Anthropometric and genetic distance between Gonds of Central India

A morphological and genetic study was undertaken on five Gondi-speaking populations of Central India (Andhra Pradesh and Maharashtra States). There has been no systematic biological study on this large Dravidian-speaking tribal group, 4 million in number, amounting to 13% of the total tribal population of India. Data was collected on 16 anthropometric measurements and seven genetic markers (blood groups, hemoglobin, G6PD and plasma protein polymorphisms) on the Raj Gonds, Kolams, Manne, Koyas and Plains Maria Gonds. Various genetic distance measures such as Mahalanobis's D2 and Nei's and Sanghvi's measures and cluster analysis techniques were used to determine the relationship between these groups based on anthropometrics and genetic variables. The statistical analysis revealed the Gonds to be a heterogenous group in both morphology and genetic characteristics. The morphological and genetic distances between these five groups when projected graphically revealed that the spatial distribution of these Gonds generally corresponds to their present geographical distribution. However, the actual relationships among each of the Gond populations show differences when based on these two biological variables, the possible reasons for this being discussed in the paper. The emphasis of this study is on the importance of geographical proximity in producing morphological and genetic similarity between populations, brought about by a short distance as well as similar geographical factors (such as soil, terrain, flora, etc.) drawing these populations together under a common ecocultural umbrella.     

Distribution of A1A2BO and Rho (D) blood groups in tribal populations of Andhra Pradesh, South India.

The paper reports the distribution of A1A2BO and Rho (D) blood groups among five tribal populations, Koya Dora, Raj Gond, Naikpod, Pardhan and Lambadi from three districts of Andhra Pradesh, South India. Blood samples from a total of 1090 unrelated individuals were tested. Koya Doras were, however, sampled from five distant localities to find out intratribal variation, if any. In A1A2BO blood group system the combined frequencies of "P1" and "P2" among the five Koya Groups always exceeded the frequency of "q", a characteristic feature of many tribal populations of Andhra Pradesh. However, among Raj Gond, Naikpod, Pardhan and Lambadi tribes the frequency of "q" is higher than "p" with the maximum in Pardhans. The frequency of "r" is always higher than the combined frequencies of "p1" and "p2" except in Raj Gonds. The higher frequency of "q" over "p" among Naikpod, Pardhan and Lambadi tribes is indicative of a tendency towards the distribution pattern found in North India. A few Rh negative persons were detected only in Koya Dora, Raj Gond and Lambadis indicating that the allele r (cde) is present in these populations, although in a low frequency.     

Genetic distances among the five tribal populations of Andhra, Pradesh, South India.

In this paper, data on genetic distances among five tribal populations ae given. Among the five tribes, Koya Dora, Raj Gond and Naikpod are autochthonous populations of the Deccan plateau whereas the other two groups, Pardhan and Lambadi are migrants. Kova Doras were sampled from five distant localities. Genetic markers typed are: A1A2B0, Rho(D) blood group systems glucose-6-phosphate dehydrogenase deficiency, transferrin, haptoglobin, groupspecific component, haemoglobin, colour-vision deficiency and tastability to P. T. C. Using frequency data for the above nine genetic loci, genetic distances between the five endogamous tribes, and between the five groups of Koya Dora are calculated by adopting the statistical method of Edwards (1971). While genetic distances between Koya Dora, Raj Gond and Lambadi are minimal, the genetic distance between Pardhans and other tribal groups is maximum. Naikpods occupy an intermediate position. The closeness of Lambadi with Koya Dora and RAJ Gond can be regarded as coincidental. Interestingly, the differences in the genetic distance values between five Koya Dora groups are as great as the differences between the five endogamous tribal populations tested for the same loci. Genetic affinities of these tribal populations are discussed in relation to their ethnic origin migration and geographical isolation.     

Genetic heterogeneity and population structure of Gond-related tribes in the Vidarbha region of Maharashtra.

Genetic heterogeneity in nine polymorphic loci is observed among Gond-related tribes in the Vidarbha region of Maharashtra. Pardhans, with their high ABO*A2 gene frequency (4.01%), low m gene frequency (57%), high P*1 gene frequency (42.7%), and high HbS trait (31.58%), differ significantly from other tribes. Per locus average heterozygosity among the studied tribes ranged from 36.24% to 40.37%, with Pardhans being more heterozygous. Analysis by FST and the empirical relationship between average allele frequencies and the ratio of within-gene to total gene diversity show that the tribes are isolated and that differentiation among them is at an early stage and approximately in conformity with expected differentiation under genetic drift. However, distances and principal components analysis reveal that Pardhans are far removed from the other tribes and from other central Dravidian tribes. Furthermore, of the various demographic parameters estimated, the high average heterozygosity in Pardhans is significantly correlated with mean marital distance (MMD), regression of MMD on wife's age, and effective population size. There is congruence between genetic and demographic data, showing that Pardhans are distinct. This conforms with Haimendorf's (1979) contention based on cultural traits that Pardhans are Gonds by historical accident and are later migrants to the Gond area from the north. The most significant and practical observation of the present study is that migration from an originally nontribal (Pardhan) to a tribal (Gond) area and admixture lead to severe disease course, differential selection pressure, and hence highly elevated HbS trait frequency.     

Convergent evolution in the tribes of Bastar

An investigation of the ABO blood groups, the sickle cell trait, and the ability to taste phenylthiocarbamide among four endogamous tribal groups of Bastar in Central India is reported. These tribles, the Raj Gonds, the Murias, the Bhatras and the Halbas are shown to resemble one another in the genetic traits investigated to a remarkable degree, despite genetic and social isolation from each other. It is suggested that similarities between the tribes is due to their having shared a common geographical environment for hundreds of generations.     

Admixture and population replacement of the sells Papago Indians: Three strategies

Abstract

Changes in rates of admixture on the Sells Papago Indian reservation over the last century are shown to reflect ethnohistorically recorded events of extra‐tribal contact. Three distinct strategies providing, in varying degrees, for the preservation of group identity were identified. It is argued that strategies favoring maximum preservation of ethnic identity have threatened the survival of the reservation breeding units because traditional patterns of mate selection are inconsistent with present settlement patterns and result in delay of mate selection and childbearing early in reproductive life.     

Selection intensities and inbreeding among some caste groups of Andhra Pradesh,India

Abstract

An attempt is made to study the interaction of inbreeding levels with other factors in influencing the intensity of natural selection. Results suggest that selection intensity values are high in the inbred and low socioeconomic groups of Madiga and Mala (1.545, 0.687). On the other hand, the non‐inbred and high socioeconomic group of Maheshwari shows low selection intensity (0.543). Contribution of mortality to total index of selection is greater in the groups of Madiga and Mala (1.059, 1.062) than in the Maheshwari group (0.204).     

PTC tasting and group membership

Abstract

Child mortality experience may affect subsequent fertility of couples by exerting the so‐called “physiological” and/or “replacement” responses. The influence of either effect should become apparent upon an examination of individual reproductive histories. The impact of infant and early childhood mortality on subsequent reproductive behavior of couples is analyzed for the presence and intensity of these effects. Historical data are derived from 1,261 families in two communities in western Massachusetts. Relationships of intervals between successive confinements, and parity progression ratios, according to the fate of previous births, are examined. While forms of family limitation have been employed by the study population, indicating that the capacity for replacement existed, the data do not reveal any significant attempt at child replacement.     

Sexual selection has minimal impact on effective population sizes in species with high rates of random offspring mortality: An empirical demonstration using fitness distributions

The effective population size (N_e) is a fundamental parameter in population genetics that influences the rate of loss of genetic diversity. Sexual selection has the potential to reduce N_e by causing the sex‐specific distributions of individuals that successfully reproduce to diverge. To empirically estimate the effect of sexual selection on N_e, we obtained fitness distributions for males and females from an outbred, laboratory‐adapted population of Drosophila melanogaster. We observed strong sexual selection in this population (the variance in male reproductive success was ～14 times higher than that for females), but found that sexual selection had only a modest effect on N_e, which was 75% of the census size. This occurs because the substantial random offspring mortality in this population diminishes the effects of sexual selection on N_e, a result that necessarily applies to other high fecundity species. The inclusion of this random offspring mortality creates a scaling effect that reduces the variance/mean ratios for male and female reproductive success and causes them to converge. Our results demonstrate that measuring reproductive success without considering offspring mortality can underestimate N_e and overestimate the genetic consequences of sexual selection. Similarly, comparing genetic diversity among different genomic components may fail to detect strong sexual selection.     

Individual fertility rate among minor tribal populations from Andhra Pradesh,India

Abstract

The Individual Fertility Rate (IFR), a measure of current fertility status in small and illiterate preindustrial societies, is estimated for five tribal populations from Andhra Pradesh, India. The Andhra tribes exhibit high individual fertility rates ranging between 49.62 ± 1.76 (Konda Dora) and 66.63 ± 3.16 (Manzai Mali) and fall in the high‐fertility category. The differences in IFR values between affinal and consanguineous couples are not significant. A direct positive relation between IFR and tribal hierarchy is observed with relatively higher IFR values recorded for socially higher‐ranked tribes in an ascending order from lower‐ to higher‐ranked groups.     

Condition‐dependent mortality exacerbates male (but not female) reproductive senescence and the potential for sexual conflict

Disentangling the relationship between age and reproduction is central to understand life‐history evolution, and recent evidence shows that considering condition‐dependent mortality is a crucial piece of this puzzle. For example, nonrandom mortality of ‘low‐condition’ individuals can lead to an increase in average lifespan. However, selective disappearance of such low‐condition individuals may also affect reproductive senescence at the population level due to trade‐offs between physiological functions related to survival/lifespan and the maintenance of reproductive functions. Here, we address the idea that condition‐dependent extrinsic mortality (i.e. simulated predation) may increase the age‐related decline in male reproductive success and with it the potential for sexual conflict, by comparing reproductive ageing in Drosophila melanogaster male/female cohorts exposed (or not) to condition‐dependent simulated predation across time. Although female reproductive senescence was not affected by predation, male reproductive senescence was considerably higher under predation, due mainly to an accelerated decline in offspring viability of ‘surviving’ males with age. This sex‐specific effect suggests that condition‐dependent extrinsic mortality can exacerbate survival‐reproduction trade‐offs in males, which are typically under stronger condition‐dependent selection than females. Interestingly, condition‐dependent extrinsic mortality did not affect mating success, hinting that accelerated reproductive senescence is due to a decrease in male post‐copulatory fitness components. Our results support the recent proposal that male ageing can be an important source of sexual conflict, further suggesting this effect could be exacerbated under more natural conditions.     

Sex and destiny: The role of mating signals in speciation and macroevolution

A growing body of research posits a central role for mating signals in speciation and the reproductive isolation of species, yet there has been relatively little consideration of mating signal evolution within macroevolutionary theory. Factors that influence the divergence of fertilization systems generally, and mating signals specifically, may incidentally influence rates of speciation and patterns of species sorting. Potential key processes include: genetic drift, natural selection (differential survival), selection for mate recognition, and sexual selection. This paper explores the integration of mating signal evolution into macroevolution and hierarchy theory, arguing that speciational patterns may frequently result from “effect sorting”; in which microevolutionary processes operating at the organismal level have macroevolutionary effects at the clade level. Preliminary evidence indicates that sexual selection is a widespread and potent evolutionary force that, together with other mechanisms, may have a large, though incidental impact on species sorting. The Mate Competition Hypothesis is here proposed to account for this possibility, postulating that heritable, clade‐specific variations in the intensity of sexual selection and the potential breadth of signal‐receiver systems contribute to divergent patterns of species‐richness. Several examples from the vertebrate fossil record are consistent with this hypothesis.     

Fertility and mortality differentials among the tribal population groups of Bastar District, Madhya Pradesh, India

The authors examine fertility and mortality differentials and their impact on health care and natural selection potentials among tribal populations in rural India. Data are from the Bastar District and concern 366 mothers who have completed their reproductive life span.     

Socioeconomic covariates and their impact on the opportunity for natural selection in a riparian tribe of Northeast India

The intensity of natural selection correlates with various bio-social variables which influence the genetic structure of a population. In this paper it has been sought to find out the influence of variable environmental setting and economic condition on selection intensity among the Mising tribal population of Assam, Northeast India. Detailed reproductive pattern of 309 post menopausal women is obtained and a comparison has been made between different environmental as well as economic backgrounds. The impact of secular change on selection intensity has been assessed. For this study I have proposed a modified formula of Johnston & Kensinger's (1971) index for selection intensity. Crow's index of selection intensity has also been used for comparative analyses. After considering standard statistical procedure, a clear disparity of selection intensity has been noticed in terms of varying socioeconomic condition as well as habitational background. It can be concluded from the study that environmental factors act more in terms of selection pressure on infants rather than the other post natal stages.     

Reproductive and socioeconomic determinants of child survival: Confounded,interactive, and age‐dependent effects

Abstract

Studies of infant and child mortality have evolved to distinguish between two sets of explanatory variables—factors related to reproductive or maternal characteristics and socioeconomic factors, generally described as characteristics of the family or household. Almost all multivariate analyses include variables from each of these two sets, but there has been little consideration of the relationship between them. We examine how these two sets of variables jointly affect mortality. We test first for confounded effects by examining socioeconomic effects while excluding and then including reproductive variables in nested multivariate models. Next, we look for age‐dependent effects among the explanatory variables and find that reproductive and socioeconomic factors affect mortality at differing ages of children. Finally, we examine interactive effects of the two sets of variables. We conclude that the higher mortality observed among the low status groups is not a result of greater concentration of poor reproductive patterns in those groups. Instead, higher status groups probably have more resources available for combating the negative effects of the same high‐risk reproductive patterns.     

Dance and glance: Visualizing tribal identity in Highland Yemen

This paper is a study in the ways that esthetic markers—dancing, poetry, clothing, food—underlie, define, and construct conceptions of the tribe in the northern highlands of Yemen. As the rural Yemeni economy has changed from economic and political self‐sufficiency to dependence on the world market and a strong central government, so has the significance of tribalism. Ironically, nationalism is presented by the Yemeni media in tribal terms. While rural expressions of tribal identity have declined, use of tribal markers has intensified in towns and cities even by those who were not formerly defined as tribal. The significance of esthetic phenomena in the formation of identity and the construction of culture is addressed.¹     

Fertility and mortality differentials among selected tribal population groups of north-western and eastern India

Selection potential based on differential fertility and mortality has been computed for six tribal groups inhabiting different geo-climatic conditions, namely: Sahariya, Mina and Bhil of the State of Rajasthan, north-western India, and Munda, Santal and Lodha of the State of West Bengal, eastern India. Irrespective of the methodology, the total index of selection was found to be highest among Lodhas (0.668), followed by Sahariyas (0.524), Santals (0.462), Bhils (0.386), Mundas (0.353) and Minas (0.334). Incidentally, Lodha and Sahariya are two of the seventy-four notified primitive tribal groups of India, and these two study populations show the highest index of total selection, mainly because of a higher embryonic and postnatal mortality. The relative contribution of the fertility component to the index of total selection is higher than the corresponding mortality component in all tribal groups. The analysis of postnatal mortality components indicates that childhood mortality constitutes the bulk of postnatal mortality, suggesting that children under 5 years need better health care in these tribal groups.     

Estimation of the direction and intensity of natural selection in relation to human intelligence by means of the intrinsic rate of natural increase

Abstract

A follow‐up study was made of 979 white individuals born in 1916 or 1917 who took the Terman Group Intelligence Test in the sixth grade while attending the Kalamazoo Public School System. It is the first study to take into account all of the variables that affect population growth (fertility, mortality, and generation length) by means of the intrinsic rate of natural increase when estimating the direction and intensity of natural selection in relation to human intelligence. When all the variables affecting population growth have been taken into account, the population under study has probably been in equilibrium with respect to the genetic factors favoring high intelligence, or more likely, has experienced a slight increase in the frequency of the genetic factors favoring high intelligence.     

QUANTIFYING EVOLUTIONARY POTENTIAL OF MARINE FISH LARVAE: HERITABILITY,SELECTION, AND EVOLUTIONARY CONSTRAINTS

For many marine fish, intense larval mortality may provide considerable opportunity for selection, yet much less is known about the evolutionary potential of larval traits. We combined field demographic studies and manipulative experiments to estimate quantitative genetic parameters for both larval size and swimming performance for a natural population of a common coral‐reef fish, the bicolor damselfish (Stegastes partitus). We also examined selection on larval size by synthesizing information from published estimates of selective mortality. We introduce a method that uses the Lande–Arnold framework for examining selection on quantitative traits to empirically reconstruct adaptive landscapes. This method allows the relationship between phenotypic value and fitness components to be described across a broad range of trait values. Our results suggested that despite strong viability selection for large larvae and moderate heritability (h²= 0.29), evolutionary responses of larvae would likely be balanced by reproductive selection favoring mothers that produce more, smaller offspring. Although long‐term evolutionary responses of larval traits may be constrained by size‐number trade‐offs, our results suggest that phenotypic variation in larval size may be an ecologically important source of variability in population dynamics through effects on larval survival and recruitment to benthic populations.     

RAPID LOSS OF BEHAVIORAL PLASTICITY AND IMMUNOCOMPETENCE UNDER INTENSE SEXUAL SELECTION

Phenotypic plasticity allows animals to maximize fitness by conditionally expressing the phenotype best adapted to their environment. Although evidence for such adjustment in reproductive tactics is common, little is known about how phenotypic plasticity evolves in response to sexual selection. We examined the effect of sexual selection intensity on phenotypic plasticity in mating behavior using the beetle Callosobruchus maculatus. Male genital spines harm females during mating and females exhibit copulatory kicking, an apparent resistance trait aimed to dislodge mating males. After exposing individuals from male‐ and female‐biased experimental evolution lines to male‐ and female‐biased sociosexual environments, we examined behavioral plasticity in matings with standard partners. While females from female‐biased lines kicked sooner after exposure to male‐biased sociosexual contexts, in male‐biased lines this plasticity was lost. Ejaculate size did not diverge in response to selection history, but males from both treatments exhibited plasticity consistent with sperm competition intensity models, reducing size as the number of competitors increased. Analysis of immunocompetence revealed reduced immunity in both sexes in male‐biased lines, pointing to increased reproductive costs under high sexual selection. These results highlight how male and female reproductive strategies are shaped by interactions between phenotypically plastic and genetic mechanisms of sexual trait expression.