Coca - Species and Evolution

Species and Evolution

There are two species of cultivated coca, each with two varieties:

  • Erythroxylum coca
    • Erythroxylum coca var. coca (Bolivian or Huanuco Coca) - well adapted to the eastern Andes of Peru and Bolivia, an area of humid, tropical, montane forest.
    • Erythroxylum coca var. ipadu (Amazonian Coca) - cultivated in the lowland Amazon Basin in Peru and Colombia.
  • Erythroxylum novogranatense
    • Erythroxylum novogranatense var. novogranatense (Colombian Coca) - a highland variety that is utilized in lowland areas. It is cultivated in drier regions found in Colombia. However, E. novogranatense is very adaptable to varying ecological conditions. The leaves have parallel lines on either side of the central vein.
    • Erythroxylum novogranatense var. truxillense (Trujillo Coca) - grown primarily in Peru and Colombia. the leaves of E. novogranatense var. truxillense does not have parallel lines on either side of the central vein like all other varieties.

All four of the cultivated cocas were domesticated in pre-Columbian times and are more closely related to each other than to any other species.

There are two main theories relating to the evolution of the cultivated cocas. The first (put forth by Plowman and Bohm ) suggests that Erythroxylum coca var. coca is ancestral, while Erythroxylum novogranatense var. truxillense is derived from it to be drought tolerant, and Erythroxylum novogranatense var. novogranatense derived from Erythroxylum novogranatense var. truxillense.

Recent research based on genetic evidence (Johnson et al. in 2005, Emche et al. in 2011, and Islam 2011) does not support this linear evolution and instead suggests a second domestication event as the origin of the Erythroxylum novogranatense varieties. There may be a common, but undiscovered ancestor

Wild populations of Erythroxylum coca var. coca are found in the eastern Andes, but the other 3 taxa are only known as cultivated plants.

The two subspecies of Erythroxylum coca are almost indistinguishable phenotypically. Erythroxylum novogranatense var. novogranatense and Erythroxylum novogranatense var. truxillense are phenotypically similar, but morphologically distinguishable. Under the older Cronquist system of classifying flowering plants, this was placed in an order Linales; more modern systems place it in the order Malpighiales.

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