Modelling native and alien vascular plant species richness: at which scales is geodiversity most relevant?

Aim: To explore the scale-dependency of relationships between novel geodiversity measures and 26 both native and alien vascular plant species richness. Location: Great Britain Time period: Data collected 1995-2015 Major taxa: Vascular plants Methods: We calculated terrestrial native and alien vascular plant species richness (6,932 species in total) across the island of Great Britain at 1km2 (N=219,964) and 100km2 (N=2,121) grain sizes and regional extents 25-250 km in diameter, centred around each 100km2 cell. We compiled geodiversity data on landforms, soils, hydrological and geological features using existing national datasets, and used a newly developed geomorphometric method to extract landform coverage data (e.g. hollows, ridges, valleys, peaks). We used these as predictors of species richness, alongside climate, commonly used topographic metrics, land-cover variety and human population. We analysed species richness across scales using boosted regression tree (BRT) modelling and compared models with and without geodiversity data. Results: Geodiversity significantly improved models over and above widely used topographic metrics, particularly at smaller extents and the finer grain size, and slightly more so for native species richness. For each increase in extent, the contribution of climatic variables increased and that of geodiversity decreased. Of the geodiversity variables, automatically extracted landform data added the most explanatory power, but hydrology (rivers, lakes) and materials (soil, superficial deposits, geology) were also important. Main conclusions Geodiversity improves our understanding of, and ability to model, the relationship between species richness and abiotic heterogeneity at multiple spatial scales by allowing us to get closer to the real-world physical processes that affect patterns of life. Greatest benefit comes from measuring the constituent parts of geodiversity separately, rather than one combined variable (as for most of the few studies to date). Automatically extracted landform data, the use of which is novel in ecology and biogeography, proved particularly valuable in our study

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

Assessing Climate Change Impacts on Island Bees: The Aegean Archipelago

Pollinators’ climate change impact assessments focus mainly on mainland regions. Thus, we are unaware how island species might fare in a rapidly changing world. This is even more pressing in the Mediterranean Basin, a global biodiversity hotspot. In Greece, a regional pollinator hotspot, climate change research is in its infancy and the insect Wallacean shortfall still remains unaddressed. In a species distribution modelling framework, we used the most comprehensive occurrence database for bees in Greece to locate the bee species richness hotspots in the Aegean, and investigated whether these might shift in the future due to climate change and assessed the Natura 2000 protected areas network effectiveness. Range contractions are anticipated for most taxa, becoming more prominent over time. Species richness hotspots are currently located in the NE Aegean and in highly disturbed sites. They will shift both altitudinally and latitudinally in the future. A small proportion of these hotspots are currently included in the Natura 2000 protected areas network and this proportion is projected to decrease in the coming decades. There is likely an extinction debt present in the Aegean bee communities that could result to pollination network collapse. There is a substantial conservation gap in Greece regarding bees and a critical re-assessment of the established Greek protected areas network is needed, focusing on areas identified as bee diversity hotspots over time

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