Cactus Diversity in Arid and Semiarid Regions of Mexico

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Cacti are the most ubiquitous plants in the arid regions of the American continent and Caribbean Isles. Nearly 1427 taxa of cacti, which mainly inhabit the southern USA, Mexico, and South America, have been recorded. Since Mexico has 700 cactus species, 517 of which are endemic, this country is considered to be globally rich in cacti. In this chapter, we analyzed the number and distribution of cactus genera and species in 15 climatic domains. All available records for cactus species were downloaded from the GBIF website and manually curated to create a derived database containing individual records with coordinates and the scientific names of native taxa. This curated database contained 124789 records, which were mapped onto the 15 climatic domains to construct a binary matrix composed of genera and species. We estimated β diversity (βJ) to compare turnover in species composition among domains. We documented a total of 64 genera with 654 species, 78.6% of which were distributed in some of the 15 climatic domains. The number of genera and species were positively correlated (r 2=0.92, p<0.05). Domain 15 contained the highest number of genera (40) and species (214), while the lowest numbers were documented in domains 1 (13 genera) and 18 (35 species). Among the 15 domains, the genera with the highest number of species were Mammillaria (129), Opuntia (62), Echinocereus (51), and Coryphantha (44). The mean value of βJ was 0.83, indicating high variation in species composition among the domains.