In the World Zoo and Aquarium Conservation Strategy, the world's leading zoos commit to focusing their efforts on conserving wildlife. Such a commitment is made as human activities are driving many species of wildlife towards extinction. The world's leading zoos aim to act as a counterbalance to activities that undermine the sustainability of wild populations of threatened species. However, to date, this same group of zoos has largely failed to manage its own populations of wildlife sustainably despite distinguished calls to action over the past 25 years, significant scientific input and much organizational effort. This paper explores the efforts of the global zoo community to bring sustainability and conservation value to its animal populations. It looks at where we have come from, where we are now and where we need to go from here.

Biodiversity loss is a major challenge. Over the past century, the average rate of vertebrate extinction has been about 100-fold higher than the estimated background rate and population declines continue to increase globally. Birth and death rates determine the pace of population increase or decline, thus driving the expansion or extinction of a species. Design of species conservation policies hence depends on demographic data (e.g., for extinction risk assessments or estimation of harvesting quotas). However, an overview of the accessible data, even for better known taxa, is lacking. Here, we present the Demographic Species Knowledge Index, which classifies the available information for 32,144 (97%) of extant described mammals, birds, reptiles, and amphibians. We show that only 1.3% of the tetrapod species have comprehensive information on birth and death rates. We found no demographic measures, not even crude ones such as maximum life span or typical litter/clutch size, for 65% of threatened tetrapods. More field studies are needed; however, some progress can be made by digitalizing existing knowledge, by imputing data from related species with similar life histories, and by using information from captive populations. We show that data from zoos and aquariums in the Species360 network can significantly improve knowledge for an almost eightfold gain. Assessing the landscape of limited demographic knowledge is essential to prioritize ways to fill data gaps. Such information is urgently needed to implement management strategies to conserve at-risk taxa and to discover new unifying concepts and evolutionary relationships across thousands of tetrapod species.

Inbreeding is reputed to distort sex-ratios by reducing the proportion of the homogametic sex. However, many data sets do not show such an effect, and there is a known selective publication bias. To resolve the issue, we (a) developed detailed theoretical expectations for the effects of inbreeding on sex-ratios for autosomal and sex-linked loci with sex-limited effects or with equal effects in the two sexes, (b) evaluated the effects of inbreeding on sex-ratios in a new sample of 25 vertebrate taxa, and (c) evaluated the effects of inbreeding on sex-ratios for 69 replicate populations of Drosophila melanogaster. Theoretical analyses indicated that directional distortions of sex-ratios under inbreeding due to sex-linked loci with sex-limited expression are expected to be small and uncommon and that there will be no distortions in marsupials. Further, sex linked alleles expressed equally in both sexes may also distort sex-ratios following inbreeding. Autosomal sex-limited alleles should not result in directional sex-ratio distortions in large populations or across many replicates, but may lead to distortions of random direction in some small populations. There were no significant directional distortions of sex-ratio due to inbreeding in either the vertebrates or the Drosophila populations. However, there were significant random distortions of sex-ratios in both data sets, presumably from autosomal sex-limited alleles that had drifted in individual populations. Thus, directional distortions in sex-ratio are not a consistent signal of inbreeding depression.

Koalas are the only living member of their family and therefore deserve serious conservation consideration. Koalas have low levels of genetic variation within and among populations in the southern part of their range, where they have experienced many relocations and population crashes since European colonization of Australia. The importance of this change in variation is underlined by preliminary indications that levels of genetic variation may affect fitness in koalas. Techniques have been developed to help identify and monitor genetic problems in koalas and to provide the information and tools to make genetic management an integral part of koala conservation. The koala is currently at an appropriate point for conservation intervention: there is clear evidence of decline in some populations, but the existence of other robust populations offers the possibility of a variety of creative solutions to their conservation problems. Managers should aim to maintain this species' current ecological amplitude (the range of environments in which populations are found) and minimize the loss, fragmentation, or decline of populations. There are no data to suggest that any population requires genetic supplementation. The concepts of evolutionarily significant unit ( ESU) and management unit (MU) can be useful in the genetic management of koalas, including monitoring and management regimes. But ESUs and MUs can also be misleading if they are not interpreted carefully in terms of population history and the ultimate goal of management. Translocations should not involve extensive use of stock from a single source, especially those with low genetic variation, and they require careful management to avoid possible problems when individuals encounter novel strains of the pathogen Chlamydia pecorum, because several genetically distinct strains have been found in koalas, some of which may derive from introduced species. Genetic indicators can and must make considerable contributions to koala management, but they require careful interpretation.

Wildlife populations around the world are declining and becoming increasingly fragmented, and management efforts to support them have become more intensive. This means that the delineation between extensive wildlife‐management systems (e.g. in national parks or large wildlife reserves) and intensive systems (e.g. zoos and aquariums) is becoming increasingly blurred. Furthermore, attitudes about how people fit into a traditional conservation or ecosystem‐restoration framework are being challenged. In partnership with the Rotoroa Island Trust, Auckland Zoo in New Zealand is delivering a project on Rotoroa Island, which is located in the Hauraki Gulf. The aim of this project is to contribute to the conservation of wildlife, through education, training and visitor‐engagement activities. To this end, Auckland Zoo has translocated seven native species to the Island, all selected to demonstrate a range of techniques across the spectrum of intensive and extensive wildlife‐management systems. The creation of a designed ecosystem, primarily directed towards servicing education and training programmes, is unique in New Zealand. This project also aims to demonstrate an ecosystem where human intervention is integral to enabling higher levels of biodiversity in the available area than would otherwise be possible. At the time of writing the Rotoroa Wildlife Management and Translocation Plan 2013–2038 is being used to work towards the translocation of an additional 13 species to Rotoroa Island, which would expand the number of techniques and management systems that could be demonstrated to visitors.