The koala gut microbiome is largely unaffected by host translocation but rather influences host diet

Abstract

IntroductionTranslocation is a valuable and increasingly used strategy for the management of both threatened and overabundant wildlife populations. However, in some instances the translocated animals fail to thrive. Differences in diet between the source and destination areas may contribute to poor translocation outcomes, which could conceivably be exacerbated if the animals’ microbiomes are unsuited to the new diet and cannot adapt.MethodsIn this study we tracked how the faecal microbiome of a specialist Eucalyptus folivore, the koala (Phascolarctos cinereus), changed over the course of a year after translocation. We assessed microbiome composition by 16S rRNA amplicon sequencing of faecal pellets.ResultsWe found no significant overall changes in the faecal microbiomes of koalas post-translocation (n = 17) in terms of microbial richness, diversity or composition when compared to the faecal microbiomes of koalas from an untranslocated control group (n = 12). This was despite the translocated koalas feeding on a greater variety of Eucalyptus species after translocation. Furthermore, while differences between koalas accounted for half of the microbiome variation, estimated diets at the time of sampling only accounted for 5% of the variation in the koala microbiomes between sampling periods. By contrast, we observed that the composition of koala faecal microbiomes at the time of translocation accounted for 37% of between koala variation in post-translocation diet. We also observed that translocated koalas lost body condition during the first month post-translocation and that the composition of the koalas’ initial microbiomes were associated with the magnitude of that change.DiscussionThese findings suggest that the koala gut microbiome was largely unaffected by dietary change and support previous findings suggesting that the koala gut microbiome influences the tree species chosen for feeding. They further indicate that future research is needed to establish whether the koalas’ gut microbiomes are directly influencing their health and condition or whether aspects of the koala gut microbiomes are an indicator of underlying physiological differences or pathologies. Our study provides insights into how animal microbiomes may not always be affected by the extreme upheaval of translocation and highlights that responses may be host species-specific. We also provide recommendations to improve the success of koala translocations in the future.

Association of maternal genetics with the gut microbiome and eucalypt diet selection in captive koalas

“…In general, the abundance and composition of the gut microbiome varies in response to dietary changes ( Scott et al, 2013 ). However, the koala gut microbiome has been reported to be stable within individuals ( Eisenhofer et al, 2023 ) and does not change significantly in response to dietary changes ( Blyton et al, 2019 ; Blyton et al, 2023 ). Furthermore, there is a report that geographic distance of habitat has an influence on the similarity of the gut microbiome of wild koalas ( Littleford-Colquhoun et al, 2022 ).…”

What Can the Gut Microbiota of Animals Teach Us about the Relationship between Nutrition and Burden of Lifestyle Diseases?

“…This suggests that the koalas can find suitable diets in the new habitat without necessitating significant microbiome adaptations. Consequently, it is proposed that the gut microbiomes of koalas are primarily shaped by their acquisition and development throughout their lives, with subsequent dietary changes exerting a comparatively minor influence [ 83 ].…”

Gut Microbiome Profiling of the Endangered Southern Greater Glider (Petauroides volans) after the 2019–2020 Australian Megafire

“…In July 2022, the species was uplisted to endangered under the National Environment Protection and Biodiversity Conservation Act 1999, citing rapid population declines and critical habitat destruction after the 2019-2020 Australian bushfire season as evidence that the species is now a conservation priority [14]. The koala is another arboreal herbivore that shares a similar Eucalyptus-centric diet, for which the gut microbiome has been well characterised [15][16][17][18][19][20]. Dietary differences caused by differential consumption of the foliage of different Eucalyptus sp.…”

“…High-throughput, short-read sequencing of 16S based on the Illumina MiSeq platform is designed to specifically target the V3-V4 region and offers high taxonomic resolution at a reduced cost compared to other next-generation sequencing platforms [23]. In the context of Australian marsupials, previous work has focused on using 16S sequencing to characterise gut microbiota of select members of the Dasyuridae [24][25][26], Vombatidae [17,27] and Phascolarctidae [15][16][17][18]20]. However, the gut microbiome has yet to be formally investigated through 16S sequencing in the Pseudocheiridae family, which includes all extant greater gliders and ringtail possums.…”