DICKINSON, TIMOTHY A.1,2*, RODGER C. EVANS2, AND CHRISTOPHER S. CAMPBELL2. (1)Center for Biodiversity & Conservation Biology, Royal Ontario, Museum, 100 Queen's Park, Toronto, CANADA M5S 2C6 and Botany Department, University of Toronto, 25 Willcocks Street, Toronto, CANADA M5S 3B2; (2)Department of Biological Sciences, Deering Hall, University of Maine, Orono ME 04469-5722 U.S.A. - Phylogenetic relationships between Crataegus and Mespilus
(Rosaceae subf. Maloideae) based on rDNA sequence variation.
Results from work on a phylogeny of the genus Crataegus suggest
a possible re-evaluation of the status of Mespilus.
Crataegus and Mespilus share a number of wood anatomical
and morphological features that set them apart from most other members
of Rosaceae subfamily Maloideae. Data for single species of each
genus from rDNA internal transcribed spacer regions (ITS1, ITS2)
likewise have shown Crataegus and Mespilus to be sister
genera, in a clade with Amelanchier, Peraphyllum, and
Malacomeles. We report now on sequence variation in ITS1, 5.8S
rDNA, and ITS2 in a sample of Crataegus species representing
most of the 15 sections of the genus, and both species of
Mespilus (Eurasian M. germanica L. and the Arkansas
endemic M. canescens Phipps). For outgroups we have used
Amelanchier, Malus, and Pyrus. The medlar, M.
germanica, appears to be nested within Crataegus;
preliminary results suggest that M. canescens could be of
hybrid origin. Results may also cast light on relationships between
stamen-number morphotypes in North American sections of
Key words: classification, Crataegus, ITS, Mespilus, phylogeny, Rosaceae