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The environmental variability at local scale results in different physiognomic types of mangrove forest. However, this variability has never been considered in studies of mangrove genetic variability. This study analyzed the genetic and morphological variability and structure of Rhizophora mangle at regional and local scales in the Yucatan Peninsula. Thirteen mangrove populations (eight scrub and five tall), located in seven sites, were sampled, and their morphological variability and relationship with the availability of phosphorus and salinity were analyzed. The diversity and genetic structure were estimated at different hierarchical levels with nine microsatellites, also Bayesian inference and Principal Coordinates Analysis were used. We found a great morphological variability of R. mangle that responded to local environmental variability and not to the precipitation gradient of the peninsula. The genetic diversity found in the peninsula was greater than that reported for other populations in Mexico and was grouped into two regions: the Gulf of Mexico and the Caribbean Sea. At a local scale, tall and scrub mangroves had significant genetic differentiation suggesting that ecological barriers promote genetic differentiation within sites. These results need to be considered in future population genetic studies and for mangrove management and conservation. Mangrove species Rhizophora mangle has many physiognomic forms, the short one or scrub type occupies large extensions. We evaluate whether this type is genetically different from the tall type and found that differences are greater at local scale than at regional scale, indicating that short‐distance ecological barriers exist between these two types of mangrove within a site. [ABSTRACT FROM AUTHOR]

* Premise of the study: Understanding genetic structure in wild relatives of a crop is important for crop improvement and conservation. Recently, two gene pools (MI and Mil) were reported in wild Lima bean (Phaseolus lunatus) from Mexico, a domestication center of Mesoamerican landraces. However, the evidence was based on limited genomic sampling. Here we sought to confirm the existence of these two gene pools by increased genome and population sampling. * Methods: We characterized 67 wild populations of P. lunatus from Mexico with 10 microsatellite loci and studied the genetic structure by means of AMOVA, cluster analyses, assignment tests, and a georeferenced map. * Key results: AMOVA indicated that most of the variation is found among populations (77%) rather than within populations (23%). Assignment tests were key to confirm not only the presence of the two gene pools (MI and Mil) in Mexico, but also to propose the possible existence of two subgroups within MI (Mia and MIb). While MI and Mil are mainly divergent geographically, Mia and MIb overlap in their distribution. Admixed individuals, which may represent cases of gene flow among gene pools, were detected. * Conclusions: Our results show that the genetic structure of wild Lima bean in Mexico is more complex than previously thought and propose the presence of three gene pools (Mia, MIb, and Mil), each one possessing relatively high levels of genetic diversity. We still need additional evidence, however, to confirm without doubt the split of the gene pool MI into subgroups Mia and MIb. [ABSTRACT FROM AUTHOR]

Traditional farming communities frequently maintain high levels of agrobiodiversity, so understanding their agricultural practices is a priority for biodiversity conservation. The cultural origin of agave spirits (mezcals) from west-central Mexico is in the southern part of the state of Jalisco where traditional farmers cultivate more than 20 landraces of A gave angustifolia Haw. in agroecosystems that include in situ management of wild populations. These systems, rooted in a 9000-year-old tradition of using agaves as food in Mesoamerica, are endangered by the expansion of commercial monoculture plantations of the blue agave variety (A. tequilana Weber var. Azul), the only agave certified for sale as tequila, the best-known mezcal. Using intersimple sequence repeats and Bayesian estimators of diversity and structure, we found that A. angustifolia traditional landraces had a genetic diversity (HBT = 0.442) similar to its wild populations (HBT = 0.428) and a higher genetic structure (θB = 0.405; θB =0. 212). In contrast, the genetic diversity in the blue agave commercial system (HB = 0.118) was 73% lower. Changes to agave spirits certification laws to allow the conservation of current genetic, ecological and cultural diversity can play a key role in the preservation of the traditional agroecosystems. [ABSTRACT FROM AUTHOR]