A phylogenetic analysis of the aureoidSenecio (Asteraceae) complex based on ITS sequence data

The internal transcribed spacer region of the 18S–25S nuclear ribosomal DNA repeat was sequenced from 28 populations of the aureoidSenecio complex as well as two populations from the Lugentes group and one from the Tephroseroid group. Divergence levels for populations within the aureoid complex are very low (0.0 to 4.1%). Phylogenetic trees generated from the sequence data provide no support for the recognition of Aurei, Tomentosi and Lobati subgroups within the aureoid complex. With two Lugentes and one Tephroseroid species as outgroups,Senecio glabellus is the sister group of the rest of the aureoids. The high level of divergence between the aureoids and the three outgroup species indicates that the Lugentes and the Tephroseroids may not be closely related to the aureoids.     

A comparison of the pollen wall ultrastructure of aureoid and non-aureoidSenecio species (Asteraceae) in North America

The structure of the pollen wall as revealed by transmission electron microscopy is presented for 29 speciesSenecio including 19 aureoid and ten non-aureoid species. The previous report of a helianthoid wall structure (exine with internal foramina) is confirmed for all the aureoid species examined while all of the non-aureoid taxa showed a senecioid pattern. The data provide support for the treatment of the aureoid complex as a distinct taxon.     

A phylogeny of Packera (Senecioneae; asteraceae) based on internal transcribed spacer region sequence data and a broad sampling of outgroups

A phylogeny of Packera is presented based on sequence data from the internal transcribed spacer region of nuclear ribosomal DNA of 26 species (28 populations) of Packera and 23 outgroup taxa, including representatives of all three subtribes of the Senecioneae. The results support a Mexican origin for Packera, with its closest relatives found among Old World taxa in the subtribe Senecioninae, such as Senecio jacobaea and Pericallis. Packera species from the west coast of the United States, previously included in the section Bolanderi of Greenman, are part of a basal assemblage including species of Greenman's Mexican section Sanguisorboidei. The rest of Packera separates into two sister groups, one containing species from the Arizona-New Mexico region and the other containing more geographically diverse taxa. Among the outgroups, New World Senecio species are monophyletic and two Tussilaginoid assemblages are strongly supported; the Tephroseroid group (Tephroseris and Sinosenecio) plus Petasites combine with the Luina complex to form a clade of north temperate taxa, and the four Mexican genera (Psacalium, Robinsonecio, Barkleyanthus, and Pittocaulon) form a monophyletic group.     

Elucidative studies on the generic concept of Senecio (Asteraceae)

VINCENT, P. L. D. & GETLIFFE, F. M., 1992. Elucidative studies on the generic concept of Senecio (Asteraceae) . This paper presents the results of studies of the generic concept of Senecio sensu stricto. The sample of taxa studied consisted of 93 Natal senecios (including seven varieties and two forms), five Cape heterochromous senecios and nine non-southern African senecios, including the type of the genus, S. vulgaris L. Also included in the study were six species from taxonomically closely related genera in the tribe Senecioneae and one Senecio of uncertain taxonomic position. The phenotype of these taxa was investigated with respect to a large number (122) of morphological and micromorphological characters. Six characters were selected as being taxonomically important with respect to elucidating the generic concept of Senecio sensu stricto. The generic concept of Senecio has been provisionally re-circumscribed and the generic status of each of the senecios and non-senecios studied has been tested according to this concept of Senecio sensu stricto sensu Vincent. In the light of this concept of Senecio , the following species are recommended for exclusion from Senecio sensu stricto sensu Vincent: S. cissampelinus, S. transvaalensis, S. syringifolius and S. hockii. The following species are considered to be peripheral to Senecio sensu stricto sensu Vincent: S. tanacetopsis, S. seminiveus, S. medley-woodii, S. tamoides, S. helminthioides, S. barbertonicus, S. brevilorus, S. viminalis, S. radicans and S.fulgens. Before any taxonomic changes are made to the current composition of Senecio , the concept of Senecio sensu stricto sensu Vincent, is being tested on a worldwide sample of the genus.     

Reciprocal hybridization at different times between Senecio flavus and Senecio glaucus gave rise to two polyploid species in north Africa and south-west Asia

The analysis of hybrid plant taxa using molecular methods has considerably extended understanding of possible pathways of hybrid evolution. Here, we investigated the origin of the tetraploid Senecio mohavensis ssp. breviflorus and the hexaploid Senecio hoggariensis by sequencing of nuclear and chloroplast DNA, and by analysis of the distribution of taxon-specific amplified fragment length polymorphism (AFLP) fragments. Both taxa originated from hybridization between the diploid Senecio flavus and Senecio glaucus. Whereas S. glaucus was the female parent in the origin of S. mohavensis ssp. breviflorus, S. flavus was the female parent in the origin of S. hoggariensis. The distribution of AFLP fragments suggests that S. hoggariensis is an allohexaploid species with two diploid genomes of S. glaucus and one diploid genome of S. flavus. The high frequency of S. flavus-specific fragments in S. mohavensis ssp. breviflorus is explained either as the result of introgression between a primary hybrid and S. flavus or as the result of intergenomic recombination in a primary hybrid. These two alternative processes cannot easily be distinguished.     

稻城千里光(菊科-千里光族)的名实订正

通过标本(包括模式标本)检查,发现稻城千里光(Senecio daochengensis Y. L. Chen)与黑褐千里光(S. atrofuscus Grierson)属于同一种植物,故将前者处理为后者的异名。提供了黑褐千里光的地理分布图及其与近缘种的检索表。     

Morphometric comparison of Senecio germanicus and S. nemorensis (Compositae) with a new species from Romania

Morphometric comparison of three taxa of the Senecio nemorensis group, namely S. germanicus Wallr., S. nemorensis L. and a new species S. dacicus Hodálová & Marhold is presented. S. dacicus, representing plants with eight ligules from the Romanian Carpathians, previously identified as S. nemorensis L., is shown to be clearly distinct from the Siberian plants of S. nemorensis, which include the lectotype of this Linnaean name. Detailed data on the distribution of S. dacicus are presented. Numerical methods used include principal components analysis, cluster analysis, and canonical and non-parametric classificatory discriminant analysis.     

Tumbleweed (Salsola, section Kali) species and speciation in California

Tumbleweeds (Salsola species, section Kali) are road side and rangeland pest plants throughout the 48 contiguous states in the US. Three described tumbleweed species and two undescribed Salsola taxa occur in California. The known species are Russian thistle, Salsola tragus, introduced from Eurasia in the 1800s, Russian barbwire thistle, S. paulsenii, which grows in the desert regions of California, and is also native to Eurasia, and the recently identified S. kali subspecies austroafricana, possibly native to South Africa. Our goals were to investigate karyology, genome size, and molecular genetic affinities of the described species and the other taxa within their ranges in California using recently developed microsatellite loci, dominant nuclear DNA markers (RAPD and ISSR), and DNA sequence data. Chromosome counts and genome size assessments made with flow cytometry were compared. These analyses indicated that one undescribed taxon is a new allopolyploid hybrid between S. tragus and S. kali subspecies austroafricana, and the other undescribed taxon appears to be a complex hybrid involving all three described species. The invasion potentials for the hybrid taxa are unknown. Tumbleweeds are the focus of biological controls efforts but the identification of suitable agents for the hybrid taxa may be problematic because of the large amount of genetic variability encompassed within this evolving Salsola complex.     

GENETIC SIMILARITY IS HIGH BETWEEN INTERCONTINENTAL DISJUNCT SPECIES OF SENECIO (ASTERACEAE)

Senecio flavus (Decne.) Schultz-Bip. of the Saharo-Arabian and Namibian deserts and Senecio mohavensis Gray of the Mojave and Sonoran deserts form a pair of closely related disjunct annual taxa. The two species exhibit slight morphological differences and have different ploidy levels: all North American populations examined are tetraploid, while African and Asian populations are diploid. Senecio flavus comprises two morphologically and geographically distinct subspecies, subsp. flavus and subsp. breviflorus Kadereit. Electrophoretic examination of 13 enzymes revealed that the subsp. breviflorus has two additional isozymes relative to subsp. flavus, and that 5. mohavensis has four additional isozymes relative to subsp. breviflorus. Senecio flavus subsp. breviflorus and S. mohavensis are identical at 20 of the 21 (I = 0.952) remaining homologous loci. This value is much higher than the genetic identity values observed in other taxa with disjunct intercontinental distributions such as members of Agastache, Datisca, Liriodendron, and Styrax. This suggests that the Senecio disjunction may be of recent origin. Senecio flavus subsp. flavus from North Africa and Namibia has lower genetic identity values with S. mohavensis (0.857 and 0.805, respectively), implicating S. flavus subsp. breviflorus as the progenitor of 5. mohavensis. The complete lack of heterozygosity confirms that the plants are highly autogamous, and thus could have attained their disjunct distribution through long distance dispersal.     

A phylogenetic delimitation of the "Sphagnum subsecundum complex" (Sphagnaceae, Bryophyta)

A seemingly obvious but sometimes overlooked premise of any evolutionary analysis is delineating the group of taxa under study. This is especially problematic in some bryophyte groups because of morphological simplicity and convergence. This research applies information from nucleotide sequences for eight plastid and nuclear loci to delineate a group of northern hemisphere peat moss species, the so-called Sphagnum subsecundum complex, which includes species known to be gametophytically haploid or diploid (i.e., sporophytically diploid-tetraploid). Despite the fact that S. subsecundum and several species in the complex have been attributed disjunct ranges that include all major continents, phylogenetic analyses suggest that the group is actually restricted to Europe and eastern North America. Plants from western North America, from California to Alaska, which are morphologically similar to species of the S. subsecundum complex in eastern N. America and Europe, actually belong to a different deep clade within Sphagnum section Subsecunda. One species often considered part of the S. subsecundum complex, S. contortum, likely has a reticulate history involving species in the two deepest clades within section Subsecunda. Nucleotide sequences have a strong geographic structure across the section Subsecunda, but shallow tip clades suggest repeated long-distance dispersal in the section as well.     

Can hybridization cause local extinction: a case for demographic swamping of the Australian native Senecio pinnatifolius by the invasive Senecio madagascariensis?

Hybridization between native and invasive species can have several outcomes, including enhanced weediness in hybrid progeny, evolution of new hybrid lineages and decline of hybridizing species. Whether there is a decline of hybridizing species largely depends on the relative frequencies of parental taxa and the viability of hybrid progeny. Here, the individual- and population-level consequences of hybridization between the Australian native Senecio pinnatifolius and the exotic Senecio madagascariensis were investigated with amplified fragment length polymorphism (AFLP) markers, and this information was used to estimate the annual loss of viable seeds to hybridization. A high frequency (range 8.3-75.6%) of hybrids was detected in open pollinated seeds of both species, but mature hybrids were absent from sympatric populations. A hybridization advantage was observed for S. madagascariensis, where significantly more progeny than expected were sired based on proportional representation of the two species in sympatric populations. Calculations indicated that S. pinnatifolius would produce less viable seed than S. madagascariensis, if hybridization was frequency dependent and S. madagascariensis reached a frequency of between 10 and 60%. For this native-exotic species pair, prezygotic isolating barriers are weak, but low hybrid viability maintains a strong postzygotic barrier to introgression. As a result of asymmetric hybridization, S. pinnatifolius would appear to be under threat if S. madagascariensis increases numerically in areas of contact.     

Molecular phylogenetics and diagnosis of Anisakis, Pseudoterranova, and Contracaecum from northern Pacific marine mammals

Individual specimens of Anisakis, Pseudoterranova, and Contracaecum collected from marine mammals inhabiting northern Pacific waters were used for comparative diagnostic and molecular phylogenetic analyses. Forty-eight new sequences were obtained for this study of 14 Anisakis taxa, 8 Pseudoterranova taxa, 4 Contracaecum taxa, and 4 outgroup species. Partial 28S (LSU) and complete internal transcribed spacer (ITS-1, 5.8S, ITS-2) ribosomal DNA was amplified by the polymerase chain reaction and sequenced. Sequences of ITS indicated that Pseudoterranova specimens from Zalophus californianus (California sea lion), Mirounga angustirostris (northern elephant seal), Phoca vitulina (harbor seal), Enhydra lutris (sea otter), and Eumetopias jubatus (Steller's sea lion) exactly matched P. decipiens s. str., extending the host and geographic range of this species. Anisakis from northern Pacific marine mammals were most closely related to members of the A. simplex species complex. Comparison of Anisakis ITS sequences diagnosed the presence of A. simplex C in 2 M. angustirostris hosts, which is a new host record. Anisakis specimens from Phocoena phocoena (harbor porpoise), Lissodelphis borealis (Pacific rightwhale porpoise), and E. jubatus included 3 ITS sequences that did not match any known species. Contracaecum adults obtained from Z. californianus were most closely related to C. ogmorhini s.l. and C. rudolphii, but ITS sequences of these Contracaecum specimens did not match C. ogmorhini s. str. or C. margolisi. These novel Anisakis and Contracaecum ITS sequences may represent previously uncharacterized species. Phylogenetic analysis of LSU sequences revealed strong support for the monophyly of Anisakinae, Contracaecum plus Phocascaris, Pseudoterranova, and Anisakis. Phylogenetic trees inferred from ITS sequences yielded robustly supported relationships for Pseudoterranova and Anisakis species that are primarily consistent with previously published phenograms based on multilocus electrophoretic data.     

Inferring species trees from gene trees in a radiation of California trapdoor spiders (Araneae, Antrodiaetidae, Aliatypus)

Background

The California Floristic Province is a biodiversity hotspot, reflecting a complex geologic history, strong selective gradients, and a heterogeneous landscape. These factors have led to high endemic diversity across many lifeforms within this region, including the richest diversity of mygalomorph spiders (tarantulas, trapdoor spiders, and kin) in North America. The trapdoor spider genus Aliatypus encompasses twelve described species, eleven of which are endemic to California. Several Aliatypus species show disjunct distributional patterns in California (some are found on both sides of the vast Central Valley), and the genus as a whole occupies an impressive variety of habitats.

Methodology/Principal Findings

We collected specimens from 89 populations representing all described species. DNA sequence data were collected from seven gene regions, including two newly developed for spider systematics. Bayesian inference (in individual gene tree and species tree approaches) recovered a general “3 clade” structure for the genus (A. gulosus, californicus group, erebus group), with three other phylogenetically isolated species differing slightly in position across different phylogenetic analyses. Because of extremely high intraspecific divergences in mitochondrial COI sequences, the relatively slowly evolving 28S rRNA gene was found to be more useful than mitochondrial data for identification of morphologically indistinguishable immatures. For multiple species spanning the Central Valley, explicit hypothesis testing suggests a lack of monophyly for regional populations (e.g., western Coast Range populations). Phylogenetic evidence clearly shows that syntopy is restricted to distant phylogenetic relatives, consistent with ecological niche conservatism.

Conclusions/Significance

This study provides fundamental insight into a radiation of trapdoor spiders found in the biodiversity hotspot of California. Species relationships are clarified and undescribed lineages are discovered, with more geographic sampling likely to lead to additional species diversity. These dispersal-limited taxa provide novel insight into the biogeography and Earth history processes of California.     

Natural hybridization between Senecio jacobaea and Senecio aquaticus: molecular and chemical evidence

Hybridization is known to be involved in a number of evolutionary processes, including species formation, and the generation of novel defence characteristics in plants. The genus Senecio of the Asteraceae family is highly speciose and has historically demonstrated significant levels of interspecific hybridization. The evolution of novel chemical defence characteristics may have contributed to the success of Senecio hybrids. Chemical defence against pathogens and herbivores has been studied extensively in the model species Senecio jacobaea, which is thought to hybridize in nature with Senecio aquaticus. Here, we use amplified fragment length polymorphisms (AFLPs) and pyrrolizidine alkaloid (PA) composition to confirm that natural hybridization occurs between S. jacobaea and the closely related species S. aquaticus. AFLPs are also used to estimate the ancestry of hybrids. We also demonstrate that even highly back-crossed hybrids can possess a unique mixture of defence chemicals specific to each of the parental species. This hybrid system may therefore prove to be useful in further studies of the role of hybridization in the evolution of plant defence and resistance.     

Contributions toward understanding the biodiversity of Passiflora in North America: Updates and a new combination from the Baja California Peninsula,Mexico and vicinity

The Baja California Peninsula and surrounding landmasses harbor an abundant flora in an otherwise harsh and arid environment. Of the many plant groups native to this peninsular and insular region, passionflowers (Passiflora, Passifloraceae) are represented by several conspicuous taxa that all belong to a single lineage, section Dysosmia. Basic questions remain regarding this group, particularly the taxonomic status among the Passiflora arida complex. Therefore, we investigated the claims of endemism, habitat characteristics, and taxon boundaries with in section Dysosmia in the Baja California region using extensive sampling of herbarium specimens and iNaturalist observations. We confirmed that only one of the native Passiflora taxa (P. fruticosa) was endemic to the Baja California Peninsula, with an additional taxon (P. palmeri) considered near‐endemic. Environmental data revealed significant distinctions between the habitats of many of the native taxa as well as within the P. arida complex, especially with respect to precipitation and temperature tolerances. Geometric morphometric analyses of leaf shape were largely not successful at separating taxa, indicating leaf shape may not be a good indicator of taxon identity in this particular group. Based on ecological differences and discrete macro‐ and micromorphological features, a varietal name is here synonymized and a new combination is proposed: Passiflora pentaschista.     

Tackling speciose genera: species composition and phylogenetic position of Senecio sect. Jacobaea (Asteraceae) based onplastid and nrDNA sequences

The molecular phylogeny of Senecio sect. Jacobaea (Asteraceae; Senecioneae) was studied to clarify species composition and interspecific relationships of Senecio sect. Jacobaea. This information is necessary for studies seeking explanations of the evolutionary success of Senecio, in terms of high species numbers and the evolution of chemical defense mechanisms. Parsimony analyses with 60 species of the tribe Senecioneae, representing 23 genera and 11 sections of Senecio, based on DNA sequence data of the plastid genome (the trnT-L intergenic spacer, the trnL intron, and two parts of the trnK intron, flanking both sides of the matK gene) and nuclear genome (ITS1, 5.8S, and ITS2 gene and spacers) show that sect. Jacobaea is a strongly supported monophyletic group. Fifteen species have been identified as members of section Jacobaea, including three species that have been consistently ascribed to this section in taxonomic literature and 12 species that were either placed in other sections of Senecio or not exclusively ascribed to sect. Jacobaea. This section was traditionally circumscribed as a group of European, biennial, or perennial herbs with pinnately incised leaves, but the results of this study show that one annual species, a species from northeastern Asia, and a species growing in the Himalayas are members of sect. Jacobaea as well. Furthermore, not all species in the section have pinnately incised leaves. The genera Emilia, Packera, and Pseudogynoxys form the sister clade of sect. Jacobaea, but this relationship lacks strong bootstrap support and thus remains provisional.     

Genetic and morphological divergence within the Sebastes pachycephalus complex (Scorpaeniformes: Scorpaenidae)

Genetic and morphological divergence among the four subspecies in the Sebastes pachycephalus complex (S. pachycephalus pachycephalus, S. p. nigricans, S. p. nudus and S. p. chalcogrammus) was clarified. Principal coordinate analysis (PCoA) based on AFLP clearly divided 55 specimens of the complex into two groups, the S. p. pachycephalus?CS. p. nigricans group (P-Ni group) and the S. p. nudus?CS. p. chalcogrammus group (Nu-C group), although three specimens occupied intermediate positions. The minimum spanning network (MSN) based on partial sequences of the mitochondrial control region (mtCR) failed to separate either the P-Ni and Nu-C groups or the four subspecies into distinct clades, although restricted gene flow and genetic differentiation between the former were indicated by the F _ST estimation. Differences in morphological characters, including counts of pectoral fin rays and counts of dorsal fin spines lacking basal scales, were also evident between the two groups. However, little or no genetic or morphological difference was found between the two subspecies within each group. It was concluded that the P-Ni and Nu-C groups of the S. pachycephalus complex actually represent two different species, which is further supported by their sympatric distribution. Differences in dorsal body coloration and the presence or absence of brown spots on the ventral surface, which were formerly used to discriminate between four ??subspecies,?? may simply represent intraspecific variation. The three specimens occupying intermediate positions in the AFLP PCoA also occupied equivocal positions between the two species in the principal component analysis (PCA) based on morphometric characters, suggesting that they were hybrids between the two species. The star-shaped MSN of mtCR, which lacks distinct clades representing the two species, may be due to not only interspecific hybridization but also the sharing of ancestral haplotypes.     

Molecular evaluation of nominal species in the Ceratitis fasciventris, C. anonae, C. rosa complex (Diptera: Tephritidae)

Ceratitis fasciventris, C. anonae and C. rosa form a complex of economically important fruit fly pests infesting a variety of crops in African countries. Hitherto only adult males of these species can be distinguished easily by morphological characters. Other stages cannot, and for some taxa the taxonomic interpretation and species boundaries remain unclear. In order to clarify phylogenetic relationships and taxonomic status of these species, sequences of mitochondrial (16S, COI, ND6) and nuclear markers (period, ITS1) were analysed in specimens of the three morphospecies throughout the distribution of the complex. Maximum likelihood trees did not recover monophyletic groups corresponding to the morphospecies. Conversely, ND6 and COI divided West African C. fasciventris specimens in two consistent and bootstrap supported clades, involving specimens from Benin and from Mali/Ivory Coast, while the nuclear gene fragments per and ITS1 recovered a well-supported clade corresponding to C. fasciventris from Kenya/Uganda. Hence, the phylogenetic relationships and taxonomic interpretation of the complex appear more intricate than previously hypothesised. The current molecular data do not allow to identify C. fasciventris, C. anonae and C. rosa as distinct phylogenetic species but rather suggest that the morphospecies C. fasciventris is itself a complex of cryptic taxa.