Document ID: chunk:federal_register_of_legislation:F2022L00555:body:0:p61
Version: federal_register_of_legislation:F2022L00555
Segment Type: other
Provision Reference: 
Character Range: 192880–195890

Indeed, Koalas do not appear to exhibit inbreeding avoidance behaviour, a characteristic thought to making them vulnerable to inbreeding (Schultz et al. 2020), although they do appear to exhibit mate choice based on genetic variation at the MHC region (Brandies et al. 2018). Inbreeding increases the probability of homozygosity and the likelihood of the accumulation of recessive deleterious alleles, inbreeding depression and the reduction of population viability (Bouzat 2010; Charlesworth and Charlesworth 1999; Hedrick and Fredrickson 2010; Schultz et al. 2020), although this is not always found to be the case in wild populations (Milot et al. 2007).
Studies into genetic structuring within and between populations of the Koala have provided insights into social structuring within a locality (Thompson 2006), inbreeding (Seymour et al. 2001; Johnson et al. 2018), immunity (Lau et al. 2014; Johnson et al. 2018), bottlenecks and patterns of movement (Thompson 2006; Norman et al. 2019) and therefore is a valuable tool for conservation of the listed Koala.
Levels of inbreeding vary across regions and is more prevalent in the southern unlisted populations (Houlden et al. 1996; Johnson et al. 2018) that have experienced sequential translocation events (Menkhorst 2008). Fortunately, although listed Koala populations are under threat from habitat loss and fragmentation (TSSC 2012a; 2012b; DERM 2009), high levels of contemporary genetic diversity exist within many of these populations (Houlden et al. 1996; Johnson et al. 2018; Kjedlen et al. 2016; Thompson 2006). Nevertheless, genetic evidence indicates that fragmentation of habitat is impacting heterozygosity within populations (Thompson 2006) and presenting an impediment to gene flow (Thompson 2006) noting; however, genetic studies have not been undertaken in large areas of the Koala's range. Strategies to maintain linkages in populations threatened by habitat loss and fragmentation, such as revegetation or genetic augmentation, are required to mitigate potential adverse genetic affects in these landscapes.

20.4 Genetic effects and disease
Genetic diversity is one important factor linked to the ability of individuals to survive with, and/or recover, from disease events. Immune genes are some of the most genetically diverse gene families as they evolve under pathogen pressure. Marsupials, including Koala, have a complex immune system (Belov et al. 2013) and have high genetic diversity at the major histocompatibility complex (MHC), one of the most studied immune gene families, due to its direct role in disease resistance. Recent work has indicated a role for the MHC in resistance to Chlamydia (Cheng et al. 2018; Jobbins et al. 2012; Lau et al. 2014; Johnson et al. 2018; Robins et al. 2020) but evidence identifying particular resistance or susceptibility alleles is equivocal. Other immune gene families also contribute to disease resistance and new target capture methods which can characterise thousands of genes at once