The ecology of Maesopsis eminii Engl. in tropical Africa

Maesopsis eminii is referred to as one of the most widely distributed African tree species. However, its occurrence in Africa has never been mapped and little is known as to how this species can sustain in different environments. To gain insight into Maesopsis’ ecology, we (i) made a synthesis of its functional trait data from the literature, (ii) investigated phenological patterns using data on four M. eminii trees from Yangambi, DR Congo, (iii) assessed an empirical provenance trial from Uganda on 600 Maesopsis trees and (iv) synthesized geo‐referenced point location maps of Maesopsis entailing WorldClim precipitation and temperature and FAO soils, rainfall and ecological zones for Africa. We found M. eminii to straddle the equator equidistantly in terms of latitude (10.97°N and 10.98°S) covering five forest types where twenty soil types and variable rainfall regimes support complex plant biodiversity. Maesopsis eminii was, however, largely concentrated in the tropical rainforest ecosystem which contains fertile Orthic Ferralsol soils. More than 97% of the point locations were found where annual precipitation was >1000 mm, and 82% occurred where average annual temperature was 22–28°C. Its functional traits, phenology and provenance trial findings explained its occurrence in Africa.     

The ecology of human birth seasonally

This article examines birth seasonality in two environmentally and ethnographically distinct societies: the Copper Inuit of the Central Canadian Arctic and the Samukundi Abelam of Papua New Guinea. Although the regions inhabited by these societies differ dramatically in degrees of seasonal variation, both populations display significant seasonality in conceptions and births. For the Copper Inuit, such seasonal variation was found to be the consequence of social and economic responses to extreme environmental change. Birth seasonality for the Samukundi Abelam is also pronounced and was determined to be the result of social ideologies which are only indirectly linked to environmental factors. The article also proposes a research paradigm designed to facilitate the cross-cultural investigation of birth seasonality in human populations.     

Female stress and birth seasonality in Tanzania

Delivery records from hospitals in Ikwiriri and Ifakara show that the number of births increases throughout the dry season (June-October) and declines throughout the rainy season (November), reaching a peak just before the rains and the lowest level at the end of the rainy season. This pattern does not correspond with the usual explanations of birth seasonality. Conceptions are most frequent at the period of highest temperature, which is contrary to the theory that predicts them to be more frequent during the dry season. The drop of the conception rate during the wet agricultural season suggests that stress on women may be the main cause of birth seasonality in Tanzania. Due to wet conditions and frequent staying on in the rice fields, exposure to malaria increases during the rainy season's latter part. The negative association of the number of births with rainfall in the months preceding conception indicates that almost half of the variation in the number of births may be due to the effects of malaria and physical exhaustion on fecundity. The remainder may be attributable to seasonal variations in pregnancy loss and sexual behavior. The absence of strong birth seasonality in nonholoendemic areas of Tanzania and the low birth rate in holoendemic areas provide further support for a critical role for malaria infection. The fact that the magnitude of seasonal variation in births increases with high parity and has decreased over the past decade results from recent changes in Tanzania's rural economy. Young people in Tanzania are progressively withdrawing from agriculture, especially when they have no children yet.     

The ecology of Potamogeton species in central North America

The distribution of 17 Potamogeton species was examined at 430 sites in central North America with respect to water body type, bottom substrate and 8 water chemistry parameters (pH, total dissolved solids, total alkalinity, chloride, sulphate, phosphorus, combined nitrate and nitrite, and dissolved organic matter). All except 2 of the species showed statistically significant distributions with respect to some of the environmental parameters examined. Each species occupied a different combination of chemical parameter ranges. The species formed a distribution spectrum with respect to water chemistry, with P. epihydrus and P. obtusifolius frequenting low inorganic concentrations at one end of the scale, and P. filiformis, P. pectinatus and P. vaginatus at the other end, these species characterized by high mean inorganic values and occurring most often in saline or alkaline habitats. While 41 significant positive interspecific associations were found within the genus in lentic waters, only 4 were apparent in lotic habitats. Potamogeton species richness (PR) was related to water body and bottom type, with lakes and sand bottoms showing the highest mean PR values. Stepwise multiple regression analysis showed that, in the area as a whole, the water chemistry parameters examined accounted for <25% of the observed variability in PR. The relative importance of individual chemical parameters in relation to PR varied in different water body types.     

Age and sex differences in the impact of seasonal energy stress among Andean agriculturalists

It has been widely argued that children and females are most severely affected during periods of food scarcity. This proposition is tested using dietary and anthropometric data from the Andean community of Nuñoa, Peru. Contrary to expectation, children (ages 12 years and under) are relatively protected from seasonal food scarcity while adults experience severe caloric stress. Anthropometric measures of nutritional status corroborate the dietary analysis, indicating significantly better nutritional status in children. Sex differences in dietary adequacy are not evident. Adult males, however, have significantly poorer measures of nutritional status than adult females. These differences in dietary adequacy and nutritional status reflect adaptations to marked seasonality in work demands and energy availability.     

Effects of the fertility transition on birth seasonality in the Netherlands

Synchronous with the decline in fertility that took place in the post-war period in the Netherlands, patterns of birth seasonality changed as well. In this paper seasonal fluctuations in fertility in the Netherlands are examined using population register data for the period 1952 to 2005. The peak in births has changed from spring to summer and subsequently to August/September, thereby shifting from the European to the American pattern. The seasonal shift can be attributed to parity-specific changes. Before the transition, birth seasonality did not differ much between the different parities. In the transition period from higher to low fertility, differences between parities increased which persist up to today. At present, the overall seasonality pattern is determined by first births. Moreover, birth seasonality varies by maternal age. The findings stimulate the discussion on the role of planning as a cause of birth seasonality.     

Home range and birth seasonality of Saguinus nigricollis graellsi in Ecuadorian Amazonia

A field study ofSaguinus nigricollis graellsi in the Cuyabeno Faunal Production Reserve, Ecuadorian Amazonia, established the characteristics of the home range and some reproductive aspects of the species. Field data were collected in two climatic seasons: dry, from December 1989 through March 1990, and rainy, from May through August 1990. Eight groups visited and/or lived in the study area during the dry season and ten during the rainy season. Group sizes ranged from two to nine individuals. Population density was estimated at 22–33 individuals per square km. The central group, which was followed intensively, had a home range which included both flooded and non-flooded forests. Terra firme forest was most used by the species. The home range of this group was reduced from 56.2 hectares (ha) in the dry season to 41.7 ha in the rainy season, probably as a result of a differential distribution of food plants between seasons. The presence of dense undergrowth where monkeys could hide to avoid predation and or a high concentration of food plants seem related to the preferential use of certain areas in the home range. The home ranges of neighboring groups overlapped considerably and peaceful temporary large groups were frequently observed. A generalized birth peak occurred in January 1990, dry season. In June 1990, rainy season, 40% of the groups exhibited a second birth peak. This reproductive bimodality of S. nigricollis graellsi indicates a high productivity of the forests at the Cuyabeno site. © 1995 Wiley-Liss, Inc.     

The pollination ecology of an assemblage of grassland asclepiads in South Africa

The KwaZulu-Natal region of South Africa hosts a large diversity of asclepiads (Apocynaceae: Asclepiadoideae), many of which are endemic to the area. The asclepiads are of particular interest because of their characteristically highly evolved floral morphology. During 3 months of fieldwork (November 2000 to January 2001) the flower visitors and pollinators to an assemblage of nine asclepiads at an upland grassland site were studied. These observations were augmented by laboratory studies of flower morphology (including scanning electron microscopy) and flower colour (using a spectrometer). Two of the specialized pollination systems that were documented are new to the asclepiads: fruit chafer pollination and pompilid wasp pollination. The latter is almost unique in the angiosperms. Taxa possessing these specific pollination systems cluster together in multidimensional phenotype space, suggesting that there has been convergent evolution in response to similar selection to attract identical pollinators. Pollination niche breadth varied from the very specialized species, with only one pollinator, to the more generalized, with up to ten pollinators. Pollinator sharing by the specialized taxa does not appear to have resulted in niche differentiation in terms of the temporal or spatial dimensions, or with regards to placement of pollinaria. Nestedness analysis of the data set showed that there was predictability and structure to the pattern of plant-pollinator interactions, with generalist insects visiting specialized plants and vice versa. The research has shown that there is still much to be learned about plant-pollinator interactions in areas of high plant diversity such as South Africa.     

Effects of maternal birth season on birth seasonality in the Canadian population during the seventeenth and eighteenth centuries

Birth records of the French-Canadian population for the period 1621-1765 were analyzed retrospectively to examine the effect of maternal birth season on the seasonal distribution of births. Preliminary examination indicated that there was a bimodal pattern in birth seasonality: a major peak in early spring, a trough in early summer, a minor peak in autumn, and a trough around December. Because this seasonality was strongly biased at the level of the first birth by the month of marriage, which was concentrated in November, the seasonality of nonfirst births (n = 32,926) was examined in relation to the four seasons of maternal birth. Mothers born in May-July showed a flatter monthly distribution of nonfirst births at a maternal age of 28 years or more. Analysis of marriage-first birth intervals indicated that mothers who married in August-October showed a lower percentage of immediate conception (intervals of 8-10 months), whereas those mothers born in May-July had a higher percentage of immediate conception. This difference in birth seasonality shown by mothers born in May-July is similar to results from early twentieth-century Japan. Some seasonal infertility factors could have affected the embryos at the earliest stage of pregnancy, modifying a part of the seasonal variation in birth rate.     

Weaning and the nature of early childhood interactions among bofi foragers in central Africa

Western scholarly literature suggests that (1) weaning is initiated by mothers; (2) weaning takes place within a few days once mothers decide to stop nursing; (3) mothers employ specific techniques to terminate nursing; (4) semi-solid foods (gruels and mashed foods) are essential when weaning; (5) weaning is traumatic for children (it leads to temper tantrums, aggression, etc.); (6) developmental stages in relationships with mothers and others can be demarcated by weaning; and (7) weaning is a process that involves mothers and children exclusively, with weaned children moving from close relationships with their mothers to strengthened relationships with other children. In many respects, these presumptions are consistent with contemporary Euroamerican practices: nursing stops early (usually before six months) relative to other cultures and takes place over a few days or weeks with the help of bottles and baby foods. Because bottles are available, weaning seldom appears traumatic, but it is seen as an important step in the establishment of independence between mothers and infants. By contrast, weaning from the bottle is often perceived as traumatic. Despite considerable academic and popular interest, weaning has seldom been studied systematically, especially in small-scale cultures. Qualitative and quantitative data from a study of Bofi foragers in Central Africa are used here to evaluate the cross-cultural applicability of the assumptions summarized above. Hillary N. Fouts is a Ph.D. student in cultural anthropology at Washington State University, Pullman. Her research interests include breastfeeding, weaning, childfeeding, parenting and alloparenting, cross-cultural child development, and life-history theory. Barry S. Hewlett is a professor of anthropology at Washington State University, Vancouver (Washington). His research interests include paternal involvement, cross-cultural child development, and dual transmission models. Michael E. Lamb is the Head of the Section on Social and Emotional Development at the National Institute of Child Health and Human Development. He has written extensively on parent-child relations in a variety of contexts and cultures.     

Declining tibial curvature parallels ∼6150 years of decreasing mobility in central european agriculturalists

Long bones respond to mechanical loading through functional adaptation in a suite of morphological characteristics that together ensure structural competence to in vivo loading. As such, adult bone structure is often used to make inferences about past behavior from archaeological remains. However, such biomechanical approaches often investigate change in just one aspect of morphology, typically cross‐sectional morphology or trabecular structure. The relationship between longitudinal bone curvature and mobility patterns is less well understood, particularly in the tibia, and it is unknown how tibial curvature and diaphyseal cross‐sectional geometry interact to meet the structural requirements of loading. This study examines tibial curvature and its relationship with diaphyseal cross‐sectional geometry (CSG) and body size in preindustrial Central Europeans spanning ～6150 years following the introduction of agriculture in the region. Anteroposterior centroid displacement from the proximo‐distal longitudinal axis was quantified at nine diaphyseal section locations (collectively representative of diaphyseal curvature) in 216 tibial three‐dimensional laser scans. Results documented significant and corresponding temporal declines in midshaft centroid displacement and CSG properties. Significant correlations were found between mid‐diaphyseal centroid displacement and all mobility‐related CSG properties, while the relationship weakened toward the diaphyseal ends. No significant relationship was found between centroid displacement and body size variables with the exception of the most distal section location. Results support a relationship between tibial curvature and cross‐sectional geometry among prehistoric Central European agricultural populations, and suggest that changes in mechanical loading may have influenced a suite of morphological features related to bone adaptation in the lower limb. Am J Phys Anthropol 157:260–275, 2015. © 2015 Wiley Periodicals, Inc.     

Extreme seasonality of births among nomadic Turkana pastoralists

Births to nomadic Turkana women in northwest Kenya follow one of the most highly seasonal distributions ever reported for a human population, with more than half of all births falling between March and June. Important aspects of the Turkana environment also fluctuate greatly over the course of the year. The rate of conception is apparently highest during the early dry season, when the food supply has been at its best for some time, and when women are attaining their peak nutritional status. The seasonal dynamics of Turkana fertility seem to be driven, ultimately, by fluctuations in rainfall; Fourier analysis indicates that changes in numbers of conceptions follow changes in rainfall with a lag of 3.6 months. The specific biological and behavioral changes in the human population through which the environmental changes may affect fertility are considered.