Genetic variation in natural populations: Morphological traits inDrosophila melanogaster

1978 ◽  
Vol 34 (7) ◽  
pp. 833-834 ◽  
Author(s):  
Dolores Ochando
Keyword(s):  
Genetic Variation ◽  
Morphological Traits ◽  
Natural Populations

Analysis of Genetic Variation in Natural Populations of Medicago truncatula of Southern Tunisian Ecological Areas, Using Morphological Traits and SSR Markers

2009 ◽  
Vol 2 (3-4) ◽  
pp. 122-132 ◽  
Author(s):  
Soumaya Arraouadi ◽  
Mounawer Badri ◽  
Cheruth Abdul Jaleel ◽  
Naceur Djébali ◽  
Houcine Ilahi ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Ssr Markers ◽  
Medicago Truncatula ◽  
Morphological Traits ◽  
Natural Populations

scholarly journals 561 Using AFLPs to Examine Genetic Diversity in Umbrella Fern

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 543A-543
Author(s):  
F.J. Keiper ◽  
R. McConchie
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Molecular Markers ◽  
Dna Markers ◽  
Morphological Traits ◽  
Natural Populations ◽  
Cost Effective ◽  
Molecular Techniques ◽  
Breeding Systems ◽  
Detailed Knowledge

Umbrella fern [Sticherus flabellatus (R. Br.) St John] is a successful Australian native foliage product. Currently, all umbrella fern sold on the market is bush-harvested. To meet the growing demand for this product on local and international markets, a commercially viable method for its production must be developed, with effective management of the germplasm resource in terms of conservation and exploitation. To manage this resource, breeders require a detailed knowledge of the amount and distribution of genetic variability within the species. Traditionally, plant breeders focus on a combination of agronomic and morphological traits (phenotype) to measure genetic diversity. In umbrella fern there are a limited number of morphological traits, and these are influenced by environmental factors and therefore do not reflect true genetic diversity. To overcome these problems, molecular techniques such as PCR-based DNA markers are used to complement traditional strategies for genotype assessment. DNA markers have the advantages of being independent of environmental effects, as well as being fast, cost-effective, reproducible, and largely accessible to the nonmolecular geneticist. Amplified fragment length polymorphisms (AFLPs) fulfil many of the desirable features of molecular markers, as well as requiring little knowledge of the genome to be investigated. AFLPs have been used widely in the analysis of breeding systems, ecogeographical variation, and genetic variation within and between natural populations. To date there are no published accounts of DNA molecular marker research on umbrella fern. A DNA extraction protocol has been developed for this species, and AFLP markers have been used to analyse genetic diversity within and between natural populations sampled in the Sydney Basin. A large number of polymorphic loci were revealed using 11 primer combinations. The genetic variation detected was partitioned between rather than within populations, suggesting that the mating system in Sticherus is primarily inbreeding. Data will be presented illustrating AFLPs as useful molecular markers for assessing genetic diversity within and between populations of umbrella fern and providing insight on the breeding system used by the species.

scholarly journals POPULATION GENETICS OF ALLOZYME VARIATION IN NEUROSPORA INTERMEDIA

Genetics ◽  
1975 ◽  
Vol 80 (4) ◽  
pp. 785-805
Author(s):  
P T Spieth
Keyword(s):  
Genetic Variation ◽  
Vegetative Reproduction ◽  
Vascular Plant ◽  
Natural Populations ◽  
Allozyme Variation ◽  
Regular Feature ◽  
Local Populations ◽  
Neurospora Intermedia ◽  
Pattern Of Variation ◽  
High Level

ABSTRACT Electrophoretically detectable variation in the fungus Neurospora intermedia has been surveyed among isolates from natural populations in Malaya, Papua, Australia and Florida. The principal result is a pattern of genetic variation within and between populations that is qualitatively no different than the well documented patterns for Drosophila and humans. In particular, there is a high level of genetic variation, the majority of which occurs at the level of local populations. Evidence is presented which argues that N. intermedia has a population structure analogous to that of an annual vascular plant with a high level of vegetative reproduction. Sexual reproduction appears to be a regular feature in the biology of the species. Substantial heterokaryon function seems unlikely in natural populations of N. intermedia. Theoretical considerations concerning the mechanisms underlying the observed pattern of variation most likely should be consistent with haploid selection theory. The implications of this constraint upon the theory are discussed in detail, leading to the presentation of a model based upon the concept of environmental heterogeneity. The essence of the model, which is equally applicable to haploid and diploid situations, is a shifting distribution of multiple adaptive niches among local populations such that a given population has a small net selective pressure in favor of one allele or another, depending upon its particular distribution of niches. Gene flow among neighboring populations with differing net selective pressures is postulated as the principal factor underlying intrapopulational allozyme variation.

scholarly journals Female Genotypes Affect Sperm Displacement in Drosophila

Genetics ◽  
1998 ◽  
Vol 149 (3) ◽  
pp. 1487-1493 ◽  
Author(s):  
Andrew G Clark ◽  
David J Begun
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Natural Populations ◽  
Isogenic Line ◽  
Female Fitness ◽  
Sperm Displacement ◽  
Extensive Variation ◽  
Polymorphic Genes ◽  
Displacement Parameter ◽  
Competitive Success

Abstract Differential success of sperm is likely to be an important component of fitness. Extensive variation among male genotypes in competitive success of sperm in multiply mated females has been documented for Drosophila melanogaster. However, virtually all previous studies considered the female to be a passive vessel. Nevertheless, under certain conditions female fitness could be determined by her role in mediating use of sperm from multiple males. Here we ask whether females differ among genotypes in their tendency to exhibit last-male precedence. Competition of sperm from two tester male genotypes (bwD and B3-09, a third-chromosome isogenic line from Beltsville, MD) was quantified by doubly mating female lines that had been rendered homozygous for X, second, or third chromosomes isolated from natural populations. The composite sperm displacement parameter, P2′, was highly heterogeneous among lines, whether or not viability effects were compensated, implying the presence of polymorphic genes affecting access of sperm to eggs. Genetic variation of this type is completely neutral in the absence of pleiotropy or interaction between variation in the two sexes.

scholarly journals Genetic variation in the dietary sucrose modulation of enzyme activities in Drosophila melanogaster

1984 ◽  
Vol 43 (3) ◽  
pp. 307-321 ◽  
Author(s):  
Billy W. Geer ◽  
Cathy C. Laurie-Ahlberg
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Enzyme Activities ◽  
Glycogen Synthesis ◽  
Krebs Cycle ◽  
Natural Populations ◽  
Substitution Lines ◽  
Chromosome Substitution Lines ◽  
High Sucrose Diet ◽  
Selection Of

SUMMARYGenetic variation in the modulating effect of dietary sucrose was assessed in Drosophila melanogaster by examining 27 chromosome substitution lines coisogenic for the X and second chromosomes and possessing different third isogenic chromosomes derived from natural populations. An increase in the concentration of sucrose from 0·1% to 5% in modified Sang's medium C significantly altered the activities of 11 of 15 enzyme activities in third instar larvae, indicating that dietary sucrose modulates many, but not all, of the enzymes of D. melanogaster. A high sucrose diet promoted high activities of enzymes associated with lipid and glycogen synthesis and low activities of enzymes of the glycolytic and Krebs cycle pathways, reflecting the physiological requirements of the animal. Analyses of variance revealed significant genetic variation in the degrees to which sucrose modulated several enzyme activities. Analysis of correlations revealed some relationships between enzymes in the genetic effects on the modulation process. These observations suggest that adaptive evolutionary change may depend in part on the selection of enzyme activity modifiers that are distributed throughout the genome.

scholarly journals GENETIC VARIATION FOR CLUTCH SIZE IN NATURAL POPULATIONS OF BIRDS FROM A REACTION NORM PERSPECTIVE

Ecology ◽  
2005 ◽  
Vol 86 (9) ◽  
pp. 2344-2357 ◽  
Author(s):  
Erik Postma ◽  
Arie J. van Noordwijk
Keyword(s):  
Genetic Variation ◽  
Clutch Size ◽  
Natural Populations ◽  
Reaction Norm

scholarly journals Behavior and Genetic Variation in Natural Populations

1970 ◽  
Vol 10 (1) ◽  
pp. 53-66 ◽  
Author(s):  
ROBERT K. SELANDER
Keyword(s):  
Genetic Variation ◽  
Natural Populations
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