Resetting the paradigm of reproductive science and conservation

Postmortem Collection of Gametes for the Conservation of Endangered Mammals: A Review of the Current State-of-the-Art

The collection of gametes from recently deceased domestic and wildlife mammals has been well documented in the literature. Through the utilization of gametes recovered postmortem, scientists have successfully produced embryos in 10 different wildlife species, while in 2 of those, offspring have also been born. Thus, the collection of gametes from recently deceased animals represents a valuable opportunity to increase genetic resource banks, obviating the requirement for invasive procedures. Despite the development of several protocols for gamete collection, the refinement of these techniques and the establishment of species-specific protocols are still required, taking into account both the limitations and the opportunities. In the case of wildlife, the optimization of such protocols is impeded by the scarcity of available animals, many of which have a high genetic value that must be protected rather than utilized for research purposes. Therefore, optimizing protocols for wildlife species by using domestic species as a model is crucial. In this review, we focused on the current advancements in the collection, preservation, and utilization of gametes, postmortem, in selected species belonging to Equidae, Bovidae, and Felidae, both domestic and wildlife.

Conservation Biology and Reproduction in a Time of Developmental Plasticity

The objective of this review is to ask whether, and how, principles in conservation biology may need to be revisited in light of new knowledge about the power of epigenetics to alter developmental pathways. Importantly, conservation breeding programmes, used widely by zoological parks and aquariums, may appear in some cases to reduce fitness by decreasing animals' abilities to cope when confronted with the 'wild side' of their natural habitats. Would less comfortable captive conditions lead to the selection of individuals that, despite being adapted to life in a captive environment, be better able to thrive if relocated to a more natural environment? While threatened populations may benefit from advanced reproductive technologies, these may actually induce undesirable epigenetic changes. Thus, there may be inherent risks to the health and welfare of offspring (as is suspected in humans). Advanced breeding technologies, especially those that aim to regenerate the rarest species using stem cell reprogramming and artificial gametes, may also lead to unwanted epigenetic modifications. Current knowledge is still incomplete, and therefore ethical decisions about novel breeding methods remain controversial and difficult to resolve.

Modelling Genetic Benefits and Financial Costs of Integrating Biobanking into the Captive Management of Koalas

Simple Summary

Managed wildlife breeding faces high costs and genetic diversity challenges associated with caring for small populations. Biobanking (freezing of sex cells and tissues for use in assisted breeding) and associated reproductive technologies could help alleviate these issues in koala captive management by enhancing retention of genetic diversity in captive-bred animals and lowering program costs through reductions in the size of the required live captive colonies. Australia’s zoos and wildlife hospitals provide rare opportunities to refine and cost-effectively integrate these tools into conservation outcomes for koalas due to extensive already-existing infrastructure, technical expertise, and captive animals.

Abstract

Zoo and wildlife hospital networks are set to become a vital component of Australia’s contemporary efforts to conserve the iconic and imperiled koala (Phascolarctos cinereus). Managed breeding programs held across zoo-based networks typically face high economic costs and can be at risk of adverse genetic effects typical of unavoidably small captive colonies. Emerging evidence suggests that biobanking and associated assisted reproductive technologies could address these economic and genetic challenges. We present a modelled scenario, supported by detailed costings, where these technologies are optimized and could be integrated into conservation breeding programs of koalas across the established zoo and wildlife hospital network. Genetic and economic modelling comparing closed captive koala populations suggest that supplementing them with cryopreserved founder sperm using artificial insemination or intracytoplasmic sperm injection could substantially reduce inbreeding, lower the required colony sizes of conservation breeding programs, and greatly reduce program costs. Ambitious genetic retention targets (maintaining 90%, 95% and 99% of source population heterozygosity for 100 years) could be possible within realistic cost frameworks, with output koalas suited for wild release. Integrating biobanking into the zoo and wildlife hospital network presents a cost-effective and financially feasible model for the uptake of these tools due to the technical and research expertise, captive koala colonies, and ex situ facilities that already exist across these networks.

Common goals, different stages: the state of the ARTs for reptile and amphibian conservation

Amphibians and reptiles are highly threatened vertebrate taxa with large numbers of species threatened with extinction. With so many species at risk, conservation requires the efficient and cost-effective application of all the tools available so that as many species as possible are assisted. Biobanking of genetic material in genetic resource banks (GRBs) in combination with assisted reproductive technologies (ARTs) to retrieve live animals from stored materials are two powerful, complementary tools in the conservation toolbox for arresting and reversing biodiversity decline for both amphibians and reptiles. However, the degree of development of the ARTs and cryopreservation technologies differ markedly between these two groups. These differences are explained in part by different perceptions of the taxa, but also to differing reproductive anatomy and biology between the amphibians and reptiles. Artificial fertilisation with cryopreserved sperm is becoming a more widely developed and utilised technology for amphibians. However, in contrast, artificial insemination with production of live progeny has been reported in few reptiles, and while sperm have been successfully cryopreserved, there are still no reports of the production of live offspring generated from cryopreserved sperm. In both amphibians and reptiles, a focus on sperm cryopreservation and artificial fertilisation or artificial insemination has been at the expense of the development and application of more advanced technologies such as cryopreservation of the female germline and embryonic genome, or the use of sophisticated stem cell/primordial germ cell cryopreservation and transplantation approaches. This review accompanies the publication of ten papers on amphibians and twelve papers on reptiles reporting advances in ARTs and biobanking for the herpetological taxa.