A biosystematic study of Pacific Northwestern blue-eyed grasses (Sisyrinchium,Iridaceae)

Thirteen species of blue-eyed grasses had been described for the Pacific Northwest prior to this study. Contemporary taxonomic treatments vary; some authors recognize several of the taxa as valid species, others recognize only one highly variable, widely distributed species. Work has been directed to achieve an understanding of the biological integrity of all previously described species within the northwest. Living plants from natural populations were utilized in controlled artificial hybridization experiments, analysis of breeding systems, and cytological investigations. Hybrids of intraand interspecific crosses were examined for pollen fertility, and investigated cytologically for meiotic behavior. Eight genetically compatible groups are indicated from these experiments. Additional information gained from cytological analysis, breeding systems, ecology, distribution, and morphological studies substantiates the recognition of each genetically compatible group at the specific level, including the new species,S. hitchcockii, from southern Oregon. The following taxa are recognized for the Pacific Northwest: tetraploids (n = 16)S. bellum S. Wats.,S. halophilum Greene,S. septentrionale E. P. Bicknell; octoploids (n = 32)S. idahoense E. P. Bicknell (including the vars.segetum,macounii, andoccidentale), andS. hitchcockii D. Henderson; duodecaploids (n = 48)S. idahoense E. P. Bicknell var.idahoense, S. littorale Greene,S. montanum Greene, andS. sarmentosum Suksd. ex Greene.     

Taxonomy and distribution of Clematis,sect. Atragene (Ranunculaceae), in North America

Two North American species ofClematis, sect.Atragene (L.) DC, are recognized.C. occidentalis (Hörnern.) DC. is divided into three varieties, native respectively to eastern North America, the Rocky Mountains, and the Cascade Mountains of Washington.C. columbiana (Nutt.) Torr. & Gray is divided into two extensively intergrading varieties, one prevailing in the southern Rocky Mountains, the other in the northern foothills and in outlying mountain ranges. After a study of the type specimen ofC. columbiana, it was concluded that this name should be applied to the species hitherto commonly known asC. pseudoalpina (O. Kuntze) A. Nels., rather than to the taxon with which it has usually been associated. The two species are evidently closely related and appear occasionally to have hybridized in nature.     

Low levels of hybridization across two contact zones among three species of woodpeckers (Sphyrapicus sapsuckers)

Three species of closely related woodpeckers (sapsuckers; Sphyrapicus) hybridize where they come into contact, presenting a rare ‘λ‐shape’ meeting of hybrid zones. Two of the three arms of this hybrid zone are located on either side of the Interior Plateau of British Columbia, Canada bordering the foothills of the Coast Mountains and the Rocky Mountains. The third arm is located in the eastern foothills of the Rocky Mountains. The zones of hybridization present high variability of phenotypes and alleles in relatively small areas and provide an opportunity to examine levels of reproductive isolation between the taxa involved. We examined phenotypes (morphometric traits and plumage) and genotypes of 175 live birds across the two hybrid zones. We used the Genotyping By Sequencing (GBS) method to identify 180 partially diagnostic single nucleotide polymorphisms (SNPs) to generate a genetic hybrid index (GHI) for each bird. Phenotypically diverged S. ruber and S. nuchalis are genetically closely related, while S. nuchalis and S. varius have similar plumage but are well separated at the genetic markers studied. The width of both hybrid zones is narrower than expected under neutrality, and analyses of both genotypes and phenotypes indicate that hybrids are rare in the hybrid zone. Rarity of hybrids indicates assortative mating and/or some form of fitness reduction in hybrids, which might maintain the species complex despite close genetic distance and introgression. These findings further support the treatment of the three taxa as distinct species.     

Genetic evidence for species cohesion,substructure and hybrids in spruce

The origin and history of species are shaped by various evolutionary dynamics, including their persistence in the face of potential gene flow from related taxa. In this study, we use broad geographical and taxonomic sampling (2,219 individuals) to establish the distribution of species, hybrids and cryptic genetic variation within the conifer genus Picea (spruce) across western North America. We demonstrate that the six species of spruce in this region are distinguishable based on their genetic composition, and that the more closely related Engelmann spruce (P. engelmannii) and white spruce (P. glauca) have generated numerous and widespread hybrids. These hybrids occur in the central Rocky Mountains, well to the south of the well‐established region of admixture in Canada. Additionally, we provide evidence for subdivision within Engelmann spruce, manifested as a southern Rocky Mountains form, and a northern Rocky Mountain and Cascade mountains (western) form. In the intervening central Rocky Mountains region (forests in Wyoming and adjacent states) we found primarily individuals with admixed ancestry. Following their origin, these species of spruce have interacted repeatedly and in different geographical contexts. Multiple pairs of species have been shown to hybridize, yet the species persist and retain distinguishable compositions. At the same time, large geographical areas exist where hybrids are pervasive. Consequently, spruce provide a case study for the maintenance of species boundaries, particularly for how widespread hybridization need not lead to the collapse and loss of species.     

Chromosome numbers in Great Plains species of Penstemon (Scrophulariaceae)

Chromosome numbers are reported for 79 populations ofPenstemon representing 20 species. All but two species counted here are diploids. First counts are reported for seven taxa, all asn=8 or 2n=16.     

Chromosome numbers,polyploidy, and hybridization in castilleja (scrophulariaceae ) of the Great Basin and Rocky Mountains

Chromosome numbers are reported for 190 collections ofCastilleja of the Great Basin-Rocky Mountains and adjacent regions in western North America. Polyploidy has played a major role in evolu tion of this genus. Of the 35 taxa represented, 14 are exclusively diploid (n =12). The remaining 21 taxa exhibit polyploidy: eight are tetraploid only, two are octopIoid only, while 11 of the more wide-ranging species have two or more levels of polyploidy. BothC. rhexifolia andC. sulphured have diploid, tetraploid, and octoploid races while the widespreadC. miniata has four (2x, 4x, 8x, and 10x). Where appropriate, the role of polyploidy and hybridization inCastilleja evolution and their relevance to taxonomy are discussed for individual species.     

Papaver at high altitudes in the rocky mountains

In the Rocky Mountains south of the Yukon Territory there are two, possibly three,Papaver species at alpine elevations. The diploidP. pygmaeum Rydb. is found only in and around the Glacier-Waterton International Park. It is a member of thealpinum complex of sect.Scapiflora and linked to the EuropeanP. alpinum L. by a chain of taxa through inner Asia. The hexaploidP. kluanense D. Löve is an alpine representative of the circumpolarradicatum complex of the same section and occurs disjunct from Alaska and Yukon south to New Mexico. In the Uintah Mountains of Utah is a small population ofPapaver whose affiliation and rank within the sectionScapiflora is not yet established. It seems to be related most closely toP. pulvinatum A. Tolm. andP. alaskanum Hultén. A key to the taxa of this region is presented.     

Taxonomy of Pedicularis parryi (Scrophulariaceae)

The karyology and taxonomy ofPedicularis parryi A. Gray is discussed, and it is proposed that the species consists of three subspecies: ssp.parryi, ssp.purpurea, and ssp.mogollonica. A key to these taxa, and also a key to the Rocky Mountain species most likely to be confused with them are presented.     

Chromosome numbers of goldenrods,Euthamia and Solidago (Compositae: Astereae). II. Additional counts with comments on cytogeography

Chromosome number determinations were made from 407 wild or transplanted individuals and seedlings representing 65 taxa and hybrids inEuthamia andSolidago. The following are first reports:Euthamia remota, 2n=9II;Solidago leavenworthii, 2n=54;S. mollis, 2n=36;S. mollis var.angustata, 2n=36;S. rigida var.glabrata, 2n=9II;S. sempervirens var.azorica, 2n=9II; andS. sparsiflora, 2n=54. Most species have been sampled only a few times or are consistently of one cytotype. Sufficient counts have been made to indicate some general patterns of cytotype distribution in the following species complexes:S. gigantea, S. canadensis, S. flexicaulis, S. rugosa, andS. uliginosa.     

A biosystematic analysis of the Caltha leptosepala (Ranunculaceae) complex in the Rocky Mountains I. Chromatography and cytotaxonomy

Part one of a biosystematic study of theCaltha leptosepala complex in the Rocky Mountains involves a brief history of the taxonomic problem in addition to analyses of phenolic chromatography and cytotaxonomy. Data obtained from the natural populations sampled support the premise that only one species,Caltha leptosepala, can be taxonomically justified for the Rocky Mountains.     

Polyploidy and Evolution in Wild and CultivatedDahliaSpecies

Observations on the chromosomes of nine species ofDahliaCav.(Asteraceae, Heliantheae—Coreopsidinae) show that somehave 2n=32, others 2n=64, with a third group having both chromosomenumbers in the same taxon. Karyotype investigations showed thatthe chromosomes can be divided into groups of 14 metacentricsplus two submetacentrics per set of 16 chromosomes.In situhybridizationusing an rRNA gene probe indicated that the 2n=32 species haveeight hybridization sites whilst the 2n=64 species have 16 sites.Silver nitrate staining of these regions showed that not allof these nucleolar organizers are active. Meiotic analysis atmetaphase I and pachytene, by synaptonemal complex spreading,shows that the 2n=32 species have exclusive bivalent formationwhereas the 2n=64 species have small numbers of univalents plusquadrivalents in addition to bivalents. This study proposesthatDahliaspecies with 2n=32 are allotetraploids whereas thosespecies and chromosome races with 2n=64 are their autopolyploidderivatives. We suggest that a bivalent-promoting mechanismin the 2n=32 species may account for their meiotic behaviouras their component genomes appear so similar, and that thismechanism is also responsible for the low number of quadrivalentsin the 2n=64 taxa.Copyright 1998 Annals of Botany Comapny Chromosome pairing,Dahlia, in situhybridization, karyotype analysis, polyploidy, synaptonemal complex analysis     

Myriophyllum quitense and myriophyllum ussuriense (Haloragaceae) in British Columbia,Canada

Myriophyllum quitense andM. ussuriense are added to the flora of British Columbia, Canada.Myriophyllum quitense has not been previously reported in Canada, and this is the first report ofM. ussuriense for the North American continent. Problems with the identification of these species, and their distributions and habitats are discussed. The somatic chromosome numbers of 2n=42 forM. quitense and 2n=21 forM. ussuriense were found. A key for the identification ofMyriophyllum taxa growing in British Columbia is given.     

Chromosome numbers of Orthocarpus and related monotypic genera (Scrophulariaceae: Subtribe castillejinae)

A chromosome number ofn=12 is reported for the three monotypic genera of subtribe Castillejinae:Clevelandia beldingii, Gentrya racemosa, andOpicopephalus angustifolius. Chromosome numbers ofOrthocarpus correspond mostly with current infrageneric classification. SubgenusTriphysaria hasn=11.Orthocarpus sectionsCastillejoides andCordylanthoides, which are closely related toCastilleja (x=12) and the three monotypic genera above, haven=12 with aneuploid reductions ton=10 inO. linearilobus andn=11 inO. lacerus (a species also withn=12). Tetraploids are found in two species.O. brevistylus (n=24) andO. hispidus (n=12, 24). The polyploid.O. laciniatus (n=36, 48) of Peru is postulated to be of hybrid origin between a species ofCastilleja andOrthocarpus attenuatus. SubgenusOrthocarpus sectionOrthocarpus, which hasn=14 in all species except.O. bracteosus (n=15), stands apart both morphologically and in chromosome number from the remainder of the genus.     

The variation and evolution of selected species of Solanum section Basarthrum (Solanaceae). II

Five taxa ofSolanum sect.Basarthrum were studied in an effort to clarify their taxonomic position and to determine the effective evolutionary mechanisms. Methods included an analysis of chromosome number and behavior, artificial hybridizations and a study of herbarium material. The data suggest thatS. canense andS. suaveolens are closely related and that 5.suaveolens may have been the progenitor ofS. canense. The only successful interspecific cross involving one of these two species was vigorous but highly sterile. Evidence from both morphology and crossing studies indicates a close relationship betweenS. basendopogon andS. caripense. Hybrids between these two species with relatively high fertility through the F₃ generation were secured. The status ofS. basendopogon f.obtusum remains a problem since there is but one collection of the typical form. The placement ofS. sanctae-marthae in sect.Basarthrum is considered problematic. Virtually none of 170 interspecific crosses with this species were successful. Seed size and the presence and size of a seed wing are proposed as useful morphological characters in sect.Basarthrum. There is apparently a correlation between short styles and self-compatibility. All species are diploid (n = 12) and no chromosomal or meiotic aberrations were noted in the species or hybrids. Most of the more than 1,000 interspecific crosses failed. Most of the hybrid fruits bore no seeds or seeds which did not germinate. The primary barriers separating species are considered to be strong prefertilization isolating mechanisms and ecogeographic factors.     

Misapplication of the name stachys nuttallii (Lamiaceae) to a new southeastern species

A recent study of Southeastern species ofStachys points out a problem involving the identity ofS. nuttallii Shuttlew. ex Bentham. Type material ofS. nuttallii is clearly representative of what is commonly known asS. riddellii House.S. riddellii of current authors must now be calledS. nuttallii, S. riddellii becoming a taxonomic synonym. However, no valid names have been uncovered in the literature that can be correctly applied to the species, primarily from the Blue Ridge Mountains, previously known to most botanists as “S. nuttallii.” These plants are described as a new species,Stachys eplingii.     

Population genetic structure of Picea engelmannii, P. glauca and their previously unrecognized hybrids in the central Rocky Mountains

Areas of geographic overlap between potentially hybridizing species provide the opportunity to study interspecific gene flow and reproductive barriers. Here we identified hybrids between Picea engelmannii and P. glauca by their genetic composition at 17 microsatellite markers, and determined the broad-scale geographic distribution of hybrids in the central Rocky Mountains of North America, a geographic region where hybrids and isolation between species had not previously been studied. Parameter estimates from admixture models revealed considerable variation in ancestry within and among collection sites, suggesting that within this area of geographic overlap, the interaction of the two species varies extensively. The results document a previously unrecognized patchy distribution of hybrids between P. engelmannii and P. glauca, including locations where hybrids were not known or expected to exist. Further, the ancestry of many hybrids was consistent with multiple generations of hybridization, with probable directional backcrossing to P. engelmannii, suggesting a relatively porous species boundary. The identification and characterization of hybridization between these spruce in this region raises the question of what factors maintain barriers to gene flow in these long-lived forest trees. The current research lays the groundwork for future study of the ecological and evolutionary contexts of their hybridization, as well as of differential introgression and permeability of species boundaries.     

New Karyotypes and Some Considerations about the Chromosomal Diversification of Ctenomys minutus (Rodentia: Ctenomyidae) on the Coastal Plain of the Brazilian State of Rio Grande do Sul

The dominant mammals occupying the subterranean niche in South America are rodents of the genus Ctenomys, which form a large group of 56 species with chromosome numbers ranging from 2n= 10 to 70. In southern Brazil, Ctenomys minutus is the species with the widest geographic distribution, inhabiting sandy fields and dunes extending from Jaguaruna beach in the state of Santa Catarina to the town of São José do Norte in the state of Rio Grande do Sul. Eleven karyotypes (2n= 42; 2n= 46a; 2n= 46b; 2n= 47a; 2n= 47b; 2n= 48a; 2n= 48b; 2n= 49a; 2n= 49b; 2n= 50a and 2n= 50b) were described for this species and zones of hybridization are also known. A sample of 51 C. minutus specimens was collected from five sampling sites about 20 km apart along the coastal plain of Rio Grande do Sul between the municipalities of Tavares (31°23′S 51°09′W) and São José do Norte (31°52′S 51°54′W). We were able to extend the known geographic distribution of C. minutus by 90 km, from Tavares southwards to São José do Norte. During our study we found five karyotypes (2n= 46b, 47b, 48b, 49b and 50b), four of which (2n= 47b, 48b, 49b and 50b) have not previously been described for this species.     

A study of morphological variability in chenopodium incanum (Chenopodiaceae) and the recognition of two new varieties

Study ofChenopodium incanum has revealed considerable variability in what has been viewed previously as a uniform species. Variation is correlated with geographic distribution, and thus two new varieties are described. Varietyeatum Crawford occurs in western Texas, southern New Mexico and southern Arizona, whereas var.occidentale Crawford is restricted to the Great Basin and Mohave Desert. The var.incanum grows primarily on the western Great Plains and eastern slopes of the Rocky Mountains. Morphological features serving to distinguish the varieties are presented and discussed. Also considered are the characters that allow the separation ofC. incanum andC. fremontii.