The phylogeny of the Hyles euphorbiae complex (Lepidoptera: Sphingidae): Molecular evidence from sequence data and ISSR-PCR fingerprints

The evolutionary history of the Hyles euphorbiae complex (HEC) was studied using mitochondrial DNA sequences comprising about 2300 bp derived from the genes cytochrome c oxidase subunits I (COX I) and II (COX II) and tRNA-leucine. In addition, we collected genomic fingerprinting data by ISSR-PCR to assess if and how the bi-parentally inherited nucleome may have diverged differently to the maternally inherited mitochondria. The COX sequences revealed a clear geographical pattern of genetic differentiation of the HEC into two main lineages, H. euphorbiae and H. tithymali. Our results provide no evidence that H. dahlii falls within a HEC s. str., although a sister-group relationship cannot be ruled out. The sequence data indicated intraspecific subdivisions and gene flow patterns, and possibly detected both introgression and a major contact zone on Mediterranean islands between these two evolutionary lineages. Hyles tithymali is hypothesized to have been able to retain ancient polymorphisms until the present, whereas H. euphorbiae appears to have (re)colonized its current distribution range after the Ice Ages from a few (or even only one) refugial populations by leptokurtic dispersal, resulting in low diversity. The ISSR-PCR data showed much higher variability among individuals of the HEC than did mtDNA sequence data. They provided insights into the genomic distribution of the simple sequence repeat (GACA)4 and appear to describe a more complex pattern of introgression in the HEC. Our data revealed the HEC as a very young species complex, in which we have detected two distinct mitochondrial lineages, corresponding to H. tithymali (including the deserticola, mauretanica and himyarensis lineages) and H. euphorbiae (including H. robertsi), respectively.