Continuing fertility transitions in a plural society: ethnic trends and differentials in Peninsular Malaysia

Fertility in Peninsular Malaysia has declined continuously from the late 1950s, reaching a total fertility rate of 3735 in 1983. All ethnic groups in Malaysia have contributed to this modern demographic transition but the rate of change has been most rapid for Chinese and Indians, Malay fertility having reached a plateau in the early 1980s. The effect of age structure, marital patterns and marital fertility (by parity) on the fertility declines for each ethnic community are analyzed. There has been a tendency, in each ethnic group, for the age distribution within the group of reproductive-age women to grow younger, reflecting the entry into the younger reproductive ages of the large birth cohorts of the 1950s and early 1960s. The effect of this on crude birth rates is hard to determine, because rising age at marriage and increasing use of contraception meant that fertility was increasingly concentrated in the more central reproductive ages. By the 1990s, the earlier declines in fertility will bring about a decline in the proportion of the total population made up of females in the main reproductive ages. After that point, further declines in fertility will be reflected in a sharper decline in the crude birth rate and hence the rate of population increase. Between 1947 and 1980, the age at marriage changed dramatically for females of all ethnic groups. The transition to higher age at marriage for Chinese was completed earlier, and since 1970 has risen by only a year. For Malays and Indians, the rise began later, proceeded faster and continued right up to 1980 when the medium ages at 1st marriage were Malays 22, Indians 23, Chinese 24 years. In 1980, Malay women on average were marrying 5 years later, and Indian women 6 years later than had their mothers' generation in 1947. The proportion never-married among Malay and Indian women aged 20-24 rose from 1/10 to 1/2 over this period; relatively greater changes are evident at ages 25-29. Other factors are the almost complete shift from parent-arranged to self-arranged marriages. Family size desired has decreased for all groups and the decline in breastfeeding has been offset by the sharp increase in the practice of contraception. Continuation of these trends would lead to replacement-level fertility for Malaysian Chinese and Indians by the year 2000. Malay fertility is likely to continue to decline but at a more moderate pace.     

Fertility Changes in Rural Moroccan Berbers during the 20th Century

Morocco’s fertility pattern evolved in the 20th century from a traditional model close to ‘natural fertility’ to a modern pattern incorporating contraception. The very high fertility rate of nearly 7 offspring per woman observed in the 1960s was still at a level of 5.5 offspring per woman in the early 1980s. The total fertility rate subsequently declined to 2.5 by 2003. This decline was apparently, principally, the result of two factors in the urban context: the relative increase in women’s age at marriage and the use of contraception to regulate and to close reproduction. This research studied a group of Berber agriculturists in the region of Marrakech to better understand the extension and modalities of fertility changes in a rural environment. Though delayed, the changes observed in rural Berbers paralleled the general trends seen at the national level. As in the urban environment, the changes affecting reproductive patterns resulted from an increase in the age at marriage of women and the introduction of contraception. However, these changes were apparently minor adaptations to the traditional pattern, in that the progressive increase in mean age at marriage was obtained by the decrease in the frequency of pre-nubile unions (<15 years old) and not from the upward shift of the modal age. On the other hand, contraception apparently was employed to stop childbearing after the expected family size was already attained.     

Rapid fertility decline in Iran: analysis of intermediate variables

The remarkable decline in fertility in Iran, which saw the total fertility rate fall from 7 children per woman in 1986 to 2 in 2000, has received only limited analysis in the demographic literature. Using the 2000 Iran Demographic and Health Survey and Bongaarts' age-specific fertility model, this paper examines the role of the major proximate determinants of fertility in bringing about the rapid decrease in fertility in Iran. The analysis indicates that contraception had the largest effect on fertility, accounting for 61% of the reduction in fertility from its theoretical maximum. The fertility-inhibiting effect of marriage patterns accounted for an additional 31% reduction, and was most important among the young. Further analysis of contraceptive behaviour suggests that the current period fertility rate of 2.0 children per woman is an outcome of a synchronization of delaying and spacing of births among younger women with stopping of childbearing among women in the middle and late reproductive ages. The policy implications of the results are discussed.     

Effect of nuptiality, contraception and breast-feeding on fertility in Bangladesh

The effects of marriage, contraception, and post-partum lactational infecundability on fertility in Bangladesh are assessed by applying Bongaarts' formula to survey data for the period 1975-1985. Marriage is universal and age at marriage is low. Breastfeeding is prolonged and has a pronounced effect on fertility. The fertility-reducing effect of contraception increased over the period through increased use of modern methods. The total fertility rate (TFR) declined by 24% from 1975 to 1985. This study shows that the 3 major proximate determinants cannot account completely for variation in national fertility levels.     

Craniometric analysis in groups from tierra del Fuego/Patagonia and the peopling of the south extreme of the Americas

Five large craniometric samples from extinct tribes (Selk’nam, Kawéskar and Yámana) from Tierra del Fuego and from Patagonia have been analyzed through multivariate techniques. The purpose was to test the hypothesis of one or two different migration waves in the peopling of the south extreme of South America. A cluster analysis has been made, using the squared Euclidean distance as a measure of proximity, and the UPGMA and neighbor joining algorithms as a tree building method. The robustness of the branches has been assessed with bootstrap analysis through 100 random iterations of the original data set. Results show that, despite their cultural differences, the three hunter-gatherer groups. from Tierra del Fuego tend to cluster together, indicating a similar morphological pattern. This suggests that geographic distance (in latitudinal sense) is the main factor that influenced the differentiation of the human groups from Tierra del Fuego and Patagonia, from a single ancestral population.     

Historical ecology and current abundance of the translocated Chilla or Grey fox Lycalopex griseus on the large Tierra del Fuego Island shared by Argentina and Chile

In 1951, a batch of 24 young animals of both sexes of Chilla or Grey fox Lycalopex griseus from continental Magallanes region, Chile – and perhaps also from adjacent continental Argentina – were released at Onaisin (65 km ESE Porvenir town, 53°18′S) on Tierra del Fuego Island in southernmost South America, to control a European rabbit (Oryctolagus cuniculus) irruption that was considered detrimental to sheep (Ovis aries) ranching. Up to now, no attention has been paid to the temporal course of that introduction. Here we provide a historical account of the presence of foxes on the Tierra del Fuego Archipelago, starting with Charles Darwin account of 1839 until present. We also review the regulatory framework concerning hunting of those foxes and tally their culling for export of pelts. Finally, we provide estimates of the abundance of Chilla foxes on Tierra del Fuego Island for the period 1999–2007 and for 2021, and highlight their current spread. These translocated foxes have become an abundant and functional part of both steppe and forest ecosystems on the Fuegian archipelago, even though they are killed by hunters, without spatial, temporal, or numerical limits. We conclude that interesting scientific opportunities are being missed regarding the population genetics of a species that may have left founding effects and genetic bottlenecks in Tierra del Fuego, and perhaps some peculiar continental markers among the island population. We also raise the question whether this introduced native species may be deemed invasive, calling for research to determine its impact in its new environment.     

SUMMER DISTRIBUTION OF PELAGIC BIRDS OFF THE COAST OF ARGENTINA

Eighteen species of sea–birds were observed from CSS 'Hudson' in the South Atlantic between the Rio de la Plata and Tierra del Fuego in late January and late February 1970. Major feeding areas were noted off Mar del Plata, the Valdes Peninsula and Tierra del Fuego, Argentina, the first two in rich modified or unmodified water of the subantarctic Falkland Current, associated with upwelling. The southernmost area had most birds, the northernmost fewest. A temperate–latitude assemblage including Yellow–nosed Albatross and Cory's Shearwater occurred off Mar del Plata in warmed water of subantarctic (Falkland Current) origin. South of 39°S these two species were replaced by Black–browed Albatross and Great Shearwater in cold offshore water of the Falkland Current. Off the Valdes Peninsula Black–browed Albatross, Great and Sooty Shearwaters, White–chinned Petrels and family groups of Magellanic Penguins occurred near the edge of highly–productive water of the Falkland Current. The largest feeding area, east of Tierra del Fuego, had Magellanic and Rockhopper Penguins, Great Shearwaters, King Cormorants, South American Terns and jaegers, but no oceanographic information is available. At 50°S prions and diving petrels appeared for the first time, marking a possible oceanographic discontinuity or proximity to colonies on the Falkland Islands. Several common species of the South Atlantic were not seen on the transect including Cape Pigeon, Southern Fulmar, Soft–plumaged Petrel, Schlegel's Petrel and Pediunker. Kelp Gull, South American Tern, Manx Shearwater and jaegers were rare or absent far from land. New southern limits for the western South Atlantic Ocean were established for Cory's and Manx Shearwaters, and the Great Shearwater was observed for the first time in Chilean waters.     

Effects of age,cigarette smoking,and other factors on fertility: findings in a large prospective study.

Of 17 032 women taking part in the Oxford Family Planning Association contraceptive study, 4104 stopped using a birth control method to plan a pregnancy on a total of 6199 occasions. The influence of various factors on fertility in these women was assessed by measuring the time taken to give birth to a child. An appreciable inverse relation was observed between age at stopping contraception and fertility both in nulliparous and parous women, but the effect was much greater in the nulliparous women. The most important finding was a consistent and highly significant trend of decreasing fertility with increasing numbers of cigarettes smoked per day; it was estimated that five years after stopping contraception 10.7% of smokers smoking more than 20 cigarettes a day, but only 5.4% of non-smokers, remained undelivered. Some relation was found between fertility and social class, age at marriage, and a history of gynaecological disease, but weight, height, and Quetelet''s index were without noticeable effect.     

Trichomycetes living in the guts of aquatic insects of Misiones and Tierra del Fuego, Argentina

Fourteen species of Trichomycetes living in the guts of aquatic insects are reported from two provinces of Argentina, Misiones and Tierra del Fuego. Twelve of the species belong to the Harpellales and two are Amoebidiales. Five harpellid species are reported from Misiones in the extreme northeast of the country (Genistellospora homothallica, Harpella tica, Smittium culisetae, Smittium sp., Stachylina sp.) and seven are from Tierra del Fuego, the southern tip of South America (H. meridianalis, Glotzia sp., S. culicis, S. cellaspora, S. imitatum, Stachylina minima, Penella simulii). Insect hosts all were immature stages of Culicidae, Simuliidae, Chironomidae, Ceratopogonidae (Insecta: Diptera), and Ephemeroptera and Plecoptera. The lower diversity of Trichomycetes found at Misiones, which has a subtropical climate and rainforest vegetation, was due possibly to the warmer temperatures of the water (15-24 C), compared to the colder streams of Tierra del Fuego (9-15 C), with forests and steppes as typical vegetation.     

Demographic and endocrinological aspects of low natural fertility in Highland New Guinea

The Gainj of highland Papua New Guinea do not use contraception but have a total fertility rate of only 4.3 live births/woman, 1 of the lowest ever recorded in a natural fertility setting. Reproductive and marital histories were obtained from 305 females and 206 males aged 10+. Each subject was asked about: number of live born offspring ever produced; number of stillbirths ever produced; number and names of offspring currently being nursed; number of current and past spouses; and the cause of dissolution of all past marriages. Blood samples were drawn from 172 volunteer female subjects aged 10-60 years and ovarian function was classified by concentration of progesterone. From an analysis of these cross-sectional demographic and endocrinological data, the causes of low reproductive output have been identified in women of this population as: late menarche and marriage, a long interval between marriage and 1st birth, a high probability of widowhood at later reproductive ages, low effective fecundability and prolonged lactational amenorrhea. These are combined with near-universal marriage, and a low prevalence of primary sterility similar to that found in other populations. Of all the factors limiting fertility, by far the most important are those involved in birth spacing, especially lactational amenorrhea. The effects of widowhood on Gainj fertility are negligible. Factors acting to lower fertility fall into 2 categories: those that determine the age of onset of reproduction and those that act to space births. Given the observed pattern of birth spacing, however, the delay in commencement of reproduction represents on average no more than 1 or 2 live births averted/woman. In contrast, were age at 1st reproduction held constant while reducing birth intervals to a mean of 2.0-2.5 years, total fertility would increase to about 7 or 8. Future research on natural fertility should focus on specific behavioral and physiological mechanisms governing the reproductive process.     

Annual gonadal cycle and reproduction in Patagonotothen tessellata (Richardson 1845 (Nototheniidae: Pisces) from the Beagle Channel, Argentina

The reproductive biology of Patagonotothen tessellata (Richardson 1845) in the Beagle Channel, Tierra del Fuego, Argentina was analysed from weekly captures over a 3-year period (1987–1989). The spawning periods and lengths thereof were analysed using GSI curves and monthly percentage distributions of maturation stages. Two gonadal maturation cycles and two spawning periods (winter and summer) within 1 year were defined. Also discussed is whether the same specimens are able to mate successfully in winter and summer, and whether the reproductive effort varies between the seasons. Male parental behaviour and the likely consequences on their energy levels are considered.     

Holocene glaciations in the Ema Glacier valley, Monte Sarmiento Massif, Tierra del Fuego

Investigations carried out in the Ema Glacier valley, Tierra del Fuego, on the eastern side of Monte Sarmiento Massif, enable the recognition of five Holocene glacial events. The oldest glacial advance deposited the so-called external moraines of Ema Glacier, with a probable occurrence between 6000 and 5000 14 C y BP without discarding the potential for these deposits to be from Lateglacial time. The remaining four readvances built up a complex inner moraine system named informally internal moraines of Ema Glacier. The oldest recognized till unit that constitutes this proximal moraine system was deposited shortly before 3135 14 C y BP, when glaciolacustrine sedimentation took place during glacier recession. Subsequent glacial advances accumulated till at about 1288 14 C y, shortly after 695 14 C y, and between 379 14 C y and 60 y BP. This chronology of Holocene glacier events coincides with and is well complemented by the one established by other authors for Fiordo Pía at Cordillera Darwin, 75 km to the east. The Ema-Pía chronology is used to calibrate tentatively a series of moraine belts previously identified in the mountain ranges adjacent to Ushuaia, 150 km SE of the surveyed region. A comparative chart shows that the chronological data obtained for the neoglacial readvances in Tierra del Fuego are in accordance with those for the southern Patagonian Andes further north. It follows that the Holocene behavior of the glaciers in the Andean region of Tierra del Fuego and southern Patagonia is essentially a response to the same regional climate change.     

Extra‐pair paternity in a population of Chilean Swallows breeding at 54 degrees south

Geographic patterns of variation in life‐history traits have puzzled researchers for decades. However, the widely accepted idea that mating systems exhibit a tropical–temperate latitudinal trend, with extra‐pair mating systems being the norm among temperate species and genetic monogamy the norm among tropical species, is supported by sparse data, particularly for birds breeding in the tropics and even more so for birds that breed in the southern hemisphere temperate zone. Our objective was to examine the genetic mating system of Chilean Swallows (Tachycineta meyeni) breeding at 54°S in Tierra del Fuego, Argentina. From 2006 to 2009, we examined the paternity of young in 52 broods. Contrary to predictions based on their congeners that breed at equivalent latitudes in the northern hemisphere, Chilean Swallows in our study had low rates of extra‐pair paternity (EPP), with 13.5% of nests (N = 52) having at least one extra‐pair young and 6.8% of all nestlings (N = 161) fathered by extra‐pair males. These rates are also lower than those reported for species of Tachycineta swallows that breed at tropical latitudes. We found no support for a tropical–south temperate latitudinal cline in EPP rates. The highly unpredictable weather of the island of Tierra del Fuego might be influencing parental investment at this site; small clutch sizes and low EPP rates are expected if biparental attention is crucial for chick survival and reproductive success for these aerial insectivores. We argue that the sparse sampling of mating systems in birds worldwide may have contributed to a misapprehension of a global pattern. More studies of tropical and south‐temperate systems are needed to build on theories based on a wider set of taxa.     

Mallomonas fuegiana (Synurophyceae), a new species of silica scaled chrysophytes from Tierra del Fuego, Argentina

Vigna, M. S. & Kristiansen, J. 1995. Mallomonas fuegiana (Synurophyceae), a new species of silica scaled chrysophytes from Tierra del Fuego, Argentina. — Nord. J. Bot. 15: 439–442. Copenhagen. ISSN 0107–055X.
During the research project "Cryptogamic Flora of Tierra del Fuego", a new species of Mallomonas has been found. It is described here as M. fuegiana , and is placed in the section Torquatae , close to Mallomonas schwemmlii and M. dickii .     

Human colonization of the central territory of Argentina: design matrix models and craniometric evidence

In this study we test several hypotheses about the peopling of the central territory of Argentina, archaeologically known as Sierras Centrales, by testing the association between four alternative models of the peopling of the area and cranial morphological variation through distance and matrix correlation analyses. Our results show that the ancient inhabitants of Sierras Centrales demonstrated close morphological similarities with the Patagonian and Tierra del Fuego populations. Moreover, the correlation and partial correlation analyses suggest that the peopling of the Sierras Centrales most likely took place as a migratory wave proceeding from the present area of Northeastern Argentina, and continued southward to Patagonia and Tierra del Fuego.     

The influence of female education,labor force participation,and age at marriage on fertility behavior in Bangladesh

Abstract

This paper studies the relationship between three aspects of female status (education, work experience, and age at marriage) and the use of contraception and fertility in Bangladesh. Education is found to be the variable most strongly correlated with use of contraception and is also one of the significant variables explaining fertility behavior. The most important factor explaining fertility behavior is age at marriage. The higher the age at marriage, the lower the fertility, when all other factors are held constant. Work experience has very little or no effect on current use of contraception and fertility.     

Reproductive change in Zimbabwe and Kenya: the role of the proximate determinants in recent fertility trends

This study examines trends in proximate determinants of fertility in Zimbabwe and Kenya. Findings from the four Demographic and Health Surveys conducted in these countries show that the dramatic fall in fertility in these countries is consistent with the underlying trends in the most important proximate determinants of fertility. In Zimbabwe, contraceptive use far exceeds other proximate determinants in influencing fertility levels and trends. The results show that the fertility inhibiting effects of contraception are more important than the effects of postpartum infecundability, marriage patterns, or sterility. The results also show that contraceptive use has its greatest suppressing effects in the middle and younger age groups. However, in Kenya, the dominant fertility inhibiting effect is postpartum infecundability, with contraception coming in second.     

Nest site selection of the Kelp gull (Larus dominicanus) in the Beagle Channel, Tierra del Fuego, Argentina

Nest site selection of Kelp gulls Larus dominicanus breeding in Conejo and Bridges islands, Tierra del Fuego, Argentina, was assessed between 14 and 30 December 2005 to describe variability in nest site features and determine variables affecting nest choice. Fourteen microhabitat variables were quantified at 40 nest sites and at 40 random points in each island during the late incubation stage. Nests at the two colonies were placed on different kinds of substrates across areas with varying degrees of cover provided either by rocks or vegetation. Despite the variability observed in nest site features, rock cover and rocky substrates were the main factors determining nest site selection. At Conejo Island, nest sites presented more rock cover, less percentage of vegetation cover and of vegetation debris substrate, and were placed further from the nearest vegetation in comparison to random points. Similarly, gulls at Bridges Island selected nest sites with more rock cover which were placed mainly on rocky and vegetation substrates. This contrasts with results previously obtained in Argentina, which indicated that vegetation is a key factor influencing Kelp gull nest site selection. Over 80% of the nests at both study colonies were placed on the northern slopes of the islands, relatively more protected from the strong prevailing southwest winds, and nests at both colonies tended to be more protected on their southern side either by rocks or vegetation. Results obtained at Tierra del Fuego confirm the plasticity of microhabitat use by Kelp gulls, and their ability to take advantage of nesting sites according to availability and local environmental factors.     

Reproduction in high altitude Aymara: physiological stress and fertility planning?

Reproductive characteristics at high altitude are described based on the reproductive histories of 720 Aymara women, collected in 1998 and 1999 in a group of twelve peasant communities at a mean altitude of 4000 m in the Bolivian Altiplano. The reproductive pattern is shaped by a late onset of childbearing, associated with a rather short reproductive span and large birth intervals. Environmental conditions could explain the particularly late age at menarche of rural girls compared with their urban counterparts, whereas the age at first birth is likely to be under cultural control. The short reproductive span appears to result from a large mean interval between last birth and menopause, which is essentially determined by cultural decisions. The birth intervals, which are longer than in many traditional societies, could be the result of a slower restoration of postpartum fecundability induced by the hard way of life inherent in the Altiplano (including poor sanitary and nutritional conditions and high workload), perhaps aggravated by hypoxia. However, a secular trend in fertility is perceptible, towards earlier menarche, earlier age at first birth, increasing reproductive span and a slight increase in live births and surviving offspring, which is probably the result of a slow improvement in living conditions. The existence of birth control on the one hand, and a total fertility rate averaging six live births among the couples who do not practise contraception on the other, are other arguments against the hypothesis of a low natural fecundity in these Aymara groups.