Evolutionary Trends in Columnar Cacti under Domestication in South-Central Mexico

AbstractThis article challenges the widely held view that, during the Mexican Revolution, the Zapatista villages governed themselves with complete autonomy from the state and according to the pueblos’ customary justice. It shows how Zapatistas in the multi-state region of south-central Mexico dealt with quarrels over small and medium-sized properties, the restitution of usurped pueblo lands and water resources, as well as village boundary disputes. They did so by blending nineteenth-century judicial procedures and civil law, limited but radical reforms to the existing judicial system and new forms of land and water management – all of which strengthened state authority.

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Fossil legume fruits from tertiary strata of Puebla, Mexico

Canadian Journal of Botany ◽

10.1139/b94-129 ◽

1994 ◽

Vol 72 (7) ◽

pp. 1027-1038 ◽

Cited By ~ 26

Author(s):

Susana Magallón-Puebla ◽

Sergio R. S. Cevallos-Ferriz

Keyword(s):

Plant Communities ◽

Fossil Flora ◽

Central Mexico ◽

Arid Environments ◽

The Past ◽

South Central ◽

Modern Species ◽

Tropical America ◽

Extinct Genus ◽

The Town

A small assemblage of fossil legume fruits, leaf fragments, and leaflets has been recovered from the Tertiary (Oligocene) "Los Ahuehuetes" flora near the town of Tepexi de Rodríguez, Puebla, in south-central Mexico. Five legume fruits are described and compared with fruits of extant genera. Four fruit types were identified as belonging to the modern genera Prosopis (Mimoseae; Mimosoideae), Mimosa (Mimoseae; Mimosoideae), Lysiloma (Ingeae; Mimosoideae), and Sophora (Sophoreae; Papilionoideae). Another fruit exhibits a combination of characters unknown among extant legumes, and although superficially similar to some species of Papilionoideae, it represents an extinct genus. The four identified genera are diverse in the extant vegetation of Mexico; in fact, Mexico represents an important area of distribution for them. The presence of Prosopis, Mimosa, Lysiloma, and Sophora in the fossil flora of Puebla documents the occurrence of these genera in this part of their present area of distribution by the Oligocene. The climatic affinities of modern species of Mimosa, Lysiloma, and Sophora are so varied as to preclude any useful paleoclimatic inference. Prosopis is regularly associated with arid environments; however, the genus has been reported from fossil localities where humid conditions prevailed. This observation, together with the assemblage of plants that co-occur in the Los Ahuehuetes flora, suggests that plant communities of the past may have been composed, at least partly, of elements that today are associated with different habitats and environmental conditions. The fossil legume fruits from Los Ahuehuetes flora add to the previously known diversity of Leguminosae by the Tertiary, confirm tropical America as one of the important areas of radiation and diversification for Leguminosae, and contribute to the knowledge of Tertiary floras of southern North America. Key words: Leguminosae, Tertiary, Mexico, paleobotany, fossil legume.

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Chemical composition of rainwater collected from 2006 to 2009 in Mexico City and at a rural site at Morelos State, south central Mexico

Revista Mexicana de Ciencias Geológicas ◽

10.22201/cgeo.20072902e.2020.1.1101 ◽

2020 ◽

Vol 37 (1) ◽

pp. 1-8

Author(s):

Rocío García-Martínez ◽

Alejandro Carrillo-Chavez ◽

Ricardo Torres-Jardón ◽

Alejandro Ramirez-Guzmán ◽

Moisés López-Carrasco

Keyword(s):

Chemical Composition ◽

Mexico City ◽

Atmospheric Transport ◽

Sampling Site ◽

Air Pollutant ◽

Rural Site ◽

Central Mexico ◽

Strong Positive Correlation ◽

Back Trajectories ◽

South Central

The objective of the study was to evaluate the chemical composition of rainwater in urban and suburban areas of central Mexico to identify the possible sources of rainwater contamination. The rainwater was collected at Universidad Nacional Autónoma de Mexico, Campus Ciudad Universitaria (CU), in the southern part of Mexico City at 2200 meters above sea level (m a.s.l.). CU has many green areas with high to moderate traffic densities where air quality presents serious problems of pollution by particulate matter. The other sampling site is a forested rural area (Tlalnepantla), State of Morelos, Mexico, a suburban area 86 km to the south of Mexico City. A total of 145 rainwater samples were collected in the rain period from 2006 to 2009. The ions analyzed were the following: SO42-, NO3-, Cl-, HCO3-, Na+, K+, Ca2+, Mg2+, NH4+ and H+. Ammonium was the most abundant cation in both sites and is one of those responsible for the neutralization of acidic compounds in the atmosphere. The relative abundance of the inorganic anions present in the rainwater was in the following order: SO42- > NO3- > Cl-, for the alkaline metals the order was Ca2+ >Mg2+ > Na+ > K+ and Ca2+ >Mg2+ >K+ >Na+ for CU and Morelos, respectively. A correlation analysis shows a strong positive correlation among the ions, indicating that the most important source was anthropogenic. Air mass back trajectories were associated with the SO42-, Ca2+, Mg2+, NH4+ and H+ concentrations observed on each rainy day. Four factors were used in the statistic analysis and was weighted within each factor. Weights greater than 0.5 are considered to be significant components of each factor. The four factors explain 84.7 % of the total variance of all of the data for CU and 66.9 % for Morelos. All of these factors were associated with all of the analyzed ions. Air pollutant back trajectories were used to understand atmospheric transport and to identify the origins and pathways of air masses influencing the concentrations of the measured ions in rainwater.

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