il ' ii - Northern Research Station - USDA Forest Service

Among species groups, the topology remains the same has intermittently connected the westem Nearctic and the
for the flanged-femur species group whatever the data set eastern Palaearctic during much of the Tertiary until 3-5
used (namely D. radicum being the most basal species, mya ago and has played an important role in plant and
followed by D. triforma, then by D. spinosa, being the . animal dispersal (Cox 1974).
sister group of D. californica + D. triforma). In the D. ,
rosae group, D. fructuum appears to be the most basal D.nebulosa .
species with D. spinosissimae and D. mayri the most D ignota
derived ones in all analyses based on 12S data set (figs.
3a, 4a, and 5a). In contrast, D. fructuum and D. rosae are
the most derived taxa and D. spinosissimae is not D. rosaefotii
D. fusifbrmans
associated With this group when using the Cytochrome B polita
data set (figs. 315,4b, and 5b).
D. bicolor
Comparison of the Trees Obtained Using the D.centifoliae
Different Phylogenetic Reconstruction Methods o eglanteriae
,'
D. radicum
For a given data set, very similar results are found
whatever the phylogenetic reconstruction method used. • D.triforma
The tree based on the combined data set with the o californica
Maximum Likelihood method (fig. 5c) has been chosen o. noduiosa
as•the "working phylogeny" because of its slightly better D.spinosa
resolution.
I1_D. spinosissimae
DISCUSSION O.mayri
D. fructuum
' Our results.clearly identify Liebeliafukudae as belonging
to a distinct genus from Diplolepis, confirming the D rosae
. Lieb. fukudae
interpretation of Vyrzhikovskaja (1963) but contrasting Geographic range
With the opinion of Weld (1952). However, additional Lipo.glechomae
species of the genus Liebelia (in particular those consid-
Asiatic
ered to belong to the other subgenus L. Liebelia) are m European q'
• needed for a complete revision of the Rhoditini tribe. 1 Nearctic
Eurasiatic
Although there is no morphology-based phylogeny of the ff==l Equivocal
genus Diplolepis to date, the species showing closest
morphological features (i.e., D. centifoliae and D. Figure 6._Estimated phylogeny of the Rhoditini (tree
eglanteriae; D. fructuum, D. mayri and D. rosae; D. recovered using Maximum Likelihood method analysis
polita and D. bicolor) are always associated in our of the combined data set) on which the range of each
analyses. The association of all species of Diplolepis species has been mapped.
with a flanged,femur (this conspicuous character--first
reported by Dailey and Campbell 1973 in D.
inconspicuis, and subsequently observed in several other This hypothesis is in general agreement with the _llow-
. Nearctic species by Shorthouse and Ritchie 1984--- ing arguments:
constitutes a unique synapomorphy in the tribe) in the w
same Glade, confirms the relevance of our phylogeny. • The dispersal starting point in Holarctic-distributed
animals is more frequently the western Nearctic
Phylogeography of the Rhoditini Tribe region than East Nearctic or Palaearctic (Enghoff
- 1995). However, Diplolepis may constitute an
In all the resolved trees recovered with the combined interesting case, as genera dispersal between conti-
data set and whatever the type of analysis performed, the nents has rarely been reported even though such
three Nearctic species groups (namely nebulosa, polita, distributions are more frequent in family-Glades.
rosaefolii ) are ancestral (fig. 6). This suggests that
Diplolepis had a Nearctic rather than Palaearctic origin. • The highest species richness in Diplolepis occurs in
' After evolving in North America; we suggest that the North America, where about three-quarters of the
. genus dispersed across Beringia to eastern Asia and from known species are found. However, this finding may
there to western Europe. The trans-Pacific Bering bridge be due to a lack of collecting in central Asia.
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