Silla, Aimee

Top Publications

Year	Title
2021	Amphibian reproductive technologies: Approaches and welfare considerations Published in Conservation Physiology
2021	Evidence that genetic compatibility underpins female mate choice in a monandrous amphibian Published in Evolution
2021	Hormone-induced ovulation and artificial fertilisation in four terrestrial-breeding anurans Published in Reproduction, Fertility and Development
2019	Genetic benefits of extreme sequential polyandry in a terrestrial-breeding frog Published in Evolution
2019	Hormone-induced sperm-release in the critically endangered Booroolong frog (Litoria booroolongensis): Effects of gonadotropin-releasing hormone and human chorionic gonadotropin Published in Conservation Physiology
2019	The Role of Reproductive Technologies in Amphibian Conservation Breeding Programs Published in Annual Review of Animal Biosciences
2018	Hormone-induced spawning of the critically endangered northern corroboree frog Pseudophryne pengilleyi Published in Reproduction Fertility and Development
2013	Emerging trends for biobanking amphibian genetic resources: the hope, reality and challenges for the next decade Published in Biological Conservation

Research Areas

Research Overview

I am a Reproductive Biologist primarily focussed on developing Assisted Reproductive Technologies (ART) for the conservation of anurans. ART encompass a range of techniques that manipulate gametes for the purpose of controlling reproduction and enhancing fertility. My research includes manipulating hormone profiles to induce gamete-release, short-term gamete-storage, sperm cryopreservation, and artificial reproduction. I am also interested in comparative studies investigating response patterns among species, in order to expedite the application of ART to novel species.

My research also employs evolutionary theory to predict ART outcomes. In particular, I am interested in investigating phenotypic indicators of male fertility, gamete adaptation to localised fertilisation environments, and how parental genetic incompatibilities effect fertilisation.

Member Of

University of Wollongong, Faculty of Science, Medicine and Health Associate Research Fellow 2015 - 2021

Has Collaborator

Byrne, Phillip Associate Professor

Selected Publications

Journal Article

Year	Title
2022	Captive diet does not influence exploration behavior upon reintroduction to the wild in a critically endangered amphibian Published In Frontiers in Conservation Science
2022	Multiple phenotypic traits predict male mating success in a critically endangered frog Published In Behavioral Ecology and Sociobiology
2021	Amphibian reproductive technologies: Approaches and welfare considerations Published In Conservation Physiology
2021	Disease influences male advertisement and mating outcomes in a critically endangered amphibian Published In Animal Behaviour
2021	Does dietary β-carotene influence ontogenetic colour change in the southern corroboree frog? Published In Journal of Experimental Biology
2021	Evidence that genetic compatibility underpins female mate choice in a monandrous amphibian Published In Evolution
2021	Hormone-induced ovulation and artificial fertilisation in four terrestrial-breeding anurans Published In Reproduction, Fertility and Development
2021	Mate Preference Plasticity in a Critically Endangered Frog: Implications for Conservation Breeding Published In Frontiers in Conservation Science
2021	Sex differences in response to environmental and social breeding cues in an amphibian Published In Behaviour
2020	An experimental test of the genetic consequences of population augmentation in an amphibian Published In Conservation Science and Practice
2020	Carotenoid supplementation affects the post-hibernation performance of southern corroboree frogs Published In Behaviour
2020	Do dietary carotenoids improve the escape-response performance of southern corroboree frog larvae? Published In Behaviour
2020	Nest site selection in a terrestrial breeding frog: interrelationships between nest moisture, pH and male advertisement Published In Animal Behaviour
2020	The effect of injection and topical application of hCG and GnRH agonist to induce sperm-release in the roseate frog, Geocrinia rosea Published In Conservation Physiology
2019	Dietary carotenoids affect the development of individual differences and behavioral plasticity Published In Behavioral Ecology
2019	Effect of carotenoid class and dose on the larval growth and development of the critically endangered southern corroboree frog Published In Conservation Physiology
2019	Female choice for related males in wild red-backed toadlets (Pseudophryne coriacea) Published In Behavioral Ecology
2019	Genetic benefits of extreme sequential polyandry in a terrestrial-breeding frog Published In Evolution
2019	Hormone-induced sperm-release in the critically endangered Booroolong frog (Litoria booroolongensis): Effects of gonadotropin-releasing hormone and human chorionic gonadotropin Published In Conservation Physiology
2019	Sperm collection and storage for the sustainable management of amphibian biodiversity Published In Theriogenology
2019	The Role of Reproductive Technologies in Amphibian Conservation Breeding Programs Published In Annual Review of Animal Biosciences
2018	Animal personality and behavioral syndromes in amphibians: a review of the evidence, experimental approaches, and implications for conservation Published In Behavioral Ecology and Sociobiology
2018	Dose and life stage-dependent effects of dietary beta-carotene supplementation on the growth and development of the Booroolong frog Published In Conservation Physiology
2018	Effect of long-term dietary beta-carotene supplementation on sperm concentration and motility in an endangered amphibian Published In Animal Reproduction Science
2018	Hormone-induced spawning of the critically endangered northern corroboree frog Pseudophryne pengilleyi Published In Reproduction Fertility and Development
2018	The unexpected genetic mating system of the red-backed toadlet (Pseudophryne coriacea): A species with prolonged terrestrial breeding and cryptic reproductive behaviour Published In Molecular Ecology
2017	Body size predicts between-individual differences in exploration behaviour in the southern corroboree frog Published In Animal Behaviour
2017	Dietary carotenoid supplementation enhances the cutaneous bacterial communities of the critically endangered southern corroboree frog (Pseudophryne corroboree) Published In Microbial Ecology: an international journal
2017	Sperm motility activation in the critically endangered booroolong frog: the effect of medium osmolality and phosphodiesterase inhibitors Published In Reproduction Fertility and Development
2017	Testing the effect of dietary carotenoids on larval survival, growth and development in the critically endangered southern corroboree frog Published In Zoo Biology
2017	The effect of antioxidants on sperm motility activation in the Booroolong frog Published In Animal Reproduction Science
2017	The effect of dietary antioxidants and exercise training on the escape performance of Southern Corroboree frogs Published In Behavioural Processes
2017	The effect of gentamicin on sperm motility and bacterial abundance during chilled sperm storage in the Booroolong frog Published In General and Comparative Endocrinology
2016	Dietary carotenoid supplementation improves the escape performance of the southern corroboree frog Published In Animal Behaviour
2016	Dietary carotenoids change the colour of Southern corroboree frogs Published In Biological Journal of the Linnean Society
2016	Planning for ex situ conservation in the face of uncertainty Published In Conservation Biology
2016	The influence of carotenoid supplementation at different life-stages on the foraging performance of the Southern Corroboree frog (Pseudophryne corroboree): a test of the Silver Spoon and Environmental Matching Hypotheses Published In Behavioural Processes
2015	Antibiotics and oxygen availability affect the short-term storage of spermatozoa from the critically endangered booroolong frog, Litoria booroolongensis Published In Reproduction Fertility and Development
2015	Environmental osmolality influences sperm motility activation in an anuran amphibian Published In Journal of Evolutionary Biology
2013	Artificial fertilisation in a terrestrial toadlet (Pseudophryne guentheri): effect of medium osmolality, sperm concentration and gamete storage Published In Reproduction Fertility and Development
2013	Emerging trends for biobanking amphibian genetic resources: the hope, reality and challenges for the next decade Published In Biological Conservation
2012	Investigating patterns in the spermiation response of eight Australian frogs administered human chorionic gonadotropin (hCG) and luteinizing hormone-releasing hormone (LHRHa) Published In General and Comparative Endocrinology
2011	Effect of priming injections of luteinizing hormone-releasing hormone on spermiation and ovulation in Gϋnther's Toadlet, Pseudophryne guentheri Published In Reproductive Biology and Endocrinology
2010	Effects of luteinizing hormone-releasing hormone and arginine-vasotocin on the sperm-release response of Günther's Toadlet, Pseudophryne guentheri Published In Reproductive Biology and Endocrinology
2010	Hormone induction of gamete release and In-vitro fertilization in the critically endangered corroboree frog Published In Reproductive Biology and Endocrinology

Book

Year	Title
2022	Reproductive Technologies and Biobanking for the Conservation of Amphibians

Presentations

Invited Talk
- The role of reproductive technologies in amphibian conservation breeding programs, Symposium Lead; Speaker, World Congress of Herpetology (WCH9) 2020
- Effect of priming injections of luteinizing hormone-releasing hormone on spermiation and ovulation in Gϋnther’s Toadlet, Pseudophryne guentheri, Speaker, Joint Meeting of Ichthyologists and Herpetologists 2011
Presentation
- Dietary carotenoid supplementation enhances the cutaneous bacterial communities of the critically endangered Southern Corroboree Frog, Speaker, International Congress of Conservation Biology 2017
- Investigating patterns in the spermiation response of Australian frogs to hCG and LHRHa, Speaker, Australian Society of Herpetologists 2013

Investigator On

Year	Title
2018 - 2021	Let them eat Carotenoids: boosting corroboree frog immunity Awarded by: NSW Environmental Trust Funding Scheme: Environmental Research Program
2012	Assisted reproductive technologies (ART) for frog conservation Awarded by: NSW Environmental Trust Funding Scheme: Environmental Research Program
	Using evolutionary theory to advance reproductive technologies Awarded by: Australian Research Council (ARC) Funding Scheme: Discovery Early Career Researcher Award (DECRA)

Other Research Activities

Zoo Aquarium Association (ZAA), Wildlife Conservation Fund Chief Investigator 2020 - 2023

Impact Story

Hormones help critically endangered frogs get in the mood to breed
Summary
Research led by Dr Aimee Silla and Dr Phillip Byrne at the University of Wollongong (UOW) has enabled the generation of hundreds of offspring of the critically endangered Northern Corroboree Frog, using hormone application to induce reproduction. Although the northern corroboree frog has been bred successfully in captivity for a number of years, captive populations display strong mating bias with less than a third of available males contributing to mating success annually. Over time, such captive mating biases may lead to a loss of genetic variation and adaptive potential that could compromise long-term re-introduction success. In an attempt to boost breeding success and increase the genetic diversity of offspring, reproductive biologists Silla and Byrne teamed up with Michael McFadden from Taronga Conservation Society Australia to trial the use of hormone-induced breeding protocols to assist the genetic management of the species. The reproductive hormone GnRH-a was administered to male and female Corroboree frogs prior to putting pairs in breeding tanks. The hormones help encourage the frogs to mate, getting them in the right ‘mood’ for courtship and reproduction. Overall, in excess of 800 viable eggs have generated using hormone-assisted breeding techniques over the past four years. Offspring of different developmental stages (eggs, tadpoles and juvenile frogs) have been released into natural sites in the Northern Brindabella Ranges by herpetofauna experts from UOW and Taronga Zoo. The research has been conducted with the support of Senior Threatened Species Officer Dr David Hunter from NSW Office of Environment and Heritage (OEH), who oversees the recovery program for Corroboree frogs. In a world first, our team has also effectively applied the reproductive hormones topically to the abdomen of the frogs. Amphibians have highly permeable skin, so we were able to administer the hormones non-invasively. Topical application of reproductive hormones eliminates the need for specialised training in amphibian injection, which has been one of the main reasons that reproductive technologies have not yet been widely adopted by captive facilities, particularly in developing countries. We hope that by developing user-friendly, cost-effective methods for hormone application will lead to more captive facilities using hormone treatment to boost the breeding success of endangered frogs, particularly in developing countries within Neotropical, Afrotropical and Indomalayan regions (collectively harbouring >82% of rapidly declining amphibians).

Detail View

Detail View Summary View
Detail of Impact
An insurance colony was established for the northern corroboree frog at Tidbinbilla Nature Reserve in the ACT, following the annual collection of fertilised eggs from wild populations between 2003 and 2008. Since then, a substantial number of animals have been transferred to Taronga Zoo and a collaborative captive breeding and reintroduction program has been established from a partnership between the two captive institutions and the NSW Office of Environment and Heritage (OEH) (<a href="display/aimee_silla#_ENREF_6" target="_blank" rel="noopener">McFadden et al., 2016</a>). Captive breeding protocols have been established for the northern corroboree frog, with the first viable clutch of eggs laid in captivity in 2008. As with its sister species the southern corroboree frog (Pseudophryne corroboree) key requirements for achieving successful breeding of this species include adequate temperature cycling that incorporates a winter cooling period prior breeding, and the provision of large breeding tanks containing multiple males to allow for female mate-choice (<a href="display/aimee_silla#_ENREF_5" target="_blank" rel="noopener">McFadden et al., 2013</a>). Incorporating assisted reproductive technologiesAlthough the northern corroboree frog has been bred successfully in captivity for a number of years, captive populations display strong mating bias with less than a third of available males contributing to mating success annually. The natural mating system of this species has similarly been shown to exhibit strong mating bias toward a small number of male individuals, so this mating pattern is not unique among captive populations. However, over time, such captive mating biases may lead to a loss of genetic variation in the offspring generated for re-introduction. Between 2014 and 2016, experimental trials were conducted as part of a strategic research collaboration between the University of Wollongong and Taronga Conservation Society Australia, employing hormone-induced spawning protocols to assist the genetic management of the species. Hypothalamic hormones, administered via a single injection, were used to induce spawning in isolated male-female pairs housed together in small aquaria. Hormone administration significantly improved the number of pairs producing viable embryos and total egg number (<a href="https://www.publish.csiro.au/rd/rd18011" target="_blank" rel="noopener">Silla et al., 2018</a>). Overall, in excess of 800 viable eggs (from 37 clutches) were generated using ART over the past four years, which were subsequently released into natural sites in the Northern Brindabella Ranges. Following on from initial experiments, in 2017 our research team developed successful techniques for the topical application of reproductive hormones to induce breeding in the northern corroboree frog in order to further improve animal welfare, and allow ART technologies to be more widely adopted by amphibian captive breeding facilities nationally. Incorporating ARTs into existing conservation breeding programs has a number of potential benefits, including: 1) enhanced species propagation, 2) synchronisation of breeding events, 3) increased genetic diversity and adaptive potential of the offspring generated, and 4) better control over breeding designs, including an opportunity for selective breeding of particular genotypes. As a result, ARTs are being increasingly employed by captive facilities to compliment traditional breeding methods and enhance species recovery. Research article available at: <a href="https://www.publish.csiro.au/rd/rd18011" target="_blank" rel="noopener">https://www.publish.csiro.au/rd/rd18011</a> 
Field of Research
Countries / Regions
Beneficiaries

Beneficiary Quantification Description
External Partners
Evidence of Impact

Evidence Description
UOW Centres / Programs
UOW Researchers / Collaborators

Potential Supervision Topics

- Eating to fuel fertility: Investigating the influence of female nutrition on yolk provisioning, egg quality and offspring fitness in Australian myobatrachid frogs
- Investigating sperm trait evolution, sperm-egg interactions and genetic incompatibility to improve artificial fertilisation success in Australian hylid frogs
- Investigating whether frogs show local adaptation or phenotypic plasticity in sperm traits, and whether knowledge of these adaptions can improve the success of artificial fertilisation

Advisees

Graduate Advising Relationship

Degree	Research Title	Advisee
Doctor of Philosophy	The Influence of Temperature on the Growth, Development and Fitness of the Endangered Baw Baw Frog	Gilbert, Deon
Doctor of Philosophy	Improving the Output of Australian Ex-Situ Conservation Breeding Programs for Threatened Amphibian Recovery	McFadden, Michael
Doctor of Philosophy	Investigating proximate mechanisms underpinning behaviour to improve captive management and reintroduction of the critically endangered Southern Corroboree Frog (Pseudophryne corroboree)	Walton, Sara

Education And Training

Doctor of Philosophy, School of Animal Biology, Development and application of assisted reproductive technologies for the conservation of anuran amphibians 2013
B Science (Hon) in Environmental Science (Zoology; Land and Water Management), School of Animal Biology, Effect Of Cattle Grazing On Benthic Macroinvertebrate Communities In The Kalgan River System, south-west Western Australia 2007

Awards And Honors

Perth Zoo Prize for Conservation Research, conferred by Perth Zoo, 2012
WA Young Person of the Year, conferred by WA Youth Awards, Youth Affairs Council, 2007
Luke Pen Scholarship, conferred by Department of Water, 2006

Keywords

Herpetology, amphibian, conservation, threatened species, reproduction, assisted reproductive technologies, gamete, IVF, sperm

Orcid Id

http://orcid.org/0000-0002-2277-9030 (confirmed)

Top Publications

Year	Title
2021	Amphibian reproductive technologies: Approaches and welfare considerations Published in Conservation Physiology
2021	Evidence that genetic compatibility underpins female mate choice in a monandrous amphibian Published in Evolution
2021	Hormone-induced ovulation and artificial fertilisation in four terrestrial-breeding anurans Published in Reproduction, Fertility and Development
2019	Genetic benefits of extreme sequential polyandry in a terrestrial-breeding frog Published in Evolution
2019	Hormone-induced sperm-release in the critically endangered Booroolong frog (Litoria booroolongensis): Effects of gonadotropin-releasing hormone and human chorionic gonadotropin Published in Conservation Physiology
2019	The Role of Reproductive Technologies in Amphibian Conservation Breeding Programs Published in Annual Review of Animal Biosciences
2018	Hormone-induced spawning of the critically endangered northern corroboree frog Pseudophryne pengilleyi Published in Reproduction Fertility and Development
2013	Emerging trends for biobanking amphibian genetic resources: the hope, reality and challenges for the next decade Published in Biological Conservation

Research Areas

Research Overview

I am a Reproductive Biologist primarily focussed on developing Assisted Reproductive Technologies (ART) for the conservation of anurans. ART encompass a range of techniques that manipulate gametes for the purpose of controlling reproduction and enhancing fertility. My research includes manipulating hormone profiles to induce gamete-release, short-term gamete-storage, sperm cryopreservation, and artificial reproduction. I am also interested in comparative studies investigating response patterns among species, in order to expedite the application of ART to novel species.

My research also employs evolutionary theory to predict ART outcomes. In particular, I am interested in investigating phenotypic indicators of male fertility, gamete adaptation to localised fertilisation environments, and how parental genetic incompatibilities effect fertilisation.

Member Of

University of Wollongong, Faculty of Science, Medicine and Health Associate Research Fellow 2015 - 2021

Has Collaborator

Byrne, Phillip Associate Professor

Selected Publications

Journal Article

Year	Title
2022	Captive diet does not influence exploration behavior upon reintroduction to the wild in a critically endangered amphibian Published In Frontiers in Conservation Science
2022	Multiple phenotypic traits predict male mating success in a critically endangered frog Published In Behavioral Ecology and Sociobiology
2021	Amphibian reproductive technologies: Approaches and welfare considerations Published In Conservation Physiology
2021	Disease influences male advertisement and mating outcomes in a critically endangered amphibian Published In Animal Behaviour
2021	Does dietary β-carotene influence ontogenetic colour change in the southern corroboree frog? Published In Journal of Experimental Biology
2021	Evidence that genetic compatibility underpins female mate choice in a monandrous amphibian Published In Evolution
2021	Hormone-induced ovulation and artificial fertilisation in four terrestrial-breeding anurans Published In Reproduction, Fertility and Development
2021	Mate Preference Plasticity in a Critically Endangered Frog: Implications for Conservation Breeding Published In Frontiers in Conservation Science
2021	Sex differences in response to environmental and social breeding cues in an amphibian Published In Behaviour
2020	An experimental test of the genetic consequences of population augmentation in an amphibian Published In Conservation Science and Practice
2020	Carotenoid supplementation affects the post-hibernation performance of southern corroboree frogs Published In Behaviour
2020	Do dietary carotenoids improve the escape-response performance of southern corroboree frog larvae? Published In Behaviour
2020	Nest site selection in a terrestrial breeding frog: interrelationships between nest moisture, pH and male advertisement Published In Animal Behaviour
2020	The effect of injection and topical application of hCG and GnRH agonist to induce sperm-release in the roseate frog, Geocrinia rosea Published In Conservation Physiology
2019	Dietary carotenoids affect the development of individual differences and behavioral plasticity Published In Behavioral Ecology
2019	Effect of carotenoid class and dose on the larval growth and development of the critically endangered southern corroboree frog Published In Conservation Physiology
2019	Female choice for related males in wild red-backed toadlets (Pseudophryne coriacea) Published In Behavioral Ecology
2019	Genetic benefits of extreme sequential polyandry in a terrestrial-breeding frog Published In Evolution
2019	Hormone-induced sperm-release in the critically endangered Booroolong frog (Litoria booroolongensis): Effects of gonadotropin-releasing hormone and human chorionic gonadotropin Published In Conservation Physiology
2019	Sperm collection and storage for the sustainable management of amphibian biodiversity Published In Theriogenology
2019	The Role of Reproductive Technologies in Amphibian Conservation Breeding Programs Published In Annual Review of Animal Biosciences
2018	Animal personality and behavioral syndromes in amphibians: a review of the evidence, experimental approaches, and implications for conservation Published In Behavioral Ecology and Sociobiology
2018	Dose and life stage-dependent effects of dietary beta-carotene supplementation on the growth and development of the Booroolong frog Published In Conservation Physiology
2018	Effect of long-term dietary beta-carotene supplementation on sperm concentration and motility in an endangered amphibian Published In Animal Reproduction Science
2018	Hormone-induced spawning of the critically endangered northern corroboree frog Pseudophryne pengilleyi Published In Reproduction Fertility and Development
2018	The unexpected genetic mating system of the red-backed toadlet (Pseudophryne coriacea): A species with prolonged terrestrial breeding and cryptic reproductive behaviour Published In Molecular Ecology
2017	Body size predicts between-individual differences in exploration behaviour in the southern corroboree frog Published In Animal Behaviour
2017	Dietary carotenoid supplementation enhances the cutaneous bacterial communities of the critically endangered southern corroboree frog (Pseudophryne corroboree) Published In Microbial Ecology: an international journal
2017	Sperm motility activation in the critically endangered booroolong frog: the effect of medium osmolality and phosphodiesterase inhibitors Published In Reproduction Fertility and Development
2017	Testing the effect of dietary carotenoids on larval survival, growth and development in the critically endangered southern corroboree frog Published In Zoo Biology
2017	The effect of antioxidants on sperm motility activation in the Booroolong frog Published In Animal Reproduction Science
2017	The effect of dietary antioxidants and exercise training on the escape performance of Southern Corroboree frogs Published In Behavioural Processes
2017	The effect of gentamicin on sperm motility and bacterial abundance during chilled sperm storage in the Booroolong frog Published In General and Comparative Endocrinology
2016	Dietary carotenoid supplementation improves the escape performance of the southern corroboree frog Published In Animal Behaviour
2016	Dietary carotenoids change the colour of Southern corroboree frogs Published In Biological Journal of the Linnean Society
2016	Planning for ex situ conservation in the face of uncertainty Published In Conservation Biology
2016	The influence of carotenoid supplementation at different life-stages on the foraging performance of the Southern Corroboree frog (Pseudophryne corroboree): a test of the Silver Spoon and Environmental Matching Hypotheses Published In Behavioural Processes
2015	Antibiotics and oxygen availability affect the short-term storage of spermatozoa from the critically endangered booroolong frog, Litoria booroolongensis Published In Reproduction Fertility and Development
2015	Environmental osmolality influences sperm motility activation in an anuran amphibian Published In Journal of Evolutionary Biology
2013	Artificial fertilisation in a terrestrial toadlet (Pseudophryne guentheri): effect of medium osmolality, sperm concentration and gamete storage Published In Reproduction Fertility and Development
2013	Emerging trends for biobanking amphibian genetic resources: the hope, reality and challenges for the next decade Published In Biological Conservation
2012	Investigating patterns in the spermiation response of eight Australian frogs administered human chorionic gonadotropin (hCG) and luteinizing hormone-releasing hormone (LHRHa) Published In General and Comparative Endocrinology
2011	Effect of priming injections of luteinizing hormone-releasing hormone on spermiation and ovulation in Gϋnther's Toadlet, Pseudophryne guentheri Published In Reproductive Biology and Endocrinology
2010	Effects of luteinizing hormone-releasing hormone and arginine-vasotocin on the sperm-release response of Günther's Toadlet, Pseudophryne guentheri Published In Reproductive Biology and Endocrinology
2010	Hormone induction of gamete release and In-vitro fertilization in the critically endangered corroboree frog Published In Reproductive Biology and Endocrinology

Book

Year	Title
2022	Reproductive Technologies and Biobanking for the Conservation of Amphibians

Presentations

Invited Talk
- The role of reproductive technologies in amphibian conservation breeding programs, Symposium Lead; Speaker, World Congress of Herpetology (WCH9) 2020
- Effect of priming injections of luteinizing hormone-releasing hormone on spermiation and ovulation in Gϋnther’s Toadlet, Pseudophryne guentheri, Speaker, Joint Meeting of Ichthyologists and Herpetologists 2011
Presentation
- Dietary carotenoid supplementation enhances the cutaneous bacterial communities of the critically endangered Southern Corroboree Frog, Speaker, International Congress of Conservation Biology 2017
- Investigating patterns in the spermiation response of Australian frogs to hCG and LHRHa, Speaker, Australian Society of Herpetologists 2013

Investigator On

Year	Title
2018 - 2021	Let them eat Carotenoids: boosting corroboree frog immunity Awarded by: NSW Environmental Trust Funding Scheme: Environmental Research Program
2012	Assisted reproductive technologies (ART) for frog conservation Awarded by: NSW Environmental Trust Funding Scheme: Environmental Research Program
	Using evolutionary theory to advance reproductive technologies Awarded by: Australian Research Council (ARC) Funding Scheme: Discovery Early Career Researcher Award (DECRA)

Other Research Activities

Zoo Aquarium Association (ZAA), Wildlife Conservation Fund Chief Investigator 2020 - 2023

Impact Story

Hormones help critically endangered frogs get in the mood to breed
Summary
Research led by Dr Aimee Silla and Dr Phillip Byrne at the University of Wollongong (UOW) has enabled the generation of hundreds of offspring of the critically endangered Northern Corroboree Frog, using hormone application to induce reproduction. Although the northern corroboree frog has been bred successfully in captivity for a number of years, captive populations display strong mating bias with less than a third of available males contributing to mating success annually. Over time, such captive mating biases may lead to a loss of genetic variation and adaptive potential that could compromise long-term re-introduction success. In an attempt to boost breeding success and increase the genetic diversity of offspring, reproductive biologists Silla and Byrne teamed up with Michael McFadden from Taronga Conservation Society Australia to trial the use of hormone-induced breeding protocols to assist the genetic management of the species. The reproductive hormone GnRH-a was administered to male and female Corroboree frogs prior to putting pairs in breeding tanks. The hormones help encourage the frogs to mate, getting them in the right ‘mood’ for courtship and reproduction. Overall, in excess of 800 viable eggs have generated using hormone-assisted breeding techniques over the past four years. Offspring of different developmental stages (eggs, tadpoles and juvenile frogs) have been released into natural sites in the Northern Brindabella Ranges by herpetofauna experts from UOW and Taronga Zoo. The research has been conducted with the support of Senior Threatened Species Officer Dr David Hunter from NSW Office of Environment and Heritage (OEH), who oversees the recovery program for Corroboree frogs. In a world first, our team has also effectively applied the reproductive hormones topically to the abdomen of the frogs. Amphibians have highly permeable skin, so we were able to administer the hormones non-invasively. Topical application of reproductive hormones eliminates the need for specialised training in amphibian injection, which has been one of the main reasons that reproductive technologies have not yet been widely adopted by captive facilities, particularly in developing countries. We hope that by developing user-friendly, cost-effective methods for hormone application will lead to more captive facilities using hormone treatment to boost the breeding success of endangered frogs, particularly in developing countries within Neotropical, Afrotropical and Indomalayan regions (collectively harbouring >82% of rapidly declining amphibians).

Detail View

Detail View Summary View
Detail of Impact
An insurance colony was established for the northern corroboree frog at Tidbinbilla Nature Reserve in the ACT, following the annual collection of fertilised eggs from wild populations between 2003 and 2008. Since then, a substantial number of animals have been transferred to Taronga Zoo and a collaborative captive breeding and reintroduction program has been established from a partnership between the two captive institutions and the NSW Office of Environment and Heritage (OEH) (<a href="display/aimee_silla#_ENREF_6" target="_blank" rel="noopener">McFadden et al., 2016</a>). Captive breeding protocols have been established for the northern corroboree frog, with the first viable clutch of eggs laid in captivity in 2008. As with its sister species the southern corroboree frog (Pseudophryne corroboree) key requirements for achieving successful breeding of this species include adequate temperature cycling that incorporates a winter cooling period prior breeding, and the provision of large breeding tanks containing multiple males to allow for female mate-choice (<a href="display/aimee_silla#_ENREF_5" target="_blank" rel="noopener">McFadden et al., 2013</a>). Incorporating assisted reproductive technologiesAlthough the northern corroboree frog has been bred successfully in captivity for a number of years, captive populations display strong mating bias with less than a third of available males contributing to mating success annually. The natural mating system of this species has similarly been shown to exhibit strong mating bias toward a small number of male individuals, so this mating pattern is not unique among captive populations. However, over time, such captive mating biases may lead to a loss of genetic variation in the offspring generated for re-introduction. Between 2014 and 2016, experimental trials were conducted as part of a strategic research collaboration between the University of Wollongong and Taronga Conservation Society Australia, employing hormone-induced spawning protocols to assist the genetic management of the species. Hypothalamic hormones, administered via a single injection, were used to induce spawning in isolated male-female pairs housed together in small aquaria. Hormone administration significantly improved the number of pairs producing viable embryos and total egg number (<a href="https://www.publish.csiro.au/rd/rd18011" target="_blank" rel="noopener">Silla et al., 2018</a>). Overall, in excess of 800 viable eggs (from 37 clutches) were generated using ART over the past four years, which were subsequently released into natural sites in the Northern Brindabella Ranges. Following on from initial experiments, in 2017 our research team developed successful techniques for the topical application of reproductive hormones to induce breeding in the northern corroboree frog in order to further improve animal welfare, and allow ART technologies to be more widely adopted by amphibian captive breeding facilities nationally. Incorporating ARTs into existing conservation breeding programs has a number of potential benefits, including: 1) enhanced species propagation, 2) synchronisation of breeding events, 3) increased genetic diversity and adaptive potential of the offspring generated, and 4) better control over breeding designs, including an opportunity for selective breeding of particular genotypes. As a result, ARTs are being increasingly employed by captive facilities to compliment traditional breeding methods and enhance species recovery. Research article available at: <a href="https://www.publish.csiro.au/rd/rd18011" target="_blank" rel="noopener">https://www.publish.csiro.au/rd/rd18011</a> 
Field of Research
Countries / Regions
Beneficiaries

Beneficiary Quantification Description
External Partners
Evidence of Impact

Evidence Description
UOW Centres / Programs
UOW Researchers / Collaborators

Potential Supervision Topics

- Eating to fuel fertility: Investigating the influence of female nutrition on yolk provisioning, egg quality and offspring fitness in Australian myobatrachid frogs
- Investigating sperm trait evolution, sperm-egg interactions and genetic incompatibility to improve artificial fertilisation success in Australian hylid frogs
- Investigating whether frogs show local adaptation or phenotypic plasticity in sperm traits, and whether knowledge of these adaptions can improve the success of artificial fertilisation

Advisees

Graduate Advising Relationship

Degree	Research Title	Advisee
Doctor of Philosophy	The Influence of Temperature on the Growth, Development and Fitness of the Endangered Baw Baw Frog	Gilbert, Deon
Doctor of Philosophy	Improving the Output of Australian Ex-Situ Conservation Breeding Programs for Threatened Amphibian Recovery	McFadden, Michael
Doctor of Philosophy	Investigating proximate mechanisms underpinning behaviour to improve captive management and reintroduction of the critically endangered Southern Corroboree Frog (Pseudophryne corroboree)	Walton, Sara

Education And Training

Doctor of Philosophy, School of Animal Biology, Development and application of assisted reproductive technologies for the conservation of anuran amphibians 2013
B Science (Hon) in Environmental Science (Zoology; Land and Water Management), School of Animal Biology, Effect Of Cattle Grazing On Benthic Macroinvertebrate Communities In The Kalgan River System, south-west Western Australia 2007

Awards And Honors

Perth Zoo Prize for Conservation Research, conferred by Perth Zoo, 2012
WA Young Person of the Year, conferred by WA Youth Awards, Youth Affairs Council, 2007
Luke Pen Scholarship, conferred by Department of Water, 2006

Keywords

Herpetology, amphibian, conservation, threatened species, reproduction, assisted reproductive technologies, gamete, IVF, sperm

Orcid Id

http://orcid.org/0000-0002-2277-9030 (confirmed)

Overview

Top Publications

Research Areas

Research Overview

Affiliation

Member Of

Has Collaborator

Publications

Selected Publications

Journal Article

Book

Presentations

Invited Talk

Presentation

Funding

Investigator On

Other Research Activities

Impact

Impact Story

Hormones help critically endangered frogs get in the mood to breed

Supervision

Potential Supervision Topics

Advisees

Graduate Advising Relationship

Background

Education And Training

Awards And Honors

Keywords

Identity

Orcid Id

Overview

Top Publications

Research Areas

Research Overview

Affiliation

Member Of

Has Collaborator

Publications

Selected Publications

Journal Article

Book

Presentations

Invited Talk

Presentation

Funding

Investigator On

Other Research Activities

Impact

Impact Story

Hormones help critically endangered frogs get in the mood to breed

Supervision

Potential Supervision Topics

Advisees

Graduate Advising Relationship

Background

Education And Training

Awards And Honors

Keywords

Identity

Orcid Id

Visualisations

Research Areas