ONLINE IMAGE COLLECTION

About the Image

Flowers of three Peruvian species of Caiophora (Loasacae subfam. Loasoideae) and a natural hybrid (bottom left: C. cirsiifolia C.Presl × C. deserticola Weigend & Mark.Ackermann, raised in Berlin from seeds from a plant of C. deserticola in Omate in southern Peru [top left]). Hybrid formation is the result of secondary contact of the parental species due to human impact: the maternal population of C. deserticola grows in a dry, high Andean habitat, whereas the paternal C. cirsiifolia populations (bottom right) are usually found in more humid areas at lower elevations. Localized populations of C. cirsiifolia, however, are found in higher, drier habitats where hedges and irrigation channels provide a suitable habitat for this species. In these areas, populations of the two usually allopatric species are neighbors, permitting cross-pollination and consequently interspecific hybridization. In experimental inter- and intraspecific crosses between morphologically and ecologically differentiated taxa, all species of Caiophora tested were highly interfertile. Crossability indices were generally higher in the progeny from interspecific crosses than from intraspecific crosses, indicating a marked heterosis effect and the possible presence of an inbreeding depression in the parental populations. Hybridization is thus expected to occur wherever human impact brings different taxa of Caiophora into secondary contact. Intensifying agriculture and new road construction are common in the Andes, likely increasing the levels of secondary contact and interspecific hybridization in Caiophora, thus threatening the genetic integrity of the Caiophora species and probably of other Andean taxa with a similar lack of crossing barriers.

For further details, See Ackermann et al.—Hybridization and crossability in Caiophora (Loasaceae subfam. Loasoideae): Are interfertile species and inbred populations results of a recent radiation?, American Journal of Botany, Volume 95, Issue 9, pages 1109–1121, http://www.amjbot.org/cgi/content/short/95/9/1109.