Sperm collection and storage for the sustainable management of amphibian biodiversity

Abstract

Current rates of biodiversity loss pose an unprecedented challenge to the conservation community, particularly with amphibians and freshwater fish as the most threatened vertebrates. An increasing number of environmental challenges, including habitat loss, pathogens, and global warming, demand a global response toward the sustainable management of ecosystems and their biodiversity. Conservation Breeding Programs (CBPs) are needed for the sustainable management of amphibian species threatened with extinction. CBPs support species survival while increasing public awareness and political influence. Current CBPs only cater for 10% of the almost 500 amphibian species in need. However, the use of sperm storage to increase efficiency and reliability, along with an increased number of CBPs, offer the potential to significantly reduce species loss. The establishment and refinement of techniques over the last two decades, for the collection and storage of amphibian spermatozoa, gives confidence for their use in CBPs and other biotechnical applications. Cryopreserved spermatozoa has produced breeding pairs of frogs and salamanders and the stage is set for Lifecycle Proof of Concept Programs that use cryopreserved sperm in CBPs along with repopulation, supplementation, and translocation programs. The application of cryopreserved sperm in CBPs, is complimentary to but separate from archival gene banking and general cell and tissue storage. However, where appropriate amphibian sperm banking should be integrated into other global biobanking projects, especially those for fish, and those that include the use of cryopreserved material for genomics and other research. Research over a broader range of amphibian species, and more uniformity in experimental methodology, is needed to inform both theory and application. Genomics is revolutionising our understanding of biological processes and increasingly guiding species conservation through the identification of evolutionary significant units as the conservation focus, and through revealing the intimate relationship between evolutionary history and sperm physiology that ultimately affects the amenability of sperm to refrigerated or frozen storage. In the present review we provide a nascent phylogenetic framework for integration with other research lines to further the potential of amphibian sperm banking.

Integrating biobanking minimises inbreeding and produces significant cost benefits for a threatened frog captive breeding programme

“…Biobanks (frozen living cell repositories of germ cells, embryos and somatic tissues for use in conservation genetic management) in conjunction with ARTs to utilise this stored genetic material have been proposed as a strategy to reduce holding requirements, labour and other costs needed to run captive breeding programmes (Ananjeva et al, 2017;Clulow & Clulow, 2016;Holt, Bennett, Volobouev, & Watwon, 1996;Silla & Byrne, 2019). Recent advances in successful biobanking and ARTs for amphibians over the past decade has resulted in the ability to hormonally induce gamete release (Clulow et al, 2018), freeze and store sperm long-term (Browne et al, 2019;Clulow & Clulow, 2016;Clulow et al, 2014;Kouba et al, 2013;Kouba, Vance, & Willis, 2009) and routinely perform in vitro fertilisations (IVF) (Clulow & Clulow, 2016;Clulow et al, 2014;Kouba et al, 2009). These advances have now paved the way for routinely incorporating cryopreserved sperm from founder captive animals (or wild animals temporarily collected) into the management of captive amphibian populations to reduce costs and the need for large numbers of animals to maintain heterozygosity targets (Beauclerc, Johnson, & White, 2010;Dreitz, 2006;Gagliardo et al, 2008;Griffiths & Pavajeau, 2008;Kouba et al, 2011;Murphy & Gratwicke, 2017).…”

Criopreservación espermática de Ambystoma mexicanum (Shaw & Nodder, 1798)

“…Estos resultados son similares a los publicados por Doyle et al (2011), en el número de espermatozoides entre los espermatóforos liberados de ejemplares de A maculatum. La cantidad y el tamaño de los espermatóforos que pueden ser liberados varía ampliamente, relacionándose con la fisiología y adaptación reproductiva de cada especie (Browne et al, 2019); así como de tres características físicas: tamaño corporal, tamaño de los testículos o la edad (Uribe y Mejía-Roa, 2014), lo cual también fue observado en nuestro estudio. La viabilidad espermática observada en fresco fue de 80 a 98%, siendo este el primer trabajo que registra el porcentaje de espermatozoides vivos extraídos de los espermatóforos.…”

Integrating biobanking could produce significant cost benefits and minimise inbreeding for Australian amphibian captive breeding programs

“…Ex situ conservation tools, particularly captive breeding and assisted reproductive technologies (ARTs) are becoming increasingly important for amphibian species recovery (Bishop et al 2012;Kouba et al 2012;Clulow and Clulow 2016;Browne et al 2019;Clulow et al 2019). Australian animals face significant in situ declines across multiple taxa due to expanding and persistent anthropogenic threats, policy failings and funding neglect (Woinarski et al 2017;Howell and Rodger 2018;Wintle et al 2019).…”