Endomycorrhizae of selected forest and shade tree species

The roots of Acer nigrum Michx.f., Fraxinus pennsylvanica Marsh., Platanus occidentalis L., Juglans nigra L. and Populus deltoides Bart., growing in lawn and woods, were examined for endomycorrhizae. Some of these species were part of one greenhouse and 2 microplot studies in which screening of endomycorrhizal fungi and fungal infestations of fumigated and nonfumigated soils were examined for growth enhancement potential. In a 1979 microplot study, F. americana L., J. nigra and P. x euramericana (Dode) Guinier \u27Eugenii\u27 were grown in fumigated or nonfumigated Nicollet-Webster loam to which the mycorrhizal fungi, Glomus etunicatus Becker and Gerdemann, Glomus fasciculatus Isolate 1 Gerdemann and Trappe, G. fasciculatus Isolate 2 or pot culture filtrate was added. No significant difference in tree growth was noted among the fungal infestants. White ash and black walnut were significantly smaller when only pot culture filtrate was added to the fumigated soil. In 1980, a microplot study was performed in which F. americana, F. pennsylvanica and P. occidentalis were planted in a less fertile sandy loam soil. Two mycorrhizal fungi (G. fasciculatus Isolate 1 and G. etunicatus) and pot culture filtrate were added to fumigated and nonfumigated soil. Fungal infestations took place in a greenhouse several weeks before outplanting (preplant) and at the time of outplanting (post-plant) seedlings into microplots. In all instances, fumigated soil infestations with either fungus resulted in significantly larger trees. In general, trees grown in soil infested with G. fasciculatus exhibited greater growth than G. etunicatus and fungal infestations of nonfumigated soil resulted in larger trees than when soil was not infested with mycorrhizal fungi. In 1981, a greenhouse study was performed in which one mycorrhizal fungus (G. etunicatus), 2 tree species (F. americana and P. occidentalis), 2 infestation times and 2 soil types (Nicollet-Webster loam and unknown sandy subsoil loam) from previous microplot studies were used. In both soil types and with both tree species, fungal infestations of fumigated soil resulted in significantly larger trees. Growth results of infestation time treatments were influenced by soil type with preplant infestations showing more growth stimulation in Nicollet-Webster loam while post-plant infestations were more effective in sandy loam. In general, fungal infestations of nonfumigated soil stimulated greater tree growth than when no fungal infestations were made

Hawaiian Picture‐Winged Drosophila Exhibit Adaptive Population Divergence along a Narrow Climatic Gradient on Hawaii Island

1. Anthropogenic influences on global processes and climatic conditions are increasingly affecting ecosystems throughout the world. 2. Hawaii Island’s native ecosystems are well studied and local long‐term climatic trends well documented, making these ecosystems ideal for evaluating how native taxa may respond to a warming environment. 3.This study documents adaptive divergence of populations of a Hawaiian picture‐winged Drosophila, D. sproati, that are separated by only 7 km and 365 m in elevation. 4.Representative laboratory populations show divergent behavioral and physiological responses to an experimental low‐intensity increase in ambient temperature during maturation. The significant interaction of source population by temperature treatment for behavioral and physiological measurements indicates differential adaptation to temperature for the two populations. 5.Significant differences in gene expression among males were mostly explained by the source population, with eleven genes in males also showing a significant interaction of source population by temperature treatment. 6.The combined behavior, physiology, and gene expression differences between populations illustrate the potential for local adaptation to occur over a fine spatial scale and exemplify nuanced response to climate change

Balancing complexity and pragmatism to drive agricultural adaptation

Agricultural systems are highly complex, due to both inherent characteristics such as emergent processes and transient dynamics, and often high levels of ignorance and uncertainty regarding the relevant system components and interactions. Agricultural systems are also often targeted for change to increase various performance measures or decrease undesired social and environmental externalities. As a result, this complexity is not merely a theoretical issue, but also a practical one, and effective adaptation of these systems requires balancing an appreciation for complexity with the pragmatic goals and constraints of these efforts. This dissertation presents three related interdisciplinary studies that wrestle with this problem in three distinct contexts and for three often-distinct audiences. The first chapter focuses on the field of development studies, where academics, government officials, and members of non-government organizations discuss ways to bring about societal change, often relating to rural livelihoods and non-industrialized nations heavily dependent on agricultural systems. This chapter assesses the discussions among these diverse participants and provides a resolution for semantic entanglements so that the complexity of the problems does not undermine the practical efforts for change. The second chapter is directed towards land managers working in Mediterranean landscapes as they seek to influence land use changes and alternative agricultural practices to increase soil carbon storage. This chapter summarizes the relevant scientific literature and discusses related issues to both inform immediate action and direct future research. The third chapter is a multi-year study in Senegal and The Gambia that uses a network of farmer field trials to test alternative seed and soil management practices within a socially and spatially heterogeneous system. Rather than supporting the current recommendations or identifying alternative “best practices,” these trials identified a range of adaptive options that were comparably effective but varied widely in cost, risks, and availability. This finding encourages farmers to actively explore their alternatives rather then simply adopt official recommendations, and for researchers to support this through more collaboration and less prescription in agricultural research

Balancing complexity and pragmatism to drive agricultural adaptation

Agricultural systems are highly complex, due to both inherent characteristics such as emergent processes and transient dynamics, and often high levels of ignorance and uncertainty regarding the relevant system components and interactions. Agricultural systems are also often targeted for change to increase various performance measures or decrease undesired social and environmental externalities. As a result, this complexity is not merely a theoretical issue, but also a practical one, and effective adaptation of these systems requires balancing an appreciation for complexity with the pragmatic goals and constraints of these efforts. This dissertation presents three related interdisciplinary studies that wrestle with this problem in three distinct contexts and for three often-distinct audiences. The first chapter focuses on the field of development studies, where academics, government officials, and members of non-government organizations discuss ways to bring about societal change, often relating to rural livelihoods and non-industrialized nations heavily dependent on agricultural systems. This chapter assesses the discussions among these diverse participants and provides a resolution for semantic entanglements so that the complexity of the problems does not undermine the practical efforts for change. The second chapter is directed towards land managers working in Mediterranean landscapes as they seek to influence land use changes and alternative agricultural practices to increase soil carbon storage. This chapter summarizes the relevant scientific literature and discusses related issues to both inform immediate action and direct future research. The third chapter is a multi-year study in Senegal and The Gambia that uses a network of farmer field trials to test alternative seed and soil management practices within a socially and spatially heterogeneous system. Rather than supporting the current recommendations or identifying alternative “best practices,” these trials identified a range of adaptive options that were comparably effective but varied widely in cost, risks, and availability. This finding encourages farmers to actively explore their alternatives rather then simply adopt official recommendations, and for researchers to support this through more collaboration and less prescription in agricultural research

Data from: Patterns and processes in complex landscapes: testing alternative biogeographic hypotheses through integrated analysis of phylogeography and community ecology in Hawai'i

The Island of Hawai‘i is a dynamic assemblage of five volcanoes with wet forest habitat currently existing in four distinct natural regions that vary in area, age, and geographic isolation. In this complex landscape, alternative assumptions of the relative importance of specific habitat characteristics on evolutionary and ecological processes predict strikingly different general patterns of local diversity and regional similarity. In this study we compare alternative a priori hypotheses against observed patterns within two distinct biological systems and scales: community composition of wet forest vascular plant species and mitochondrial and nuclear genes of Drosophila sproati, a wet forest restricted endemic. All observed patterns display strong and similar regional structuring, with the greatest local diversity found in Kohala and the windward side of Mauna Loa, the least in Ka‘ū and Kona, and a distinctive pattern of regional similarity that likely reflects the historical development of this habitat on the island. These observations largely corroborate a biogeographic model that integrates multiple lines of evidence, including climatic reconstruction, over those relying on single measures, such as current habitat configuration or substrate age. This method of testing alternative hypotheses across biological systems and scales is an innovative approach for understanding complex landscapes and should prove valuable in diverse biogeographic systems

Current hypotheses to explain genetic chaos under the sea

International audienceChaotic genetic patchiness (CGP) refers to surprising patterns of spatial and temporal genetic structure observed in some marine species at a scale where genetic variation should be efficiently homogenized by gene flow via larval dispersal. Here we review and discuss four mechanisms that could generate such unexpected patterns: selection, sweepstakes reproductive success, collective dispersal, and temporal shifts in local population dynamics. First, we review examples where genetic differentiation at specific loci was driven by diversifying selection, which was historically the first process invoked to explain CGP. Second, we turn to neutral demographic processes that may drive genome-wide effects, and whose effects on CGP may be enhanced when they act together. We discuss how sweepstakes reproductive success accelerates genetic drift and can thus generate genetic structure provided gene flow is not too strong. Collective dispersal is another mechanism whereby genetic structure can be maintained regardless of dispersal intensity, because it may prevent larval cohorts from becoming entirely mixed. Theoretical analyses of both the sweepstakes and the collective dispersal ideas are presented. Finally, we discuss an idea that has received less attention than the other ones just mentioned, namely temporal shifts in local population dynamics

D. sproati collection information

Detailed collection information for all D. sproati individuals sequenced in this study