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Many species of plants and a few species of animals are believed to have resulted from hybridization of parental species, and the ability of species to occasionally hybridize in captivity and in nature is even more widespread. In the present study, we describe a hybridization experiment conducted in the laboratory between the sexually dimorphic Automeris io (Fabricius), a widespread, variable species ranging from Canada to Costa Rica, and its congener A. louisiana (Ferguson and Brou), a more local, sexually monomorphic species (Lepidoptera: Saturniidae). The A. louisiana populations occur in a highly specialized habitat—the coastal marshland along the Gulf of Mexico in Louisiana and Texas and is nested inside the broad distribution of A. io, demonstrating strong differences from the latter in its ecology and morphology. No natural hybridization between the two species has been described. While the separate species status of A. io and A. louisiana is supported by morphology and ecology of their populations, we were able to create a hybrid lineage in the laboratory and maintained it for three generations. The hybrids were phenotypically intermediate between the parental species. Under a stricter reading of the biological species concept, such an ability to hybridize would be interpreted by some as a sign of conspecificity. Our experiments once again demonstrate the complexity of ‘species’ as a concept, which may need major redefinition in the popular interpretation of sciences.
Male cerci variability was used as the main source of information to separate taxonomic units in the genus Pseudochelidura. Based on these data it was considered that three species of Pseudochelidura coexisted in the Pyrenees: P. sinuata, P. minor and P. montuosa. However, our phylogeographic and phylogenetic analyses based on molecular data (mitochondrial cytb and nuclear ITS2) do not support those conclusions. Combining these analyses with morphological studies we concluded that: 1) the Pyrenees are inhabited by a single evolutionary unit: P. sinuata (Germar, 1825) (= P. minor Steinmann, 1979 syn. nov., = P. montuosa Steinmann, 1981 syn. nov.). 2) Cantabrian and Pyrenean populations are reciprocally monophyletic and morphologically diagnosable representing two independent evolutionary units: Pseudochelidura cantabrica Cuesta-Segura, Jurado-Angulo & García-París sp. nov. and P. sinuata. And, 3) their conservation status needs to be evaluated in the light of current taxonomic changes. We have shown that the use of male cerci for species identification is problematic. Patterns of variation possibly affected by sexual selection (e.g., intrapopulational variability) appear to be very difficult to separate from variation driven by natural selection or genetic drift (i.e., character divergence in geographical isolation). The large sequence divergence observed between Pyrenean and Cantabrian populations of Pseudochelidura suggest a lasting genetic and geographic isolation between them, rendering difficult to ascertain their phylogenetic relationships.