K. Schwenk et al., WHAT CAN MOLECULAR MARKERS TELL US ABOUT THE EVOLUTIONARY HISTORY OF DAPHNIA SPECIES COMPLEXES, Hydrobiologia, 307(1-3), 1995, pp. 1-7
Despite the wealth of information on the ecology of Daphnia species, t
he systematics and phylogeny of the genus is still unresolved. The tax
onomic uncertainties are based in part on the phenomenon of interspeci
fic hybridization, which has been well documented for species of the D
. galeata/cucullata/hyalina complexes. The occurrence of syntopic popu
lations of up to three species and their three hybrids suggest niche d
ifferentiation, but very little is known about genetic divergence of h
ybridizing taxa and the potential consequences of hybridization (i.e.
introgression). Since an operational species definition is necessarily
based on information on the evolutionary mechanisms that result into
the splitting of lineages, ecological and genetic consequences of inte
rspecific hybridization have to be considered. In order to reveal the
significance of hybridization and introgression, we combined several a
spects of phylogenetic investigations within the D. galeata/cucullata/
hyalina complexes. Furthermore we demonstrate how molecular markers co
ntribute to an evaluation of species complexes.