Universität Freiburg, Institut für Biologie I, 79104 Freiburg, Germany.
During the evolution of the leaf beetle genus Longitarsus (Coleoptera, Chrysomelidae,
Alticinae) many host shifts between distantly related plant
families have apparently occurred. Although all single beetle
species are specialized on just a few plants, an amazing variety
of plants from different plant families are used within the
genus. My aim is to reconstruct the host shifts in the
beetles’ evolution to test a) whether particular secondary
plant compounds have played a role as guide posts between
unrelated plant families, and b) whether beetles belonging to
different clades but being confronted with identical plant
compounds have evolved similar adaptations to deal with these
compounds. Two conspicous patterns are the repeated occurrence of
pyrrolizidine alkoloid or iridoid glycosides containing plants
from many different plant families as hosts of
Longitarsus species.
Here, I present a phylogeny
estimate of Longitarsus based on 1500bp of the
mitochondrial genes for cytochrome oxidase I and II and the
intermittent tRNA leucine. 40 Middle European
Longitarsus species feeding on the plant families
Asteraceae, Boraginaceae, Convolvulaceae, Lamiaceae, Linaceae,
Plantaginaceae, Ranunculaceae and Scrophulariaceae have so far
been included. Additional species of other alticine genera are
used as outgroups to root the tree. Based on this phylogeny, I
reconstruct the evolution of host association and test whether
particular shared secondary compounds have played a role as guide
posts between unrelated plant families.