Koala reproductive science for conservation

With over 80 koala-focused journal articles and book chapters, Associate Professor Steve Johnston’s research is helping build the reproductive tools needed to safeguard koalas into the future.

His work brings together reproductive anatomy, physiology, behaviour, sperm biology, veterinary pathology, and conservation genetics to answer one practical question: how can we better protect koala fertility and preserve genetic diversity in threatened populations?

Research topics

From reproductive biology to conservation action

Successful conservation breeding begins with a detailed understanding of how a species reproduces. Professor Johnston’s research has mapped key aspects of koala reproductive biology, including female oestrous cycles, induced ovulation, pregnancy, reproductive hormones, male semen characteristics, and sperm function. This foundational knowledge has supported the development of assisted breeding techniques for koalas, including semen collection, sperm storage, cryopreservation, and artificial insemination. His team helped achieve the first birth of a marsupial pouch young following artificial insemination and has continued to refine this technology for koala conservation and genetic management.

Protecting fertility and genetic diversity

A major focus of the research is the development of reliable methods to collect, assess, preserve, and use koala sperm. This includes investigating how chilled storage and freezing affect sperm survival, chromatin stability, mitochondrial function, and DNA integrity. These studies are essential for genome banking: safely storing reproductive cells for future breeding programmes, genetic exchange between isolated populations, and potential recovery of valuable genetic material from animals that cannot otherwise breed.

Addressing disease-related infertility

Chlamydial disease is a major threat to koala health and reproduction. Professor Johnston’s research examines how Chlamydia pecorum affects the male and female reproductive systems, including sperm quality, testicular function, reproductive-tract pathology, and fertility. By clarifying the reproductive consequences of disease, this work supports better clinical care, more informed breeding decisions, and the future rescue of gametes from affected koalas for conservation purposes.

Building the next generation of conservation tools

Current research also investigates koala reproductive anatomy, ovarian function, prostate biology, sperm DNA quality, reproductive hormones, and opportunities for oocyte recovery and advanced embryo technologies.

Together, these projects aim to create a practical conservation toolkit that can support zoos, wildlife hospitals, government agencies, and recovery programmes. The goal is not simply to understand koala reproduction, but to use that knowledge to strengthen the long-term resilience of koala populations.

Researcher