Pouch young removal and return to oestrus in wild southern hairy-nosed wombats (Lasiorhinus latifrons)

Host reproductive cycle influences the pouch microbiota of wild southern hairy-nosed wombats (Lasiorhinus latifrons)

Background

Marsupials are born much earlier than placental mammals, with most crawling from the birth canal to the protective marsupium (pouch) to further their development. However, little is known about the microbiology of the pouch and how it changes throughout a marsupial’s reproductive cycle. Here, using stringent controls, we characterized the microbial composition of multiple body sites from 26 wild Southern Hairy-nosed Wombats (SHNWs), including pouch samples from animals at different reproductive stages.

Results

Using qPCR of the 16S rRNA gene we detected a microbial community in the SHNW pouch. We observed significant differences in microbial composition and diversity between the body sites tested, as well as between pouch samples from different reproductive stages. The pouches of reproductively active females had drastically lower microbial diversity (mean ASV richness 19 ± 8) compared to reproductively inactive females (mean ASV richness 941 ± 393) and were dominated by gram positive bacteria from the Actinobacteriota phylum (81.7–90.6%), with the dominant families classified as Brevibacteriaceae, Corynebacteriaceae, Microbacteriaceae, and Dietziaceae. Three of the five most abundant sequences identified in reproductively active pouches had closest matches to microbes previously isolated from tammar wallaby pouches.

Conclusions

This study represents the first contamination-controlled investigation into the marsupial pouch microbiota, and sets a rigorous framework for future pouch microbiota studies. Our results indicate that SHNW pouches contain communities of microorganisms that are substantially altered by the host reproductive cycle. We recommend further investigation into the roles that pouch microorganisms may play in marsupial reproductive health and joey survival.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42523-021-00074-8.

Scale-dependent habitat analysis and implications for climate change risk for the southern hairy-nosed wombat

Understanding factors determining the distribution of a species is critical for developing strategies and policies in natural resources management. The southern hairy-nosed wombat (Lasiorhinus latifrons) is an excellent model species to examine species distribution patterns because of its conspicuous burrowing behaviour, making it possible to obtain highly accurate distribution maps. The aim of this study was to evaluate the relative importance of biophysical factors impacting on the species’ distribution at regional and continental scales. At the fine scale, we digitised the distribution of individual warrens within a population, whereas at the continental scale we utilised the entire species’ distribution. At the regional level, the strongest predictors of burrowing activity were soil characteristics and geology with little influence of climate. In contrast, at the continental scale, species distribution was most strongly influenced by climatic variables, with most of the distribution located in regions with narrow ranges of mean annual maximum temperature (23−25°C) and mean annual rainfall (200–300 mm). This discrepancy suggests that the species’ distribution is limited to small geographic areas where both a suitable climate and appropriate soil and geology exist and, consequently, that conservation strategies need to adopt a long-term view considering the combined effect of both regional and continental factors.

Recent advances in tools and technologies for monitoring and controlling ovarian activity in marsupials

Components of assisted reproduction technologies (ART), such as sperm cryopreservation, artificial insemination, superovulation and pouch young surrogacy, have been developed for a range of Australian and American marsupials. However, methods to effectively control ovarian function, arguably the key limiting factors in applying and integrating ART as a practical tool in conservation management, remain poorly developed. This is largely due to unique characteristics of the marsupial corpus luteum and its failure to respond to agents used to synchronize ovarian function in eutherian mammals. This paper presents an overview of relevant aspects of marsupial reproductive biology across marsupial taxonomic groups including information on the long-established technique of removal of suckling young to activate ovarian cycles. Ovarian monitoring tools for marsupials are reviewed and their usefulness for ART assessed (laparotomy, hormone cycling, vaginal cytology, laparoscopy and ultrasonography). We also discuss promising recent work examining the potential of manipulating hypothalamic-pituitary function using GnRH agonists and antagonists as the basis of ovarian control (female synchronization) strategies.

Wombat reproduction (Marsupialia; Vombatidae): an update and future directions for the development of artificial breeding technology

This review provides an update on what is currently known about wombat reproductive biology and reports on attempts made to manipulate and/or enhance wombat reproduction as part of the development of artificial reproductive technology (ART) in this taxon. Over the last decade, the logistical difficulties associated with monitoring a nocturnal and semi-fossorial species have largely been overcome, enabling new features of wombat physiology and behaviour to be elucidated. Despite this progress, captive propagation rates are still poor and there are areas of wombat reproductive biology that still require attention, e.g. further characterisation of the oestrous cycle and oestrus. Numerous advances in the use of ART have also been recently developed in the Vombatidae but despite this research, practical methods of manipulating wombat reproduction for the purposes of obtaining research material or for artificial breeding are not yet available. Improvement of the propagation, genetic diversity and management of wombat populations requires a thorough understanding of Vombatidae reproduction. While semen collection and cryopreservation in wombats is fairly straightforward there is currently an inability to detect, induce or synchronise oestrus/ovulation and this is an impeding progress in the development of artificial insemination in this taxon.

Growth and development of the southern hairy-nosed wombat, Lasiorhinus latifrons (Vombatidae)

There are few published studies on breeding and reproduction in hairy-nosed wombats and little information available on growth and development of pouch young. At a field site near Swan Reach in the Murraylands of South Australia morphometric measurements of 353 young southern hairy-nosed wombats and notes on their development were recorded. These data were combined with growth data collected from repeat measures of 10 mother-reared and 5 hand-reared joeys in order to establish information for aging young of this species and to plot developmental changes. Young weighed ~0.4 g at birth and had a head length (HL) of ~5.2 mm. Head length was the most accurate body parameter from which to assess age. Growth of pouch young was linear between birth and ~Day 310 with head length growing at ~0.4 mm HL per day. After Day 300 growth slowed, represented by a polynomial equation. Eyes were open at 5 months and pouch young started to develop fur at 5–6 months of age. Most young were permanently out of pouch at 9 months of age, and were weaned between 11 and 13 months, when they weighed 6–7 kg. Young remained in the burrow for 1–2 months following pouch exit before venturing above ground at night.