Genetic connectivity of Australian white ibis: implications for management

Anthropogenic processes often impact genetic connectivity of wild populations. Widespread degradation across Australia’s inland wetland network has contributed to severe declines for many waterbird species. Meanwhile, breeding colonies of the Australian white ibis (Threskiornis molucca) have increased along the coast. Resource availability may be influencing site fidelity among urban ibis, but whether this impacts on levels of gene flow between inland and coastal, urban areas remains unknown. This study uses single nucleotide polymorphisms (SNPs) to ascertain the structure of several urban and inland colonies of white ibis across south-eastern Australia. Associations between gene flow and several environmental factors were tested, including geographic distance, the Great Dividing Range, urbanisation intensity and surface water permanence. Additionally, effective population sizes were estimated along with the impact of various management scenarios on future genetic diversity. Spatial and regression analyses revealed no significant differences in allele frequencies, or relatedness, therefore suggesting widespread dispersal and gene flow between inland and coastal colonies. Furthermore, effective sizes were large enough to maintain genetic diversity into the future, even under various management scenarios. However, the lack of genetic partitioning found suggests that urban management of the ibis should not be undertaken in isolation of inland conservation efforts.