Population genetics study of functional brain asymmetry in the native and immigrant populations of northeastern USSR. I. Sex-age distribution and familial data

Clearly definable polymorphism of hemisphere interrelations represented by three phenotypes was established by the method of EEG cross-correlation analysis. Each phenotype of the three, representing polymorphism, is characterized by marked specificity of perception and the processing of information, which determines certain integral physiological characteristics of individuals. Phenotype frequencies in aboriginal and new-come populations of the North-East of the USSR differ significantly. In comparison with the inhabitants, Moscow Russians of Magadan are significantly closer to aboriginal population, judging by their frequency distribution, and this may be due to the strategy specificity in adaptation of populations to environmental conditions. Significant difference in phenotype frequencies is shown in representatives of both sexes, this being more pronounced in the aboriginal population. The establishment of interhemispheric reaction type by approx. 10th year of individual's life is confirmed. Phenotype frequency correlations, depending on parental phenotype, were analyzed in children. The role of genetic and environmental factors in manifestation of the hemisphere relationship type is discussed. Rationality of the population analysis of hemisphere asymmetry types is grounded, according to the study of behavioural genetics and population adaptation.     

Phosphoglycolate phosphatase (PGP. E. C. 3..3.18) polymorphism in Magadan inhabitants

PGP phenotype and gene frequency distribution in 457 Russians and 33 Chuckchies is presented. Gene frequencies are: PGP1-0.887 and 0.970; PGP2-0.101 and 0.030; PGP3-0.030 and 0.000, correspondingly. It is shown that frequency of heterozygotes decreases in healthy Russians with increase of duration of dwelling under the North conditions. Such a dynamics causes approaching of PGP phenotype distribution of "long-livers" of the North to that of aboriginal population and moving away from European distribution type.     

The competitive interactions of man and deer in prehistoric California

A hypothetical model concerning the structure of aboriginal California trophic systems is presented. The dynamics of each possible state of the system is generated theoretically and then tested using previously published data. It is determined that a state of competitive coexistence of a fish-regulated predatorprey competition relationship between the deer and human populations limited the growth of both populations and should be considered a determinant of aboriginal California population levels.     

Relative role of selective migration and pathology in the formation of genetic structure

It is shown that elective migration, with respect to polymorphic loci genotypes, and their association with pathology affect unequally formation of genetic structure features of the population analysed. The correlative role of two processes mentioned is more or less specific, with respect to every concrete locus: the elective migration and the pathology have unidirectional impact in all groups, which leads to maximum dynamics of genotypes in groups with different duration of dwelling under extreme conditions (AcP, Pp loci). These processes act as antagonists, preserving constant genotype frequency (AK locus). Genotype frequency dynamics is mainly determined by the elective migration (Rh locus) or the pathology (PGD locus). The correlative role of the elective migration and the pathology is often unequal in groups with different duration of dwelling under the North-East conditions, as applied to concrete locus (GLO-1, PGM1), though the elective migration participates in groups with comparatively small dwelling-term in the North and the pathology has more influence as this term increases. The problem of genetic aspects of human adaptation is under discussion.     

The evolution of the cooperative group

Summary A simple model, illustrating the transition from a population of free swimming, solitary cells (Chlamydomonas-type) to one consisting of small colonies (Gonium-type) serves as a basis to discuss the evolution of the cooperative group. The transition is the result of a mutation of the dynamics of cell division, delayed cell separation leads to colonies of four cells. With this mutation cooperative features appear, such as synchronised cell divisions within colonies and coordinated flagellar function which enables the colony to swim in definite directions. The selective advantages under given, environmental conditions are defined and the periods necessary for complete allelic replacement in small populations are calculated for asexual and sexual reproduction. The assumption of a steady-state population during allelic substitution is critically considered, particularly under conditions of competition. It is shown that density-dependent population control must operate in the process of selection. Sexual reproduction slows down the rate of selection even though all cells dre haploid. This phenomenon can be explained in general terms of `organizational dominance', where individual units coordinate the function of their neighbours which may be of a different allelotype.Cooperativity is pointed out as an a priori systemic feature which resides in the sub-units of systems, group formation and coordination appears thus as an almost inevitable event. A particular type of system described as closed cycle of positive fitness interaction is discussed in more detail. It has the remarkable feature that its members cannot compete with each other; selection takes place between whole cycles (in analogy to Eigen's 1971 model).Gonium has a wide spectrum of `somatic plasticity' which enables it to assume various colonial configurations depending on physiological and environmental conditions. This feature can be explained as the result of dynamic flexibilities on the macro-molecular level. The particular relationship between the vast, molecular complexity and the relative simple dynamics of the cell cycle must lead eventually to the genetic fixation of an environmentally induced phenotype.     

Influence of urbanization level on the lethal load and on the intensity of natural selection in the Turkmen population]

Dynamics of genetic load in aboriginal population of the Turkmen SSR was studied using two approaches to calculate "lethal" equivalents. Intensity and structure of natural selection were measured using the Crow's index and its components. All statistics indicated were determined using the data obtained in Ashkhabad city and in two rural populations of Ashkhabad region (Yasman and Nokhur) within the time interval prior to 60s and after 70s. The results obtained made it possible to subdivide the populations under study into three different groups according to different stages of demographic process: 1) urbanized population; 2) rural (transient) population; 3) "relict" rural population.     

Genetico-demographic patterns of the prevalence of various forms of endogenous psychoses

Prevalence rates (PRs) for EFP (schizophrenic, schizoaffective and affective psychoses), with allowance for proband sex and age-of-onset data were studied in a subdivided population from the North-East of the European Region of the USSR. The population includes three subpopulations: a small old religious semi-isolate of Russians ("Rs"), aboriginal Komi people ("Ks")--an ethnic community of Ugro-Finnish lineage, and a mixed group of migrants ("Ms") from various regions of the USSR. The latter is mainly an urban population, while the "Rs" and "Ks" are, on the whole, rural populations. The total PR for EFP was found to be 0.97% for the "Rs", 0.63% for the "Ks" and 0.35% for the "Ms", whereas PRs-0.85-1.15% in other parts of the USSR, mainly for "panmixed" populations in large towns. The lower PRs for EFP in the "Ms" is caused by a backmigration flow involving certain groups of patients; consequently, the mean liability for "Ms" offsprings (as a whole) should also be lower. On the other hand, the lower PRs for EFP in the "Ks" is caused by underpresentation of clinically mild cases of the mental disease (mainly, pseudoneurotic schizophrenia), especially among female patients, probably due to that the so affected persons are sufficiently adapted to the cultural traditions of this rural population. It was shown that in the "Rs" the total PR for "nuclear" and paranoid schizophrenia is 0.68% versus 0.25% in a "panmixed" population. The increase is most likely caused by the high inbreeding level in the "Rs" semi-isolate, and if this is correct, we may suppose that at least one or two recessive genes are involved in the liability to the most heavy forms of schizophrenia. On the other hand, in the "Ms" (as in other "panmixed" populations) positive assortative mating among hereditary-predisposed persons is a more significant factor influencing family transmission of EFP, since the correlation between probands and their spouses is rpp = 0.31 (p less than 0.001) in the "Ms", as compared to rpp = 0.19 (p less than 0.1) in the "Rs". Thus, our general conclusion is that neither the place of inhabitance nor the life mode are the causal factors for EFP, but rather some genetic factors, more accurately, certain sets of specific genes.     

Olive Fruit Fly (Bactrocera oleae) Population Dynamics in the Eastern Mediterranean: Influence of Exogenous Uncertainty on a Monophagous Frugivorous Insect

Despite of the economic importance of the olive fly (Bactrocera oleae) and the large amount of biological and ecological studies on the insect, the factors driving its population dynamics (i.e., population persistence and regulation) had not been analytically investigated until the present study. Specifically, our study investigated the autoregressive process of the olive fly populations, and the joint role of intrinsic and extrinsic factors molding the population dynamics of the insect. Accounting for endogenous dynamics and the influences of exogenous factors such as olive grove temperature, the North Atlantic Oscillation and the presence of potential host fruit, we modeled olive fly populations in five locations in the Eastern Mediterranean region. Our models indicate that the rate of population change is mainly shaped by first and higher order non-monotonic, endogenous dynamics (i.e., density-dependent population feedback). The olive grove temperature was the main exogenous driver, while the North Atlantic Oscillation and fruit availability acted as significant exogenous factors in one of the five populations. Seasonal influences were also relevant for three of the populations. In spite of exogenous effects, the rate of population change was fairly stable along time. We propose that a special reproductive mechanism, such as reproductive quiescence, allows populations of monophagous fruit flies such as the olive fly to remain stable. Further, we discuss how weather factors could impinge constraints on the population dynamics at the local level. Particularly, local temperature dynamics could provide forecasting cues for management guidelines. Jointly, our results advocate for establishing monitoring programs and for a major focus of research on the relationship between life history traits and populations dynamics.     

Are numbers enough? Colonizer phenotype and abundance interact to affect population dynamics

1. Ecologists have long recognized that the number of colonizers entering a population can be a major driver of population dynamics, but still struggle to explain why the importance of colonizer supply varies so dramatically. While there are indications that differences in the phenotype among dispersing individuals could also be important to populations, the role of phenotypic variation relative to the number of individuals, and the extent to which they interact, remains unknown. 2. We simultaneously manipulated the phenotype (dispersal duration) and abundance of settlers of a marine bryozoan and measured subsequent population structure in the field. 3. Increases in the number of colonizing individuals increased the subsequent recruitment and biomass of populations, regardless of colonizer phenotype. However, the relationship between colonizer abundance and the subsequent reproductive yield of the population was strongly reduced in populations containing individuals that had long dispersal durations. 4. The interactive effects of colonizer phenotype and abundance on the reproductive yield of populations occurred because longer dispersal durations decreased the proportion of individuals that reproduced. In fact, populations established from a few individuals with short dispersal durations had similar reproductive yield to populations c. 30 times larger established from individuals with long dispersal durations. 5. Interactions between colonizer phenotype and abundance have important implications for predicting population dynamics beyond those previously provided by numerical abundance or recruit phenotype alone.     

Morphogenetic Effects of Resettlement of Mole Voles (<Emphasis Type="Italic">Ellobius talpinus</Emphasis> Pall., 1770) from the Southern Population to the Northern Boundary of the Species Range

Geometric morphometry has been used to reveal transformations of mandible morphogenesis in the offspring of mole voles resettled to the northern part of the species range from a southern population. The transformations were new compared to both the original (southern) and the aboriginal (northern) populations. A significant increase in the intragroup morphological disparity estimated by the mean nearest neighbor distance (MNND) in the resettled animals compared to both aboriginal populations is an indirect indication of an increased developmental instability in the resettled animals exposed to new climatic conditions.     

Genetic diversity of X-chromosome in populations of aboriginal Siberian ethnic groups: linkage disequilibrium structure and haplotype philogeography of ZFX locus

The structure of gene pool of the Siberian aboriginal population has been described based on the data on polymorphism of ZFX gene located on X-chromosome. In ten populations under study 49 haplotypes have been determined, three of which are presented with high frequency. Comparing the obtained results with the available data from HapMap project unique "African" haplotypes were revealed, which occurred in Yoruba population with the frequency of 3-7% and were not found in other populations. A coefficient of genetic differentiation of the Siberian ethnic groups under study amounted to 0.0486. Correlation analysis involving Mantel test did not reveal any significant correlations between a matrix of genetic distances and the matrices of geographic, linguistic and anthropological differences, where a maximum coefficient was obtained at the comparison with the anthropological matrix. Phylogenetic analysis proved strong isolation of African population from the other investigated ethnic groups. The Siberian populations were subdivided into two separate clusters: the first one included Yakuts, Buryats and Kets, while the second cluster included Altaians, Tuvinians and Khanty. A principal component analysis enabled to combine the investigated populations in three groups, which clearly differed by a degree of manifestation of Caucasoid and Mongoloid components. The first group included Europe inhabitants and one of Khanty populations, the second one--populations of South Siberia and China inhabitants. Mongoloid populations of East Siberia, the Japanese and Kets were combined in the third group. The results of barrier analysis revealed similar structure of genetic differentiation in the Siberian population. Linkage disequilibrium structure was obtained for six ethnic groups of Siberia. A unified linkage block by ten SNP of ZFX gene was found in five of the presented ethnic groups (excluding Ket population).     

Variation in cannibalistic polyphenism between populations in the salamander Hynobius retardatus

Organisms sometimes change their phenotype to maximize fitness according to local environments. If the frequency of the broad-headed "cannibal" morph in the larvae of the salamander Hynobius retardatus has been evolutionarily maintained at a certain level within a population as a result of local adaptation, variations in its frequency should be found among different populations with environmental variation. We investigated whether variations in the frequency of the broad-headed morph were present in 2 different populations, Nopporo (a low-density population) and Erimo (a high-density population), by raising larvae from the respective populations under the same experimental conditions. The occurrence rate of the broad-headed "cannibal" morph was significantly different between the 2 populations when examined with different experimental larval densities. These results suggest that the reaction norm with respect to the frequency of the broad-headed morph is different between the Nopporo and Erimo populations. Because the local populations are assumed to be selected for under different environments, the different reaction norm might have evolved in response to different selection pressures.     

Aboriginal overkill

Prior to European influence, predation by Native Americans was the major factor limiting the numbers and distribution of ungulates in the Intermountain West. This hypothesis is based on analyses of (1) the efficiency of Native American predation, including cooperative hunting, use of dogs, food storage, use of nonungulate foods, and hunting methods; (2) optimal-foraging studies; (3) tribal territory boundary zones as prey reservoirs; (4) species ratios, and sex and age of aboriginal ungulate kills; (5) impact of European diseases on aboriginal populations; and (6) synergism between aboriginal and carnivore predation. Native Americans had no effective conservation practices, and the manner in which they harvested ungulates was the exact opposite of any predicted conservation strategy. Native Americans acted in ways that maximized their individual fitness regardless of the impact on the environment. For humans, conservation is seldom an evolutionarily stable strategy. By limiting ungulate numbers and purposefully modifying the vegetation with fire, Native Americans structured entire plant and animal communities. Because ecosystems with native peoples are entirely different than those lacking aboriginal populations, a “hands-off” or “natural regulation” approach by today’s land managers will not duplicate the ecological conditions under which those ecosystems developed. The modern concept of wilderness as areas without human influence is a myth. North America was not a “wilderness” waiting to be discovered, instead it was home to tens of millions of aboriginal peoples before European-introduced diseases decimated their numbers.     

Nonlinear Effects on Population Dynamics Related to Age Structure and Fishery Impact

Population dynamics of commercial fish populations with an age structure was studied by the example of salmons. The relationship between the amount of catch on fishing efforts and total abundance of a stock fished is described by a nonlinear “trophic” function. Special attention is given to the analysis of population dynamics stability under conditions for maximum profit. Simulation results are compared to statistical data on the catch of Pacific salmon species in the Bering Sea.     

Relation between complexity and stability in food webs with adaptive behavior

We investigate the influence of functional responses (Lotka-Volterra or Holling type), initial topological web structure (randomly connected or niche model), adaptive behavior (adaptive foraging and predator avoidance) and the type of constraints on the adaptive behavior (linear or nonlinear) on the stability and structure of food webs. Two kinds of stability are considered: one is the network robustness (i.e., the proportion of species surviving after population dynamics) and the other is the species deletion stability. When evaluating the network structure, we consider link density as well as the trophic level structure. We show that the types of functional responses and initial web structure do not have a large effect on the stability of food webs, but foraging behavior has a large stabilizing effect. It leads to a positive complexity-stability relationship whenever higher "complexity" implies more potential prey per species. The other type of adaptive behavior, predator avoidance behavior, makes food webs only slightly more stable. The observed link density after population dynamics depends strongly on the presence or absence of adaptive foraging, and on the type of constraints used. We also show that the trophic level structure is preserved under population dynamics with adaptive foraging.     

Comparative Population Dynamics of Two Closely Related Species Differing in Ploidy Level

Background

Many studies compare the population dynamics of single species within multiple habitat types, while much less is known about the differences in population dynamics in closely related species in the same habitat. Additionally, comparisons of the effect of habitat types and species are largely missing.

Methodology and Principal Findings

We estimated the importance of the habitat type and species for population dynamics of plants. Specifically, we compared the dynamics of two closely related species, the allotetraploid species Anthericum liliago and the diploid species Anthericum ramosum, occurring in the same habitat type. We also compared the dynamics of A. ramosum in two contrasting habitats. We examined three populations per species and habitat type. The results showed that single life history traits as well as the mean population dynamics of A. liliago and A. ramosum from the same habitat type were more similar than the population dynamics of A. ramosum from the two contrasting habitats.

Conclusions

Our findings suggest that when transferring knowledge regarding population dynamics between populations, we need to take habitat conditions into account, as these conditions appear to be more important than the species involved (ploidy level). However, the two species differ significantly in their overall population growth rates, indicating that the ploidy level has an effect on species performance. In contrast to what has been suggested by previous studies, we observed a higher population growth rate in the diploid species. This is in agreement with the wider range of habitats occupied by the diploid species.     

The effects of admixture and population subdivision on cytonuclear disequilibria

We examine the generation of cytonuclear disequilibria by admixture and continued gene flow. General formulas analogous to the nuclear case are first derived showing that the allelic and genotypic disequilibria from admixture or population subdivision equal their expected value across the contributing (sub) populations plus the covariance across these sources between the cytoplasmic gene frequency and the relevant nuclear frequency. A detailed study is then presented of the cytonuclear dynamics, in a random-mating population under two different migration scenarios. In both cases closed-form solutions are given for all variables as a function of the initial conditions and relevant migration parameters. The dynamics of the gene frequencies and allelic disequilibria, which dominate each system, are the same as those involving two unlinked nuclear loci, while the dynamics of the genotypic disequilibria and cytonuclear frequencies have no nuclear counterpart. The continent-island formulation focuses on a population receiving continued immigration from a large source of constant composition. A major discovery is that cytonuclear disequilibria can transiently build up on the "island" to levels far exceeding those found at equilibrium. In contrast, the admixture formulation focuses on the dynamics within two populations undergoing continued intermigration. Although in this case all cytonuclear associations must ultimately decay to zero, long-term transient disequilibria can develop which are many times their initial admixture values. For both migration scenarios it is shown that the time of population censusing relative to migration and reproduction dramatically affects both the amount and pattern of the nonrandom associations produced. The empirical relevance of these models is discussed in light of nuclear-mitochondrial data from a hybrid zone between European and North American eels and from a zone of racial admixture in humans.     

Spatial and temporal stability of mtDNA haplogroup frequencies in native North America

Mitochondrial DNA lineage frequencies in prehistoric Aleut, eastern Utah Fremont, Southwestern Anasazi, Pyramid Lake, and Stillwater Marsh skeletal samples from northwest Nevada and the Oneota of western Illinois are compared with those in 41 contemporary aboriginal populations of North America. The ancient samples range in age from 300 years to over 6,000 years. The results indicate that the prehistoric inhabitants of North America exhibit the same level of mtDNA variability as contemporary populations of the continent. Variation in modern mtDNA haplogroup frequencies is highly geographically structured, and the prehistoric samples exhibit the same geographic pattern of variation. This indicates that differentiation of regional patterns of mtDNA lineage variation occurred early in North American prehistory (much more than 2,000 years B.P.), has remained relatively stable since its origin, and was little influenced by the disruptions hypothesized for other genetic systems as a result of population declines and relocations at contact.     

Offspring fitness and the optimal propagule size in a fluctuating environment

Propagule size is an important maternal effect on offspring fitness and phenotype in birds and other oviparous animals. The performance of propagules often increases with size, but a fluctuating environment may introduce temporal variation in the optimal phenotype. Understanding these mechanisms will provide novel insights into the eco‐evolutionary dynamics of life history strategies in parental reproductive investment. We investigated the interaction between propagule size (measured as egg volume) and environmental conditions on offspring mortality and phenotype in a Norwegian house sparrow population. Increased propagule size reduced offspring mortality in early life, with more pronounced effects under heavy precipitation. However, the optimal propagule size for low offspring mortality until recruitment shifted from large to small as temperature increased. Propagule size had no significant effect on fledgling body mass and tarsus length. These results reveal a potential for eco‐evolutionary dynamics in propagule size, as populations adapt to fluctuating environmental conditions. The ultimate outcome of this dynamic process will also depend on variation in parental fitness and tradeoffs with other life‐history traits, particularly clutch size.     

New view of population genetics of zooplankton: RAD‐seq analysis reveals population structure of the North Atlantic planktonic copepod Centropages typicus

Detection of population genetic structure of zooplankton at medium‐to‐small spatial scales in the absence of physical barriers has remained challenging and controversial. The large population sizes and high rates of gene flow characteristic of zooplankton have made resolution of geographical differentiation very difficult, especially when using few genetic markers and assuming equilibrium conditions. Next‐generation sequencing now allows simultaneous sampling of hundreds to thousands of genetic markers; new analytical approaches allow studies under nonequilibrium conditions and directional migration. Samples of the North Atlantic Ocean planktonic copepod, Centropages typicus, were analysed using restriction site‐associated DNA (RAD) sequencing on a PROTON platform. Although prior studies revealed no genetic differentiation of populations across the geographical range of the species, analysis of RAD tags showed significant structure across the North Atlantic Ocean. We also compared the likelihood for models of connectivity among NW Atlantic populations under various directional flow scenarios that replicate oceanographic conditions of the sampled domain. High‐density marker sampling with RAD sequencing markedly outperformed other technical and analytical approaches in detection of population genetic structure and characterization of connectivity of this high geneflow zooplankton species.