The Leptynia hispanica species complex (Insecta Phasmida): polyploidy, parthenogenesis, hybridization and more.

The Leptynia hispanica stick-insect species complex includes bisexuals, triploid and tetraploid parthenogenetic populations, suggesting that polyploidy has played a central role in the evolution of this complex. An in-depth analysis of karyotype, mtDNA (cox2) and nuclear DNA (ef1-a) markers was carried out in order to clarify phylogenetic relationships and microevolutionary/phylogeographic patterns of the L. hispanica complex. Our analyses suggested a subdivision of bisexual populations into four groups, tentatively proposed as incipient species. Moreover, triploids and tetraploids showed two independent origins, the latter being more ancient than the former. From ef1-a analysis, triploids showed a clear hybrid constitution, while the hybrid constitution of tetraploids is likely, but more data are needed. We suggest that L. hispanica is a case of “geographic parthenogenesis” with parthenogenetic strains colonizing large peripheral ranges, and bisexuals confined to post-glacial refuge areas. Moreover, the age, wide distribution and competitive advantage of polyploids over diploids, demonstrate their significance in the evolution of the L. hispanica species complex.