scholarly journals The molecular through ecological genetics of abnormal abdomen. IV. Components of genetic variation in a natural population of Drosophila mercatorum.

Genetics ◽  
1992 ◽  
Vol 130 (2) ◽  
pp. 355-366
Author(s):  
H Hollocher ◽  
A R Templeton ◽  
R DeSalle ◽  
J S Johnston
Keyword(s):  
Genetic Variation ◽  
Natural Population ◽  
Allelic Variation ◽  
Natural Populations ◽  
Developmental Time ◽  
Ecological Genetics ◽  
Adult Longevity ◽  
Genetic Determinants ◽  
Drosophila Mercatorum ◽  
Y Chromosomes

Abstract Natural populations of Drosophila mercatorum are polymorphic for a phenotypic syndrome known as abnormal abdomen (aa). This syndrome is characterized by a slow-down in egg-to-adult developmental time, retention of juvenile abdominal cuticle in the adult, increased early female fecundity, and decreased adult longevity. Previous studies revealed that the expression of this syndrome in females is controlled by two closely linked X chromosomal elements: the occurrence of an R1 insert in a third or more of the X-linked 28S ribosomal genes (rDNA), and the failure of replicative selection favoring uninserted 28S genes in larval polytene tissues. The expression of this syndrome in males in a laboratory stock was associated with the deletion of the rDNA normally found on the Y chromosome. In this paper we quantify the levels of genetic variation for these three components in a natural population of Drosophila mercatorum found near Kamuela, Hawaii. Extensive variation is found in the natural population for both of the X-linked components. Moreover, there is a significant association between variation in the proportion of R1 inserted 28S genes with allelic variation at the underreplication (ur) locus such that both of the necessary components for aa expression in females tend to cosegregate in the natural population. Accordingly, these two closely linked X chromosomal elements are behaving as a supergene in the natural population. Because of this association, we do not believe the R1 insert to be actively transposing to an appreciable extent. The Y chromosomes extracted from nature are also polymorphic, with 16% of the Ys lacking the Y-specific rDNA marker. The absence of this marker is significantly associated with the expression of aa in males. Hence, all three of the major genetic determinants of the abnormal abdomen syndrome are polymorphic in this natural population.

Natural selection and ribosomal DNA in Drosophila

Genome ◽  
1989 ◽  
Vol 31 (1) ◽  
pp. 296-303 ◽  
Author(s):  
Alan R. Templeton ◽  
Hope Hollocher ◽  
Susan Lawler ◽  
J. Spencer Johnston
Keyword(s):  
Life History ◽  
Natural Selection ◽  
Ribosomal Dna ◽  
Allelic Variation ◽  
Natural Populations ◽  
Population Level ◽  
Developmental Time ◽  
Adult Age ◽  
Drosophila Hydei ◽  
Drosophila Mercatorum

Natural populations of Drosophila mercatorum are variable for the number of X-linked 28S ribosomal genes bearing a 5-kilobase insert. A separate polymorphic X-linked gene controls whether 28S repeats bearing the insert are preferentially underreplicated during the formation of polytene tissue. Female flies having at least a third of their 28S genes bearing the insert and lacking the ability to preferentially underreplicate inserted repeats display the abnormal abdomen syndrome. The syndrome is characterized by retention of juvenile abdominal cuticle into the adult, a slowdown in larval developmental time, and an increase in early female fecundity. The life history traits are expressed in nature and provide a basis for strong natural selection. The abnormal abdomen syndrome should be favored whenever the adult age structure is skewed towards young individuals, and field studies confirm this prediction. The closely related species, Drosophila hydei, also bears these inserts and appears to be subject to similar selection. However, D. mercatorum responds to this selection primarily through the allelic variation that controls preferential underreplication, whereas D. hydei responds primarily through adjustment of the proportion of inserted 28S genes. This is interpreted to mean that the evolution of a multigene family arises from the interaction of population-level and DNA-level processes.Key words: ribosomal DNA, natural selection, concerted evolution, life history, multigene families, Drosophila mercatorum, Drosophila hydei.

scholarly journals The molecular through ecological genetics of abnormal abdomen in Drosophila mercatorum. V. Female phenotypic expression on natural genetic backgrounds and in natural environments.

Genetics ◽  
1993 ◽  
Vol 134 (2) ◽  
pp. 475-485 ◽  
Author(s):  
A R Templeton ◽  
H Hollocher ◽  
J S Johnston
Keyword(s):  
Life History ◽  
Phenotypic Expression ◽  
Developmental Time ◽  
Ecological Genetics ◽  
Adult Longevity ◽  
Natural Environments ◽  
X Chromosomes ◽  
Rdna Genes ◽  
Drosophila Mercatorum ◽  
Female Life History

Abstract The abnormal abdomen (aa) syndrome in Drosophila mercatorum depends on the presence of R1 inserts in a third or more of the X-linked 28S rDNA genes and the absence of selective underreplication of inserted repeats in polytene tissues that is controlled by an X-linked locus (ur) half a map unit from the rDNA complex. This syndrome affects both life history and morphology in the laboratory. Because abnormal morphologies are rarely encountered in nature, the purpose of this study is to see if the female life history traits are still affected under more natural genetic backgrounds and environmental conditions. Two outbred stocks were extracted from the natural population living near Kamuela, Hawaii: KaaX that has only X chromosomes with uraa alleles, and K+X that has only ur+ alleles. These two stocks have nonoverlapping distributions of insert proportions, indicating strong disequilibrium between the ur locus and the rDNA complex. The KaaX stock had almost no morphological penetrance of uraa, indicating that genetic background is important. KaaX expressed longer female egg-to-adult developmental times, increased early adult female fecundity, and decreased female adult longevity compared with K+X. By bagging natural rots of the cactus Opuntia megacantha near Kamuela, Hawaii, it was shown that egg-to-adult developmental time is slowed down by 0.92 days in females bearing uraa alleles in nature, with no detectable slowdown in uraa males. The bagged rot data also indicate that females bearing uraa alleles have a strong fecundity advantage in nature under some ecological conditions but not others.

scholarly journals Mhc polymorphisms fail to explain the heritability of phytohaemagglutinin-induced skin swelling in a wild passerine

2009 ◽  
Vol 5 (6) ◽  
pp. 784-787 ◽  
Author(s):  
Camille Bonneaud ◽  
Janet S. Sinsheimer ◽  
Murielle Richard ◽  
Olivier Chastel ◽  
Gabriele Sorci
Keyword(s):  
Genetic Variation ◽  
Immune Responses ◽  
Environmental Effects ◽  
Natural Populations ◽  
Wild Populations ◽  
Genetic Determinants ◽  
House Sparrows ◽  
Additive Genetic Variation ◽  
Significant Heritability ◽  
Mhc Polymorphisms

Genetic estimates of the variability of immune responses are rarely examined in natural populations because of confounding environmental effects. As a result, and because of the difficulty of pinpointing the genetic determinants of immunity, no study has to our knowledge examined the contribution of specific genes to the heritability of an immune response in wild populations. We cross-fostered nestling house sparrows to disrupt the association between genetic and environmental effects and determine the heritability of the response to a classic immunological test, the phytohaemagglutinin (PHA)-induced skin swelling. We detected significant heritability estimates of the response to PHA, of body mass and tarsus length when nestlings were 5 and 10 days old. Variation at Mhc genes, however, did not explain a significant portion of the genetic variation of nestling swelling to PHA. Our results suggest that while PHA-induced swelling is influenced by the nest of origin, the importance of additive genetic variation relative to non-additive genetic variation and the genetic factors that influence the former in wild populations still need to be identified for this trait.

scholarly journals Enzyme variability in the Drosophila willistoni Group. V. Genic variation in natural populations of Drosophila equinoxialis

1972 ◽  
Vol 20 (1) ◽  
pp. 19-42 ◽  
Author(s):  
Francisco J. Ayala ◽  
Jeffrey R. Powell ◽  
Martin L. Tracey
Keyword(s):  
Genetic Variation ◽  
Allelic Variation ◽  
Natural Populations ◽  
Starch Gel Electrophoresis ◽  
Gene Frequencies ◽  
Group V ◽  
Neutral Genetic Variation ◽  
Starch Gel ◽  
Genic Variation ◽  
Standard Techniques

SUMMARYWe have studied genetic variation at 27 loci in 42 samples from natural populations of a neotropical species, Drosophila equinoxialis, using standard techniques of starch-gel electrophoresis to detect allelic variation in genes coding for enzymes. There is considerarle genetic variability in D. equinoxialis. We have found allelic variation in each of the 27 loci, although not in every population. On the average, 71% of the loci are polymorphic – that is, the most common allele has a frequency no greater than 0·95 – in a given population. An individual is heterozygous on the average at 21·8% of its loci.The amount of genetic variation fluctuates widely from locus to locus. At the Mdh-2 locus arout 1% of the individuals are heterozygotes; at the other extreme more than 56% of the individuals are heterozygous at the Est-3. At any given locus the configuration of allelic frequencies is strikingly similar from locality to locality. At each and every locus the same allele is generally the most common throughout the distribution of the species. Yet differences in gene frequencies occur between localities. The pattern of genetic variation is incompatible with the hypothesis that the variation is adaptively neutral. Genetic variation in D. equinoxialis is maintained by balancing natural selection.The amount and pattern of genetic variation is similar in D. equinoxialis and its sibling species, D. willistoni. Yet the two species are genetically very different. Different sets of alleles occur at nearly 40% of the loci.

scholarly journals GENETIC ANALYSIS OF NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER IN JAPAN. II. THE MEASUREMENT OF FITNESS AND FITNESS COMPONENTS IN HOMOZYGOUS LINES

Genetics ◽  
1984 ◽  
Vol 108 (1) ◽  
pp. 213-221 ◽  
Author(s):  
Tsuneyuki Yamazaki ◽  
Yasuko Hirose
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Analysis ◽  
Natural Population ◽  
Natural Populations ◽  
Distribution Patterns ◽  
Developmental Time ◽  
Fitness Components ◽  
Isogenic Lines ◽  
Genetic Structures

ABSTRACT Fifty lethal-free, sterility-free isogenic lines of Drosophila melanogaster that were randomly sampled from a natural population were tested for net fitness and other components of fitness by competition with D. hydei. Larval viability and developmental time were also measured using the balanced marker method. Distribution patterns of these fitness components were similar, but correlation between the fitness components varied depending on the combinations used. The highest correlations were obtained between net fitness and productivity (rp = 0.6987, rg = 0.9269). The correlation between net fitness and total larval viability was much lower (rp = 0.1473 and rg = 0.2171). These results indicate that measuring net fitness, not just a component of fitness, is necessary for the good understanding of the genetic structures of natural populations.

scholarly journals Enzymatic analysis in Anopheles nuneztovari Gabaldón (Diptera, Culicidae)

2000 ◽  
Vol 60 (4) ◽  
pp. 539-550 ◽  
Author(s):  
V. M. SCARPASSA ◽  
W. P. TADEI
Keyword(s):  
Genetic Variation ◽  
Genetic Variability ◽  
Genetic Divergence ◽  
Allelic Variation ◽  
Natural Populations ◽  
Brazilian Amazon ◽  
High Variability ◽  
The Other ◽  
Enzymatic Analysis ◽  
Phenotypic Variations

Enzymatic analysis in Anopheles nuneztovari was made using four populations from the Brazilian Amazon and two from Colombia. The enzymes ME and XDH presented a monomorphic locus in all of the studied populations. EST and LAP presented a higher number of loci. In EST, genetic variation was observed in the five loci; LAP presented four loci, with allec variation in two loci. In IDH, three activity regions were stained, with genetic variation for locus Idh-1 in the Brazilian Amazon populations. A locus for MDH was observed, with genetic variation in the six populations. A region was verified for ACON, with four alleles in Sitronela and three in the other populations. PGM constituted one locus, with a high variability in the Brazilian Amazon populations. A locus was observed for 6-PGD with allelic variation in all of the populations with the exception of Tibú. Enzyme PGI presented two loci, both with genetic variability in the Tucuruí population. The enzyme alpha-GPD showed an activity region with polymorphism in the Tucuruí, Tibú and Sitronela populations. The phenotypic variations detected for these enzymes suggest that four (EST, LAP, ACON and PGM) possess monomeric structures and five (IDH, MDH, 6-PGD, PGI and alpha-GPD) dimeric structures in their proteins. These enzymes constitute in important markers to estimate variability and genetic divergence in natural populations of A. nuneztovari.

Conservation of the Threatened Species, Pulsatilla vulgaris Mill. (Pasqueflower), is Aided by Reproductive System and Polyploidy

2019 ◽  
Vol 110 (5) ◽  
pp. 618-628 ◽  
Author(s):  
Roberta Gargiulo ◽  
Gemma Worswick ◽  
Corinne Arnold ◽  
Lindsay J Pike ◽  
Robyn S Cowan ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Allelic Variation ◽  
Natural Populations ◽  
Wild Populations ◽  
Multiple Sources ◽  
Demographic Trends ◽  
Multiple Allele ◽  
Population Loss ◽  
Nuclear Microsatellite ◽  
Source Populations

AbstractPopulation loss due to habitat disturbance is a major concern in biodiversity conservation. Here we investigate the genetic causes of the demographic decline observed in English populations of Pulsatilla vulgaris and the consequences for conservation. Using 10 nuclear microsatellite markers, we compare genetic variation in wild populations with restored and seed-regenerated populations (674 samples). Emergence of genetic structure and loss of allelic variation in natural populations are not as evident as expected from demographic trends. Restored populations show genetic variation comparable to their source populations and, in general, to the wild ones. Genetic homogeneity is observed in regeneration trials, although some alleles not captured in source populations are detected. We infer that polyploidy, longevity, and clonal reproduction have provided P. vulgaris with the standing genetic variation necessary to make the species resilient to the effects of demographic decline, suggesting that the use of multiple sources for reintroduction may be beneficial to mimic natural gene flow and the availability of multiple allele copies typical of polyploid species.

scholarly journals ENZYME VARIABILITY IN THE DROSOPHILA WILLISTONI GROUP. IV. GENIC VARIATION IN NATURAL POPULATIONS OF DROSOPHILA WILLISTONI

Genetics ◽  
1972 ◽  
Vol 70 (1) ◽  
pp. 113-139
Author(s):  
Francisco J Ayala ◽  
Jeffrey R Powell ◽  
Martin L Tracey ◽  
Celso A Mourão ◽  
Santiago Pérez-Salas
Keyword(s):  
Genetic Variation ◽  
Central America ◽  
West Indies ◽  
Allelic Variation ◽  
Natural Populations ◽  
Group Iv ◽  
The West ◽  
Drosophila Willistoni ◽  
Genic Variation ◽  
South Brazil

ABSTRACT We describe allelic variation at 28 gene loci in natural populations of D. willistoni. Seventy samples were studied from localities extending from Mexico and Florida, through Central America, the West Indies, and tropical South America, down to South Brazil. At least several hundred, and often several thousand, genomes were sampled for each locus. We have discovered a great deal of genetic variation. On the average, 58% loci are polymorphic in a given population. (A locus is considered polymorphic when the frequency of the most common allele is no greater than 0.95). An individual fly is heterozygous, on the average, at 18.4% loci.—Concerning the pattern of the variation, the most remarkable finding is the similarity of the configuration of allelic frequencies from locality to locality throughout the distribution of the species. Our observations support the conclusion that balancing natural selection is the major factor responsible for the considerable genetic variation observed in D. willistoni.

scholarly journals AN EXPERIMENTAL TEST OF THE RELATIONSHIP BETWEEN GENETIC VARIATION AND ENVIRONMENTAL VARIATION IN TRIBOLIUM FLOUR BEETLES

Genetics ◽  
1986 ◽  
Vol 113 (2) ◽  
pp. 391-404
Author(s):  
Russel A Riddle ◽  
Peter S Dawson ◽  
Dave F Zirkle
Keyword(s):  
Genetic Variation ◽  
Environmental Heterogeneity ◽  
Natural Populations ◽  
Experimental System ◽  
Developmental Time ◽  
Pupal Weight ◽  
Environment Interaction ◽  
Fitness Components ◽  
Flour Beetles ◽  
Experimental Treatments

ABSTRACT The hypothesis that a component of genetic variation for polygenic fitness traits is maintained by environmental heterogeneity was tested using an experimental system involving two species of flour beetles, Tribolium castaneum and T. confusum. Replicated populations of each species from a number of environmental treatments were analyzed for various fitness components following almost 60 generations of natural selection. Environmental differences consisted of flours of cereals commonly invaded by natural populations of these insects.—Tests for adaptation to environments were based on experiments in which populations were reared factorially on each flour, such that population treatment x flour interactions could be detected. Measurements were made of survival, growth rate, larval weight, pupal weight, developmental time, fecundity of individuals at low density and fecundity and cannibalism at high density in both fresh and conditioned media.—Flour differences were found to have significant effects on most traits. Evidence for significant genetic variation and significant genotype x environment interaction was also found. However, no evidence could be found to support the hypothesis that genetic variation was maintained by environmental heterogeneity in food resources. The absence of adaptation to the experimental treatments despite the presence of genetic variation in fitness components suggests that pleiotropy may assume an important role in determining net fitness values of polygenes.

scholarly journals Compensatory evolution via cryptic genetic variation: Distinct trajectories to phenotypic and fitness recovery

2017 ◽  
Author(s):  
Sudarshan Chari ◽  
Christian Marier ◽  
Cody Porter ◽  
Emmalee Northrop ◽  
Alexandra Belinky ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Natural Selection ◽  
Allelic Variation ◽  
Courtship Behavior ◽  
Natural Populations ◽  
Wing Morphology ◽  
Cryptic Genetic Variation ◽  
Compensatory Evolution ◽  
Compensatory Adaptation ◽  
Deleterious Alleles

AbstractPopulations are constantly exposed to deleterious alleles, most of which are purged via natural selection. However, deleterious fitness effects of alleles can also be suppressed by compensatory adaptation. Compensatory mutations can act directly to reduce deleterious effects of an allele. Alternatively, compensation may also occur by altering other aspects of an organisms’ phenotype or performance, without suppressing the phenotypic effects of the deleterious allele. Moreover, the origin of allelic variation contributing to compensatory adaptation remains poorly understood. Compensatory evolution driven by mutations that arise during the selective process are well studied. However less is known about the role standing (cryptic) genetic variation plays in compensatory adaptation. To address these questions, we examined evolutionary trajectories of natural populations of Drosophila melanogaster fixed for mutations that disrupt wing morphology, resulting in deleterious effects on several components of fitness. Lineages subjected only to natural selection, evolved modifications to courtship behavior and several life history traits without compensation in wing morphology. Yet, we observed rapid phenotypic compensation of wing morphology under artificial selection, consistent with segregating variation for compensatory alleles. We show that alleles contributing to compensation of wing morphology have deleterious effects on other fitness components. These results demonstrate the potential for multiple independent avenues for rapid compensatory adaptation from standing genetic variation, which ultimately may reveal novel adaptive trajectories.

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