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Using publicly available data on land use and transportation corridors we calculated the human footprint index for the whole of Mexico to identify large-scale spatial patterns in the anthropogenic transformation of the land surface. We developed a map of the human footprint for the whole country and identified the ecological regions that have most transformed by human action. Additionally, we analyzed the extent to which (a) physical geography, expressed spatially in the form of biomes and ecoregions, compared to (b) historical geography, expressed as the spatial distribution of past human settlements, have driven the patterns of human modification of the land. Overall Mexico still has 56% of its land surface with low impact from human activities, but these areas are not evenly distributed. The lowest values are on the arid north and northwest, and the tropical southeast, while the highest values run along the coast of the Gulf of Mexico and from there inland along an east-to-west corridor that follows the Mexican transversal volcanic ranges and the associated upland plateau. The distribution of low- and high footprint areas within ecoregions forms a complex mosaic: the generally well-conserved Mexican deserts have some highly transformed agro-industrial areas, while many well-conserved, low footprint areas still persist in the highly-transformed ecoregions of central Mexico. We conclude that the spatial spread of the human footprint in Mexico is both the result of the limitations imposed by physical geography to human development at the biome level, and, within different biomes, of a complex history of past civilizations and technologies, including the 20th Century demographic explosion but also the spatial pattern of ancient settlements that were occupied by the Spanish Colony.

Abstract:The objective of this research is to assess the main social and economic effects on local fishermen in El Golfo de Santa Clara, as a result of the severe fishing restrictions enforced to protect the marine mammal "vaquita" (Phocoena sinus). Sustainable development includes natural resources conservation and the improvement of the social and economic conditions of local inhabitants. In Mexico, the vaquita is in imminent danger of extinction. It is a marine cetacean endemic to the Upper Gulf of California. Conservation measures to save this species, such as gear-switching and transformation subsidies from fishing activities to tourist services, have caused severe social and economic impacts on the local fishermen of this region. Presently, it is estimated that there are only 30 vaquita individuals left in the wild, and none are in captivity. In this study, we conduct surveys of the human local population involved in the incidental bycatch fishing of the vaquita, and also use secondary sources to come up with recommendations, based on taking into account stakeholder needs. For this fishing community the economic and social problems have worsened because currently there are limited economic activity options in the area for the human population, and the vaquita population continues to decline. Recommendations are offered to contribute to the ecological sustainability of this species, and for economic and social sustainability of local fishermen.

The complex geological and ecological processes that have generated high levels of biodiversity and endemism in the Baja California Peninsula have been the subject of intensive study. However, relatively little is known about phylogeography of the iconic endemic palm species of this region. We therefore analyzed a total of 2,294 bp of chloroplast and 738 bp of nuclear sequence data in 169 samples of five native palm species from Baja California, Sonora and Guadalupe Island. We found that Washingtonia and Brahea palms had low levels of genetic diversity and were highly structured, with the majority of species and major geographic regions being characterized by distinct haplotypes. We also found strong support for currently recognized species in Washingtonia, but our results were less clear cut for Brahea due to haplotype sharing. Furthermore, patterns of population structure were broadly consistent with historical vicariant events such as the inundation of the Isthmus of La Paz, the formation of the Sea of Cortez, and the more recent colonization and isolation of Guadalupe Island's palms. Our findings contribute toward a growing appreciation of the complexity of plant responses to past geological changes and also provide valuable baseline genetic data on relict American palm species.

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