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Geomorphic evidence of past glaciation, such as U-shaped valleys, aretes, glacial lakes, and moraines, is preserved in the highland surrounding Cerro Chirripó in the Cordillera de Talamanca, Costa Rica. Previous work to establish a glacial chronology has focused on relative age dating of moraines and on radiocarbon dating of basal lake sediments to infer the timing of deglaciation. We used cosmogenic 36Cl surface exposure dating to constrain the ages of moraines within two formerly glaciated valleys, the Morrenas and Talari valleys. Forty-nine boulder samples were processed and measured from four moraine complexes in the Morrenas Valley and two moraine complexes in the Talari Valley. The exposure ages of these samples indicate a major glacial event occurred in this area from ~25 to 23 ka, broadly synchronous with the global last glacial maximum. Our results also indicate periods of glacial retreats and standstills from the deglacial period to the Early Holocene (~16–10 ka) before the complete disappearance of glaciers in this highland. These findings provide important insights into the glacial chronology and paleoclimate of tropical America.
Moringa oleifera seeds are currently being used as a livestock feed across tropical regions of the world due to its availability and palatability. However, limited knowledge exists on the effects of the raw seeds on ruminant metabolism. As such, the rumen stimulation technique was used to evaluate the effects of substituting increasing concentrations of ground Moringa seeds (0, 100, 200 and 400 g/kg concentrate dry matter (DM)) in the diet on rumen fermentation and methane production. Two identical, Rusitec apparatuses, each with eight fermenters were used with the first 8 days used for adaptation and days 9 to 16 used for measurements. Fermenters were fed a total mixed ration with Urochloa brizantha as the forage. Disappearance of DM, CP, NDF and ADF linearly decreased (P<0.01) with increasing concentrations of Moringa seeds in the diet. Total volatile fatty acid production and the acetate to propionate ratio were also linearly decreased (P<0.01). However, only the 400 g/kg (concentrate DM basis) treatment differed (P<0.01) from the control. Methane production (%), total microbial incorporation of 15N and total production of microbial N linearly decreased (P<0.01) as the inclusion of Moringa seeds increased. Though the inclusion of Moringa seeds in the diet decreased CH4 production, this arose from an unfavourable decrease in diet digestibility and rumen fermentation parameters.
The objective of the current paper is to review research findings in organic poultry or free-range systems and its perspectives for the tropical Latin America region, including genotypes adapted to production systems in semi-captivity, according to the specific characteristics of each country. Different feeding systems schemes are analysed as well as low cost feed resources that could be used. Most of the studies reviewed for free-range systems propose feeding schemes based on two stages, which are starter (1-5 weeks old) and finisher (5-15 weeks old) diets. Carcass yield and quality are covered; however there is still debate due to the great variety of results observed, depending on age, genotype, feed ingredients and characteristics of the system used. It has been suggested that carcass characteristics improved due to increased activity, which enhances bird comfort and welfare. The findings of this review indicated that producing meat in these systems is feasible in tropical countries. However, it is necessary to establish adequate conditions for every country to ensure viability, on the basis of meat quality and economic variables.
The objective of this article is to reappraise both the accuracy of the official export statistics and the narrative of Brazilian export growth during the period immediately following independence. We undertake an accuracy test of the official values of Brazilian export statistics and find evidence of considerable under-valuation. Once corrected, during the post-independence decades (1821–50) Brazil's current exports represented a larger share of its economy and its constant growth is found to be more dynamic than any other period of the nineteenth century. We posit that this dynamism was related to an exogenous institutional shock in the form of British West Indies slave emancipation that afforded Brazil a competitive advantage.
The past decade has witnessed a significant resurgence of academic and developmental interest in the tropical zones of the world. The task of translating big picture academic institutional vision into practical research can, however, be quite daunting for those at the coalface of implementing such visions, not least because there is no guidance as to where exactly to start. Using James Cook University's tropical vision as a case, this commentary proposes a set of guidelines to assist research teams and organisations to translate the global tropical vision, especially the social and psychological dimensions, into practical research questions.
In the tropical regions of southern Asia, Southeast Asia and the southern Maya lowlands, the management of water was crucial to the maintenance of political power and the distribution of communities in the landscape. Between the ninth and sixteenth centuries AD, however, this diverse range of medieval socio-political systems were destabilised by climatic change. Comparative study reveals that despite their diversity, the outcome for each society was the same: the breakdown of low-density urban centres in favour of compact communities in peripheral regions. The result of this, an ‘urban diaspora’, highlights the relationship between the control of water and power, but also reveals that the collapse of urban centres was a political phenomenon with society-wide repercussions.
Methane (CH4) emissions associated with beef production systems in northern Australia are yet to be quantified. Methodologies are available to measure emissions, but application in extensive grazing environments is challenging. A micrometeorological methodology for estimating herd-scale emissions using an indirect open-path spectroscopic technique and an atmospheric dispersion model is described. The methodology was deployed on five cattle properties across Queensland and Northern Territory, with measurements conducted during two occasions at one site. On each deployment, data were collected every 10 min for up to 7 h a day over 4 to 16 days. To increase the atmospheric concentration of CH4 to measurable levels, cattle were confined to a known area around water points from ~0800 to 1600 h, during which time measurements of wind statistics and line-averaged CH4 concentration were taken. Filtering to remove erroneous data accounted for 35% of total observations. For five of the six deployments CH4 emissions were within the expected range of 0.4 to 0.6 g/kg BW. At one site, emissions were ~2 times expected values. There was small but consistent variation with time of day, although for some deployments measurements taken early in the day tended to be higher than at the other times. There was a weak linear relationship (R2=0.47) between animal BW and CH4 emission per kg BW. Where it was possible to compare emissions in the early and late dry season at one site, it was speculated that higher emissions at the late dry season may have been attributed to poorer diet quality. It is concluded that the micrometeorological methodology using open-path lasers can be successfully deployed in extensive grazing conditions to directly measure CH4 emissions from cattle at a herd scale.
Annual rings are not commonly produced in tropical trees because they grow in a relatively aseasonal environment. However, in the subalpine zones of Hawaiʻi's highest volcanoes, there is often strong seasonal variability in temperature and rainfall. Using classical dendrochronological methods, annual growth rings were shown to occur in Sophora chrysophylla, a native tree species on Maunakea, Hawaiʻi. Chronologies were established from nearby non-native, live conifer trees and these were used to verify the dates from a total of 52 series from 22 S. chrysophylla trees, establishing an 86-y chronology (1926–2011). Ring-width patterns were significantly correlated with monthly rainfall from August of the previous year. This study is the first in the eastern tropical Pacific region to demonstrate annual growth rings in trees.
This paper provides landmarks for the study of the historical development and current expansion of academic psychology and clinical psychology education in Australia and three countries of the Malay Archipelago (Indonesia, Malaysia, Singapore). It reviews literature on the history of clinical psychology, and information from universities and psychological associations, and includes an overview of the current providers and forms of psychology education programmes and their curricula. A critical analysis informed by cultural anthropology indicates that psychology has only to a small extent been adjusted to different cultural contexts, while ‘western’ models of the discipline remain dominant. The neglect of attention to culture in psychology and clinical psychology raises important questions about the future of the discipline in the tropical regions of Australia and the Malay Archipelago.
Globally, pressure on concentrate feed resources is increasing, especially in the tropics where many countries are net importers of food. Forage plants are a possible alternative, but their use as feed ingredients for pigs raises several issues related to their higher fibre and plant secondary metabolites contents as well as their lower nutritive value. In this paper, the nutritive value of several forage species and the parameters that influence this nutritive value in relationship to the plant family, the physiological stage, the plant part and the preservation method (fresh, hay and silage) are reviewed. The influence of the breed and the physiological status of the animal on animal voluntary intake of fibre-rich ingredients, digestibility as related to gastrointestinal volume and transit time and growth performances are also discussed. The final section highlights the advantages and drawbacks of forage plants in pig diets and stresses the need for proper economic evaluation to conclude on the benefits of the use of forage plants in pig feed.
Patterns of social organization and mating systems have been shown to be functions of ecological factors such as resource allocation and breeding density. In some species, particularly birds, social organization and genetic mating systems differ with molecular studies providing evidence of extra-pair young frequently occurring within broods of socially monogamous species. Here we examine the social and genetic mating system of an ecologically little-known forest raptor endemic to the island of Hispaniola in the Caribbean. From 2005–2009, our field observations of over 60 breeding pairs verified a social mating system of monogamy for the species. During the same time period, we collected blood samples (n = 146 birds, 48 nests) and used microsatellite profiles from 10 loci to estimate genetic relatedness among nestlings in a brood and assign putative fathers. We found no evidence of extra-pair paternity in 41 broods. We had one instance where a social male was not assigned as the putative father, however, the confidence level of this assignment was not significant since the genotypes of the social and assigned males were very similar. Our results support our hypothesis that genetic monogamy would be exhibited by Ridgway's hawk, an island-endemic tropical raptor.
The conventional method of feeding broilers, using high density diets has been
found to be associated with increases in fatness and a number of metabolic
disorders. The adverse effect of high density diets on the performance of
broilers was found to be more pronounced under a tropical environment. Allowing
broilers free access to feed using low density diets (quantitative nutrition)
has been suggested as a strategy to improve the performance of the broilers
within the prevailing environmental conditions in the tropics. A specific
approach had been evaluated as suitable for reducing the available metabolisable
energy (AME) intakes of the broiler and increasing feed intake. This involves
diet dilution with high fibre feedstuffs to reduce the available metabolisable
energy (AME) value of the diet.
This paper reviews experiences with cross-breeding for milk production in the tropics. Data were compiled from 23 different studies evaluating the performance of different grades of cross-bred animals as well as local breeds. Relative performance of indigenous breeds compared with different grades of cross-breeds was calculated for three climatic zones. Traits considered were milk yield per lactation, age at first calving, services per conception, lifetime milk yield and total number of lactations completed. At 50 percent Bos taurus blood, lactation milk yields were 2.6, 2.4 and 2.2 times higher than those of local cattle in the highland, tropical wet and dry, and semi-arid climatic zones, respectively; lactation lengths increased by 1.2, 1.2 and 1.9 months in the above-mentioned climatic zones, respectively; there was a reduction in calving interval by 0.8 times and in age at first calving by 0.9 times. Similarly, cross-breds with 50 percent B. taurus genes had 1.8 times higher lifetime milk yields and a 1.2 times higher number of total lactations. Although cross-breeding faces a number of challenges such as better infrastructure, higher demand for health care, there are many advantages of using it. These are higher production per animal, higher income for the families and provision of high-value food. It is therefore likely to continue to be an important livestock improvement tool in the tropics in the future, where farmers can provide sufficient management for maintaining animals with higher input requirements and access to the milk market can be secured.
The aim of the present investigation was to determine whether temporal variation in environmental factors such as rainfall or temperature influence long-term fluctuations in the prevalence and mean abundance of the nematode Mexiconema cichlasomae in the cichlid fish Cichlasoma uropthalmus and its crustacean intermediate host, Argulus yucatanus. The study was undertaken in a tropical coastal lagoon in the Yucatan Peninsula (south-eastern Mexico) over an 8-year period. Variations in temperature, rainfall and monthly infection levels for both hosts were analysed using time series and cross-correlations to detect possible recurrent patterns. Infections of M. cichlasomae in A. yucatanus showed annual peaks, while in C. urophthalmus peaks were bi-annual. The latter appear to be related to the accumulation of several generations of this nematode in C. urophthalmus. Rainfall and temperature appear to be key environmental factors in influencing temporal variation in the infection of M. cichlasomae over periods longer than a year together with the accumulation of larval stages throughout time.
Mangroves generally grow in nutrient-poor environments and maintain high levels of productivity through unique adaptations for nutrient conservation (Reef et al. 2010). One such adaptation in mangroves is highly efficient resorption of limiting nutrients from senescing leaves prior to abscission (Feller et al. 2003). Thus processes that lead to loss of foliage prior to senescence and nutrient resorption (e.g. storms and herbivory) can be detrimental to tree growth and productivity (Bryant et al. 1983, May & Killingbeck 1992). Furthermore, decomposition of fallen leaves by soil microbial communities (Alongi 1994, Holguin et al. 2001) and crabs (Nagelkerken et al. 2008) is another important process contributing to the recycling of nutrients that are in short supply. Therefore, processes that lead to a substantial reduction in litterfall can have a strong negative effect on nutrient cycling and forest productivity. Mangroves have long been recognized as an important source of organic carbon (both particulate and dissolved) for the surrounding tropical coastal ecosystems (Bouillon et al. 2008, Kristensen et al. 2008). Thus, processes affecting litterfall in mangroves can affect the surrounding marine food webs.
This paper covers the domestication and distribution of chickens in different parts of the world and describes the global data bases containing information on chicken genetic resources. The review shows the dispersion of chickens from the putative centres of domestication to different parts of the world, although introduction of the domesticated chicken into Africa is poorly documented. Currently, there are three globally accessible data bases containing information on chickens; however none of these provide a comprehensive system for systematically classifying domestic chickens in developing countries in terms of their present-day uses, potential for the future and distribution within and across countries. Such a system should be developed to include indigenous chicken genetic resources at the same level of detail as for other farm animals. The data management systems should incorporate all available information at the molecular level. Such information is important not only for discerning the existing diversity but also for making decisions on conservation priorities. Addressing the gaps in information on indigenous chicken genetic resources should primarily be the focus on the Domestic Animal Genetic Resources Information System (DAGRIS). DAGRIS, as a virtual library of indigenous animal genetic resources in developing countries, could play a leading role in delivering systematic information on the diversity, distribution and classification of domestic chicken in the tropics.
Neotropical fruit-eating bats play a crucial role in forest regeneration by dispersing seeds of pioneer plants from forests into deforested areas. However, later in succession bats may carry seeds in both directions. We used an isotopic approach to reveal the direction of seed transfer mediated by three co-existing short-tailed fruit bats (Carollia castanea, C. sowelli and C. perspicillata) between a forest and an adjacent mid-successional site (>15 y since deforestation); two habitats where individuals of the genus Piper differed in stable carbon isotope ratios by ~2.5‰. In a feeding experiment, we confirmed that δ13C of seeds is not altered by digestive processes. We then collected seeds defecated by bats of the genus Carollia and found that δ13C of these seeds is higher than those of Piper individuals growing in the forest, irrespective of whether bats were captured in or outside the forest. We conclude that bats of the genus Carollia were more likely to carry seeds from successional areas into the forest than in the opposite direction.
Studies on Sahiwal cattle genetic resources in the tropics have mainly concentrated on evaluating their performance levels, with only a few published reports describing the breed characteristics. The aim of this study was to critically examine the existing breeding and conservation programmes for Sahiwal cattle in the tropics, focusing on Pakistan, India and Kenya as the core regions of development. The study was based on review of both published and unpublished literature highlighting shortcomings and strengths in the existing strategies, and opportunities for improvement and conservation. The Sahiwal breed is utilized for dairy and beef production under smallholder dairy, pastoral extensive and ranching production systems, both as pure-breds or cross-breds. The necessary components to strengthen the breeding programmes such as performance recording, genetic evaluation and artificial insemination (AI) facilities exist to differing degrees. Breeding and conservation efforts benefit from the technical and financial support from government research institutions which also provide incentives to enhance participation in the programmes. However, breeding goals are rather informal and only defined in terms of high-production levels with functional traits largely ignored. There is need for participatory identification of breeding and production goals, and structured cooperation of the small herds, so as to accommodate the specific contributions of the breed in future breeding and conservation programmes.
Corallita (Antigonon leptopus) is a perennial vine, lauded as an ornamental for its vigorous growth, and plentiful (usually) pink flowers, and even its ability to smother unsightly landscapes. In the United States it thrives in horticultural zones 8 to 10, and also is successfully grown worldwide in tropical climates. When corallita is neglected, it can grow quickly over other vegetation, spreading beyond its area of introduction. Once established, it is difficult to eradicate because it produces many tuberous roots that can propagate vegetatively. Its fruits are buoyant, allowing for successful seed dispersal in water. The islands of Guam (South Pacific Ocean) and St. Eustatius (Caribbean Sea) represent two regions where corallita has become so pervasive that it threatens local diversity. In Florida, already it is classified as a Category II invasive. Our report reviews the literature and past studies of corallita, in addition to adding new taxonomic and distribution information from herbarium specimens to clarify the identity and geographic range. It is recommended that introductions of this plant by the horticultural industry in both tropical and temperate regions be closely monitored to prevent spread. On tropical island nations, we advise against any new introductions.
The rearing of indigenous chickens is an integral part of the smallholder farming system in the tropics, where they are kept by the rural poor to fulfil multiple functions. Their special adaptation to environmental stresses and poor husbandry practices has made them the choice of breed for smallholder production systems. However, little effort has been made to characterise the indigenous chicken and their production environment, despite the increase in emerging works recently. This paper aims at reviewing the current state of phenotypic characterisation work on indigenous chickens in the tropics. By and large, studies conducted on indigenous chickens to evaluate their performance usually ignore their unique physiological and behavioural characteristics and their socio-cultural values. Moreover, unfair comparisons with exotic chickens are not uncommon, especially for yield related traits. Due to their high genetic diversity, there is also remarkable variation in the performance of indigenous chickens within and among breeds. This variation is an important genetic attribute of the indigenous chicken, whereby selection can act to improve their performance. It is recommended that characterisation works use a common set of descriptions developed by international institutions with proven poultry experience so results across countries and regions can be accurately compared.