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Agricultural Populations (agricultural + population)

Distribution by Scientific Domains

Life Sciences	75%

Selected Abstracts

Notes on the distribution and abundance of the caecilian Boulengerula uluguruensis (Amphibia: Gymnophiona: Caeciliidae) in the Uluguru Mountains, Tanzania

AFRICAN JOURNAL OF ECOLOGY, Issue 1 2006
G. John Measey
Abstract Boulengerula uluguruensis is a terrestrial caeciliid caecilian described from the Uluguru Mountains of Tanzania. We investigated the relative abundance of B. uluguruensis in agricultural and forested habitats at the beginning of the rainy season. This caecilian was found over a wide altitudinal range (450,1175 m a.s.l.), and in many land cover types (including natural forest, plantation forest and small scale agriculture), and different soil textures (including very compact soil). Based on quantitative and semi-quantitative surveys, B. uluguruensis is more abundant than any other subterranean lower vertebrate in this area, with densities up to 0.4 individuals m,2 in some agricultural plots. The hypothesis proposed, that B. uluguruensis is more abundant in agriculture than their native forest, could not be conclusively tested during this brief visit, although the data that were collected do not indicate to the contrary. Likewise, the size of animals from forest and agricultural populations could not be objectively compared. Résumé Boulengerulauluguruensis est un caecilian caeciliid terrestre décrit des montagnes d'Ulguru en Tanzanie. Nous avons relevé l'abondance relative du B. uluguruensis dans des habitats agricoles et boisés au début de la saison des pluies. Ce caecilian fut trouvé dans une grande envergure d'altitude (450 to 1175 m asl), et dans plusieurs genres de couverture des terres (y compris forêt naturelle, plantation, et agriculture à petite échelle), et differenté textures du sol (y compris sol de forte densité). Basé sur des enquêtes quantitatives et semi- quantitatives, le B. uluguruensis fut plus abondant que toute autre vertébré souterrain dans cette région, avec une densité jusqu'à 0,4 individus par m2 dans quelques terrains agricoles. Notre visite fut trop brève pour que nous puissions vérifier l'hypothèse avancée que B.uluguruensis est plus abondant dans l'agriculture que dans la forêt native dont ils sont indigènes, bien que les données accumulées ne montrent pas le contraire. De la même manière, la taille des animaux provenant des populations forestières et agricoles n'a pas pu être comparé objectivement. [source]

Interspecific hybridization in plant-associated fungi and oomycetes: a review

MOLECULAR ECOLOGY, Issue 11 2003
C. L. Schardl
Abstract Fungi (kingdom Mycota) and oomycetes (kingdom Stramenopila, phylum Oomycota) are crucially important in the nutrient cycles of the world. Their interactions with plants sometimes benefit and sometimes act to the detriment of humans. Many fungi establish ecologically vital mutualisms, such as in mycorrhizal fungi that enhance nutrient acquisition, and endophytes that combat insects and other herbivores. Other fungi and many oomycetes are plant pathogens that devastate natural and agricultural populations of plant species. Studies of fungal and oomycete evolution were extraordinarily difficult until the advent of molecular phylogenetics. Over the past decade, researchers applying these new tools to fungi and oomycetes have made astounding new discoveries, among which is the potential for interspecific hybridization. Consequences of hybridization among pathogens include adaptation to new niches such as new host species, and increased or decreased virulence. Hybrid mutualists may also be better adapted to new hosts and can provide greater or more diverse benefits to host plants. [source]

Docosahexaenoic acid biosynthesis and dietary contingency: Encephalization without aquatic constraint

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2007
Bryce A. Carlson
Reconstructing evolutionary processes in the distant past is necessarily an inductive endeavor, typically appealing to numerous considerations thought to be relevant to the veracity of a particular conclusion. In this respect, it is essential that the considerations invoked to support hypotheses are in turn well-established truths. It is with these concerns that we sought to examine the nutritional, physiological, and archeological premises underlying the perspective that access to an aquatic diet rich in docosahexaenoic acid (DHA, 22:6n -3) was critical to human brain evolution (Carlson and Kingston [2007]: Am J Hum Biol 19:132,141). In our report investigating links between omega-3 (n -3) fatty acids and hominin encephalization, we concluded that the regular consumption of aquatic resources rich in preformed DHA may not have been essential given a varied diet of wild terrestrial foods (Carlson and Kingston [2007]). This assessment was based primarily on evidence of potential physiological adaptations in modern humans to ensure sufficient availability of DHA during critical periods of brain growth. While modern human physiology provides critical information regarding DHA as a constraint in evolving a large brain, it is also important to consistently contextualize interpretations within a framework of eclectic foraging diets rather than nutritionally limited modern agricultural populations or even modern foragers. We contend that current interpretations of Pleistocene hominin nutritional ecology do not uniquely support a shore-based foraging niche as claimed by Cunnane et al. ([2007]: Am J Hum Biol, 19:578,581). Specific issues raised in response to our article by Cunnane et al. and Joordens et al. ([2007]: Am J Hum Biol, 19:582,584) are addressed here. Am. J. Hum. Biol. 19:585,588, 2007. © 2007 Wiley-Liss, Inc. [source]

Environmental change and adaptation in degraded agro-ecosystems: the case of highland Madagascar

AREA, Issue 3 2010
Jon Unruh
While the view that the poorer agricultural populations in developing countries will be at the forefront of negative consequences due to environmental change is widely accepted, this perspective must become considerably more nuanced in order to recognise and take advantage of emerging opportunities for realistic adaptation. This paper presents a case from Madagascar that suggests adaptation opportunities involve more than looking for alternatives to what are presently perceived to be negative socio-ecologic processes. In Madagascar the severe erosion occurring on the deforested central plateau actually appears to create, over time, opportunities for increased food security and environmental management compared with uneroded portions of the same landscape. The paper proposes that while concern and action are needed to attend to the problems that the poor of the developing world will face due to impacts from environmental change, the repercussions of such change on agricultural systems also need to be looked at in ways that involve recognising the local and aggregate potential opportunities that they may present in certain systems, in order to realise the prospects for adaptation. [source]