scholarly journals Population structure of the butternut canker fungus, Ophiognomonia clavigignenti-juglandacearum, in North American forests

2012 ◽  
Vol 2 (9) ◽  
pp. 2114-2127 ◽  
Author(s):  
K. D. Broders ◽  
A. Boraks ◽  
A. M. Sanchez ◽  
G. J. Boland
Keyword(s):  
Population Structure ◽  
North American ◽  
Butternut Canker

Population structure of Heterobasidion annosum from North America and Europe

1993 ◽  
Vol 71 (8) ◽  
pp. 1064-1071 ◽  
Author(s):  
William J. Otrosina ◽  
Thomas E. Chase ◽  
Fields W. Cobb Jr. ◽  
Kari Korhonen
Keyword(s):  
Population Structure ◽  
North America ◽  
North American ◽  
Forest Tree ◽  
Heterobasidion Annosum ◽  
Evolutionary Relationships ◽  
The North ◽  
Isozyme Loci ◽  
Intersterility Groups ◽  
European Populations

Isolates of Heterobasidion annosum (Fr.) Bref. representing North American S and P and European S, P, and F intersterility groups were subjected to isozyme analysis. European S, P, and F groups had more variability than the North American S and P groups in expected hterozygosity, number of alleles per locus, and percent polymorphic loci. In contrast with the North American S and P groups, the European intersterility groups could not be distinguished from each other on the basis of individual isozyme loci, although significant differences in allele frequencies exist between European S and P groups. This suggests that evolution proceeded at different rates in the intersterility groups, or intersterility barriers appeared later in the European populations relative to the North American populations of H. annosum. Changes in climate and host species associations during the Tertiary may have been a major factor in evolution of H. annosum intersterility groups. Key words: allozymes, forest tree hosts, playnological events, evolutionary relationships, Hymenomycetes, root disease.

Effects of Pleistocene glaciations on population structure of North American chestnut-backed chickadees

2006 ◽  
Vol 15 (9) ◽  
pp. 2409-2419 ◽  
Author(s):  
THERESA M. BURG ◽  
ANTHONY J. GASTON ◽  
KEVIN WINKER ◽  
VICKI L. FRIESEN
Keyword(s):  
Population Structure ◽  
North American ◽  
American Chestnut ◽  
Pleistocene Glaciations

scholarly journals Population Structure and Mitochondrial Polyphyly in North American Gadwalls (Anas Strepera)

The Auk ◽  
2007 ◽  
Vol 124 (2) ◽  
pp. 444-462 ◽  
Author(s):  
Jeffrey L. Peters ◽  
Kevin E. Omland
Keyword(s):  
Population Structure ◽  
Genetic Structure ◽  
North America ◽  
North American ◽  
Incomplete Lineage Sorting ◽  
Population Expansion ◽  
Lineage Sorting ◽  
Clade B ◽  
Base Pair Fragment ◽  
Anas Strepera

Abstract We examined population genetic structure in Gadwalls (Anas strepera) to test the prediction that female philopatry and fidelity to migratory flyways have contributed to the partitioning of mitochondrial variation across North America. Sequencing a 658–659 base-pair fragment of the mitochondrial DNA (mtDNA) control region from 348 Gadwalls, we found two distinct clades that were broadly intermixed across both breeding and nonbreeding populations. Clade A was abundant in North America as well as among published sequences from Eurasia. Clade B was sequenced from 5.5% of North American Gadwalls and was more similar to Asian Falcated Duck (A. falcata) haplotypes than to clade A haplotypes. Maximum likelihood indicated that Gadwall clade B haplotypes were a monophyletic group nested within Falcated Duck haplotypes, which suggests mtDNA introgression of clade B into Gadwalls. However, that topology was weakly supported, and we could not reject topologies that were consistent with incomplete lineage-sorting as the cause of mitochondrial polyphyly. Migratory flyways did not contribute significantly to population structure and, in general, we found a lack of genetic structure among most populations. However, Gadwalls sampled in Alaska and Washington were well differentiated from other populations. Coalescent analyses supported a historical population expansion for clade A, and this expansion could have contributed to the high genetic similarity among some populations but the strong differentiation of others. Female-mediated gene flow, along with both historical and contemporary population and range expansions, has likely contributed to the overall weak mtDNA structure in North American Gadwalls. Estructura Poblacional y Polifilia Mitocondrial en Anas strepera

scholarly journals Understanding the population structure of North American patients with cystic fibrosis

2011 ◽  
Vol 79 (2) ◽  
pp. 136-146 ◽  
Author(s):  
W Li ◽  
L Sun ◽  
M Corey ◽  
F Zou ◽  
S Lee ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Population Structure ◽  
North American

Allozyme variation and population structure of Carex humilis var. nana (Cyperaceae) in Korea

2001 ◽  
Vol 79 (4) ◽  
pp. 457-463 ◽  
Author(s):  
Man Kyu Huh
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Variation ◽  
North American ◽  
Population Level ◽  
Allozyme Variation ◽  
Population Divergence ◽  
Geographic Ranges ◽  
The Mean ◽  
Allozyme Loci

Genetic diversity and population structure of 22 Carex humilis var. nana Ohwi (Cyperaceae) populations in Korea were determined using genetic variation at 23 allozyme loci. This is a long-lived herbaceous species with a widespread distribution in eastern Asia. The 12 enzymes revealed 23 putative loci, of which 11 were polymorphic (47.8%). Genetic diversity at the varietal level and at the population level was 0.131 and 0.118, respectively. Total genetic diversity (HT = 0.274) and within population genetic diversity (HS = 0.256) were high, whereas the extent of the population divergence was relatively low (GST = 0.068). An indirect estimate of the number of migrants per generation (Nm = 3.42) indicated that gene flow was high among Korean populations. Wide geographic ranges, perennial herbaceous nature, and the persistence of multiple generations are associated with the high level of genetic variation. A distinct difference between Asian and North American Carex is shown in the proportion of genetic variation (GST) (p < 0.001). The mean GST of Asian Carex was estimated as 0.056; thus, only 5.6% of genetic variability was distributed among populations, whereas the mean GST of North American Carex was estimated as 19.5% (3.5 times higher). It is probable that the geographical distance between population pairs and presence or absence of glacial history may play roles in the substantial difference between both groups.Key words: Carex humilis var. nana, genetic diversity, population structure.

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