Corolla morphology influences diversification rates in bifid toadflaxes (Linaria sect. Versicolores)

Background and Aims

The role of flower specialization in plant speciation and evolution remains controversial. In this study the evolution of flower traits restricting access to pollinators was analysed in the bifid toadflaxes (Linaria sect. Versicolores), a monophyletic group of ∼30 species and subspecies with highly specialized corollas.

Methods

A time-calibrated phylogeny based on both nuclear and plastid DNA sequences was obtained using a coalescent-based method, and flower morphology was characterized by means of morphometric analyses. Directional trends in flower shape evolution and trait-dependent diversification rates were jointly analysed using recently developed methods, and morphological shifts were reconstructed along the phylogeny. Pollinator surveys were conducted for a representative sample of species.

Key Results

A restrictive character state (narrow corolla tube) was reconstructed in the most recent common ancestor of Linaria sect. Versicolores. After its early loss in the most species-rich clade, this character state has been convergently reacquired in multiple lineages of this clade in recent times, yet it seems to have exerted a negative influence on diversification rates. Comparative analyses and pollinator surveys suggest that the narrow- and broad-tubed flowers are evolutionary optima representing divergent strategies of pollen placement on nectar-feeding insects.

Conclusions

The results confirm that different forms of floral specialization can lead to dissimilar evolutionary success in terms of diversification. It is additionally suggested that opposing individual-level and species-level selection pressures may have driven the evolution of pollinator-restrictive traits in bifid toadflaxes.     

Significance of ecological vicariance and long-distance dispersal in the diversification of Carex sect. Spirostachyae (Cyperaceae)

Plant disjunctions have provided one of the most intriguing distribution patterns historically addressed by biogeographers. Carex sect. Spirostachyae (Cyperaceae) displays an interesting pattern of disjunction to evaluate these scenarios, with species occurring in the main continental landmasses and in oceanic islands of the two hemispheres. Internal transcribed spacer and 5'-trnK intron plastid gene sequences were analyzed to determine (1) the times of diversification using penalized likelihood, and (2) reconstructions of the regions using maximum likelihood and Bayesian approaches of origin of sect. Spirostachyae and internal main lineages. The times for the diversification of sect. Spirostachyae are dated to between the end of the Eocene and the Oligocene, whereas the two main lineages are dated to between the end of the Oligocene and the beginning of Miocene. The phylogenetic analyses reveal a Mediterranean-Eurasian center of differentiation for sect. Spirostachyae and subsection Spirostachyae, whereas no clear, single ancestral area could be inferred for subsection Elatae. Both long-distance dispersal and ecological vicariance appear to have been involved in the evolutionary history of the disjunct distribution of the main lineages of sect. Spirostachyae. These organisms appear to have a special ability to colonize remote areas (through transoceanic and interhemispherical colonizations), but special long-distance dispersal mechanisms are not evident.     

Two new species in Justicia sect. Harnieria (Acanthaceae) from tropical Africa

Two new species of Justicia sect. Harnieria (Acanthaceae) are described: J. afromontana from Sudan and Uganda, and J. huambensis from Angola.     

Twenty‐five years after: post‐introduction association of Mecinus janthinus s.l. with invasive host toadflaxes Linaria vulgaris and Linaria dalmatica in North America

Linaria vulgaris, common or yellow toadflax, and Linaria dalmatica, Dalmatian toadflax (Plantaginaceae), are Eurasian perennial forbs invasive throughout temperate North America. These Linaria species have been the targets of classical biological control programmes in Canada and the USA since the 1960s. The first effective toadflax biological control agent, the stem‐mining weevil Mecinus janthinus (Coleoptera: Curculionidae) was introduced from Europe in the 1990s. This weevil has become established on L. dalmatica and L. vulgaris in both countries, although it has shown greater success in controlling the former toadflax species. Genetic and ecological studies of native range M. janthinus populations revealed that weevils previously identified as a single species in fact include two cryptic species, now recognised as M. janthinus, associated with yellow toadflax, and the recently confirmed species Mecinus janthiniformis, associated with Dalmatian toadflax. The results of a comprehensive study characterising haplotype identities, distributions and frequencies within M. janthinus s.l. native range source populations were compared to those populations currently established in the USA and Canada. The presence of both Mecinus species in North America was confirmed, and revealed with a few exceptions a high and consistent level of host fidelity throughout the adopted and native ranges. Genetic analysis based on mitochondrial cytochrome oxidase subunit II gene (mtCOII) defined the origin and records the subsequent North American establishment, by haplotype, of the European founder populations of M. janthinus (northern Switzerland and southern Germany) and M. janthiniformis (southern Macedonia), and provided population genetic indices for the studied populations. This analysis together with existing North American shipment receipt, release and rearing records elucidates probable redistribution routes and sources of both weevil species from initially released and established adopted range populations.     

Floral morphology to discriminate taxa between and within Cytisus sect. Alburnoides, sect. Spartopsis and sect. Verzinum (Genisteae, Fabaceae)

Delimitation of sections is controversial within the genus Cytisus L. (Fabaceae, Genisteae). A morphological study has been conducted on 19 taxa from sections Alburnoides, Spartopsis and Verzinum to clarify their discrimination. Thirty-five quantitative and qualitative characters were recorded on a maximum of 15 dry or living flowers per taxon. Three multiple correspondence factor analyses (MCFA) were performed on a matrix based on 22 of the 35 recorded morphological characters to (1) compare the variability within and between individuals and (2) distinguish groups among the studied taxa. MCFA showed that both flowers sampled from the same plant or different individuals could represent the morphological variability of a taxon. MCFA also clustered the 19 taxa into three groups corresponding to sections Alburnoides, Spartopsis and Verzinum as defined by Cristofolini and Troia (Taxon 44:733–746, 2006). However, floral morphology has not been sufficient to discriminate taxa within sections. A key of the three studied sections based on floral characters is given.     

The Justicia striata complex in tropical Africa (Justicia sect. Harnieria, Acanthaceae)

The Justicia striata complex is revised. Ten species are recognised, some of which are subdivided into subspecies and/or varieties. The morphological variation within the complex has been analysed by PC A and clustering methods. The complex is shown to be heterogeneous and the relationships with other parts of sect. Harnieria are discussed. Scatter diagrams, illustrations and distribution maps are also provided in addition to the enumeration of taxa.     

Three new species of Justicia sect. Justicia (Acanthaceae) from tropical Africa

Three new species of Justicia sect. Justicia (Acanthaceae) are described: Justicia regis from Kenya, Justicia acutifolia from Tanzania, and Justicia telloensis from Cameroun.     

Chromosome numbers in selected species ofHieracium sect.Alpina (Asteraceae) from Central and eastern Europe

Chromosome numbers are reported for 15 taxa ofHieracium sect.Alpina (Griseb.)Gremli from Central and eastern Europe (Austria, the Czech Republic, Poland, Romania, Slovakia, Ukraine). The mode of reproduction was also studied for some of the taxa. For the first time the chromosome counts of 5 taxa from theHieracium rohacsense group are given:H. rohacsense Kit. (the West Carpathians),H. ratezaticum (Nyár. etZahn)Mráz (the South Carpathians) and a still unnamed taxon of theH. rohacsense group from Mt. Pop Ivan (the East Carpathians) are tetraploid (2n=36);H. rauzense Murr (the Eastern Alps) andH. borsanum Mráz (the East Carpathians) are triploid (2n=27).H. krivanense (Woł. etZahn)Schljakov (the West Carpathians) is tetraploid,H. brevipiliferum Mráz (the South Carpathians) is triploid; these are the first karyological reports of both taxa belonging to theH. fritzei group. The tetraploid chromosome number was revealed for the first time in an unnamed taxon of theH. nigrescens group from the West Carpathians, and inH. nigrescens subsp.koprovanum Rech. f. etZahn. InH. alpinum L. s.str. triploid (2n=27) populations from the West Carpathians and diploid populations (2n=18) from the East Carpathians were confirmed. ForH. halleri Vill. (theH. alpinum group, the West Carpathians) andH. nigrescens Willd. (the West Sudeten), the numbers 2n=27 and 2n=36, respectively were found, which is in accordance with previous data. The triploid level (2n=27) forH. pinetophilum (theH. fritzei group) and the tetraploid level (2n=36) forH. stygium Uechtr. (theH. chlorocephalum group) both from the West Carpathians were confirmed. One new species, onenomen novum and one new combination at the level of species are published in this paper.     

Relationships between three species ofFestuca sect.Bovinae (Poaceae)

Seed protein electrophoresis confirms the existence of polymorphism among hexaploid populations ofFestuca arundinacea. Both protein and morphological results suggest thatF. pratensis andF. arundinacea should retain independent specific status. High protein homology of these two species withF. gigantea points towards phylogenetic links between these taxa.     

Cladistics and Biogeography of Artemisia sect. Viscidipubes and sect. Albiraotea (Compositae)

Twenty-six species and eight varieties of Sect．Viscidipubes & Sect．Albibractea are endemic to Asia．Most species of Sect．Viscidipubes are distributed from low to high altitudes and cold areas in the Hengduan-Himalayan Mountains,with only a few species extending to E or S Asia．Sect．Albibractea is distributed mainly in the subtropics and tropics,lower altitudes and moist areas in S & SE Asia,with a few species extending to the Qinling range of China．Both sections are more advanced than the other sections．They were studied by cladistic analysis and outgroup comparison．Data matrix of 55 characters from stems,leaves,inflorescences,female flowers,bisexual flowers,achenes,pollen grains and chemical constitution was employed in separate and combined studies．Eighteen most parsimonious cladograms were generated with 358 steps,consistency index of 0．72 and retention index of 0．87． 1．Within Artemisia,Sect．Viscidipubes and Sect．Albibractea are sister groups to all the other groups． 2．We support the idea to separate Sect．Viscidipubes (incl．Ser．Viscidipubes,Ser．Erlangshanenses and Ser. Pleiocephalea) and Sect．Albibractea (incl．Ser．Albibractea,Ser．Flaccidae and Ser. Anomalae)．The authors suggest that Ser．Anomalae include A．deversa and Ser．Erlangshanenses include A．zayuensis and A．yadongensis as well as Ser．Viscidipubes include A．gyitangensis and A．boreali-siamensis．As the result of the cladistic analysis,the authors tend to propose a new series, Ser．Tanguticae,incl．A．tangutica in the section． 3．We consider that SW China,especially W Sichuan,is the speciation center and the tration of the present distribution center．4．A．boreali-siamensis,only in N Thailand,is not related to the widely distributed species in Ser．Pleiocephalae,such as A．atrovirens,A．chingii and A．myriantha,but rather closely related to species,such as A．vexans,A．occidentali-sichuanensis,which are endemic to W.Sichuan and E．Xizang．     

Two new species of Justicia sect. Ansellia (Acanthaceae) from E and NE tropical Africa

The new species Justicia ornatopila from Sudan, Ethiopia, Somalia, Uganda, Kenya and Tanzania, and J. lorata from Kenya are described and illustrated. Information on pollen morphology is also provided     

Astragalus sect. Dissitiflori (Fabaceae) in Iran

Two new species, Astragalus ghahremaninejadii and A. kharvanensis are described from Iran and illustrated. They belong to A. sect. Dissitiflori , which contains species with bifurcate hairs. The first is similar to A. pendulinus, A. baldschuanicus, A. kustanaicus and properly A. marguzaricus and only known from a single collection close to the Turkmenistan frontier. The second shows morphological similarities with A. dendroproselius especially A. viridis. Also A. dendroproselius is reported as a new record for the flora of Iran.     

Astragalus sect. Trachycercis (Fabaceae) in Iran

A diagnostic key, and new data are provided for seven species of Astragalus sect. Trachycercis , which occur within the area covered by the Flora of Iran. Astragalus brevipedunculatus Ranjbar is described as new, and A. armeniacus Boiss. is reported as new for the flora of Iran. The micromorphology of the seed coat surface of ten Astragalus taxa has been studied by SEM. Considerably different types of sculpturing at species level and similarities between related taxa were observed. In addition, differences between A . sect. Trachycercis and the closely related sections A . sect. Erioceras and A. sect. Wettsteiniana are discussed. Astragalus durandianus , A. pseudoshebarensis and A. shebarensis , which all have strongly inflated pods, are transferred from A . sect. Erioceras to A. sect. Wettsteiniana. Astragalus brevipedunculatus sp. nov., described from a small region near Aras River in Iran, is the only geographically isolated species of the section. Members of the section prefer habitats from coastal dune climates of the Azarbaijan Sharqi Province to the Armenian and Azarbaijan frontiers, although possibly also growing in the adjacent southern parts of Armenia and Azarbaijan. Astragalus brevipedunculatus sp. nov. is the only species of the section in Iran and neighboring countries that has few pairs of leaflets and is completely glabrous. The new species should be considered as a 'Critically Endangered' (CR) following the IUCN criteria. A distribution map for A. brevipedunculatus and A. armeniacus is presented.     

Novelties in Satureia sect. Gardoquia (Labiatae)

A new key is provided to the North American species of sect.Gardoquia; two varieties are recognized in the widespread Mexican speciesS. macrostema; andS. jaliscana, a species associated with barranca-forests in Jalisco, Mexico, is described as new.     

Astragalus sect. Astragalus (Fabaceae) in Iran

Astragalus rahiminejadii , a new species endemic to Iran, is described and illustrated. This species, which belongs to section Astragalus , is confined to the western part of Iran (Prov. Kermanshah) and is known only from a single population. Seed testa morphology as viewed under the scanning electron microscope is discussed and photomicrographs are provided. In addition, the geographical distribution and ecology of the species belonging to this section are discussed.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 147 , 363–368.     

Molecular data to elucidate the taxonomy of Seseli sect. Seseli (Apiaceae) in east Mediterranean and southern Europe

The taxonomy of the type section of the genus Seseli is revised based on newly obtained molecular data. The type species of the genus, Seseli tortuosum, is shown to be a polyphyletic taxon and is split into two species: the western Mediterranean S. tortuosum and the eastern Mediterranean S. arenarium. The Turkish endemics S. hartvigii, S. serpentinum and S. andronakii, and the Transcaucasian S. grandivittatum form a complex of closely related species together with S. arenarium. The results of the molecular analysis confirm the specific rank of S. corymbosum, S. phrygium and S. paphlagonicum and the status of S. gummiferum as distinct from either of these three. The latter species is strictly endemic to Crimea and does not occur in Turkey.     

The acaulescent and succulent species of Dorstenia sect. Kosaria (Moraceae) from NE tropical Africa and Arabia

The acaulescent and succulent species of Dorstenia sect. Kosaria in NE tropical Africa include the well defined D. ellenbeckiana and the two polymorphic taxa, the D. barnimiana complex and the D. foetida complex. The D. barnimiana complex is treated as two species, D. barnimiana Schweinf. and D. tropaeolifolia (Schweinf.) Bureau. One specific name and four varietal names are reduced to synonymy. The D. foetida complex is treated as one species, D. foetida (Forssk.) Schweinf., with two subspecies, ssp. foetida and ssp. lancifolia (Rendle) Friis comb, nov., of which the former is further divided into var. foetida and var. obovata (A. Rich.) Schweinf. & Engl. Three species arc reduced to synonymy of D. foetida. The distribution of all the species is mapped.