Crisp & Chandler, Paraphyletic species 
825 
Helianthus petiolaris 
Using restriction fragment polymorphisms of nuclear and chloroplast DNA, Rieseberg 
and Brouillet (1994) constructed a phylogeny of populations representing Helianthus 
neglcctus (Asteraceae: Astereae) and two subspecies of H. petiolaris. Helianthus annuus 
was used as the outgroup. This phylogeny showed H. negiectus as a metaspecies, 
H. petiolaris subsp. fallax as paraphyletic with respect to H. negiectus, and H. petiolaris 
subsp. petiolaris as paraphyletic with respect to both subsp. fallax and H. negiectus 
(Fig. 6). Not too much should be made of their result because only four character- 
state changes occur on a tree with 12 terminal taxa. Additional informative characters 
may well produce a different topology. 
Examples of metaspecies 
Phylogenetic analyses at the level of populations, as decribed above, are uncommon. 
In the absence of a broad-based sample of such studies, we have no reliable estimate 
of the overall frequency of paraphyletic species. An indirect estimate may be gained 
from the lack of identified autapomorphies in terminal taxa (species and subspecies) 
which have been included in cladistic analyses. A taxon lacking an autapomorphy is 
potentially paraphyletic, a 'metaspecies' (Donoghue 1985; de Queiroz & Donoghue 
1988). This simpler approach allows the possibility of using large samples. However, 
it is restricted to taxa for which there are phytogenies using species as terminal taxa. 
In the absence of a phylogeny there is no basis for judging whether a character fixed 
in a species is an autapomorphy or a retained plesiomorphy. 
E. arenacea 
E. alpina 2 
E. baxteri 
E. alpina 3 
E. baxteri 
E. alpina 1 
Fig. 5. Phylogeny of populations of Eucalyptus baxteri, E. arenacea and £. alpina, based on leaf 
volatile oil composition and derived using distance Wagner with Manhattan distance (Whiffin & 
Ladiges 1992; Figs 8a and 9a combined). E. arenacea is monophyletic, and both £. baxteri and 
£. alpina are paraphyletic. 
