Stylops undetermined

Jůzová, Kateřina, Nakase, Yuta & Straka, Jakub, 2015, Host specialization and species diversity in the genus Stylops (Strepsiptera: Stylopidae), revealed by molecular phylogenetic analysis, Zoological Journal of the Linnean Society 174 (2), pp. 228-243 : 240

DEFINITION OF STYLOPS SPECIES

The crucial question is how can we define Stylops species. Defining species is problematic in general ( Nixon & Wheeler, 1990; de Queiroz, 2005). For the result of phylogenetic study, we can apply a basic phylogenetic species concept (species as the smallest aggregation of populations or lineages diagnosable by a unique combination of character states in comparable individuals; Nixon & Wheeler, 1990). When we consider the results from analyses of all three genes, we can say that the result is highly comparable. Mitochondrial DNA data maintain female genetic information (female lineage), whereas nuclear DNA data provide more information about population structure. The information about gene flow among lineages of Stylops species is obtained from congruence in the tree topology results and branch lengths (or better DNA distances among lineages). There is obviously no gene flow among the crown lineages.

The possible species seem to be well defined, except in clades 2 and 10 of Figure 4, where distances within the crown group suggest that there are more than one species with uncertain division. The species delimitations seem to be especially clear for the mapping of information about the hosts (species, subgenus, and genus in Fig. 4) onto the tree. From a basic mapping of the hosts to the phylogenetic tree, it is evident that host species and subgenera cluster with Stylops clades in a common sense, usually irrespective of the collecting locality. Most Stylops species extracted from the same host species or subgenus are closely related and form crown groups. These lineages are well support- ed by high posterior probabilities (0.98–1.00) in the majority of cases, and they are also well supported by bootstrap values (80–100). Such good support for the monophyly of lineages that are regularly clustered according to the host species/subgenus support our understanding of these lineages as different species with different life strategies.

We can conclude that the delimitation of Stylops species seems to be quite sharp in most cases, and that the DNA distances of COI (DNA barcoding sequence) can by relatively easily applied. The DNA distances among species lineages seem to be quite distinct, i.e. 3–23% of different base pairs, but usually more than 7% in distance. Variability within reconstructed crown groups is usually much less than 2%, but sometimes exceeds this number. In such lineages, cryptic species and taxonomic problems can be expected. In Stylops , we found the standard variability in DNA barcode sequences found elsewhere in insects ( Hebert, Ratnasingham & Waard, 2003). The common 3% threshold in DNA distances for barcode sequence distance ( Hebert et al., 2003) can be applied for Stylops species in future studies; however, groups with lower variability can also consist of more than a single species, and such groups need to be studied by comprehensive population genetic methods.