Abstract
Natural hybridization between species provides an opportunity to study the mechanisms that maintain independent lineages and may help us understand the process of speciation. The New Zealand tree wētā species Hemideina thoracica produces F₁ hybrids where it lives in sympatry with two closely related species: Hemideina crassidens and Hemideina trewicki. This study looked at the viability and fertility of F₁ hybrid wētā between H. thoracica and H. crassidens that were collected from the wild and kept in captivity. The hybrids appeared to have normal viability from the late juvenile stage, with all male wētā maturing at a late instar. Male F₁ hybrids displayed normal mating behavior and one male produced offspring in captivity. In contrast to Haldane’s rule, female F₁ hybrids appeared to be infertile; they refused to mate and did not produce eggs. No evidence of Wolbachia infection was identified in any of the three North Island Hemideina species.