Identification Of Two Walkerella Species And Their Male Morphs From Ficus Benjamina Based On Morphological And Molecular Evidences

Fig wasps (Insecta: Hymenoptera: Chalcidoidea) and their host figs (Moraceae: Ficus) is an excellent model for the study of such evolutionary topics as adaptation, male polymorphism, etc. Fig wasps have many adaptive evolution on their morphological characters and lifestyles due to their long-time hosted life in the syconium of fig. The head of pollinators and some non-pollinators females are extraordinarily specialized for crawling through the ostiole; the diversity of ovipositing places and styles resulted in the diversity of the ovipositor length and the timing of ovipositing; males have peculiar respiratory organs and other morphological changes in relation with their habitat in the enclosed fig cavity.The two most outstanding characteristics of these adaptive changes are distinct sexual dimorphism (SD) and male polymorphism. Mature females emerge from the syconium and fly to appropriate ovipositing places, so they have developed compound eyes and wings. But the life cycle of most males is restricted to the cavity of the fig, so they are wingless and have vestigial eyes. Different male species may have different morphs and behaviors since they adopt different strategies. There can also be two or more male phenotypes intra-species with different phenotype having different mating tactics.Sexual dimorphism is common among various species, and some fig wasps are perhaps among the most extreme cases of sexual dimorphism in the animal kingdom. Each fig shelters a very diverse assemblage of fig wasps species in TIS enclosed inflorescence- syconium, which makes the taxonomy of fig wasps a difficult task. What's more, the prevalent phenomena of sexual dimorphism and male polymorphism bring much intricacy to the problem. So the species identification of fig wasps based on traditional morphology is not only difficult but also fuzzy and false-prone. Assistance from other measure besides morphology is requisite for well fulfilling the species identification in the complex assemblage of fig wasps. We here want to compare the practicability of several gene fragments with different evolution rates in species identification of fig wasps. We amplified four fragments of COI and ITS2 from 40 individuals of 2 species of Walkerella associated with Ficus benjamini (Ficus, Moraceae) and analyzed their utilization in species identification. Our results showed that ITS2 can cluster all the individuals of the same species into a highly supported clade, so it is the best marker used in species classification of these fig wasps. COI could also act well but with a few unordinary exceptions, which indicates TIS deficient use in DNA barcoding due to the possible effect of Numts or symbionts.