Until recently, studies of plant reproductive systems have been at the popu
lation level, using microevolutionary approaches. The development of cladis
tic approaches, combined with the emergence of molecular systematics, has r
esulted in an explosion of phylogenetic studies and an increase in interdis
ciplinary approaches combining ecological and systematic methodology. These
new approaches offer the possibility of testing explicit hypotheses about
the number of evolutionary transitions in reproductive characters and the e
volutionary relationship of these characters to changes in the environment.
Character mapping may be especially useful for detecting convergent evolut
ion. In a number of cases, character mapping has provided new insights into
the evolution of plant breeding systems and pollination biology, especiall
y in suggesting the number of times evolutionary transitions have taken pla
ce, indicating where there have been reversals and suggesting when preadapt
ation has been important. The insights provided by character mapping are de
termined by a number of factors, including the degree of confidence in phyl
ogenies underlying these studies and the identification of appropriate outg
roups. Assumptions about character coding, character ordering, inclusion vs
. exclusion of characters that are mapped on trees in the data matrix, and
weighting of characters will have profound effects on interpretation of cha
racter evolution. Highly labile characters that evolve frequently and have
the potential to undergo reversals may make it difficult to detect the patt
ern of character evolution. Characters that are very strongly correlated wi
th each other or with ecological shifts may make prediction of cause and ef
fect using phylogenetic approaches difficult because changes in characters
and ecological shifts will occur, apparently simultaneously, on the same br
anches. Results from microevolutionary studies have been used in several ca
ses to weight transitions, suggesting that results of phylogenetic studies
may not provide fully independent assessments of character evolution. While
not a simple cure to understanding problems that have been studied only in
the realm of microevolutionary studies, phylogenetic approaches offer clea
r potential for providing new insights for evolutionary studies.