An analysis of morphological variation in Senecio cymbalaria (Asteraceae)

1992 ◽  
Vol 70 (2) ◽  
pp. 285-290 ◽  
Author(s):  
Jeannette Whitton ◽  
John F. Bain
Keyword(s):  
North America ◽  
Morphological Variation ◽  
Rocky Mountains ◽  
Morphological Analysis ◽  
Morphological Characters ◽  
Geographic Range ◽  
Data Matrix ◽  
Chromosome Counts ◽  
Southern Rocky Mountains ◽  
Key Words Biogeography

Senecio cymbalaria Pursh is an arctic-alpine perennial that exhibits a broad range of morphological variation and occurs in four disjunct regions within North America. In this study, a morphological analysis of herbarium material is undertaken to determine whether the observed morphological variation is primarily attributable to morphological discontinuities among geographically isolated groups. Eighty individuals representing the total geographic range of the species were scored for 24 morphological characters and the data matrix subjected to principal components and cluster analyses. Individuals from the southern Rocky Mountains, previously recognized as Senecio conterminus, are separated from the remainder of S. cymbalaria in both analyses. Our results support recognition of two species, S. conterminus and S. cymbalaria. Although populations from the Gaspé and from Newfoundland form somewhat distinct clusters, neither can clearly be distinguished from populations of S. cymbalaria from Alaska, the Yukon, and Northwest Territories. Chromosome counts of 2n = 138 were obtained from two individuals from the Gaspé peninsula. Key words: biogeography, phenetics, Gulf of St. Lawrence, Senecio, disjunction, chromosome numbers.

Studies of the Salix lucida and Salix reticulata complexes in North America

1986 ◽  
Vol 64 (3) ◽  
pp. 541-551 ◽  
Author(s):  
George W. Argus
Keyword(s):  
North America ◽  
Morphological Variation ◽  
Rocky Mountains ◽  
Rocky Mountain ◽  
Western North America ◽  
Northeastern North America ◽  
Southern Rocky Mountains ◽  
The North ◽  
Rocky Mountain Region ◽  
Hybridization And Introgression

A study of morphological variation in the Salix lucida complex revealed three geographical races: one in northeastern North America, a second in western North America extending from Alaska to California, and a third in the southern Rocky Mountains, S. lucida ssp. lucida, Salix lucida ssp. lasiandra comb, nov., and Salix lucida ssp. caudata comb, nov., respectively. The Salix reticulata complex in the Rocky Mountain region is represented by two geographical races, ssp. reticulata in the north and ssp. nivalis in the south. Variation in ssp. nivalis suggests that hybridization and introgression occur where the two races overlap, and that the results of past hybridization are still evident in the southern Rocky Mountains.

SYSTEMATICS OF THE TRICHADENOTECNUM ALEXANDERAE SPECIES COMPLEX (PSOCOPTERA: PSOCIDAE) BASED ON AN INVESTIGATION OF MODES OF REPRODUCTION AND MORPHOLOGY

1983 ◽  
Vol 115 (10) ◽  
pp. 1329-1354 ◽  
Author(s):  
B. W. Betz
Keyword(s):  
Life History ◽  
North America ◽  
Sibling Species ◽  
Species Complex ◽  
Morphological Analysis ◽  
Geographic Range ◽  
Eastern North America ◽  
Facultative Parthenogenesis

AbstractTrichadenotecnum alexanderae Sommerman is shown to represent one biparental (= euphrasic) species capable of facultative parthenogenesis (thelytoky) and three uniparental (= obligatorily parthenogenetic) sibling species, as determined by tests for mating, life history observations, and morphological analysis of specimens over the geographic range of the species complex. The name T. alexanderae is restricted to the biparental species because the holotype is a male. The three uniparental species are here named and described as T. castum n. sp., T. merum n. sp., and T. innuptum n. sp. The female of T. alexanderae is redescribed to allow its separation from the three uniparental species. A key to females of the species complex is supplied. All three uniparental species were derived from the biparental ancestor of T. alexanderae. Most collections of populations represented only by females consist of one or more uniparental species. Facultative parthenogenesis is shown to maintain a population of T. alexanderae through one generation only. The biparental species is found not to be restricted geographically to a relictual or peripheral range within the species complex, but to occupy a rather wide, north-temperate distribution across eastern North America.

Morphological variation in the genus Juliomys (Rodentia: Cricetidae: Sigmodontinae) and taxonomic status of Juliomys anoblepas (Winge 1887) from the Quaternary of Southeast Brazil

Zootaxa ◽  
2020 ◽  
Vol 4861 (3) ◽  
pp. 429-443
Author(s):  
CAROLINA PIRES ◽  
MARCELO WEKSLER ◽  
CIBELE R. BONVICINO
Keyword(s):  
Principal Component Analysis ◽  
Morphological Variation ◽  
Morphological Analysis ◽  
Principal Component ◽  
Taxonomic Status ◽  
Morphological Characters ◽  
The Other ◽  
Anterior Portion ◽  
Living Species ◽  
Qualitative Characters

The region of Lagoa Santa, Minas Gerais, Brazil, is one of the most important karstic areas of the Brazilian Quaternary due to the faunistic diversity of living and extinct forms. Among them, some taxa remain poorly studied, as is the case of Calomys anoblepas Winge 1887. Despite the recent allocation of the taxon within Juliomys, its description and morphological analysis are condensed, based on comparative few specimens and on few informative characters. In this study, we investigate characters proposed to distinguish species of Juliomys, and reevaluate the taxonomic status of the fossil Juliomys anoblepas. We analyzed 80 cranio-dental morphological characters in 233 specimens represented by the four species currently recognized: J. pictipes (Osgood 1933), J. rimofrons Oliveira & Bonvicino 2002, J. ossitenuis Costa, Pavan, Leite & Fagundes 2007, and J. ximenezi Christoff, Vieira, Oliveira, Gonçalves, Valiati & Tomasi 2016. We also performed principal component analysis on eight craniodental measurements available for the J. anoblepas hypodigm. The review of morphological systems and the evaluation of the characters used in the literature revealed that there are no diagnostic characters in the anterior portion of the skull and in the molar series of Juliomys, being difficult to differentiate the fossil from the other living species. Only six qualitative characters were variable and applicable to the hypodigm of J. anoblepas. Characters are polymorphic, invariable, or the fossil is not sufficiently complete to determinate its states. The taxon could not be morphometrically differentiated from J. pictipes and J. ossitenuis. Based on the results presented herein, we consider J. anoblepas as a nomen dubium and restrict its name to the taxon’s hypodigm. 

scholarly journals Morphological variation in the hydromedusa genus Polyorchis on the west coast of North America

1980 ◽  
Vol 58 (11) ◽  
pp. 2089-2095 ◽  
Author(s):  
John T. Rees ◽  
R. J. Larson
Keyword(s):  
North America ◽  
Morphological Variation ◽  
West Coast ◽  
Baja California ◽  
Geographic Range ◽  
Valid Species ◽  
The West ◽  
Radial Canal

Morphological variation in the hydromedusan genus Polyorchis on the west coast of North America is analyzed in relation to gonad number, tentacle number, and radial canal diverticula number relative to the height of the bell. In specimens of Polyorchis examined, it is concluded that P. penicillatus (Eschscholtz, 1829) is highly variable morphologically over its known geographic range from Alaska to Baja California. Polyorchis montereyensis Skogsberg, 1948 is considered a synonym of P. penicillatus, and P. haplus Skogsberg, 1948, is retained as a valid species.

Taxonomic studies on the genus Atrichum in North America

1969 ◽  
Vol 47 (3) ◽  
pp. 353-368 ◽  
Author(s):  
Robert R. Ireland
Keyword(s):  
United States ◽  
North America ◽  
North American ◽  
Distinct Species ◽  
The United States ◽  
Morphological Characters ◽  
Taxonomic Study ◽  
Chromosome Counts ◽  
The Status ◽  
Taxonomic Studies

A taxonomic study was made of several North American taxa in the genus Atrichum. The primary emphasis was on the Canadian taxa and a key to the six species (A. altecristatum, A. angustatum, A. crispum, A. oerstedianum, A. selwynii, A. undulatum) and one variety (A. undulatum var. gracilisetum) of the country is presented. Atrichum oerstedianum, which has been confused with A. undulatum, is added to the moss flora of the United States and Canada. The distribution of A. crispum is clarified and a detailed study of the species revealed new morphological characters that are useful to distinguish it. A variety of A. undulatum, the var. altecristatum, is raised to the rank of a species and morphological and distributional data are given to support the status of A. selwynii as a distinct species. The first chromosome counts are reported for A. selwynii (n = 7) and A. altecristatum (n = 14). Detailed descriptions are provided for A. altecristatum, A. crispum, A. oerstedianum, and A. selwynii.

Cytogeography of the Solidago spathulata–glutinosa complex (Compositae: Astereae)

1987 ◽  
Vol 65 (11) ◽  
pp. 2458-2462 ◽  
Author(s):  
Gordon S. Ringius ◽  
John C. Semple
Keyword(s):  
North America ◽  
Rocky Mountains ◽  
Pacific Coast ◽  
Lake Superior ◽  
Lake Huron ◽  
Chromosome Counts ◽  
Upper Great Lakes ◽  
Canadian Prairies ◽  
Northeastern North America ◽  
The Pacific

One hundred and eight new chromosome counts are reported for the Solidago spathulata–glutinosa complex: 49 diploids (2n = 18) and 59 tetraploids (2n = 36). Only diploids are known in S. spathulata, which occurs along the Pacific coast from southern California to northern Oregon. Diploids, tetraploids, and one hexaploid are known in S. glutinosa, which occurs across North America. Solidago glutinosa ssp. glutinosa is composed of diploids only and is widespread in the Rocky Mountains from Mexico to Alaska and across the Canadian prairies. It also occurs disjunctly on the northern shores of Lake Superior and Lake Huron and farther east on the Gaspé Peninsula in Quebec. Solidago glutinosa ssp. glutinosa var. chlorolepis was found to be diploid (first report). Tetraploids of S. glutinosa ssp. randii were found in scattered locations in northeastern North America and around most of the upper Great Lakes, where they occur sympatrically with diploid populations of ssp. glutinosa. A single hexaploid population of ssp. randii was reported previously from West Virginia; no hexaploids were encountered in this study.

Morphological and chromosomal variation in Dodecatheon pulchellum (Primulaceae)

1992 ◽  
Vol 70 (12) ◽  
pp. 2476-2483 ◽  
Author(s):  
Terri A. Suttill ◽  
Geraldine A. Allen
Keyword(s):  
North America ◽  
Morphological Variation ◽  
Genetic Basis ◽  
Common Garden ◽  
Chromosomal Variation ◽  
Western North America ◽  
Chromosome Counts ◽  
Alpine Habitats ◽  
Variable Species ◽  
Ecological Differences

Dodecatheon pulchellum (Raf.) Merr. is a widespread and morphologically variable species of western North America. Analysis of morphological variation, combined with chromosome counts and evidence from a transplant study, showed this species to consist of two subspecies. Subspecies cusickii is pubescent, mainly diploid, and occurs in the drier parts of the species range. The more variable ssp. pulchellum is glabrous to sparsely pubescent, mainly polyploid, and is widely distributed. Within ssp. pulchellum, three varieties can be recognized: the tall, many-flowered var. alaskanum, of wet, low-elevation habitats; the diminutive var. watsonii, generally of alpine habitats; and the intermediate and widely distributed var. pulchellum. Common garden studies indicate that size differences among these varieties have a genetic basis and that ecological differences exist in D. pulchellum even among morphologically similar forms. Key words: Dodecatheon, Primulaceae, systematics, morphology, chromosome numbers, common garden studies.

Characterizing polyploidy in Arabidopsis lyrata using chromosome counts and flow cytometry

2004 ◽  
Vol 82 (2) ◽  
pp. 185-197 ◽  
Author(s):  
Sara Dart ◽  
Paul Kron ◽  
Barbara K Mable
Keyword(s):  
Flow Cytometry ◽  
North America ◽  
Dna Content ◽  
Geographic Range ◽  
Chromosome Counts ◽  
Dynamic Nature ◽  
Ploidy Levels ◽  
Arabidopsis Lyrata ◽  
Genomic Changes ◽  
European Populations

Protocols were developed for both chromosome counts and flow cytometry to assess ploidy level and DNA content for populations of Arabidopsis lyrata L. sampled from Europe (Arabidopsis lyrata subsp. petraea), North America (Arabidopsis lyrata subsp. lyrata), and Japan (Arabidopsis lyrata subsp. kawasakiana). Ploidy variation within this species is not clear, with previous studies having documented both diploid and tetraploid populations. Chromosome counts in this study confirmed ploidy expectations for all populations examined. Individuals from Iceland and North America were diploid (2n = 2x = 16), whereas those from Japanese and Austrian populations were tetraploid (2n = 4x = 32). Flow cytometry was also used successfully to distinguish between ploidy levels, but the need to calibrate DNA content measures with chromosome counts was demonstrated by a deviation from the expected 2:1 ratio between tetraploid and diploid values among European populations (A. lyrata subsp. petraea). This deviation might be explained by a hybrid (allopolyploid) origin or by genomic changes following polyploidization, emphasizing the dynamic nature of polyploid genomes. Variation in DNA content among families was found only for North American populations, but these individuals were sampled from a broader geographic range than those from other regions.Key words: cytogenetics, flow cytometry, polyploidy, Arabidopsis lyrata, genome size, chromosome counts.

A practical treatment of the Solidago gigantea complex

1984 ◽  
Vol 62 (6) ◽  
pp. 1279-1282 ◽  
Author(s):  
Gary H. Morton
Keyword(s):  
Ploidy Level ◽  
Chromosome Numbers ◽  
Single Species ◽  
Morphological Characters ◽  
Geographic Range ◽  
Chromosome Counts ◽  
Separate Species ◽  
Ploidy Levels ◽  
Solidago Gigantea ◽  
Infraspecific Taxa

The Solidago gigantea complex is usually treated in floristic works as being composed of a single species with two infraspecific taxa: var. gigantea and var. serotina. Recent studies by Beaudry revealed that the complex is composed of individuals of three different chromosome numbers. He proposed that the individuals at each ploidy level be treated as belonging to separate species: S. gigantea, 2n = 18; S. serotina, 2n = 36; and S. shinnersii, 2n = 54. Chromosome counts reported in this paper of individuals of the S. gigantea complex from a wide geographic range verify the existence of the three different ploidy levels. Evaluation of the morphological characters of these vouchers, however, shows that plants with different chromosome numbers cannot be consistently separated using morphological characters. It is proposed, therefore, that the complex be treated as a single species without any infraspecific categories.

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