Genetic structure at range edge: Low diversity and high inbreeding in Southeast Asian mangrove (Avicennia marina) populations

Understanding the genetic composition and mating systems of edge populations provides important insights into the environmental and demographic factors shaping species’ distribution ranges. We analysed samples of the mangrove Avicennia marina from Vietnam, northern Philippines and Australia, with microsatellite markers. We compared genetic diversity and structure in edge (Southeast Asia, and Southern Australia) and core (North and Eastern Australia) populations, and also compared our results with previously published data from core and southern edge populations. Comparisons highlighted significantly reduced gene diversity and higher genetic structure in both margins compared to core populations, which can be attributed to very low effective population size, pollinator scarcity and high environmental pressure at distribution margins. The estimated level of inbreeding was significantly higher in northeastern populations compared to core and southern populations. This suggests that despite the high genetic load usually associated with inbreeding, inbreeding or even selfing may be advantageous in margin habitats due to the possible advantages of reproductive assurance, or local adaptation. The very high level of genetic structure and inbreeding show that populations of A. marina are functioning as independent evolutionary units more than as components of a metapopulation system connected by gene flow. The combinations of those characteristics make these peripheral populations likely to develop local adaptations and therefore to be of particular interest for conservation strategies as well as for adaptation to possible future environmental changes.

Hydrodynamic and sediment fluxes through the inlets of the Ria Formosa

Tese de dout., Ciências do Mar, da Terra e do Ambiente (Ciências do Mar-Oceanografia Física), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2011

Reinventing America on the battlefields of Spain or following the party line: conflicting perceptions of the Spanish Civil War in the present and in the past

Isolationism and neutrality are two of the recurrent themes in the study of the history of the U.S. foreign policy in the interwar years. The trauma of the Great War, which had swept away 130.000 U.S. lives and had cost $30 billion, had led public opinion to strongly oppose any involvement with European affairs. Besides, the urgent need for economic recovery during the dismal years of the Great Depression did not leave Roosevelt much room for manoeuvre to influence international events. His positions regarding the intentions of the Fascist states remained, at best, ambivalent. These facts notwithstanding, about 2800 U.S. citizens crossed the Atlantic and rushed in to help democratic Spain, which was on the verge of becoming one more hostage in the hands of the Fascism. They joined the other British, Irish and Canadian volunteers and formed the XV International Brigade. 900 Americans never returned home. This alone should challenge the commonly held assumption that the American people were indifferent to the rise of the Fascist threat in Europe. But it also begs other questions. Considering the prevailing isolationist mood, what really motivated them? With what discursive elements did these men construct their anti Fascist representations? How far did their understanding of the Spanish democracy correspond to their own American democratic ideal? In what way did their war experience across the Atlantic mould their perception of U.S. politics (both domestic and foreign)? How far did the Spanish Civil War constitute one first step towards the realization that the U.S. might actually be drawn into another international conflict of unpredictable consequences? Last but not the least, what ideological, political and cultural complicity existed between the men from the English-speaking battalions? In order to unearth some of the answers, I intend to examine their letters and see how these men recorded the historical events in which they took part. Their correspondence emerged from the desire to prove their commitment to a common cause and spoke of a common war experience, but each letter, in its uniqueness, ends up mirroring not only the social and political background of each individual fighter, but also his own particular perspective of the war, of world politics and of the Spanish people. We shall see how these letters differ and converge and how these particular accounts weave, as in an epistolary novel, a larger-than-life narrative of outrage and solidarity, despair and hope.