Annual Review of Animal Biosciences - Volume 7, 2019

Hepatitis E virus (HEV) is an important human pathogen that historically has been difficult to study. Limited levels of replication in vitro hindered our understanding of the viral life cycle. Sporadic and low-level virus shedding, lack of standardized detection methods, and subclinical infections made the development of animal models difficult. Better diagnostic techniques and understanding of the virus increased our ability to identify and characterize animal strains and animals that are amenable to model human-relevant infection. These advances are translating into the development of useful HEV animal models so that some of the greatest concerns associated with HEV infection, including host immunology, chronic infection, severe pregnancy mortality, and extrahepatic manifestations, can now be studied. Continued development of these animal models will be instrumental in understanding the many complex questions associated with HEV infection and for assessing therapeutics and prevention strategies to minimize HEV becoming a greater risk to the human population.

Dogs are second only to humans in medical surveillance and preventative health care, leading to a recent perception of increased cancer incidence. Scientific priorities in veterinary oncology have thus shifted, with a demand for cancer genetic screens, better diagnostics, and more effective therapies. Most dog breeds came into existence within the last 300 years, and many are derived from small numbers of founders. Each has undergone strong artificial selection, in which dog fanciers selected for many traits, including body size, fur type, color, skull shape, and behavior, to create novel breeds. The adoption of the breed barrier rule—no dog may become a registered member of a breed unless both its dam and its sire are registered members—ensures a relatively closed genetic pool within each breed. As a result, there is strong phenotypic homogeneity within breeds but extraordinary phenotypic variation between breeds. One consequence of this is the high level of breed-associated genetic disease. We and others have taken advantage of this to identify genes for a large number of canine maladies for which mouse models do not exist, particularly with regard to cancer.

Conservation genomics aims to preserve the viability of populations and the biodiversity of living organisms. Invertebrate organisms represent 95% of animal biodiversity; however, few genomic resources currently exist for the group. The subset of marine invertebrates includes the most ancient metazoan lineages and possesses codes for unique gene products and possible keys to adaptation. The benefits of supporting invertebrate conservation genomics research (e.g., likely discovery of novel genes, protein regulatory mechanisms, genomic innovations, and transposable elements) outweigh the various hurdles (rare, small, or polymorphic starting materials). Here we review best conservation genomics practices in the laboratory and in silico when applied to marine invertebrates and also showcase unique features in several case studies of acroporid corals, crown-of-thorns starfish, apple snails, and abalone. Marine conservation genomics should also address how diversity can lead to unique marine innovations, the impact of deleterious variation, and how genomic monitoring and profiling could positively affect broader conservation goals (e.g., value of baseline data for in situ/ex situ genomic stocks).

Anthropogenic environmental change has led to unprecedented rates of species extinction, presenting a major threat to global biodiversity. Among vertebrates, amphibians have been most severely impacted, with an estimated 41% of species now threatened with extinction. In response to this biodiversity crisis, a moral and ethical obligation exists to implement proactive interventionist conservation actions to assist species recovery and decelerate declines. Conservation breeding programs have been successfully established for several threatened amphibian species globally, aiming to prevent species’ extinction by maintaining genetically representative assurance colonies ex situ while providing individuals for population augmentation, translocation, and reestablishment in situ. Reproductive technologies have enormous potential to enhance the propagation and genetic management of threatened species. In this review, we discuss the role of reproductive technologies in amphibian conservation breeding programs and summarize technological advancements in amphibian hormone therapies, gamete storage, and artificial fertilization.

Of all the big cats, or perhaps of all the endangered wildlife, the tiger may be both the most charismatic and most well-recognized flagship species in the world. The rapidly changing field of molecular genetics, particularly advances in genome sequencing technologies, has provided new tools to reconstruct what characterizes a tiger. Here we review how applications of molecular genomic tools have been used to depict the tiger's ancestral roots, phylogenetic hierarchy, demographic history, morphological diversity, and genetic patterns of diversification on both temporal and geographical scales. Tiger conservation, stabilization, and management are important areas that benefit from use of these genome resources for developing survival strategies for this charismatic megafauna both in situ and ex situ.