribution Modelling, whether this pattern is consistent with projections based on the species’ response to climate change. We predicted the species’ future distribution based on three different climate models in two climate scenarios. We also explored the species’ potential distribution during the Last Interglacial and the Last Glacial Maximum. O. helenae is projected to shift mainly southeast and experience considerable area changes. The species is expected to become extinct in the core of its current distribution, but to establish a strong presence in the mid-and high-altitude areas of the Central Peloponnese, a region that could have provided shelter in previous climatic extremes. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Multivariate morphometric analysis of Petrorhagia subsect. Saxifragae (Caryophyllaceae) in Greece, with a new species from SE Peloponnisos: P. laconica

The intra-generic relationships within the intriguing genus Petrorhagia are currently debated, as the genus is underrepresented in recent taxonomic studies. In this study, we investigate the relationships among the species of Petrorhagia [sect. Petrorhagia] subsect. Saxifragae occurring in Greece. Based on a combination of ordination methods and discriminant analyses of 36 macromorphological characters, five species are recognized in Greece. The analyses showed that all currently known species from Greece (P. fasciculata, P. graminea, P. phthiotica and P. saxifraga) represent distinct taxonomic entities. According to our results, two recently collected populations from SE Peloponnisos represent a fifth, new Petrorhagia species, which is first described and illustrated here as P. laconica. It is related to the widespread P. saxifraga and the Greek endemic P. graminea, but clearly distinct from both species by a combination of morphological characters, including indumentum, inflorescence, calyx, capsule and seed characters. © 2018 The Authors ·