No abstract

Coevolutionary theory suggests that an arms race between plants and herbivores yields increased plant specialized metabolite diversity and the geographic mosaic theory of coevolution predicts that coevolutionary interactions vary across geographic scales. Consequently, plant specialized metabolite diversity is expected to be highest in coevolutionary hotspots, geographic regions, which exhibit strong reciprocal selection on the interacting species. Despite being well-established theoretical frameworks, technical limitations have precluded rigorous hypothesis testing. Here we aim at understanding how geographic separation over evolutionary time may have impacted chemical differentiation in the cosmopolitan plant genus Euphorbia . We use a combination of state-of-the-art computational mass spectral metabolomics tools together with cell-based high-throughput immunomodulatory testing. Our results show significant differences in specialized metabolite diversity across geographically separated phylogenetic clades. Chemical structural diversity of the highly toxic Euphorbia diterpenoids is significantly reduced in species native to the Americas, compared to Afro-Eurasia. The localization of these compounds to young stems and roots suggest a possible ecological relevance in herbivory defense. This is further supported by reduced immunomodulatory activity in the American subclade as well as herbivore distribution patterns. We conclude that computational mass spectrometric metabolomics coupled with relevant ecological data provide a strong tool for exploring plant specialized metabolite diversity in a chemo-evolutionary framework.

Aim The aim of this study was to resolve the phylogenetic placement of island taxa, reconstruct ancestral origins and resolve competing hypotheses of dispersal patterns and biogeographical histories for oceanic island endemic taxa within subgenus Plantago (Plantaginaceae). Location Juan Fernández Islands, the Auckland Islands, Lord Howe Island, New Amsterdam Island, New Zealand, Tasmania, Falkland Islands, Rapa Iti and the Hawaiian Islands. Taxon Island endemics within Plantago (Plantaginaceae), a globally distributed taxonomic group comprising approximately 250 species. Methods We use Bayesian phylogenetic and divergence time analyses and historical biogeographical analysis of molecular sequence data to infer the ancestral origins of the oceanic island species in Plantago . Results Taxa within subgenus Plantago form clades based on geographic proximities and challenge previous phylogenetic relationships and classification based on morphology. We infer that biogeographic histories of oceanic island taxa from multiple islands were shaped by dispersal at different scales and possibly by different types of birds. The highly remote Hawaiian Islands and Rapa Iti were colonized from North American taxa in a pattern corresponding to known migration routes of large marine birds, rather than from New Zealand as previously hypothesized. The island endemics of Juan Fernández, the Falkland Islands, Lord Howe, Auckland Islands and New Zealand are found to have sources in the nearest continental areas. The analyses confirm recent speciation within subgenus Plantago – which is particularly heightened in island lineages in Hawaii and Rapa Iti – but show slightly older divergence times than previous molecular dating studies. Main conclusions Using molecular data to infer ancestral ranges for plants with uncertain taxonomic relationships can greatly improve our understanding of biogeographical histories and help elucidate origins, dispersal modes and routes in widespread lineages with complex distribution patterns such as Plantago . We improve understanding of important floristic exchange areas between continents and islands as a result of long‐distance dispersal. We infer that a combination of both stepping stone dispersal and extreme long‐distance dispersal can shape insular floras, and that multiple floristic areas can be the sources of closely related island taxa. However, despite the successful dispersal of Plantago , radiation in island archipelagos is generally limited suggesting specific traits may limit diversification.

No abstract

No abstract

This contribution presents and describes Tradescantia schwirkowskiana, a narrow endemic new species from Santa Catarina state, southern Brazil. We assess here the conservation status of this new species as critically endangered, according to the IUCN criteria. We present here a complete description, illustrations and comments on the new species, along with an identification key to the species of Tradescantia that occur in Santa Catarina. Furthermore, we designate here a lectotype and an epitype for T. crassula, the morphologically-closest species to T. schwirkowskiana.

No abstract

This study raises two rather poorly understood subspecies to the rank of species, and revalidates two subspecies in Plantago (Plantaginaceae) section Virginica. Plantago napiformis, formerly P. tomentosa subsp. napiformis, is an uncommon species from grasslands in northeastern Argentina, southern Paraguay and southern Brazil. Plantago pretoana, formerly P. australis subsp. pretoana, is a rare species, endemic to high-elevation bogs in two small areas in southern Brazil: Serra do Itatiaia, and around Lagoa Dourada. Plantago australis subsp. angustifolia and P. australis subsp. hirtella have been recently synonymised under P. australis subsp. australis, but we present evidence here for the revalidation of these two subspecies. We also revise the distribution of P. australis subsp. angustifolia, greatly reducing it, and expand the distribution of P. australis subsp. australis. Finally, we provide an updated identification key to all 22 Plantago species and subspecies in Brazil, Paraguay, Uruguay and northeastern Argentina.Key words: Lamiales; neotropics; Plantagineae; South America; taxonomy ResumoEste estudo eleva à categoria de espécie duas subespécies relativamente pouco estudadas, e revalida duas subespécies, em Plantago (Plantaginaceae) seção Virginica. Plantago napiformis, anteriormente P. tomentosa subsp. napiformis, é uma espécie pouco freqüente, que ocorre em campos naturais no nordeste da Argentina, sul do Paraguai e sul do Brasil. Plantago pretoana, anteriormente P. australis subsp. pretoana, é uma espécie rara, endêmica de banhados de altitude em duas áreas muito restritas nas regiões Sul e Sudeste do Brasil: a Serra do Itatiaia, e ao redor da Lagoa Dourada (Ponta Grossa, Paraná). Plantago australis subsp. angustifolia e P. australis subsp. hirtella foram recentemente sinonimizadas sob P. australis subsp. australis, mas nós apresentamos aqui evidências justificando a revalidação destas duas subespécies. Nós também revisamos a distribuição de P. australis subsp. angustifolia, reduzindo-a muito, e expandimos a distribuição de P. australis subsp. australis. Por fim, nós fornecemos uma chave de identificação atualizada para todas as 22 espécies e subespécies de Plantago que ocorrem no Brasil, Paraguai, Uruguai e nordeste da Argentina.