Weitzman, C. L.Day, K.Zozaya, S. M.Skelton, K.Brown, G. P.Gibb, K.Christian, K.2026-07-032026-07-030952-8369ORCID:/0000-0003-3451-3552/work/219176700https://hdl.handle.net/1885/733812821The success of parthenogenic populations is facilitated by high fecundity, though studies show that parthenogenic hybrids can express traits of compromised fitness compared with their parent species, such as higher rates of evaporative water loss and greater susceptibility to ectoparasites. Recent works highlighting the importance of microbiomes on host health also show that both host lineage and the environment contribute to an animal's microbiome. In this study, we investigated how reproductive mode and the presence of mites affect evaporative water loss and if the skin bacterial microbiome differs between sympatric sexual and parthenogenic populations of the gecko Heteronotia binoei in central Australia. We collected sexual (n = 17) and parthenogenic (n = 66) H. binoei from six local sites (within 3 km of each other) to measure evaporative water loss, record mite infestations, and characterise skin bacterial communities from a subsample of individuals (n = 17 per reproductive mode). Only parthenogenic individuals had mites, and mite infestations were not severe at our site. We found that neither reproductive mode nor the presence of mites affected evaporative water loss in our study populations, contrary to prior studies elsewhere for the species. In microbiome analyses, we found that reproductive mode significantly predicted community structure and composition; however, local site explained more of the observed variation than other variables. While these findings challenge previously observed differences in physiology between parthenogenic and sexual H. binoei, we found support for ectoparasite susceptibility in parthenogenic individuals. Our microbiome results reinforce that even in sympatry, host lineages harbour unique microbiomes, although the environment largely influences the skin bacterial communities in our study system.We respectfully acknowledge the Arrernte and Larrakia peoples, the traditional owners of the land where this work was undertaken. This study was supported by grants from the Australian Research Council (DP210102176; DP190102395). All sampling was conducted under permits 69132 and 71211 from the Northern Territory Parks and Wildlife Commission and permission from the Charles Darwin University Animal Ethics Committee (permit A21010). We thank two anonymous reviewers for their helpful comments to improve the quality of this paper. Open access publishing facilitated by Charles Darwin University, as part of the Wiley - Charles Darwin University agreement via the Council of Australian University Librarians.11en© 2025 The Author(s).bacterial microbiomeectoparasiteevaporative water lossgeckoHeteronotiahybridparthenogeneticskin bacteria202510.1111/jzo.70044105010236104