Spatial scales of interactions among bacteria and between bacteria and the leaf surface.

Microbial life on plant leaves is characterized by a multitude of interactions between leaf colonizers and their environment. While the existence of many of these interactions has been confirmed, their spatial scale or reach often remained unknown. In this study, we applied spatial point pattern analysis to 244 distribution patterns of Pantoea agglomerans and Pseudomonas syringae on bean leaves. The results showed that bacterial colonizers of leaves interact with their environment at different spatial scales. Interactions among bacteria were often confined to small spatial scales up to 5-20 μm, compared to interactions between bacteria and leaf surface structures such as trichomes which could be observed in excess of 100 μm. Spatial point-pattern analyses prove a comprehensive tool to determine the different spatial scales of bacterial interactions on plant leaves and will help microbiologists to better understand the interplay between these interactions

Unlocking the microbiome communities of Banana (Musa spp.) under disease stressed (Fusarium wilt) and non-stressed conditions

We assessed the diversity, structure, and assemblage of bacterial and fungal communities associated with banana plants with and without Fusarium oxysporum f. sp. cubense (Foc) symptoms. A total of 117,814 bacterial and 17,317 fungal operational taxonomy units (OTUs) were identified in the rhizosphere, roots, and corm of the host plant. Results revealed that bacterial and fungal microbiota present in roots and corm primarily emanated from the rhizosphere. The composition of bacterial communities in the rhizosphere, roots, and corm were different, with more diversity observed in the rhizosphere and less in the corm. However, distinct sample types i.e., without (asymptomatic) and with (symptomatic) Fusarium symptoms were the major drivers of the fungal community composition. Considering the high relative abundance among samples, we identified core microbiomes with bacterial and fungal OTUs classified into 20 families and colonizing distinct plant components of banana. Our core microbiome assigned 129 bacterial and 37 fungal genera to known taxa

Former land use affects the nitrogen and phosphorus concentrations and biomass of forest herbs

The colonization rates of understorey plants into forests growing on former agricultural land differ remarkably among species. Different dispersal and recruitment largely account for the contrasting colonization rates, but different effects of the soil legacies of former agricultural land use on plant performance may also play a role. Seven herbaceous forest species were sampled in paired post-agricultural and ancient forest stands to study whether land-use history has an effect on the aboveground nutrient concentrations (N, P and N:P ratios) and biomass of forest herbs and, if so, whether slow and fast colonizing species respond differently. Results showed that P concentrations were significantly affected by former land use with higher concentrations in the post-agricultural stands. N concentrations were unaffected and N:P ratios were significantly higher in the ancient stands. Nutrient concentrations varied considerably among species, but the variation was unrelated to their colonization capacity. Six out of the seven species had higher biomass in the post-agricultural stands relative to the ancient stands, and the degree to which the species increased biomass was positively related to their colonization capacity, i.e., the fast colonizing species showed the strongest increase. Such differential responses to past land use may contribute to the contrasting colonization capacity of forest plants. Land-use history thus affected both the nutrient concentrations and biomass of forest herbs, and only the biomass response was related to colonization capacity

Individualistic responses of forest herb traits to environmental change

Intraspecific trait variation (ITV; i.e. variability in mean and/or distribution of plant attribute values within species) can occur in response to multiple drivers. Environmental change and land-use legacies could directly alter trait values within species but could also affect them indirectly through changes in vegetation cover. Increasing variability in environmental conditions could lead to more ITV, but responses might differ among species. Disentangling these drivers on ITV is necessary to accurately predict plant community responses to global change. We planted herb communities into forest soils with and without a recent history of agriculture. Soils were collected across temperate European regions, while the 15 selected herb species had different colonizing abilities and affinities to forest habitat. These mesocosms (384) were exposed to two-level full-factorial treatments of warming, nitrogen addition and illumination. We measured plant height and specific leaf area (SLA). For the majority of species, mean plant height increased as vegetation cover increased in response to light addition, warming and agricultural legacy. The coefficient of variation (CV) for height was larger in fast-colonizing species. Mean SLA for vernal species increased with warming, while light addition generally decreased mean SLA for shade-tolerant species. Interactions between treatments were not important predictors. Environmental change treatments influenced ITV, either via increasing vegetation cover or by affecting trait values directly. Species' ITV was individualistic, i.e. species responded to different single resource and condition manipulations that benefited their growth in the short term. These individual responses could be important for altered community organization after a prolonged period

Law, Endowment, and Finance

This paper assesses two theories regarding the historical determinants of international differences in financial development. The law and finance theory holds that legal traditions differ in terms of the priority they attach to protecting the rights of private investors vis-a-vis the State and this has important implications for financial development. The endowment theory argues that the disease and geographical environment influence the formation of long-lasting institutions that influence financial development. Using a sample of former colonies, we explore whether the legal system brought by colonizers and/or the initial disease/geographical endowments encountered by colonizers explain financial development today. The empirical results indicate that both the legal systems brought by colonizers and the initial endowments in the colonies are important determinants of stock market development and private property rights protection. However, initial endowments are more robustly associated with financial intermediary development than legal origin and initial endowments explain more of the cross-country variation in financial intermediary and stock market development than legal origin.

Oppression, Sexual Violence and Their Effects on Native American Women

This paper is a response to the chapter “Sexual Violence as a Tool of Genocide” in Andrea Smith’s book Conquest: Sexual Violence and American Indian Genocide. Smith argues that U.S. colonial culture strategically uses sexual violence against Native women as a weapon to ensure the oppression and marginalization of Native people. This paper details and examines Smith’s argument and also considers the influence of Native Women on White feminism. Despite the great influence Native culture has on White feminism, White Feminists’ perceptions of Native women is often skewed and biased, as a result of the systematic oppression that is utilized by U.S. colonizers on Native Americans

Political Globalization and Civil War in Former British Colonies

The purpose of this paper to determine why civil war onset reduces political globalization in former British colonies. I set out by testing the relationship between being a former British colony and civil war presence, demonstrating a positive, though not statistically significant, relationship. I also examine the history of British colonialism. Through setting up specific system of indirect rule, British colonizers created conditions that contributed to intra-state conflict. Furthermore, through constructing a unique institutional system and maintaining ties to its former colonies, the British have created an atmosphere conducive to international political engagement after the onset of civil war. Yet, when the relationship between civil war presence and political globalization is tested, it is demonstrated that civil war presence actually increases political globalization. This relationship is further explained by controlling for the post-Cold War period, which gives civil war presence and British colonialism further significance in determining political globalization