Ecological Niche Modeling and Distribution of Wild Sunflower (Helianthus annuusL.) in Mexico

The distribution of sunflower (Helianthus annuus L.) in Mexico has received renewed interest recently because of the discovery of domesticated H. annuus in early archaeological deposits in Tabasco (ca. 2600 cal. BC) and elsewhere in Mexico. The modern distribution of wild sunflower was ascertained through extensive collecting in Mexico and by examining existing collections in relevant herbaria. We further modeled the ecological niche projected as a potential distribution of wild sunflower using point occurrence data, environmental variables, and a GIS platform. Predicted distributions were statistically significant and more coincident with independent test points than random expectations. Interestingly, the ecological niche model predicted that wild sunflower should occur at various localities in the southern part of Mexico, yet it has never been collected there, nor did survey transects reveal any wild populations there. The intervening Trans‐Mexican Volcanic Belt acting as a physical barrier to dispersal or biotic interactions from the presence of a high diversity of tropical Asteraceae and intense insect predation may provide explanations for the absence of wild H. annuus in southern Mexico.