Dermatoglyphics in endogamic populations of Sardinia

Several dermatoglyphic characteristics (palmar and plantar) of different populations in Sardinian communities are reported. Graphs illustrating the dermatoglyphic behaviour of the single communities examined are presented.It can be seen that each community behaves differently from the others, even when they are geographically close together. Sexual differences appear quite accentuated in some communities while in others they are negligible. From the present study, as well as from other studies on the hereditary characteristics of Sardinians, it emerges that Sardinia is in reality subdivided into many different populations, or endogamic stocks, each presenting a particular behaviour of its own, sometimes quite different from that presented by the other populations.     

Dermatoglyphics of three Hungarian populations

The dermatoglyphics of 709 individuals from three Hungarian populations living near each other but of different origin were analyzed. In dermatoglyphic traits the three populations present but slight differences from one another.     

Genetic analysis of the microevolutionary processes in cattle populations (the example of the B locus of blood groups)

Dynamics of allele frequencies for the B-locus of blood groups in cattle populations and of a number of phenotype indexes in these animals was studied. It is determined that natural stabilizing selection and prezygotic selection, leading to a change in genetic structure, act in every population. The role of sires' influence on this process is insignificant.     

A study of the genetic polymorphism of human inter-alpha-trypsin-inhibitor (ITI) in the Han population,Chengdu, China

Phenotypes of inter-alpha-trypsin-inhibitor (ITI) have been determined by isoelectric focusing on polyacrylamide gels followed by immunofixation. The phenotype frequencies of ITI in the Han population in Chengdu, P. R. China have been investigated using this method. In addition, family studies have been conducted in 21 families. The results show that ITI is polymorphic in the Han population in Chengdu, China. The allele frequencies are as follows: ITI*1 = 0.5763. ITI*2 = 0.4107, ITI*3 = 0.0130. ITI is thus a new and promising genetic marker that can be used in the field of forensic haematogenetics.     

Mating system parameters and population genetic structure in pioneer populations of Prosopis velutina (Leguminosae)

This study describes the genetic structure and provides estimates of mating system parameters in three natural populations of Prosopis velutina Woot. in southeastern Arizona. F statistics derived from isozyme data revealed the presence of both interpopulation and intrapopulation genetic differentiation. This population structure is discussed in relation to the ecological history of these populations that invaded the grasslands sites from adjacent riparian areas within the last 90 years, and possible modes of seed dispersal. The multilocus estimation program MLT of Ritland (Journal of Heredity 8: 235–237, 1990) was used to provide estimates of t_s, t_m, and the fixation index (F) of the maternal parents. Average estimates of t_s ranged from 0.591 to 0.912. Estimates of t_m ranged from 0.609 to 1.004, and averaged 0.758. The difference between t_m and t_s, which provides a measure of biparental inbreeding, averaged 0.058. This last result, together with significant heterogeneity found in pollen allele frequencies, suggests that a family structure has developed in the populations. A negative F value for one of the populations suggests selection against homozygotes between the seedling stage and maturity.     

Regulatory processes and population cyclicity in laboratory populations ofAnagasta kühniella (Zeller) (Lepidoptera: Phycitidae)

AsMatsumoto andHuffaker (1973) concluded that their initial universe size was too small for the proper separation of the effects of host density and dispersion on parasite performance, a larger universe of 38 1/2″ (length) ×38 1/2″ (width) ×3″ (height) was used. When individual parasites were exposed to fixed densities and dispersion patterns of host, they displayed an overall decrease in the parasitization rate when compared to the small universe. In all cases aHolling -type response resulted. When a group of 10 parasites per test was employed a Nicholsonian type of response resulted. In an experimentally confined space, the parasites displayed a mutual behavioral interference resulting in emigration which accelerated as the parasite density increased.     

A population genetic study in Finland: comparison of the Finnish- and Swedish-speaking populations.

In Finland there is a substantial but geographically limited Swedish-speaking minority (in 1980 6.3% of the total population) which originates mainly from Swedish immigrants during the years 1100-1300 AD. The admixture of this population with the neighbouring Finns was studied using more than 20 blood marker loci. The reference populations, Swedes and Finns, in spite of being part of the genetically rather uniform European populations, differ from each other genetically. These quantitative and also qualitative differences in gene frequencies are mostly due to the Finnish population possessing a number of genetic markers absent or rare in the rest of Europe. The results based on a sample of 620 individuals from the Swedish-speaking population in Finland showed a rather high degree of Finnish admixture, which was estimated to about 60%. This admixture most probably occurred at an early stage since it has reached such a high and geographically homogeneous degree.     

Multiple processes drive genetic structure of humpback whale (Megaptera novaeangliae) populations across spatial scales

Elucidating patterns of population structure for species with complex life histories, and disentangling the processes driving such patterns, remains a significant analytical challenge. Humpback whale (Megaptera novaeangliae) populations display complex genetic structures that have not been fully resolved at all spatial scales. We generated a data set of nuclear markers for 3575 samples spanning the seven breeding stocks and substocks found in the South Atlantic and western and northern Indian Oceans. For the total sample, and males and females separately, we assessed genetic diversity, tested for genetic differentiation between putative populations and isolation by distance, estimated the number of genetic clusters without a priori population information and estimated rates of gene flow using maximum‐likelihood and Bayesian approaches. At the ocean basin scale, structure is governed by geographical distance (IBD P < 0.05) and female fidelity to breeding areas, in line with current understanding of the drivers of broadscale population structure. Consistent with previous studies, the Arabian Sea breeding stock was highly genetically differentiated (F_ST 0.034–0.161; P < 0.01 for all comparisons). However, the breeding stock boundary between west South Africa and east Africa was more porous than expected based on genetic differentiation, cluster and geneflow analyses. Instances of male fidelity to breeding areas and relatively high rates of dispersal for females were also observed between the three substocks in the western Indian Ocean. The relationships between demographic units and current management boundaries may have ramifications for assessments of the status and continued protections of populations still in recovery from commercial whaling.     

Geography of genetic processes in the population: genetic migration in Northern Eurasia (Central Asia region)]

Based on the data of the census of 1970, a map of the rates of gene migrations in the rural population of Central Asia and Kazakhstan was drawn. The corrected average value for 35 populations of oblasts (administrative regions) and autonomous republics was m = 0.0606 +/- 0.0102. The estimate obtained from the mapped data was 0.0799 +/- 0.0014, which is 1.2-fold higher than similar values for Europe. The relationship between the rate of gene migration m, the genetically effective population size Ne, and the density of elementary populations in the studied area Pp was analyzed by means of correlation and regression analyses. The following relationship was obtained: m = A/Ne + BPp, where A > 0 and B < 0. This was accounted for by the fact that the migration flow is mainly directed to the less densely populated rural areas. Given that the region was chosen somewhat artificially, studying gene migrations in Central Asia and Kazakhstan as separate historical, geographic, and genetic subregions of northern Eurasia might be a better approach.     

Bayesian approaches for the analysis of population genetic structure: an example from Platanthera leucophaea (Orchidaceae)

We describe four extensions to existing Bayesian methods for the analysis of genetic structure in populations: (i) use of beta distributions to approximate the posterior distribution of f and theta(B); (ii) use of an entropy statistic to describe the amount of information about a parameter derived from the data; (iii) use of the Deviance Information Criterion (DIC) as a model choice criterion for determining whether there is evidence for inbreeding within populations or genetic differentiation among populations; and (iv) use of samples from the posterior distributions for f and theta(B) derived from different data sets to determine whether the estimates are consistent with one another. We illustrate each of these extensions by applying them to data derived from previous allozyme and random amplified polymorphic DNA surveys of an endangered orchid, Platanthera leucophaea, and we conclude that differences in theta(B) from the two data sets may represent differences in the underlying mutational processes.     

A population genetic study of six VNTR loci in three ethnically defined populations.

To investigate the population genetic characteristics of VNTR polymorphisms in human populations, we have studied the allele frequency distribution of six VNTR loci (D1S57, RB1, D1S77, D1S61, alpha-globin 5'HVR, D1S76) in three well-defined populations (Kachari of Northeast India; Dogrib Indian of Canada; and New Guinea Highlander of Papua New Guinea). Even though the number of alleles sampled is limited, 48 to 92 alleles per locus per population, significant variation is noticed in the number of alleles per locus for all the populations. Using alternate summary measures, we have observed that genotype distributions at the six VNTR loci apparently conform to their respective Hardy-Weinberg predictions. Multilocus genotype profiles of the individuals in each of the three populations suggest that the VNTR alleles are independently segregating with the exception of the two linked loci D1S76 and D1S77. Lack of fit of all VNTR loci to one particular model of mutational change, either the Infinite Allele Model or the Stepwise Mutation Model, suggests more than one mechanism for production of new VNTR alleles. This study also indicates that increased heterozygosity at VNTR loci in comparison to protein and blood group loci may lead to more accurate estimates of genetic distance.     

A study of genetic diversity among host-specific populations of the witchweedStriga hermonthica (Scrophulariaceae) in Africa

Striga hermonthica is a root hemiparasite that attacks onlyGramineae, includingSorghum and millet for which it is a principal cause of lowered yield. Enzyme electrophoresis was used to investigate genetic diversity inStriga hermonthica and to determine the level of differentiation between host-specialized populations. Nine genetic loci coding eight enzymes were interpreted and data obtained from three populations: oneSorghum-adapted population from Sudan and two populations from Burkina Faso, oneSorghum-adapted and the other millet-adapted. Levels of polymorphism were similarly high in all three populations (P=0.625, A=2.6–2.8, H=0.293–0.401). Genotypic frequencies at most loci conformed to Hardy-Weinberg expectations in each population, consistent with outcrossing as predicted from previous studies of floral biology. Occasional heterozygote deficiencies were probably the result of Wahlund effect. The mean value of F_ST over the three populations was 0.068, indicating a slight to moderate level of genetic differentiation among the populations. The two Burkina Faso populations were more closely related (S=0.940, D=0.006) than either was to the Sudan population, suggesting that geographic separation is more important than host specialization in contributing to population differentiation. TheSorghum-adapted population was slightly closer to the Burkina FasoSorghum-adapted population (S=0.873, D=0.047) than to Burkina Faso millet-adapted population (S=0.851, D=0.074). The absence of substantial genetic divergence between host-specific populations ofStriga could result either from recent evolution of host-specialized strains or from strong selection for physiological specialization in the face of substantial gene flow between the populations.     

Genetic diversity and population genetic structure of six dromedary camel (camelus dromedarius) populations in Saudi Arabia

Camels are an integral and essential component of the Saudi Arabian heritage. The genetic diversity and population genetic structure of dromedary camels are poorly documented in Saudi Arabia so this study was carried out to investigate the genetic diversity of both local and exotic camel breeds. The genetic diversity was evaluated within and among camel populations using 21 microsatellite loci. Hair and blood samples were collected from 296 unrelated animals representing 4 different local breeds, namely Majaheem (MG), Maghateer (MJ), Sofr (SO), and Shaul (SH), and two exotic breeds namely Sawahli (SL) and Somali (SU). Nineteen out of 21 microsatellite loci generated multi-locus fingerprints for the studied camel individuals, with an average of 13.3 alleles per locus. Based on the genetic analyses, the camels were divided into two groups: one contained the Saudi indigenous populations (MG, MJ, SH and SO) and the other contained the non-Saudi ones (SU and SL). There was very little gene flow occurring between the two groups. The African origin of SU and SL breeds may explain their close genetic relationship. It is anticipated that the genetic diversity assessment is important to preserve local camel genetic resources and develop future breeding programs to improve camel productivity.     

Fine-scale genetic structure and marginal processes in an expanding population of Biscutella laevigata L. (Brassicaceae)

Evolutionary processes acting at the expanding margins of a species' range are still poorly understood. Genetic drift is considered prevalent in marginal populations, and the maintenance of genetic diversity during recolonization might seem puzzling. To investigate such processes, a fine-scale investigation of 219 individuals was performed within a population of Biscutella laevigata (Brassicaceae), located at the leading edge of its range. The survey used amplified fragment length polymorphisms (AFLPs). As commonly reported across the whole species distribution range, individual density and genetic diversity decreased along the local axis of recolonization of this expanding population, highlighting the enduring effect of the historical colonization on present-day diversity. The self-incompatibility system of the plant may have prevented local inbreeding in newly found patches and sustained genetic diversity by ensuring gene flow from established populations. Within the more continuously populated region, spatial analysis of genetic structure revealed restricted gene flow among individuals. The distribution of genotypes formed a mosaic of relatively homogenous patches within the continuous population. This pattern could be explained by a history of expansion by long-distance dispersal followed by fine-scale diffusion (that is, a stratified dispersal combination). The secondary contact among expanding patches apparently led to admixture among differentiated genotypes where they met (that is, a reshuffling effect). This type of dynamics could explain the maintenance of genetic diversity during recolonization.     

Evolution of population genetic structure of the British roe deer by natural and anthropogenic processes (Capreolus capreolus)

Human influence typically impacts on natural populations of conservation interest. These interactions are varied and sometimes complex, and may be negative and unintended or associated with conservation and management strategy. Understanding the details of how these interactions influence and are influenced by natural evolutionary processes is essential to the development of effective conservation strategies. In this study, we investigate a species in Britain that has experienced both negative impact through overhunting in historical times and management efforts through culls and translocations. At the same time, there are regional populations that have been less affected by human influence. We use mtDNA and nuclear microsatellite DNA markers to investigate patterns of connectivity and diversity and find multiple insular populations in Britain that probably evolved within the Holocene (when the habitat was free of ice). We identify three concurrent processes. First, surviving indigenous populations show highly provincial patterns of philopatry, maintaining and generating population structure on a small geographic scale. Second, founder populations into habitat extirpated of native populations have expanded, but remained largely insular. Third, introductions into established populations generate some admixture. We discuss the implications for the evolution of diversity of the integration of natural processes with anthropogenic influences on population size and distribution.     

Common genetic pools between human populations

Summary A further inquiry on modern human origins, based on common genetic pool surveys of rigorously selected population samples and highly informative immunological polymorphisms, provides new evidence of an Occidental-Oriental population split as the origin of human gene pool divergencies. The most likely ancestral genetic profile is discussed in the context of the debate raised by preliminary DNA restriction fragment length polymorphism studies, which contradict the conclusions drawn from classical blood group analyses.