818 
Telopea Vol. 6(4): 1996 
the 'metaspecies' is shown to be monophyletic (Fig. lb); (ii) a synapomorphy may be 
found (character 4, Fig. Ic) demonstrating that some populations of the metaspecies 
are more closely related to a recognised monophyletic species, in which case the 
'metaspecies' is shown to be paraphyletic; (iii) no new apomorphy is found, and the 
species remains an unresolved metaspecies (Fig. Id), diagnosed only by a 
symplesiomorphy (character 1, Fig. Id). Both paraspecies and metaspecies are 
diagnosed by symplesiomorphy (character 1, respectively in Figs. Ic and Id). 
However, they differ in that evidence exists to show that part of the paraspecies is 
more closely related to another species (character 4 in Fig. Ic), whereas no such 
evidence is found in a metaspecies (Fig. Id). To summarise, depending upon the 
observed distribution of apomorphies among populations, the phylogenetic status 
of a species may be: unresolved (a metaspecies), non-monophyletic (a paraspecies) 
or monophyletic (an autapomorphic species). Note that irrespective of the 
phylogenetic relationship of their populations, all these species are diagnosable units 
consistent with the phylogenetic and composite species concepts. Therefore all are 
real, discoverable and corroborable entities. Moreover, the phylogenetic relationship 
of their parts (monophyletic, paraphyletic or metaphyletic) is also discoverable and 
corroborable (by the adducement of additional evidence). 
Objectives 
In this paper, we present examples of paraspecies and metaspecies and empirically 
estimate their proportion of all species. We show that any attempt to purge the 
system of these is futile, because of the asymmetric distribution of apomorphic 
(relatively advanced) characters among basal lineages (species). Consequently we 
address the conundrum of paraspecies and metaspecies in a system to which these 
are anathema. Finally, we consider the implications for comparative methods such 
as cladistic biogeography of a false assumption of species monophyly. 
For the purpose of this paper, we make no fundamental distinction between species 
and subspecies. This paper is concerned with lowest-level taxa, whether ranked as 
species or subspecies. The concepts monophyly, paraphyly and metaphyly apply 
equally to either, and to taxa of any rank. We do not consider the effects of reticulation, 
as this is a separate problem. 
Examples of paraspecies 
The following five examples report cladistic analyses using as terminals either 
populations or geographic forms that do not have evident autapomorphies and may 
well be paraphyletic. Are these suitable units for cladistic analysis? Some authors 
suggest that using paraphyletic terminals invalidates phylogenetic analysis (Cracraft 
1989; de Queiroz & Donoghue 1990a; de Queiroz & Donoghue 1990b; Nixon & 
Wheeler 1990; Wheeler &c Nixon 1990; Vrana & Wheeler 1992). Moreover, because 
evolution among populations is likely to be reticulate, the strictly hierarchical model 
of cladistic relationships may be invalidated (Crisp & Weston 1993). However, these 
problems are not restricted to populations: the monophyly of most taxa (e.g. species 
and subspecies) is untested and thus uncertain (Nelson 1989b). Moreover, this paper 
shows that many such taxa are probably paraphyletic. An extensive literature attests 
to the frequency of reticulate evolution among recognised species (e.g.. Funk 1985; 
Barton & Hewitt 1989; Harrison 1991; Arnold 1992; Grant & Grant 1992; Smith 1992). 
Thus, problems affecting cladistic analysis of populations apply at least in part to 
subspecies and species. Vrana & Wheeler (1992) advocate using as terminals 
individual organisms, whose monophyly can (perhaps) be safely presumed. However, 
