scholarly journals GENETIC VARIATION IN HAWAIIAN DROSOPHILA. IV. ALLOZYMIC SIMILARITY BETWEEN D. SILVESTRIS AND D. HETERONEURA FROM THE ISLAND OF HAWAII

Genetics ◽  
1977 ◽  
Vol 86 (1) ◽  
pp. 187-198
Author(s):  
F M Sene ◽  
H L Carson
Keyword(s):  
Genetic Variation ◽  
Sibling Species ◽  
Gene Frequency ◽  
Genetic Identity ◽  
Structural Proteins ◽  
Pairwise Comparisons ◽  
Morphological Divergence ◽  
Hawaiian Drosophila ◽  
Polymorphic Loci ◽  
Allelic Differences

ABSTRACT The species are endemic to the newest island in the archipelago and are broadly sympatric. They are easily distinguished morphologically in both sexes. Using standard electrophoretic procedures, we have examined 25 loci encoding for structural proteins from 539 silvestris and 325 heteroneura collected at three widely-separated localities where the two species are sympatric. Pairwise comparisons within and between the species show the following coefficients of genetic identity (Nei's I): within silvestris, 0.961 ± 0.01; within heteroneura, 0.949 ± 0.02; between silvestris and heteroneura, 0.939 ± 0.01. Neither the differences within nor between the species are significant. There are no fixed allelic differences either within or between the species. At the three areas of sympatry, the species show gene frequency differences (P < 0.05) at 9, 11 and 13 loci respectively. This is not much different from the variation within either one of the species across the three localities. The two species have similar heterozygosity (H) levels (silvestris, 0.083; heteroneura, 0.089) and percent of polymorphic loci (both 0.37). It is suggested that despite their morphological divergence, these species are much more newly formed than classical sibling species. Significant allozymic differences may not have had time to accumulate.

ELECTROPHORETIC EVIDENCE THAT LASIOGLOSSUM (EVYLAEUS) MEDITERRANEUM (BLÜTHGEN) IS A SPECIES DISTINCT FROM L. (E.) LATICEPS (SCHENCK) (HYMENOPTERA, HALICTIDAE), WITH NOTES ON ITS PHYLOGENETIC POSITION

1992 ◽  
Vol 124 (2) ◽  
pp. 371-380 ◽  
Author(s):  
L. Packer ◽  
C. Plateaux-Quénu ◽  
R.E. Owen
Keyword(s):  
Sibling Species ◽  
Electrophoretic Analysis ◽  
Genetic Identity ◽  
Phylogenetic Position ◽  
Allozyme Data ◽  
Sympatric Populations ◽  
Diagnostic Characteristics ◽  
Allelic Differences ◽  
Allozyme Loci

AbstractWe show that Lasioglossum mediterraneum (Blüthgen) (Hymenoptera, Halictidae) is a species distinct from L. laticeps (Schenck) based upon electrophoretic analysis of 39 allozyme loci for sympatric populations collected from the Dordogne region of France. The genetic identity between the two is below average for sibling species of insects: no fewer than 10 fixed allelic differences were found. In contrast, allopatric L. laticeps populations (from the Dordogne and Paris) are genetically almost identical (I = 0.998). Heterozygosity estimates for both species are low, as is often the case with Hymenoptera. Diagnostic characteristics that can be used to separate the two species are described. A phylogeny for nine species of the subgenus Evylaeus is constructed from allozyme data.

scholarly journals A MARKOV PROCESS OF GENE FREQUENCY CHANGE IN A GEOGRAPHICALLY STRUCTURED POPULATION

Genetics ◽  
1974 ◽  
Vol 76 (2) ◽  
pp. 367-377
Author(s):  
Takeo Maruyama
Keyword(s):  
Genetic Variation ◽  
Markov Process ◽  
Diffusion Process ◽  
Gene Frequency ◽  
Transition Probabilities ◽  
Large Population ◽  
Sample Path ◽  
Time Parameter ◽  
Frequency Change ◽  
Structured Population

ABSTRACT A Markov process (chain) of gene frequency change is derived for a geographically-structured model of a population. The population consists of colonies which are connected by migration. Selection operates in each colony independently. It is shown that there exists a stochastic clock that transforms the originally complicated process of gene frequency change to a random walk which is independent of the geographical structure of the population. The time parameter is a local random time that is dependent on the sample path. In fact, if the alleles are selectively neutral, the time parameter is exactly equal to the sum of the average local genetic variation appearing in the population, and otherwise they are approximately equal. The Kolmogorov forward and backward equations of the process are obtained. As a limit of large population size, a diffusion process is derived. The transition probabilities of the Markov chain and of the diffusion process are obtained explicitly. Certain quantities of biological interest are shown to be independent of the population structure. The quantities are the fixation probability of a mutant, the sum of the average local genetic variation and the variation summed over the generations in which the gene frequency in the whole population assumes a specified value.

Direct comparison of levels of genetic variation in tomato detected by a GACA-containing microsatellite probe and by random amplified polymorphic DNA

Genome ◽  
1994 ◽  
Vol 37 (3) ◽  
pp. 375-381 ◽  
Author(s):  
W. Rus-Kortekaas ◽  
M. J. M. Smulders ◽  
P. Arens ◽  
B. Vosman
Keyword(s):  
Tissue Culture ◽  
Genetic Variation ◽  
Somaclonal Variation ◽  
Random Amplified Polymorphic Dna ◽  
Dna Fingerprint ◽  
Pairwise Comparisons ◽  
Lycopersicon Pennellii ◽  
Lycopersicon Species ◽  
Polymorphic Bands ◽  
Simple Sequence

In this study, a direct comparison was made of the ability of four selected random amplified polymorphic DNA (RAPD) primers and a GACA-containing microsatellite probe to detect genetic variation in Lycopersicon. Of the 89 RAPD primers initially tested, 85 showed differences between a representative of Lycopersicon pennellii and L. esculentum, but only 4 distinguished among three L. esculentum cultivars. These four primers were subsequently tested on representatives of six Lycopersicon species. In pairwise comparisons of species, all or 14 of the 15 combinations could be distinguished by single primers. When the primers were tested on 15 L. esculentum cultivars, 90 of the 105 combinations could be distinguished by the four primers together. Finally, none of 118 tested primers showed reproducible differences among calli or progeny of régénérants from tissue culture, although some of the plants had inherited morphological mutations. The probe pWVA16, which detects GACA-containing microsatellites, could distinguish in TaqI-digested DNA the representatives of Lycopersicon species as well as all the L. esculentum cultivars tested. The probe was unable to detect polymorphisms among calli and the progeny of regenerants from tissue culture. An analysis of the results showed that the four selected RAPD primers were able to detect polymorphic bands among species at a frequency of 80%, and among cultivars at a frequency of 44%. In contrast, the microsatellite probe detected polymorphic bands at a frequency of 100 and 95%, respectively. The GACA-containing probe did not detect any common bands among the representatives of the six species, while band sharing with RAPDs was 48%. These results indicate that the two methods detect two types of DNA that differ in their degree of variability.Key words: DNA fingerprint, RAPD, simple sequence, somaclonal variation, tissue culture.

scholarly journals POPULATION GENETIC CONSEQUENCES OF FEEDING HABITS IN SOME FOREST LEPIDOPTERA

Genetics ◽  
1979 ◽  
Vol 92 (3) ◽  
pp. 1005-1021
Author(s):  
Charles Mitter ◽  
Douglas J Futuyma
Keyword(s):  
Genetic Variation ◽  
Environmental Heterogeneity ◽  
Feeding Habits ◽  
Functional Relation ◽  
Allozyme Variation ◽  
Unexpected Result ◽  
Polymorphic Loci ◽  
Allozyme Loci ◽  
Race Formation ◽  
Relationship Of

ABSTRACT By surveying variation at allozyme loci in several phytophagous lepidopteran species (Geometridae), we have tested two hypotheses about the relationship of genetic variation to environmental heterogeneity: (1) that allozyme polymorphisms may exist because of associations between genotypes and "niches" (different host plants, in this instance), and (2) that the overall genetic variation of a species is correlated with environmental heterogeneity (or breadth of the species' overall ecological niche) .—Genetic differentiation among samples of oligophagous or polyphagous species taken from different host species was observed in one of three species, at only one of seven polymorphic loci. The data thus provide no evidence for pronounced genetic sub-structuring, or "host race" formation in these sexually reproducing species, although host plant-genotype associations in a parthenogenetic moth give evidence of the potential for diversifying selection.—In a comparison of allozyme variation in polyphagous ("generalized") and oligophagous ("specialized") species, heterozygosity appeared to be higher in specialized species, at all polymorphic loci but one. I t is possible that this unexpected result arises from a functional relation between breadth of diet and genetic variation.

scholarly journals Genetic analysis of silver-fir populations in the Beskids

2011 ◽  
Vol 72 (2) ◽  
pp. 115-119 ◽  
Author(s):  
Leon Mejnartowicz
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Genetic Analysis ◽  
Abies Alba ◽  
Genetic Distances ◽  
Silver Fir ◽  
Geographical Distance ◽  
Polymorphic Loci ◽  
Expected Heterozygosity ◽  
Rare Alleles

Twenty-eight isozymic loci were studied in the Beskid Mts., in four populations of common silver-fir (<em>Abies alba</em>): one in Beskid Makowski (BM) and three populations in Beskid Sądecki (BS). Their genetic variation and diversity were analyzed, and Nei's genetic distances between the populations were calculated. The results show that the geographical distance between the BM population and the three BS populations is reflected in genetic distances. The BM population is clearly distinct from the others. It has the lowest genetic diversity (<em>I</em> = <em>0.42</em>), percentage of polymorphic loci <em>(%PoL </em>= <em>64.29</em>) and number of rare alleles (<em>NoRa </em>= <em>5</em>). Besides, the BM population has the highest observed heterozygosity (<em>Ho </em>= <em>0.291</em>), which exceeds the expected heterozygosity (<em>He </em>= <em>0.254</em>), estimated on the basis of the Hardy-Weinberg Principle. On the contrary, BS populations are in the state of equilibrium, which is manifested, in similar values of <em>He </em>= <em>0.262 </em>and <em>Ho </em>= <em>0.264</em>.

scholarly journals GENETIC VARIATION IN A HETEROGENEOUS ENVIRONMENT. I. TEMPORAL HETEROGENEITY AND THE ABSOLUTE DOMINANCE MODEL

Genetics ◽  
1974 ◽  
Vol 78 (2) ◽  
pp. 757-770
Author(s):  
Philip W Hedrick
Keyword(s):  
Genetic Variation ◽  
Temporal Variation ◽  
Gene Frequency ◽  
Environmental Heterogeneity ◽  
Finite Population ◽  
Environmental Variation ◽  
Dominance Model ◽  
Infinite Population ◽  
The Absolute ◽  
Absolute Dominance

ABSTRACT The conditions for a stable polymorphism and the equilibrium gene frequency in an infinite population are compared when there is spatial or temporal environmental heterogeneity for the absolute dominance model. For temporal variation the conditions for stability are more restrictive and the equilibrium gene frequency is often at a low gene frequency. In a finite population, temporal environmental heterogeneity for the absolute dominance model was found to be quite ineffective in maintaining genetic variation and is often less effective than no selection at all. For comparison, the maximum maintenance for temporal variation is related to the overdominant model. In general, cyclic environmental variation was found to be more effective at maintaining genetic variation than where the environment varies stochastically. The importance of temporal environmental variation and the maintenance of genetic variation is discussed.

scholarly journals Inter- and intra-population variation of local maize (Zea mays L.) populations from Slovakia and Czech Republic

2008 ◽  
Vol 43 (No. 1) ◽  
pp. 7-15 ◽  
Author(s):  
P. Múdry ◽  
J. Kraic
Keyword(s):  
Zea Mays ◽  
Genetic Variation ◽  
Czech Republic ◽  
Population Variation ◽  
Polymorphic Loci ◽  
Maize Populations ◽  
Expected Heterozygosity ◽  
Isoenzyme Polymorphism ◽  
New Alleles

Evaluation of genetic variation was performed within 62 local maize populations originating from Slovakia and Czech Republic. In total 48 alleles at 22 analyzed isoenzyme loci with an average of 2.2 alleles per locus were revealed. The percentage of polymorphic loci ranged from 14% to 59% and the frequencies of detected alleles varied from null to four per locus. No polymorphism was detected at the loci <i>Dia2</i>, <i>Got3</i>, <i>Mdh4</i>, <i>Mmm</i>, and <i>Pgm1</i>. The highest number of alleles (four) was detected at loci <i>Acp1</i>, <i>Cat3</i>, <i>Pgm2</i>. No new alleles were identified, nevertheless the frequency of seven alleles was only about 1%. The expected heterozygosity ranged from null to 0.492 with an average of 0.197. The revealed isoenzyme polymorphism confirmed that all analyzed populations were heterogeneous and as many as 17 of them were completely heterogeneous. None of the analyzed populations was identical in the frequency of alleles at all 22 analyzed loci.

GENETIC LOADS IN HETEROGENEOUS ENVIRONMENTS

Genetics ◽  
1975 ◽  
Vol 80 (3) ◽  
pp. 621-635
Author(s):  
Charles E Taylor
Keyword(s):  
Population Structure ◽  
Genetic Variation ◽  
Gene Frequency ◽  
Phase Plane ◽  
Genetic Load ◽  
Sufficient Conditions ◽  
Heterogeneous Environments ◽  
Niche Space ◽  
Necessary And Sufficient ◽  
Existence Of Equilibria

ABSTRACT A model of population structure in heterogeneous environments is described with attention focused on genetic variation at a single locus. The existence of equilibria at which there is no genetic load is examined.—The absolute fitness of any genotype is regarded as a function of location in the niche space and the population density at that location. It is assumed that each organism chooses to live in that habitat in which it is most fit ("optimal habitat selection").—Equilibria at which there is no segregational load ("loadless equilibria") may exist. Necessary and sufficient conditions for the existence of such equilibria are very weak. If there is a sufficient amount of dominance or area in which the alleles are selectively neutral, then there exist equilibria without segregational loads. In the N, p phase plane defined by population size, N, and gene frequency, p, these equilibria generally consist of a line segment which is parallel to the p axis. These equilibria are frequently stable.

Sign in / Sign up

Export Citation Format

Share Document