Molecular and morphological evidence for and against gene flow in sympatric apomicts of the North American Crepis agamic complex (Asteraceae)This paper is one of a selection of papers published in the Special Issue on Systematics Research.

Botany ◽  
2008 ◽  
Vol 86 (8) ◽  
pp. 877-885 ◽  
Author(s):  
Jeannette Whitton ◽  
Katrina M. Dlugosch ◽  
Christopher J. Sears
Keyword(s):  
Gene Flow ◽  
North American ◽  
Distinct Species ◽  
The Other ◽  
Morphological Data ◽  
Morphological Evidence ◽  
Hybrid Zones ◽  
Sympatric Populations ◽  
Contact Zones ◽  
The North

The study of sympatric populations of closely related plant species often reveals evidence of hybridization. Mechanisms that reduce outcrossing (e.g., selfing, apomixis) may allow co-occurrence without gene flow. In this study, we describe patterns of genetic variation in two contact zones, each comprising three closely related morphological types, that key to three distinct species in the North American Crepis agamic (apomictic) complex. We used RAPD markers to characterize individuals from two sites: one in northern California (Sardine Lookout) and another in northwestern Oregon (Summit Road). At Sardine Lookout, we discerned a total of four multilocus genotypes, two in one species, and one each in the other two species. Our findings suggest that distinct morphological types are maintained by absolute barriers to gene flow at this site. At Summit Road, we found greater genotypic diversity, with a total of 24 genotypes across 30 individuals. One of the morphological types was clearly genetically differentiated from the other two, with no variable markers shared with other species at this site. The two remaining species showed evidence of gene flow, with no unique markers discerning them. Morphological data tend to support this conclusion, with univariate and multivariate analyses indicating a pattern of variation spanning the two species. Taken together, these patterns suggest that contact zones need not represent hybrid zones, and that apomixis can serve as an effective barrier to gene flow that may allow for stable coexistence of close relatives.

Diversification of the North American Doellingeria-Eucephalus Clade (Astereae: Asteraceae) Inferred from Molecular and Morphological Evidence

2019 ◽  
Vol 44 (4) ◽  
pp. 930-942
Author(s):  
Geraldine A. Allen ◽  
Luc Brouillet ◽  
John C. Semple ◽  
Heidi J. Guest ◽  
Robert Underhill
Keyword(s):  
North American ◽  
Sequence Data ◽  
Phylogenetic Analyses ◽  
Sister Group ◽  
Morphological Evidence ◽  
South American ◽  
New Combinations ◽  
The North ◽  
Hybridization Event ◽  
Ancient Hybridization

Abstract—Doellingeria and Eucephalus form the earliest-diverging clade of the North American Astereae lineage. Phylogenetic analyses of both nuclear and plastid sequence data show that the Doellingeria-Eucephalus clade consists of two main subclades that differ from current circumscriptions of the two genera. Doellingeria is the sister group to E. elegans, and the Doellingeria + E. elegans subclade in turn is sister to the subclade containing all remaining species of Eucephalus. In the plastid phylogeny, the two subclades are deeply divergent, a pattern that is consistent with an ancient hybridization event involving ancestral species of the Doellingeria-Eucephalus clade and an ancestral taxon of a related North American or South American group. Divergence of the two Doellingeria-Eucephalus subclades may have occurred in association with northward migration from South American ancestors. We combine these two genera under the older of the two names, Doellingeria, and propose 12 new combinations (10 species and two varieties) for all species of Eucephalus.

The North American Allies of Hylobius piceus (De Geer) (Coleoptera: Curculionidae)

1957 ◽  
Vol 89 (1) ◽  
pp. 37-43 ◽  
Author(s):  
Stephen L. Wood
Keyword(s):  
North American ◽  
Distinct Species ◽  
Morphological Characters ◽  
North American Species ◽  
Winged Form ◽  
The North ◽  
The Status ◽  
Field Workers ◽  
Dimorphic Species ◽  
Biological Differences

While investigating the biology of the North American species of Hypomolyx, field workers in Manitoba found a vestigial, or short-winged, and a long-winged form under apparently identical conditions in about equal numbers. Although biological differences were nor then apparent, there was doubt as to whether they were dealing with one dimorphic species or with two distinct species, A search for morphological characters brought to light numerous differences between the two forms, supporting the view that two species were present. These differences, a description the previously unrecognized species, and notes concerning the status of the genera Hylobius and Hypomolyx are reported below.

scholarly journals Typology and nuance: relativization

2020 ◽  
pp. 104-130
Author(s):  
Marianne Mithun
Keyword(s):  
North American ◽  
Large Scale ◽  
Relative Clauses ◽  
Spontaneous Speech ◽  
The Other ◽  
Stages Of Development ◽  
Linguistic Typology ◽  
The North

Much of linguistic typology is inherently categorical. In large-scale typological surveys, grammatical constructions, distinctions, and even variables are typically classified as present, absent, or embodying one of a set of specified options. This work is valuable for a multitude of purposes, and in many cases such categorization is sufficient. In others, we can advance our understanding further if we take a more nuanced approach, considering the extent to which a particular construction, distinction, or variable is installed in the grammar. An important tool for this approach is the examination of unscripted speech in context, complete with prosody. This point is illustrated here with Mohawk, an Iroquoian language indigenous to the North American Northeast. As will be seen, the two types of construction which might be identified as relative clauses are emergent, one less integrated into the grammar than the other. Examination of spontaneous speech indicates that the earliest stages of development are prosodic, as speakers shape their messages according to their communicative purposes at each moment.

Beyond the Cold War Chessboard

Worldview ◽  
1974 ◽  
Vol 17 (6) ◽  
pp. 21-22
Author(s):  
John W. Holmes
Keyword(s):  
United States ◽  
Cold War ◽  
North Atlantic ◽  
North American ◽  
The Other ◽  
The North ◽  
Common Interests ◽  
The North Atlantic ◽  
The Cold War

The problem in judging M. Servan-Schreiber's message is that he reaches some sound conclusions on the basis of dubious premises, from which he derives recommendations which could be disastrous.There may be some satisfaction in seeing a Frenchman concerned with le défi, russe instead of le défi américain, but his interpretation of one is as crude as was his interpretation of the other. The shock of revelation that there are common interests of the Atlantic countries in economic as well as strategic matters is understandably more startling to a Frenchman than to others. It was all set out in 1949 in Article 2 of the North Atlantic Treaty and was restated eloquently in 1973 by Mr. Kissinger. But last spring European leaders were included to see the latter as a self-interested plea from a weak United States to a prosperous Europe. The North American countries were reminded that their role in Europe was simply to defend it on request.

The systematics of the south-east Asian genus Fangensis Rambla (Opiliones:Cyphophthalmi:Stylocellidae)

2005 ◽  
Vol 19 (4) ◽  
pp. 297 ◽  
Author(s):  
Peter J. Schwendinger ◽  
Gonzalo Giribet
Keyword(s):  
East Asian ◽  
Original Description ◽  
Distinct Species ◽  
Molecular Data ◽  
Ribosomal Genes ◽  
The Other ◽  
Morphological Data ◽  
Southern Thailand ◽  
New Material ◽  
Three New Species

The hitherto monotypic opilionid genus Fangensis Rambla, 1994 is re-evaluated from new material collected in northern, western and southern Thailand. The original description of F. leclerci Rambla (type material not traceable) was based on specimens belonging to at least three distinct species. Fangensis leclerci is thus redefined and the binomen restricted to specimens from a cave in northern Thailand only. Three new species are described, F. spelaeus, sp. nov. and F. cavernarus, sp. nov. from two caves in western Thailand and F. insulanus, sp. nov. from forests on two islands in southern Thailand. Taxonomic characters are discussed and relationships among Fangensis species and between Fangensis and other cyphophthalmids are evaluated using morphological data and ~4 Kb of molecular data from three loci, two nuclear ribosomal genes and a mitochondrial coding gene. Overall, data indicate monophyly of Stylocellidae and morphological and ribosomal data suggest monophyly of Fangensis, which is in turn divided into two clades, one composed of the three species from northern and western Thailand and the other represented by the species from southern Thailand. Observations on mating in F. leclerci are provided.

scholarly journals FOUR OCHODÆUS NEW TO THE UNITED STATES

1906 ◽  
Vol 38 (8) ◽  
pp. 269-272 ◽  
Author(s):  
Chas. Schaeffer
Keyword(s):  
United States ◽  
North American ◽  
Distinct Species ◽  
The United States ◽  
North American Species ◽  
The North

Working over some neglected material, I found, to my surprise, that the specimens of Ochodœus colleted by me last year in Arizona are separable into three distinct species, none of which agree with the descriptions of the North American species. A few years ago my brother sent me from California, with some other material, two specimens of what I take to be an Ochadœus. Unfortunately, I misplaced one of the specimens, and not wishing to dissect the single remaining one, I leave this species in this genus for the present, till more material is available.

REVISION OF THE NEARCTIC SPECIES OF LAUXANIA (DIPTERA: LAUXANIIDAE)

2000 ◽  
Vol 132 (4) ◽  
pp. 411-427 ◽  
Author(s):  
Joëlle R. Pérusse ◽  
Terry A. Wheeler
Keyword(s):  
Strong Evidence ◽  
North American ◽  
Male Genitalia ◽  
Distinct Species ◽  
North American Species ◽  
Related Genus ◽  
The North

AbstractThe North American species of Lauxania Latreille are revised. The genus contains five Nearctic species: L. albiseta Coquillett, L. glabrifronssp.nov., L. kafaristasp.nov., L. nigrimana Coquillett, and L. shewellisp.nov. All Nearctic species are illustrated and keyed. Consistent genitalic differences between Nearctic and Palaearctic specimens of the species usually identified as Lauxania cylindricornis (Fabricius) justify the recognition of the Nearctic specimens as a distinct species (L. shewelli). The male genitalia of Lauxania represent two types: the apparently plesiomorphic type has a simple rodlike phallapodeme, membranous phallus, and pointed unbranched postgonites; the apomorphic type has the phallapodeme expanded into a sclerotized hood surrounding the base of the phallus, a convoluted sclerotized phallus, and branched postgonites. These two genitalic types also occur in the related genus Calliopum Strand, which provides strong evidence that these genera, as currently recognized, may not be monophyletic relative to one another.

scholarly journals THE NORTH AMERICAN CALLIMORPHAS

1887 ◽  
Vol 19 (10) ◽  
pp. 181-191 ◽  
Author(s):  
H. H. Lyman
Keyword(s):  
North American ◽  
Distinct Species ◽  
North American Species ◽  
The North ◽  
Species Being

The North American species of the genus Callimorpha are exceedingly interesting both from their beauty and from the extreme variations to which some of the species are subject, and which has given rise not only tot he creation of numerous synonyms, but also to distinct species being regarded as merely varieties of other forms.

A new catostomid fish (Ostariophysi, Cypriniformes) from the Eocene Kishenehn Formation and remarks on the North American species of †AmyzonCope, 1872

2016 ◽  
Vol 90 (2) ◽  
pp. 288-304 ◽  
Author(s):  
Juan Liu ◽  
Mark V.H. Wilson ◽  
Alison M. Murray
Keyword(s):  
New Species ◽  
North American ◽  
Phylogenetic Analyses ◽  
Distinct Species ◽  
Sister Group ◽  
North American Species ◽  
Pelvic Bone ◽  
The North ◽  
Basal Clade ◽  
Osteological Characters

AbstractFossil catostomids were very rare prior to the Eocene. After the Eocene, they suddenly decreased in diversity in Asia while becoming common fishes in the North American fauna. Knowledge of the taxonomy, diversity, and distribution of Eocene catostomids is critical to understanding the evolution of this fish group. We herein describe a new catostomid species of the genus †AmyzonCope, 1872 from the Eocene Kishenehn Formation in Montana, USA. The new species, †Amyzon kishenehnicum, differs from known species of †Amyzonin having hypurals 2 and 3 consistently fused to the compound centrum proximally, and differs from other Eocene catostomids in that the pelvic bone is intermediately forked. All our phylogenetic analyses suggest that the new species is the sister group of †A.aggregatumWilson, 1977 and that †Amyzonis the most basal clade of the Catostomidae. We reassessed the osteological characters of the North American species of †Amyzonfrom a large number of well-preserved specimens of the new species, as well as †A.gosiutenseGrande et al., 1982 and †A.aggregatum. Osteological characters newly discovered indicate that †A.gosiutenseis not a junior synonym of †A.aggregatum, but should be retained as a distinct species.

Sign in / Sign up

Export Citation Format

Share Document