An estimate is presented of the effective size of a natural, Greek population of Drosophila subobscura, based on data on lethal allelism. It is compared with further estimates for the same population obtained from newly-reported data by the “temporal” and the “ecological” methods. The lethal allelism and ecological estimates both suggest that the population is extremely large and effectively infinite. The conclusions from the temporal method conform to this, with the exception of data from two loci: Est-5 and Aph. Directional selection at these loci is therefore suggested. Each method is described and explained, and their validity discussed. The results are compared with the few previous estimates of effective population size.

/pdf/the-genetics-of-drosophila-subobscura-populations-2eonq80um3.pdf

The genetics of Drosophila subobscura populations

To discover the relation between mitochondrial DNA (mtDNA) polymorphism and the geographic population structure of Drosophila subobscura previously established for other genetic traits, a wide Paleartic survey was carried out. A total of 24 nucleomorphs was observed among 261 isofemale lines assayed by 11 restriction endonucleases with 38 different sites in the mtDNA cleavage map. The differentiation of the Canary Islands populations (delta = 0.0119) compared with the mean among all the other continental and insular populations (delta = 0.0002) is striking. Both the great divergence among Canary Islands nucleomorphs (delta = 0.021) compared with the maximum nucleomorph distance in all other populations (delta = 0.017) and the abundance of endemic nucleomorphs (11) on the Canary Islands (50% of the total number of different nucleomorphs found in the entire distribution area) suggest that this molecular differentiation most probably results from the very old age of the Canary Islands populations rather than from drift and founder effects.

Mitochondrial DNA variation and genetic structure in Old-World populations of Drosophila subobscura.

The rate of allelism of lethals on the O chromosome of Drosophila subobscura in two natural populations and the interpopulation allelism rate are 0.0062, 0.0025 and 0.0058 respectively. They do not differ statistically. It is concluded that the natural populations studied have practically an infinite size. This conclusion is corroborated by ecological data on density and dispersion, and partly by data based on the temporal method. The allelism rate of genes producing male and female sterility was also studied. From the study of the allelism rate for lethal and sterility genes the number of such genes on the O chromosome ofD. subobscura was inferred.

The genetics of Drosophila subobscura populations XIII. A study of lethal allelism

Species belonging to the obscura group of Drosophila have played an important role in population genetics and evolution, The best studied species of this group in North America are D. pseudoobscura and D. persimilis (Dobzhansky and Powell, 1975); in the Old World D. subobscura has received the most attention (Krimbas and Loukas, 1980). The feature of these species which has been most thoroughly studied is the genetic differentiation of populations for the chromosome inversion polymorphisms. These species show considerable quantitative (frequency) as well as qualitative (presence or absence) geographic differentiation for inversion polymorphisms. The degree to which a species is genetically structured depends on many things, among which dispersal behavior is surely important (Taylor and Powell, 1983). In a comparison of the genetic structure of these species, Ferrari and Taylor (1981) used the hierarchical analytical procedures of Wright (1978). They found that D. subobscura is geographically structured on a finer scale than is D. pseudoobscura. This was thought to be consistent with the dispersal behavior of the two species, D. pseudoobscura dispersing at a higher rate than D. subobscura (Begon, 1976; Powell et aI., 1976). However, the dispersal rates of these species had not been analyzed in a manner that permitted direct comparison, so that explanation had to be considered tentative, We present here: (a) the results of a dispersal study with D, subobscura on Mljet, Yugoslavia, done in the same manner as those done with D. pseudoobscura; and (b) a re-analysis of an early study of D. subobscura and D. obscura at Wangenerwald, near Zurich, Switzerland, done by Burla and Greuter (1959a, 1959b, 1963; Greuter, 1963). These are compared to measures of active dispersal by D. pseudoobscura and D. persimilis in California, USA. We conclude that there is no compelling evidence for significantly different dispersal rates among the four species mentioned above. Indeed, considering the variety of experimental designs employed, the measured dispersal parameters of the four species seem remarkably similar. Thus differences in population structuring among these species must be due to factors other than active dispersal behavior (sensu Dobzhansky, 1973).

Dispersal rates of species of the drosophila obscura group: implications for population structure.

We analyzed changes in the genetic structure and effective population size of two ecologically distinct populations of Drosophila subobscura over several years. Population sizes of D. subobscura in beech and oak wood habitats for a period of 6 years were estimated by the capture-mark-release-recapture method. Inversion polymorphism parameters were also assessed in the same populations for a period of 3 years.

Monitoring of the genetic structure of natural populations: change of the effective population size and inversion polymorphism in Drosophila subobscura.

We have studied the active dispersal behaviour of Drosophila subobscum Coll. in a citrus orchard near Preveza (in N. W. Greece) following the experimental design proposed by Crumpacker & Williams and using fluorescent dusts to mark wild animals captured which were subsequently released. The parameters quantifying dispersal have been estimated and do not differ from the ones found in similar studies of Begon in English populations and of Burla & Greuter in Swiss populations. D. subobscura however does differ from its American relatives of the obscura group in having a lower dispersion activity. Density estimations of the autumn size indicate that natural populations in Greece are larger than the ones in England. From these densities we derived a tentative estimation of the effective size of the panmictic unit. This size is 20 to 340 times greater than the one estimated by a genetic method based on the temporal differences of allozyme frequencies. However an accurate ecological estimation of the effective size requires a density estimation of the minimal (winter) size and the figure calculated by us is no doubt an overestimation. Drosophila species usually used in populationat genetic studies. The well known ecological technique of releasing marked individuals and recapturing them was used, at the beginning with visual mutants bred in the laboratory. Since then the technique has been improved in experimental design as well as in the marking technique by the use of ultra-violet fluores: cent dusts. The interest of these studies has been revived by the selectionist-neutralist controversy and especially by some models proposed by the Kimura school (Crow & Kimura, 1970) which predict that the immigration of even one individual per generation in every local population is enough to ~ansform them in to a single panmictic unit. We have assembled some genetical information concerning the effective density in Greek natural populations of Drosophila subobscum (Loukas, Krimbas & Vergini, in press). With the present paper we start reporting ecological data which will eventually permit us to arrive at comparisons between ecological and genetical estimations. Thus the present paper reports an effort to quantify dispersal in this species and provides also some density estimations.

The genetics of drosophila subobscura populations X. A study of dispersal

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

M. Loukas

Author Tools

Chat about Author

Papers

The genetics of drosophila subobscura populations X. A study of dispersal