查看更多>>摘要：With c. 24 700 species (10% of all flowering plants), Asteraceae are one of the largest and most phenotypically diverse angiosperm families, with considerable economic and ecological importance. Asteraceae are distributed worldwide, from nearly polar latitudes all the way to the tropics, and occur across a diverse range of habitats from extreme deserts to swamps and from lowland rainforests to alpine tundra. Altogether, these characteristics make this family an outstanding model system to address a broad range of eco-evolutionary questions. In this review, we summarize recent progress in our understanding of Asteraceae on the basis of joint efforts by specialists in the fields of palaeobotany, cytogenetics, comparative genomics and phylogenomics. We will highlight how these developments are opening up new possibilities for integrating fields and better comprehending evolution beyond Asteraceae.
Chen, Cheng-WeiChao, Yi-ShanAndi, Maryani A. MustapengLindsay, Stuart...
29页
查看更多>>摘要：A close relationship of the three Old World taenitidoid genera Austrogramme, Syngramma and Taenitis was traditionally suggested on the basis of morphology, and later gained further support from molecular phylogenetic analyses. However, due to insufficient sampling, the monophyly and intrageneric and interspecific relationships of these genera are still largely untested, and the systematic value of diagnostic morphological characteristics is unclear. In this study, we generated a molecular phylogenetic tree with 18 species representing nearly half of the known species diversity for this group. In addition to macromorphological characteristics, we also observed microscopic characteristics, including soral paraphyses and spores. Our results confirm the monophyly of the three genera and their delimitating characteristics. We found that most of the previously proposed sections are not monophyletic, and their diagnostic characteristics are homoplastic. We propose new hypotheses concerning both intergeneric and interspecific hybridization and provide new taxonomic insights that are critical in understanding the diversity of the group.
Scatigna, Andre VitoSouza, Vinicius CastroSosa, Maria De las MercedesDalla Colletta, Gabriel...
24页
查看更多>>摘要：Gratioleae are the most species-rich tribe of Plantaginaceae in the tropics, spanning c. 30 genera and > 300 species, with a wide range of morphological variation and ecological strategies. As a first effort towards a phylogenetic classification of Gratioleae we generated a new phylogenetic hypothesis with improved taxa sampling, based on one nuclear and three plastid markers, using maximum parsimony and Bayesian inference approaches, and performed ancestral state reconstructions of ten morphological characters of flowers. The paraphyly of Stemodia s.l. was corroborated with members being retrieved in four clades; Bacopa, Conobea, Leucospora and Schistophragma are non-monophyletic. As actions towards recognizing only monophyletic genera in Gratioleae, we propose Stemodia s. s. as a monophyletic and morphological cohesive group, describe Umbraria as a new genus to accommodate two species segregated from Stemodia, transfer Stemodia vandelliodes to Darcya, merge Conobea with Bacopa and re-establish the names Chodaphyton ericifolium and Geochorda glechomoides. Traits used to define Stemodia s.l. are plesiomorphic in the tribe; the flower type (composed of seven floral characters) constitutes a good diagnostic set of traits for almost all genera in the tribe. Our study sheds light on the urgent need to reassess generic circumscriptions towards a unified classification in Gratioleae.
查看更多>>摘要：Sapromyophilous flowers are visited by flies seeking carrion or faeces, and flowers of this guild are typically large, purple or red-brown, often speckled and produce a pungent scent. Flowers of the South African iris Moraea lurida conform to this syndrome, but show considerable variation in colour and pattern. We were intrigued by the floral variation within a single population and investigated floral visitors and the effect of body size on pollen loads and whether different colour forms attracted different pollinator assemblages. We found a diverse array of insect visitors, but Diptera comprised the overwhelming majority, with Calliphoridae considered to be the most important for pollination on the basis of their visitation frequency and pollen loads. Effective pollination appeared to be dependent on large-bodied flies that, unlike smaller flies, fit the entire crawl space between the anthers and petals and thus acted like a key in a lock. Choice experiments revealed that the most important fly pollinators showed no colour preferences, and fly vision modelling showed that flies may not be able to discriminate among the different colour forms. This may lead to relaxed selection on colour. Floral scent was dominated by an unusual mix of aliphatic acids and alcohols, characteristic of mammalian skin products and gut microbiome, probably exploiting the perceptual bias of flies to compounds that typify the mammalian microbiome and fermenting carbohydrates.
查看更多>>摘要：The geographical distributions of the two cryptic species of the wetland moss Hamatocaulis vernicosus were mapped for western, central and northern Europe, based on identifications of the two by the nuclear ITS1 + 2 and the plastid rpl16 and trnL-trnF. The distributions of the two cryptic species overlap to a large extent. However, in the west and south-west only cryptic species 1 is present, whereas in the boreal north only cryptic species 2 occurs, which agrees with its distribution in Scandinavia. Despite these differences in distribution, no differences between the two cryptic species were revealed in habitat water chemistry, elevation distribution or climatic niches. The difference in distribution therefore suggests that cryptic species 1 could have survived the glacial period in southern Europe and cryptic species 2 in northern or eastern Europe. However, the studied molecular markers did not reveal geographical patterns suggesting origins in different glacial refugia. Although populations of both cryptic species have decreased in large portions of western Europe, a significantly negative Tajima's D may reflect the long-term expansion south of Scandinavia since the glacial bottleneck, potentially correlated with the expansion of earlier extensive agricultural management of wetlands.
查看更多>>摘要：Winter annuals comprise a large fraction of warm-desert plant species, but the drivers of their diversity are little understood. One factor that has generally been overlooked is the lack of obvious means of long-distance seed dispersal in many desert-annual lineages, which could lead to genetic differentiation at small spatial scales and, ultimately, to speciation and narrow endemism. If our gene-flow hypothesis is correct, individual winter-annual species should have populations with genetic spatial structures implying short distances of gene flow. To test this idea, we sampled six populations of Eschscholzia parishii (Papaveraceae) in three pairs of watersheds within a 28-km radius in southern California. We quantified genetic diversity and structure and inferred the distance of gene flow in these populations using single nucleotide polymorphisms derived from genotyping-by-sequencing. Estimated distances of gene flow were quite small (sigma = 10.4-14.9 m), with strong genetic structure observed within and between populations. Kinship declined steeply with ln distance (r(2) = 0.85). Petal size and shape differed significantly between the northernmost and southernmost populations. These findings support the hypothesis that the high diversity of warm-desert winter annuals might result, in part, from genetic differentiation within species at small spatial scales driven by poor seed dispersal.
查看更多>>摘要：We report the rediscovery of Lecocarpus leptolobus at its type locality, and restrict the latter to El Ripioso, San Cristobal, Galapagos. We compare the morphology of the population at this site with other populations of Lecocarpus on San Cristobal and other Galapagos islands. We conclude that L. leptolobus is a valid taxon endemic to the south-western half of San Cristobal and is not synonymous with L. lecocarpoides, whereas populations further north-east on the same island constitute a separate species validly named L. darwinii. These two taxa support the idea of a former biogeographic barrier between the two halves of San Cristobal. Plants at two of the easternmost localities of the south-western species show some characters intermediate between the two species, possibly representing introgression following easing of the barrier. The three specimens of Lecocarpus collected on San Cristobal by Charles Darwin, all mounted on a single herbarium sheet, comprise one branch of L. leptolobus and two of L. darwinii. We identify possible sites for Darwin's collections based on information about his explorations. We find grounds for accepting the taxon Acanthospermum brachyceratum as a subspecies of L. lecocarpoides endemic to Gardner-by-Espanola, Osborn and Xarifa islets, the first of these being the type locality, demonstrating that even narrow sea barriers can contribute to plant radiation in oceanic archipelagos. On the basis of our findings, we provide a new key to the taxa of Lecocarpus.
NSTL
Oxford Univ Press