Distribution and eco-geographic characterization of Carica papaya L. native to Mexico

Carica papaya L. is an important plant genetic resource that has a low level of genetic erosion. Knowing the distribution and eco-geography of native C. papaya in Mexico is critical for the implementation of strategies for its conservation and sustainable use. For such purpose, Geographic Information Systems (GIS) and multivariate analysis methods are useful for the eco-geographic characterization of plant genetic resources using external information sources and field collections of specimens. The objective of this study was to determine the distribution and environmental variables that define the eco-geographic zones of C. papaya native to Mexico, as well as to determine priority areas for in situ conservation of native papaya germplasm in Mexico. It was hypothesized that there are no differences on diversity of native papaya population among the eco-geographic zones in Mexico and that eco-geographic zones with warm-humid climate would have the best conditions for wild native papaya germplasm conservation. Data were obtained from papaya records of 222 specimens collected and belonging to the C. papaya collection ex situ (109, wild population; 108, homegardens; five, cultivated native varieties) and 449 from external sources. All records were georeferenced to perform an eco-geographic characterization using climatic, geophysical and edaphic variables, which were analyzed using GIS and multivariate methods. We found that C. papaya is distributed between 15 and 27°N, at an altitude from 2 to 2395.0 m, which shows a wide distribution. Carica papaya is distributed among four Eco-geographic Groups (EG) according to the cluster analysis. In general, C. papaya was found in warm and very hot climates with an average annual temperature higher than 18 °C. No papaya records were found for cold climates. Ten eco-geographic variables define the distribution of C. papaya in Mexico, nine climatic and one geophysical. The eco-geographic characterization of the territory (ELC maps) identified 16 eco-geographic categories for C. papaya, from which 15 were found to contain living specimens. Categories 11 and 13 presented the appropriate environmental conditions for in situ conservation. In the collection of native C. papaya, the EG and ELC maps detected categories that were represented, over-represented and under-represented.