Effects of Migration on Genetic Variability and Parent–Offspring Correlation Coefficients in Anthropometric and Physiometric Phenotypes Among Three Groups of Population in Punjab, India

In the present study, we examined the migration effects on genetic variabilities and heritabilities patterns between three groups of population like parental population in Punjab, migrant from Pakistan, and migrant from other states of India in Punjab using anthropometric and physiometric traits. A total of 500 adult individuals from 300 families were studied. Statistical comparisons were carried out through mean coefficients, Student’s t test, heritability, and regression analysis. The results suggest a significant migration effect on almost all traits. Correlation coefficient for first-degree relatives, the slope factors, and heritabilities for almost all variables have been found significant among the three groups of populations. However, the discrimination is more prominent among migrant from other states of India because of more genetic heterogeneity.     

Biological affinities between migrant and parental populations of fishermen on the east coast of India.

We examined biological affinities between the migrant groups of fishermen in Puri and their parental counterparts using 3 sets of variables: genetic markers, anthropometric measurements, and quantitative dermatoglyphics. Results of both univariate and multivariate analyses suggest a significant migration effect, diversifying migrants from their parental populations, although the distance configurations based on each set of variables resemble each other. The migration effect is particularly remarkable for the anthropometric measurements. The plot of group centroids based on the discriminant analysis of the 7 populations depicts a clear segregation of migrants from the parental populations. Because of relatively large effective population sizes and short history of these populations in Puri, the role of genetic drift can be safely ruled out. However, a founder effect is a plausible reason for the observed differentiation of the migrants from their parental groups, especially given that certain rare variants that were not observed in the parental populations appear in the migrants. That the founders were a select group of fishermen with respect to body dimensions, not a random group, can be inferred from the occupational differences among the migrant groups, which in turn suggests phenotypic plasticity in the observed differentiation. Regression of mean phenotypic variance and heterozygosity on the distance from the centroid suggests a strong possibility of external gene flow into the migrant populations in Puri.     

A study on the adult body dimensions of the oraons of eastern India: Sedente-migrant comparison

The present study deals with the effect of migration on the adult body dimensions among the Oraons of Estern India. The study was conducted on the 232 sedente Oraon of both sexes from Gumla district, Bihar, India and their 230 migrant counter-parts of both sexes from the tea gardens in Duars are, Jalpaiguri district, West Bengal, India. The results show that the migrants are lighter and slightly shorter.     

Morphological and regional variations in body dimensions of the Gujjars of different localities in north-western India

Physical features and somatometric characters of the wide spread Gujjar population in North-Western India are fascinating. It is all the more interesting to study their morphological and regional variations in the body dimensions. In this paper, anthropometric characters of 200 adult subjects each belonging to Hindu Gujjars in the Ropar District of Punjab and Muslim Gujjars in the Chamba District of Himachal Pradesh in the North-Western part of India were compared. They differ significantly from each other for many physiognomic measurements, suggesting the biological diversity between the two population groups. Further, the comparison of anthropometric measurements between the different localities of the Gujjars showed morphological variations and regional diversity of the isolates in North-Western India. These findings may be attributed to the founder effect, genetic drift, and breeding and geographical isolation of the populations under study and not to secular trends. The findings have also been compared and discussed with the available results of other local populations in North-Western India.     

Animal migration: is there a common migratory syndrome?

Ornithologists, and especially northern hemisphere ornithologists, have traditionally thought of migration as an annual return movement of populations between regular breeding and non-breeding grounds. Problems arise because selection does not ordinarily act on populations and because organisms of many taxa (including birds) are clearly migrants, but fail to undertake movements of the kind described. There are also extensive return movements that are not migratory. I propose that it is more useful to think of migration as a syndrome of behavioral and other traits that function together within individuals, and that such a syndrome provides a common ground across taxa from aphids to albatrosses. Large-scale return movements of populations are one outcome of the syndrome. Similar behavioral and physiological traits serve both to define migration and to provide a test for it. I use two insect (Hemipteran) examples to illustrate migratory syndromes and to demonstrate that, in many migrants, behavior and physiology correlate with life history and morphological traits to form syndromes at two levels. I then compare the two Hemipterans with migration in birds, butterflies, and fish to assess the question of whether there are migratory syndromes in common between these diverse migrants. Syndromes are more similar at the level of behavior than when morphology and life history traits are included. Recognizing syndromes leads to important evolutionary questions concerning migration strategies, trade-offs, the maintenance of genetic variance and the responses of migratory syndromes to both similar and different selective regimes.     

Tracking variability: recent anthropometric data for croatian population and comparison with other world populations

The variability that exists within the populations of individual countries and the variability that exists between the populations of different countries are both of interest in practical application. For these reasons, a comparison is made in this work between certain anthropometric variables of our sample of Croatian population and anthropometric variables that are available for other human populations in the world of the same or a similar age. The total sample was 1,372 subjects aged from 23 to 59 years old. For the purpose of comparison, data were taken from the study "International Data on Anthropometry" which provides an overview of anthropometric variables for many world populations, as well as data from Rudan's research that was carried out on Croatian population in the late seventies of the last century. Mean value, standard deviation and coefficient of variation have been calculated for every measured parameter. A comparison between the two research samples of Croatian population fairly displays up going trend, for body mass and other bodily dimensions, formed in three decades of difference. Mean value for body height in Rudan's sample is 161.0 cm, and for Bubas's sample in this research was 170.6 cm, both values state for Croatian population but with difference of more than 30 years. Human biologists use term "secular trend" to describe alterations in the measurable characteristics of a population of humans that occur over a century. Accordingly, in adult age, the rate of gain, concerning body height, is 10 to 30 mm per decade. The changes in body proportions during recent decades are less marked than those in body size, but the relationships between stature and weight within one national group have changed significantly.     

Distinguishing between juvenile anadromous and resident brook trout (Salvelinus fontinalis) using morphology

Phenotypic variation linked to habitat use has been observed in fish, both between and within species. In many river systems, migratory and resident forms of salmonids coexist, including anadromous (migrant) and resident brook trout, Salvelinus fontinalis. In such populations, juvenile anadromous (migrant) brook trout, prior to migration, inhabit regions of higher current velocity than residents. Because it is more costly to occupy fast currents than slow currents, differences in morphology minimizing the effects of drag were expected between the two forms. As predicted, migrant brook trout were found to be more streamlined (narrower and shallower bodies) than resident brook trout, and these differences persisted into the marine life of the fish. Migrants also exhibited shorter pectoral fins, which facilitate pelagic swimming, indicating that migrants, prior to their migration to the sea, possess the appropriate morphology for swimming in open water habitats. The reported differences between migrants and residents were powerful enough to derive discriminant functions, using only five of the seven measured traits, allowing for accurate classification of brook trout as either migrants or residents with an overall correct classification rate of 87%. Importantly, this study contributes to the notion that a link exists between morphology, habitat use, metabolic costs and life-history strategies. Contribution to the program of CIRSA (Centre Interuniversitaire de Recherche sur le Saumon Atlantique).     

THE EFFECT OF DELAYED POPULATION GROWTH ON THE GENETIC DIFFERENTIATION OF LOCAL POPULATIONS SUBJECT TO FREQUENT EXTINCTIONS AND RECOLONIZATIONS

I investigated the effects of delayed population growth on the genetic differentiation among populations subjected to local extinction and recolonization, for two different migration functions; (1) a constant migration rate, and (2) a constant number of migrants. A delayed period of population growth reduces the size of the newly founded populations for one or several generations. Whether this increases differentiation among local populations depends on the actual pattern of migration. With a constant migration rate, fewer migrants move into small populations than into large, thus providing ample opportunity for drift to act within a population. A prolonged period of population growth thus makes the conditions for enhanced differentiation between local populations less restrictive and also inflates the actual levels of differentiation. The effect depends on the relative magnitudes of k_e, the effective number of colonizers and k, the actual number of colonizers. When there is a constant number of migrants into a population per generation, migration into small populations is increased. This increase of migration in small populations counteracts the effects of genetic drift due to small population size. It increases the rate by which populations approach equilibrium, as small populations are swamped by migrants from larger populations closer to genetic equilibrium, and overall levels of differentiation are thus reduced. I also discuss situations for which the results of this paper are relevant.     

Quantitative palmar dermatoglyphics and the assessment of population affinities: data from marine fishermen of Puri, India

Variation in quantitative dermatoglyphics among three endogamous groups of marine fishermen of Puri Coast, India, is greater for the palmar variables than for the fingers. This is the case in both the sexes. The pattern of population affinities, however, differs for the males and females. In order to evaluate the importance of palmar variables in population studies, the results in males are compared with those of finger variables and anthropometrics. There is no significant heterogeneity between the groups for finger variables. Although significant intergroup variability is observed in the palmar and anthropometric traits, the two sets of results are not in the same direction. Palmar dermatoglyphic relationships reflect the caste affiliations, while the anthropometric are in line with geographic proximity.     

Comparison of variance within and between sibships in anthropometric traits of mexican migrant and sedente families

Variance between and within sibships in anthropometric traits was ascertained in a sample of Mexican families in the U.S.A. (migrants) and in Mexico (sedentes), by sex. The factor of age was eliminated by standardization. The siblings intraclass coefficient of correlation for the various traits by means of the one-way variance analysis manifested differences between the sexes in various anthropometric traits. Variance between sibships was found to be significantly higher than within sibships in all the traits in each sex, and both migrant and sedente sibships. This result, also noted in other groups, would seem to reflect a general population phenomenon.     

Divergent compensatory growth responses within species: linked to contrasting migrations in salmon?

Animals often exhibit accelerated or “compensatory” growth (CG) after periods of environmentally induced growth depression, raising important questions about how they cope with environmental variability. We tested an underexplored hypothesis regarding the evolutionary consequences of CG; namely, that natural populations differ in CG responses. Common-garden experiments were used to compare subadult growth following food restriction between groups (control, treatment) of two Atlantic salmon (Salmo salar) populations and their first-generation (F₁) hybrids. The populations are found at similar latitudes but characterized by differences in migration distance. We predicted that long-distance migrants would better maintain growth trajectories following food restriction than short-distance migrants because they: (1) require larger body sizes to offset energetic costs of migration and (2) face greater time constraints for growth as they must leave non-breeding areas earlier to return to breeding areas. Long-distance migrants grew faster, achieved quicker CG (relative to controls), and their overall body morphology was more streamlined (a trait known to improve swimming efficiency) than slower growing short-distance migrants. F₁ hybrids were generally intermediate in “normal” growth, CG, and body morphology. We concluded that CG responses may differ considerably among populations and that the conditions generating them are likely interconnected with selection on a suite of other traits.     

Changes in the timing of spring and autumn migration in North American migrant passerines during a period of global warming

Butler (2003) used first arrival dates (FADs) of 103 migrant birds in northeastern USA and found that both long-distance migrants (LDMs; wintering south of the USA) and short-distance migrants (SDMs; wintering in the southern USA) arrived earlier in the second half of the 20th century than they had in the first, consistent with scenarios of global warming; the trend was stronger in SDMs. Using FADs to characterize migration systems can be problematic because they are data from one tail of a distribution, they comprise a mostly male population and they may not correlate well with the balance of the migration period. FADs also provide no information about autumn migration. This paper uses a banding dataset from Long Point Bird Observatory, Ontario, for 14 passerines for a period of global warming (1975–2000), taking these issues into account. The data were filtered to minimize effects of unequal netting effort (147 491 resulting records), and the passage dates then calculated in each season of each year for the 1st, 2nd and 3rd quartiles for regression analysis. Only two of 13 species analysed in the spring showed significantly earlier passage times, although the overall trend was towards earlier spring migration, especially among SDMs. Autumn responses were more prevalent, however, and in some cases more dramatic with six of 13 species showing delayed migration (four SDMs, two LDMs). Two LDMs exhibited earlier autumn migration. Where earlier spring migration occurred, both sexes appeared to contribute to the change. Where delayed migration occurred in autumn, both sexes and both adults and hatch-year birds appeared to contribute in at least some cases. The spring FAD results are consistent with those of Butler, but when the whole migration is considered, change is far from universal in spring and is in fact more substantial and complex in autumn.     

Seeing ghosts: the effect of unsampled populations on migration rates estimated for sampled populations

In 2004, the term 'ghost population' was introduced to summarize the effect of unsampled subpopulations that exchange migrants with other subpopulations that have been sampled. Estimated long-term migration rates among populations sampled will be affected by ghost populations. Although it would be convenient to be able to define an apparent migration matrix among sampled populations that incorporate the exchange of migrants with ghost populations, no such matrix can be defined in a way that predicts all features of the coalescent process for the true migration matrix. This paper shows that if the underlying migration matrix is symmetric, it is possible to define an apparent migration matrix among sampled subpopulations that predicts the same within-population and between-population homozygosities among sampled populations as is predicted by the true migration matrix. Application of this method shows that there is no simple relationship between true and apparent migration rates, nor is there a way to place an upper bound on the effect of ghost populations. In general, ghost populations can create the appearance of migration between subpopulations that do not actually exchange migrants. Comparison with published results from the application of the program, MIGRATE, shows that the apparent migration rates inferred with that program in a three-subpopulation model differ from those based on pairwise homozygosities. The apparent migration matrix determined by the method described in this paper probably represents the upper bound on the effect of ghost populations.     

Convergence of human age-sex distributions to an equilibrium-state age-sex distribution

The main concern of the paper is to investigate the effects of introducing migration into the process of population growth using an overall net migration rate and an age-sex composition of net migrants (i.e., the net number of migrants) as compared with the case in which there is no migration. It is shown that the convergence to an equilibrium state occurs in the presence of a constant stream of migration with fixed age-sex structure and constant vital rates. The duration of convergence (i.e., the time required for convergence) is less when there is net immigration than when there is no migration but more when there is net emigration, provided the age-sex composition of net migrants contains nonnegative values at all ages for both sexes or at least, for the sex which is assumed to be dominant. If the age-sex composition of net migrants contains positive, negative, and/or zero values, the duration may be less than, or equal to, or greater than that in the case with no migration depending on the actual age-sex composition of the net migrants and the mignitude of the net migration rate. The instrinsic growth rate follows a trend which is opposite to that of the duration of convergence, except when the age-sex composition of net migrants contains zero values at all ages below the oldest age at which reproduction takes place. In the case of this exception, the intrinsic growth rate will remain the same as in the absence of migration provided the net migration rate is not greater than one which is true in demographic applications.     

A model of kin-migration in plants

Summary Migrants between plant populations may represent a random sample of the donor population or may be related, being identical in the extreme. There is considerable potential for kin-structured migration in many plant species through the co-dispersal of seeds from single individuals. Through simulation experiments we have shown that the greater the level of relatedness of migrants, the less a given level of migration counterbalances the effect of genetic drift among populations.     

Anthropometric variationin the Yanadi: Population structure and sex differences

Anthropometric variation and sex differences were investigated among the Yanadi tribe, who live in different regions and show differences in population structure variables and form regional breeding populations. In case of within population variation in anthropometric characters, both males and females show greater variation in a few specific characters (e.g., HB, LL) and almost no variation in FB, but least variation in HL and NB in males and in ZB, LB in females and show sex differences. Overall, females showed greater variation in more number of characters than males. In case of between population variation a few traits show clinal trend between male-female comparisons. Each character shows a specific pattern (e.g., HB, ZB, EL, GB) which vary according to the spatial distribution of the regional populations. The curves also indicate least average differences corresponding to within regional homogeneity among males and females (e.g., HB, ECD, EB) and increasing differences with males and females of other regions. A comparison of anthropometric profiles of the five populations show significant sex differences in IY subpopulation. The three mainland subpopulations show wide morphological differentiation with two coastal subpopulations, who also differ in subsistence pattern and geographically isolated. A comparison of anthropometric profiles between males and females across five populations show positive association between P1, HF and P₂ populations, whereas significant negative association with CY and HF. The correllelographs based on the male-female comparisons also indicate greater morphological similarity between sexes in cases of within regional population. They also show clinal changes of either decreasing or increasing trends of morphological variation between populations in association with spatial distribution and population structure differences. The results obtained are in agreement with the expectations from the population structure of the tribe.     

Climate and the complexity of migratory phenology: sexes,migratory distance,and arrival distributions

The intra- and inter-season complexity of bird migration has received limited attention in climatic change research. Our phenological analysis of 22 species collected in Chicago, USA, (1979–2002) evaluates the relationship between multi-scalar climate variables and differences (1) in arrival timing between sexes, (2) in arrival distributions among species, and (3) between spring and fall migration. The early migratory period for earliest arriving species (i.e., short-distance migrants) and earliest arriving individuals of a species (i.e., males) most frequently correlate with climate variables. Compared to long-distance migrant species, four times as many short-distance migrants correlate with spring temperature, while 8 of 11 (73%) of long-distance migrant species’ arrival is correlated with the North Atlantic Oscillation (NAO). While migratory phenology has been correlated with NAO in Europe, we believe that this is the first documentation of a significant association in North America. Geographically proximate conditions apparently influence migratory timing for short-distance migrants while continental-scale climate (e.g., NAO) seemingly influences the phenology of Neotropical migrants. The preponderance of climate correlations is with the early migratory period, not the median of arrival, suggesting that early spring conditions constrain the onset or rate of migration for some species. The seasonal arrival distribution provides considerable information about migratory passage beyond what is apparent from statistical analyses of phenology. A relationship between climate and fall phenology is not detected at this location. Analysis of the within-season complexity of migration, including multiple metrics of arrival, is essential to detect species’ responses to changing climate as well as evaluate the underlying biological mechanisms.     

MIGRATION ENHANCES ADAPTATION IN BACTERIOPHAGE POPULATIONS EVOLVING IN ECOLOGICAL SINKS

Migration between populations can be a major evolutionary force. However, some disagreement exists as to precisely how migration affects population adaptation. Some theories emphasize the inhibitory effects of gene flow between locally adapted populations, whereas others propose that migration can enhance adaptation. Migration has also been theorized to rescue sink populations from extinction. In our experiments, we serially passaged bacteriophage Φ6 host range mutants under sink conditions on a novel host while manipulating the source and number of migrants into these experimental populations. Migrants from two sources were used: mutant Φ6 phage able to infect a novel host (treatment) and wild‐type Φ6 phage unable to infect a novel host (control). We used quadratic regressions to determine the relationship between the number of migrants per passage and the absolute fitnesses of experimental populations following 30 passages. Our results showed that migration from a control population had no effect on absolute fitnesses of our serially passaged populations following 30 passages. By contrast, the relationship between migrants per passage and absolute fitnesses for populations receiving migrants able to infect the novel host was best described by an upwardly concave curve. These results suggest that intermediate levels of migration can have favorable impacts on evolutionary adaptation.     

Climatic responses in spring migration of boreal and arctic birds in relation to wintering area and taxonomy

Large‐scale climate fluctuations, such as the North Atlantic Oscillation (NAO), have a marked effect on the timing of spring migration of birds. It has however been suggested that long‐distance migrants wintering in Africa could respond less to NAO than short‐distance migrants wintering in Europe, making them more vulnerable to climatic changes. We studied whether migratory boreal and arctic bird species returning from different wintering areas show differences in responses to the NAO in the timing of their spring migration. We used data on 75 species from two bird observatories in northern Europe (60°N). By extending the examination to the whole distribution of spring migration and to a taxonomically diverse set of birds, we aimed at finding general patterns of the effects of climate fluctuation on the timing of avian migration. Most species arrived earlier after winters with high NAO index. The degree of NAO‐response diminished with the phase of migration: the early part of a species’ migratory population responded more strongly than the later part. Early phase waterfowl responded strongest to NAO, but in later phases their response faded to non‐significant. This pattern may be related to winter severity and/or ice conditions in the Baltic. In the two other groups, gulls and waders and passerines, all phases of migration responded to NAO and fading with phase was non‐significant. The difference between waterfowl and other groups may be related to differences between the phenological development of their respective macrohabitats. Wintering area affected the strength of NAO response in a complicated way. On average medium distance migrants responded most strongly, followed by short‐distance migrants and partial migrants. Our results concerning the response of long‐distance migrants were difficult to interpret: there is an overall weak yet statistically significant effect, but patterns with phase of migration need further study. Our results highlight the importance of examining the whole distribution of migration and warrant the use of data sets from several sampling sites when studying climatic effects on the timing of avian life‐history events.     

Do Migrants Degrade Coastal Environments? Migration,Natural Resource Extraction and Poverty in North Sulawesi,Indonesia

Recent literature on migration and the environment has identified key mediating variables such as how migrants extract resources from the environment for their livelihoods, the rate and efficiency of extraction, and the social and economic context within which their extraction occurs. This paper investigates these variables in a new ecological setting using data from coastal fishing villages in North Sulawesi, Indonesia. We do not find as many differences between migrant and non-migrant families regarding destructive fishing behavior, technology, and investment as might have been expected from earlier theories. Instead, the context and timing of migrant assimilation seems to be more important in explaining apparent associations of migration and environmental impacts than simply migrants themselves. This finding fits well with recent literature in the field of international migration and immigrant incorporation.