The idea of homology is important in biology. This is the concept that structures in different, related organisms that possess basic features in common do so because of inheritance of those features from their common ancestor. Thus the underlying similarity, for example, between the fruits of our desert mesquites and our acacias are presumed to reflect their inheriting the basic fruit type from the ancestor that gave rise to both of these groups. Of course, other features also reveal the relationship, so it's not dependent solely on the fruit type.
A recent study, though, shows that sometimes Nature can throw us a
curve. Members of the nightshade family, the family that includes such plants as the
tomato and our local silverleaf nightshade, have a rather complex flower structure. The
pollen-producing organs are held together in a cone, and this structure has always been
considered homologous among the family members. A recent study of bittersweet and
tomato, two closely related nightshades, strongly suggests that the similar-appearing
pollen-producing cones of these two species have independently evolved. Convergent
evolution strikes again!
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.
ThelBen, G. 2004. Bittersweet evolution. Nature 428:813.