STRUCTURE OF GENETIC VARIATION WITHIN AND BETWEEN POPULATIONS OF MYCOPHAGOUS DROSOPHILA

Genetics ◽  
1983 ◽  
Vol 104 (1) ◽  
pp. 81-94
Author(s):  
Robert C Lacy
Keyword(s):  
New York ◽  
Genetic Variation ◽  
Genetic Differentiation ◽  
Gel Electrophoresis ◽  
Site Fidelity ◽  
Adaptive Divergence ◽  
Gene Frequencies ◽  
Polymorphic Loci ◽  
Diversifying Selection ◽  
Study Sites

ABSTRACT Patterns of genetic variation within and between populations of five species of mycophagous Drosophila were examined by gel electrophoresis of several polymorphic loci. Populations of the five species could not be shown to be subdivided into sympatric host-adapted races. Statistically significant, but small, between-host differences in gene frequencies were observed at three of 15 loci. Mean gene frequencies at all loci were similar in New York and Tennessee, and, with one exception, relatively little genetic differentiation was observed among study sites within those two regions. Gene frequencies generally were stable over several years of collecting as well. The unpredictable nature of the fungal hosts may preclude the site fidelity and continuity of diversifying selection necessary for adaptive divergence of populations.

Genetic differentiation among various populations of the diamondback moth, Plutella xylostella Lepidoptera Yponomeutidae

2006 ◽  
Vol 96 (2) ◽  
pp. 137-144 ◽  
Author(s):  
A. Pichon ◽  
L. Arvanitakis ◽  
O. Roux ◽  
A.A. Kirk ◽  
C. Alauzet ◽  
...  
Keyword(s):  
South Africa ◽  
New York ◽  
Genetic Variation ◽  
Genetic Differentiation ◽  
Plutella Xylostella ◽  
Diamondback Moth ◽  
The Philippines ◽  
Fixation Index ◽  
Geographical Distance ◽  
Hardy Weinberg Equilibrium

AbstractGenetic variation among 14 populations of Plutella xylostella (Linnaeus) from USA (Geneva, New York), Brazil (Brasilia), Japan (Okayama), The Philippines (Caragan de Oyo), Uzbekistan (Tashkent), France (Montpellier), Benin (Cotonou), South Africa (Johannesburg), Réunion Island (Montvert), and five localities in Australia (Adelaide, Brisbane, Mareeba, Melbourne, Sydney) were assessed by analysis of allozyme frequencies at seven polymorphic loci. Most of the populations were not in Hardy–Weinberg equilibrium and had a deficit in heterozygotes. The global differentiation among populations was estimated by the fixation index (Fst) at 0.103 for the 14 populations and at 0.047 when populations from Australia and Japan, which differed most and had a strong genetic structure, were excluded from the analysis. By contrast, the populations from Benin (West Africa) and Brazil (South America) were very similar to each other. Genetic differentiation among the populations was not correlated with geographical distance.

Population differentiation in lodgepole pine, Pinus contorta spp. latifolia: a discriminant analysis of allozyme variation

1985 ◽  
Vol 27 (2) ◽  
pp. 210-218 ◽  
Author(s):  
Francis C. Yeh ◽  
William M. Cheliak ◽  
Bruce P. Dancik ◽  
Keith Illingworth ◽  
Diane C. Trust ◽  
...  
Keyword(s):  
British Columbia ◽  
Genetic Variation ◽  
Discriminant Analysis ◽  
Genetic Differentiation ◽  
Population Differentiation ◽  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Allozyme Variation ◽  
Discriminant Functions ◽  
Polymorphic Loci

Seeds from 17 populations representing most of the range of lodgepole pine in the Yukon and British Columbia were analyzed for electrophoretically demonstrable variation in 16 proteins coded by 23 genetic loci. Consistent with that reported on genetic variation in this conifer, on the average, 64% of the loci per population were polymorphic, and expected and observed heterozygosity per population were 0.165 and 0.174, respectively. Univariate F-ratio tests for homogeneity among populations indicated genetic differentiation (p < 0.05) at six loci. Two significant (p < 0.05) canonical discriminant functions accounted for 38% of the total variance in the 20 polymorphic loci. A rich structure of genetic variation associated with geography was revealed. Both latitude and altitude appeared to be important, with northern populations exhibiting a greater extent of genetic differentiation.Key words: allozymes, electromorphs, populations, Pinus, lodgepole pine.

Lack of allozymic variation in disjunct Newfoundland populations of red pine (Pinusresinosa)

1991 ◽  
Vol 21 (4) ◽  
pp. 525-528 ◽  
Author(s):  
A. Mosseler ◽  
D. J. Innes ◽  
B. A. Roberts
Keyword(s):  
Genetic Variation ◽  
Genetic Differentiation ◽  
Cellulose Acetate ◽  
Gel Electrophoresis ◽  
Red Pine ◽  
Enzyme Electrophoresis ◽  
Isolated Populations ◽  
Putative Gene ◽  
Enzyme Gene ◽  
Enzyme Systems

Disjunct, geographically isolated populations of red pine (Pinusresinosa Ait.) on the island of Newfoundland were investigated by enzyme electrophoresis to determine if these populations were genetically distinct from a range-wide sample of mainland populations. Genetic variation at 23 putative gene loci from 12 enzyme systems was assayed by cellulose acetate gel electrophoresis. Each of the 96 trees sampled was monomorphic for all enzyme gene loci assayed, and no genetic differentiation between Newfoundland and mainland populations was detected. The striking lack of genetic variation at enzyme gene loci in red pine has been confirmed for the most isolated populations at the extreme northeastern margins of its range.

scholarly journals Population genetic variation analysis of bitter gourd wilt caused by Fusarium oxysporum f. sp. momordicae in China using inter simple sequence repeats (ISSR) molecular markers

2021 ◽  
Author(s):  
Rui Zang ◽  
Ying Zhao ◽  
Kangdi Guo ◽  
Kunqi Hong ◽  
Huijun Xi ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Genetic Differentiation ◽  
Fusarium Oxysporum ◽  
Diversity Index ◽  
Gene Diversity ◽  
Pcr Amplification ◽  
Bitter Gourd ◽  
Diseased Plant ◽  
Variation Analysis ◽  
Group I

AbstractBitter gourd wilt caused by Fusarium oxysporum f. sp. momordicae (FOM) is a devastating crop disease in China. A total of 173 isolates characteristic of typical Fusarium oxysporum with abundant microconidia and macroconidia on white or ruby colonies were obtained from diseased plant tissues. BLASTn analysis of the rDNA-ITS of the isolates showed 99% identity with F. oxysporum species. Among the tested isolates, three were infectious toward tower gourd and five were pathogenic to bottle gourd. However, all of the isolates were pathogenic to bitter gourd. For genetic differences analysis, 40 ISSR primers were screened and 11 primers were used for ISSR-PCR amplification. In total, 127 loci were detected, of which 76 were polymorphic at a rate of 59.84%. POPGENE analysis showed that Nei’s gene diversity index (H) and Shannon’s information index (I) were 0.09 and 0.15, respectively, which indicated that the genetic diversity of the 173 isolates was low. The coefficient of gene differentiation (Gst = 0.33 > 0.15) indicated that genetic differentiation was mainly among populations. The strength of gene flow (Nm = 1.01 > 1.0) was weak, indicating that the population differentiation caused by gene drift was blocked to some degree. The dendrogram based on ISSR markers showed that the nine geographical populations were clustered into two groups at the threshold of genetic similarity coefficient of 0.96. The Shandong and Henan populations were clustered into Group I, while the Guangdong, Hainan, Guangxi, Fujian, Jiangxi, and Hubei populations constituted Group II. Results of the genetic variation analysis showed that the Hunan and Guangxi populations had the highest degree of genetic differentiation, while the Hubei population had the lowest genetic differentiation. Our findings enrich the knowledge of the genetic variation characteristics of FOM populations with the goal of developing effective disease-management programs and resistance breeding programs.

scholarly journals Cryptic variation and its manifestation in the Lower Trentonian Rafinesquina lineage (Ordovician, New York State)

1992 ◽  
Vol 6 ◽  
pp. 292-292
Author(s):  
Robert Titus
Keyword(s):  
New York ◽  
Genetic Variation ◽  
Natural Selection ◽  
New York State ◽  
Ecological Factors ◽  
Stabilizing Selection ◽  
Rapid Population Growth ◽  
York State ◽  
Cryptic Variation ◽  
Adaptive Peak

Species populations commonly carry a great deal of genetic variation which is not expressed in individual phenotypes. Cryptic variation can be carried in recessive alleles, in cases of heterosis, or where modifier genes inhibit expression of the hidden trait. Other genetic and ecological factors also allow cryptic variation. Stabilizing selection prevents the expression of hidden traits; normalizing selection weeds out the deviants and canalizing selection suppresses their traits. Together the two keep the species near the top of the adaptive peak. Cryptic variation balances a species' need to be well-adapted to its environment and also for it to maintain a reserve of variation for potential environmental change. Expression of cryptic traits is rare and is usually associated with times of greatly reduced natural selection and rapid population growth, when the lower slopes of the adaptive peak are exposed.A possible example of the manifestation of cryptic traits occurs within the lower Trentonian Rafinesquina lineage of New York State. The two most commonly reported species of the genus have been reappraised in terms of cryptic variation. Extensive collections of Rafinesquina “lennoxensis” reveal far more intergrading morphotypes than had hitherto been recognized. The form which Salmon (1942) described is broadly U-shaped with sulcate margins. It grades into very convex forms as well as sharply-defined or convexly geniculate types. Of great importance, all forms grade into the flat, U-shaped, alate R. trentonensis, which is, by far, the most common and widespread lower Trentonian member of the genus. The R. “lennoxensis” assemblage has a very narrow biostratigraphy, being confined to a few locations in the upper Napanee Limestone. This places it in a quiet, protected, low stress, lagoonal setting behind the barrier shoal facies of the Kings Falls Limestone.The R. “lennoxensis” assemblage does not constitute a natural biologic species; it is reinterpreted as an assemblage of phenodeviants occupying a low stress, low natural selection lagoon facies. All such forms should be included within R. trentonensis. Given the evolutionary plasticity of this genus, extensive cryptic variation is not surprising.

Studies of the inheritance of bovine serum transferrins

1964 ◽  
Vol 6 (1) ◽  
pp. 107-117 ◽  
Author(s):  
G. A. E. Gall ◽  
R. T. Berg
Keyword(s):  
Gel Electrophoresis ◽  
Bovine Serum ◽  
Embryonic Mortality ◽  
Genetic Mechanism ◽  
Starch Gel Electrophoresis ◽  
Gene Frequencies ◽  
Starch Gel ◽  
Cattle Herds

SUMMARY1. The transferrins in two cattle herds were studied by means of starch gel electrophoresis. Three phenotypes were observed in a Hereford herd and six in a Hybrid herd comprised of Galloway, Aberdeen Angus and Charolais breeds.2. Gene frequencies were calculated for each herd. Great variation was found in the frequency of the transferrin alleles between breed and source within the Hybrid herd and between the Hybrid and Hereford herds. The frequencies of the transferrin alleles found in the cows in the Hereford herd were TfA = 0·467 and TfD = 0·533; those found in the cows in the Hybrid herd were TfA = 0·382, TfD = 0·506 and TfE = 0·112.3. Progeny data were in general agreement with the three-allele theory of inheritance, although the data suggested that offspring in the Hybrid herd carrying the TfE allele occurred at a lower frequency than expected.4. The possible relation of transferrin type to embryonic mortality was studied. The results were in general agreement with those of other workers, indicating a possible interaction between the genotypes of the foetus and dam.5. The characteristics of the transferrin types and the postulated three-allele genetic mechanism for the control of the observed variation are discussed.

Survey of the Genetic Variation Among Eastern Lake Superior Lake Trout (Salvelinus namaycush)

1981 ◽  
Vol 38 (12) ◽  
pp. 1738-1746 ◽  
Author(s):  
Terrence R. Dehring ◽  
Anne F. Brown ◽  
Charles H. Daugherty ◽  
Stevan R. Phelps
Keyword(s):  
Genetic Variation ◽  
Gel Electrophoresis ◽  
Lake Trout ◽  
Lake Superior ◽  
Salvelinus Namaycush ◽  
Starch Gel Electrophoresis ◽  
Average Heterozygosity ◽  
Management Implications ◽  
Salmonid Species ◽  
Starch Gel

Patterns of genetic variation among lake trout (Salvelinus namaycush) of eastern Lake Superior were examined using starch gel electrophoresis. We used 484 individuals sampled from three areas, representing three morphological types (leans, humpers, and siscowets). Of 50 loci examined, 44 were monomorphic in all groups sampled. Genetic variation occurs at six loci AAT-1,2, MDH-3,4, ME-1, and SOD-1. The average heterozygosity found (H = 0.015) is low relative to other salmonid species. A significant amount of heterogeneity exists among the 10 lake trout samples. These differences are due to variation within as well as between morphological types. The significance and management implications of these data are discussed.Key words: genetic variation, lake trout, Salvelinus namaycush, Lake Superior

scholarly journals Intrapopulational genetic differentiation in Anopheles (N.) darlingi Root, 1926 (Diptera: Culicidae) in the amazon region

1999 ◽  
Vol 22 (3) ◽  
pp. 325-331 ◽  
Author(s):  
Joselita Maria Mendes dos Santos ◽  
Jorge Arturo Lobo ◽  
Wanderli Pedro Tadei ◽  
Eucleia P. Betioli Contel
Keyword(s):  
Genetic Differentiation ◽  
Central Region ◽  
Amazon Basin ◽  
Amazon Region ◽  
Anopheles Darlingi ◽  
Chromosomal Variation ◽  
Geographical Differentiation ◽  
Marginal Populations ◽  
Polymorphic Loci

Four natural Amazonian Anopheles darlingi populations were analyzed for 19 loci, 12 of which showed variation, i.e., 68.4% of polymorphic loci. The Ariquemes, Rondônia, population was the most variable, with a large number of alleles per locus (2.26 ± 0.27) and high polymorphism (P = 63.15). The highest values of observed and expected intralocus heterozygosity were observed in the Manaus, Amazonas, population (Ho = 0.432 ± 0.11; He = 0.375 ± 0.08), and the lowest in the Cachoeira Porteira, Pará, population (Ho = 0.236 ± 0.09; He = 0.290 ± 0.11). Wright's F-statistic revealed disequilibrium caused by an excess of homozygotes, as shown by the Fis > Fst values (Fis = 0.083 > 0.026) reflecting intrapopulational differentiation. The four populations studied were genetically similar, as indicated by distance and similarity values. Chromosomal variation of Amazon population also did not indicate geographical differentiation, and populations in the central region of the Amazon Basin showed high polymorphism in relation to the marginal populations, which were mainly monomorphic.

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