To better understand the range of adaptation of maize (Zea mays L.) landraces, climatic adaptation intervals of 42 Mexican maize races were determined. A database of 4161 maize accessions was used to characterize altitudinal and climatic conditions where the 42 maize races grow, yielding ecological descriptors for each race. Using the geographical coordinates of the collection sites of each accession, their climatic conditions were characterized using the geographic information system IDRISI and a national environmental information system. Analyses of variance and cluster analyses of the racial ecological descriptors were performed to determine possible environmental groupings of the races. We found a very high level of variation among and within Mexican maize races for climate adaptation and ecological descriptors. The general overall climatic ranges for maize were 0 to 2900 m of altitude, 11.3 to 26.6°C annual mean temperature, 12.0 to 29.1°C growing season mean temperature, 426 to 4245 mm annual rainfall, 400 to 3555 mm growing season rainfall, and 12.46 to 12.98 h mean growing season daylength. These climatic ranges of maize surpass those from its closest relative, teosinte (Z. mays ssp. parviglumis Iltis and Doebley), indicating that maize has evolved adaptability beyond the environmental range in which ancestral maize was first domesticated.

Adaptation of crops to climate change has motivated an increasing interest in the potential value of novel traits from wild species; maize wild relatives, the teosintes, harbor traits that may be useful to maize breeding. To study the ecogeographic distribution of teosinte we constructed a robust database of 2363 teosinte occurrences from published sources for the period 1842–2016. A geographical information system integrating 216 environmental variables was created for Mexico and Central America and was used to characterize the environment of each teosinte occurrence site. The natural geographic distribution of teosinte extends from the Western Sierra Madre of the State of Chihuahua, Mexico to the Pacific coast of Nicaragua and Costa Rica, including practically the entire western part of Mesoamerica. The Mexican annuals Zea mays ssp. parviglumis and Zea mays ssp. mexicana show a wide distribution in Mexico, while Zea diploperennis, Zea luxurians, Zea perennis, Zea mays ssp. huehuetenangensis, Zea vespertilio and Zea nicaraguensis had more restricted and distinct ranges, representing less than 20% of the total occurrences. Only 11.2% of teosinte populations are found in Protected Natural Areas in Mexico and Central America. Ecogeographical analysis showed that teosinte can cope with extreme levels of precipitation and temperatures during growing season. Modelling teosinte geographic distribution demonstrated congruence between actual and potential distributions; however, some areas with no occurrences appear to be within the range of adaptation of teosintes. Field surveys should be prioritized to such regions to accelerate the discovery of unknown populations. Potential areas for teosintes Zea mays ssp. mexicana races Chalco, Nobogame, and Durango, Zea mays ssp. huehuetenangensis, Zea luxurians, Zea diploperennis and Zea nicaraguensis are geographically separated; however, partial overlapping occurs between Zea mays ssp. parviglumis and Zea perennis, between Zea mays ssp. parviglumis and Zea diploperennis, and between Zea mays ssp. mexicana race Chalco and Zea mays ssp. mexicana race Central Plateau. Assessing priority of collecting for conservation showed that permanent monitoring programs and in-situ conservation projects with participation of local farmer communities are critically needed; Zea mays ssp. mexicana (races Durango and Nobogame), Zea luxurians, Zea diploperennis, Zea perennis and Zea vespertilio should be considered as the highest priority taxa.

Societal Impact Statement Crop wild relatives (CWR) are plant taxa closely related to crops and are a source of high genetic diversity that can help adapt crops to the impacts of global change, particularly to meet increasing consumer demand in the face of the climate crisis. CWR provide vital ecosystem services and are increasingly important for food and nutrition security and sustainable and resilient agriculture. They therefore are of major biological, social, cultural and economic importance. Assessing the extinction risk of CWR is essential to prioritise in situ and ex situ conservation strategies in Mesoamerica to guarantee the long‐term survival and availability of these resources for present and future generations worldwide. Summary Ensuring food security is one of the world's most critical issues as agricultural systems are already being impacted by global change. Crop wild relatives (CWR)—wild plants related to crops—possess genetic variability that can help adapt agriculture to a changing environment and sustainably increase crop yields to meet the food security challenge. Here we report the results of an extinction risk assessment of 224 wild relatives of some of the world's most important crops (i.e. chilli pepper, maize, common bean, avocado, cotton, potato, squash, vanilla and husk tomato) in Mesoamerica—an area of global significance as a centre of crop origin, domestication and of high CWR diversity. We show that 35% of the selected CWR taxa are threatened with extinction according to The International Union for Conservation of Nature (IUCN) Red List demonstrates that these valuable genetic resources are under high anthropogenic threat. The dominant threat processes are land use change for agriculture and farming, invasive and other problematic species (e.g. pests, genetically modified organisms) and use of biological resources, including overcollection and logging. The most significant drivers of extinction relate to smallholder agriculture—given its high incidence and ongoing shifts from traditional agriculture to modern practices (e.g. use of herbicides)—smallholder ranching and housing and urban development and introduced genetic material. There is an urgent need to increase knowledge and research around different aspects of CWR. Policies that support in situ and ex situ conservation of CWR and promote sustainable agriculture are pivotal to secure these resources for the benefit of current and future generations.

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The structural pattern of rainfall data exhibits random fluctuations over time and space. Utilizing concepts of fractal theory, it has been possible to identify characteristics of rainfall data beyond simple statistical indicators of their randomness. The objective of this research was to identify the spatial variation of the Hurst exponent, extracted through standard wavelet techniques from time series of daily rainfall data in the state of Zacatecas, Mexico. The Hurst exponent was extracted for 26 locations using the reference techniques for auto-affine traces-in particular, the wavelets method. Results have shown that the Hurst exponents of rainfall time series are negatively influenced by altitude; thus, stations located at higher altitudes were characterized by Hurst exponents indicating more nonpersistent behavior. The trends among geographical variables (west longitude and latitude) and climatic parameters (annual rainfall and number of rainy days) and their relationship with the Hurst exponent were also analyzed.

Seed dormancy in wild Zea species may affect fitness and relate to ecologicai adaptation. The primary objective of this study was to characterize the variation in seed germination of the wild species of the genus Zea that currently grow in México and to reiate this variation to their ecologicai zones of adaptation. In addition, we compared methods to break dormancy and measured the germination responses of seeds to environment factors that are related to seasonai changes. Teosinte popuiations representing aii the taxonomic and racial groups known in México were coliected during the period 2003 to 2008 in tweive states of México. Seed dormancy was classified according to the rate of its ioss (depth of dormancy). Results indicated that more than 90% of populations

El occidente de Jalisco alberga archipiélagos de bosque mesófilo de montaña, los cuales, al igual que en el este de México, tienen una alta riqueza de especies arbóreas raras y con distribución restringida. En su límite superior altitudinal forman ecotonos con bosques de Abies. Hipótesis: Con el incremento de la altitud, hay un cambio direccional en la distribución de las especies dominantes, estructura de la vegetación y disminución en riqueza de especies leñosas. Descripción de datos: Los datos analizados incluyeron área basal, altura, abundancia, diversidad Shannon, riqueza y variables ambientales. Sitio de estudio y año de estudio: El occidente de Jalisco, en dos localidades con bosque mesófilo de montaña y bosque de Abies, desde septiembre de 2013 hasta agosto de 2015. Métodos: Se midieron e identificaron especies leñosas en 32 unidades de muestreo de 0.1 ha; mediante análisis de regresión y métodos multivariados se exploraron variables ambientales asociadas a grupos de vegetación en relación con la altitud. Resultados: Se detectaron patrones unimodales y lineales de estructura y diversidad en ambos gradientes. Los análisis sugieren cinco grupos: bosque mesófilo de baja montaña asociado a temperatura media anual, precipitación anual y pedregosidad; bosque mesófilo de alta montaña y bosque de coníferas (Abies) asociados a la altitud y precipitación invernal; y dos grupos dominados por Quercus-Pinus. Conclusiones: Los resultados muestran que distintas especies dominantes están asociadas a diferentes condiciones climáticas y sugieren patrones distintos en cada localidad: a) la riqueza disminuye con la altitud en La Bufa; b) la riqueza y la estructura muestran un patrón unimodal en Laguna Juanacatlán. Palabras clave: Bosque de Abies, bosque mesófilo de montaña, especies indicadoras, gradiente altitudinal, precipitación, temperatura.