Bheemaiah and Shariff 1989; Korikanthimath et al. 1994; Reddy and Rao
1999), and Papua New Guinea (Bourke 1985).
Biodiversity in Coffee Agroecosystems
The biodiversity of coffee systems can be divided into the genetic diversity of
the coffee crop itself; the diversity of other vegetation including the shade
canopy and ground cover; and the diversity of fauna and microorganisms that
use the coffee ecosystem as temporary or permanent habitat, including coffee
pests and diseases and their biological control organisms.
Genetic Diversity of Coffee
Coffees originated in Africa. They are classified into two genera of the Rubi-
aceae family, Coffeaand Psilanthus,with each genus being divided into two
subgenera (Charrier and Berthaud 1985). More than 80 taxa have been iden-
tified in the subgenus Coffea,and recent collections of several new taxa in
Cameroon (Anthony et al. 1985) and Congo (de Namur et al. 1987) indicate
that the inventory is not yet complete. Commercial coffee production relies
mainly on two species, Coffea arabica(66 percent of world production) and
Coffea canephora(34 percent). Better cup quality is associated with C. arabica,
which has its primary center of diversity in the highlands of East Africa; C.
canephorahas its primary center of diversity in the lowlands of the Congo
River basin. C. arabicais the only self-fertile, tetraploid species (2n = 4x = 44);
other Coffeaspecies are diploid (2n = 2x = 22) and generally self-incompatible
(Charrier and Berthaud 1985).
Genetic diversity in existing C. arabicaplantations worldwide is very low
because of intense reductions of both genetic diversity and polymorphism
during domestication, a process favored by its self-fertility. Most commercial
cultivars currently grown (Caturra, Catuai, and Mondo novo) were selected
from two narrow genetic base populations, spread in the early eighteenth cen-
tury and known as Typica and Bourbon cultivars (Anthony et al. 2001). Both
cultivars have weak polymorphism (Anthony et al. 2002) and are highly sus-
ceptible to several major diseases, especially coffee rust (Hemileia vastatrix).
Fortunately, genes from other diploid species (Coffeaand some Psilanthus) can
be transferred into C. arabicaby controlled hybridization (Couturon et al.
1998), and this has become a priority for the genetic improvement of com-
mercial coffee (Carvalho 1988; Lashermes et al. 2000). Many modern coffee
plantations are based on the extensive use of a few introgression lines selected
from natural interspecific hybrids: the Timor hybrid in Latin America (C. ara-
bicax C. canephora) and (C. arabicax C. liberica) in India. Selected lines
include Costa Rica 95 and IHCAFE 90 in Central America, Variedad Colom-
- Biodiversity Conservation in Neotropical Coffee Plantations 205