Characterization and Genetic Diversity of Taif Chicken Ecotype Using Dense Microsatellites Panel

The current study is the first comprehensive investigation to address the native chicken ecotypes of the Taif region to unravel the genetic diversity using a dense panel of 40 microsatellites (SSR). Blood samples were collected from 25 hens randomly sampled from a village farm at Taif governorate. A total of 147 alleles were detected, with an average of 3.7 alleles per locus. The overall mean of polymorphic information content (PIC) was 0.43. The average observed heterozygosity (Hobs) of 0.28 was lower than the expected heterozygosity (Hexp) of 0.48. Out of 40l ocionly11 loci showed insignificant deviation from Hardy Weinberg expectation. The ecotypes showed low genetic diversity (HS = 0.65) and a high level of inbreeding (FIS= 0.75). The high FIS is indicative of the endangerment potentiality of this ecotype. Nine SSR showed an inbreeding coefficient of one. The significant estimate of the inbreeding coefficient of the present study calls for an immediate breeding plan to preserve such endangered ecotypes. Results of the present study will provide an initial guide to design further investigations for the development of sustainable genetic improvement and conservation programs for the Taif ecotype genetic resources.

Deviation from Hardy–Weinberg equilibrium, and temporal instability in allele frequencies at microsatellite loci in a local population of Atlantic cod

A total of 1455 spawning cod, sampled from a local spawning area in Trondheimsfjord (Norway) between 1985 and 2002, was screened at the microsatellite loci Gmo132 and Gmo2. Samples from 15 spawning years comprising 29 consecutive cohorts were analysed. At the Gmo132 locus, but not at Gmo2, allele frequencies varied significantly among sampling years as well as cohorts, corresponding to FST-values of 0.004 and 0.006, respectively. Both loci showed examples of significant deviations from Hardy–Weinberg expectation within sampling years as well as cohorts, manifested as deficiencies of heterozygotes. Combining the p-values from the single tests (Fisher's method) revealed an overall significant p-value for deviation from the Hardy–Weinberg expectations at Gmo132 but not at Gmo2. Trend tests showed significant HW deficiencies at both loci for annual samples but not for cohorts. Possible reasons for the deficiencies were discussed; inter alia the existence of null alleles, or a form of pseudo Wahlund effect due to a patchy distribution of habitats for settling O-group cod in the Trondheimsfjord. It was noted that there might be a relationship between the relatively high temporal within-population variability of allele frequencies at Gmo132 and the fact that among microsatellite loci studied so far, Gmo132 is the one that usually shows the highest genetic differentiation geographically in cod.

Nonrandom Distribution of Virulences Within Two Field Collections of Uromyces appendiculatus

Two collections of urediniospores of Uromyces appendiculatus, each from a different commercial bean field, were characterized for associations of virulence among individuals within each collection. Four bean (Phaseolus vulgaris) lines with distinct, race-specific resistance to which virulence in each population was polymorphic were used to obtain measures of all six possible pairwise virulence associations for each collection. We inoculated one of the lines and collected urediniospores only from the segment of the population that was virulent on that line. This segment, when compared with nonselected collections from susceptible Pinto 111, gave a direct measure of degree of association as the change in frequency of virulence observed. Plants of the second bean line were inoculated in separate sets with both selected and unselected collections. Frequencies of virulence were estimated from the numbers of susceptible-type and resistant-type infections. Reciprocals of each pairing also were made. For collection P21, all virulences were significantly associated, either positively or negatively, except one pair (in one direction of selection only); whereas, for collection M5, all virulences were significantly associated. Virulence association in P21 was shown to be the result of predominance of phenotypes with certain combinations of virulence by inoculation of the four bean lines with 10 randomly chosen single-uredinial individuals. In support of this, a large random-mated F1 population derived from each collection showed much less virulence association, with the majority of pairs of virulences showing nonsignificant changes in virulence frequency after passage through the first line. Random mating also significantly changed virulence frequency from that of the original population in all instances. Changes were in both directions, suggesting either that virulences were not all recessive, or that heterozygote frequency was sometimes above and sometimes below the Hardy-Weinberg expectation in the field populations.

Allozyme differentiation among gopher tortoises (Gopherus): conservation genetics and phylogenetic and taxonomic implications

The genetic diversity among 18 loci within and among four species of gopher tortoises was investigated using horizontal starch gel electrophoresis. Within species variation ranged from 2 to 4% by direct count and from 2 to 8% by Hardy–Weinberg expectation. Of the loci resolved, 11–22% expressed variation. The northern and southern populations of Gopherus flavomarginatus could not be distinguished. No fixed differences were observed between G. agassizii and G. berlandieri, as reflected in a Nei genetic distance of 0.008. These latter species may be little more than allopatric populations of G. agassizii. Differentiation between the two remaining species was not extensive; G. polyphemus was only slightly distinct from G. flavomarginatus, being separated by a Nei genetic distance of only 0.006. The two pairs of species were separated by an average genetic distance of 0.200. The evolutionary rates of divergence were observed to be unequal, especially between G. polyphemus and G. flavomarginatus. The overall genetic similarity suggests a relatively recent age of origin.

Population structure and genie diversity in tamarack, Larixlaricina (Du Roi) K. Koch

Levels of electrophoretically detectable variation at 19 loci were estimated in 36 populations representing the natural range of Larixlaricina (Du Roi) K. Koch. Results of this survey indicated that the species has levels of genic variation comparable with those of other species of woody perennials with extensive transcontinental ranges. There was no evidence of significant departures from Hardy–Weinberg expectation. However, on average, populations of this species were more differentiated and more genetically divergent from one another compared with many randomly mating tree species. A discriminant analysis of the genotypic structure of the populations analyzed indicated a general east versus west pattern, with populations in the Great Lakes basin being further differentiated. Present-day population distribution, population density, and reinvasion routes after the last glaciation could account for the observed patterns of genic variation.

Adaptation at specific loci. V. Metabolically adjacent enzyme loci may have very distinct experiences of selective pressures.

The polymorphic phosphoglucomutase (PGM) and glucose-6-phosphate dehydrogenase (G6PD) loci have been studied in parallel to experimental work on the phosphoglucose isomerase (PGI) polymorphism in Colias butterflies. PGI, PGM and G6PD are also autosomal in Colias. PGM and G6PD are loosely linked (and represent the first identified autosomal linkage group in Colias); they assort independently from PGI. Recombination occurs in both sexes. Neither PGM nor G6PD shows large, consistent differences in flight capacity through the day among its genotypes, as PGI does. PGM shows some change of allele frequencies, and match to Hardy-Weinberg expectation, with air temperature in middle and latter parts of the season, but not early in the season. G6PD may show some heterozygote excess over Hardy-Weinberg expectation early in the day, but more testing is needed. No evidence for differential survivorship was seen at PGM or G6PD, in contrast to PGI. At the PGM and G6PD loci, male heterozygotes are advantaged in mating with females, but without the evidence of female choice which occurs for PGI. These effects are not correlated among the three loci. There is no assortative mating at G6PD (nor at PGI). There is minor positive assortative mating of PGM heterozygotes, but it is too weak to account for the PGM-genotype-specific male mating advantage. No trends of multilocus genotype frequencies involving PGI are seen. Certain PGM-G6PD two-locus genotypes are over-represented, and others under-represented, in wild adult samples, particularly among males and uniformly among successfully mating males. Our results emphasize that enzyme loci sharing a substrate need not have common experience of the existence or strength of natural selection, and suggest initial food-resource processing and allocation as a possible context for fitness-related effects of the PGM and G6PD polymorphisms.

Age-related allozymic variation in the cyprinid fish Alburnus alburnus

A polymorphism in water-soluble muscle esterases in the freshwater cyprinid fish Alburnus alburnus, the bleak, is described. The variation may be attributed to three codominant alleles at a single locus. Strong distortions from Hardy–Weinberg expectation are noted in samples from all length groups of fish at all times of the year. All homozygotes and one heterozygote are generally in deficit, while the two common heterozygotes are present in excess. Analysis of the genotype frequencies on a basis of random mating indicates that the polymorphism is stable and close to equilibrium. There are significant associations between size class and the frequencies of alleles 1 and 2 and genotype 33.

MULTIVARIATE ANALYSIS OF GAMETIC DISEQUILIBRIUM IN THE YANOMAMA

ABSTRACT The gametic disequilibria between all possible pairs of loci were examined for a set of eight codominant loci in each of fifty Yanomama villages, using a multivariate correlation analysis which reduces the results to a single measure of departure from multiple-locus-gametic equilibrium. Thirty-two of the fifty villages departed significantly from multiple-locus gametic equilibrium. The largest contributions to the departure from multiple-locus equilibrium were due to the disequilibria between MN and Ss and between Rh(Cc) and Rh(Ee), indicating the effects of tight linkage. After removing the effects of these obvious sources of disequilibrium, sixteen of the fifty villages still remained significantly out of equilibrium. The disequilibrium between any particular pair of loci was highly erratic from village to village, and (with the exception of the MN-Ss and Cc-Ee disequilibria) averaged out very close to zero overall, suggesting a lack of systematic forces (epistatic selection). The departure from equilibrium in any one village is in excess of that expected from random sampling alone, and is attributed primarily to the fission-fusion mode of village formation operative in the Yanomama and the fact that a single village consists of a few extended lineages. Village allele frequencies are highly correlated across loci, and most of the non-independence is accounted for by large correlations in the average allelic frequencies of different loci for related villages. It is suggested that these correlations also are due to territorial expansion and population growth. For the tribe as a whole, all but the tightly linked markers of the MNSs and Rh complexes are approximately uncorrelated, and large departures from multiple-locus Hardy-Weinberg expectation are primarily due to substantial Wahlund variance within the tribe. There is no need to postulate a role for selection in these disequilibria.

INVERSION POLYMORPHISM IN CHIRONOMUS STAEGERI LUNDBECK

Populations of Chironomus staegeri are polymorphic for inversions in six chromosome arms. Many of these inversions do not conform to Hardy-Weinberg expectation, often with a significant deficiency of heterozygotes. Many combinations of the inversions two-at-a-time show a significant deviation from random assortment. Often this is due to the occurrence together in the same individual of rare sequences, but others, such as the association of sequences A1 and C1, A2 and C2, and A2 and B4 appear to be real effects.There is a marked dimorphism in the inversion sequences present in populations from deep water and those from shallow water in the northeastern U.S.A. and Canada. This may be associated with ability to withstand winter freezing.It is possible that a process of speciation, leading eventually to three different species, is in progress and a considerable degree of reproductive isolation may have already been achieved.