Tag Archives: Tasmanian Devils

Reinforcements in the face of ongoing threats: A case study from a critically small carnivore population

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Type: Journal Article

Reference: McLennan, E.A., Cheng, Y., Farquharson, K.A., Grueber, C.E., Elmer, J., Alexander, L., Fox, S., Belov, K. and Hogg, C.J., 2024. Reinforcements in the face of ongoing threats: a case study from a critically small carnivore population. Animal Conservation. https://doi.org/10.1111/acv.12945

Abstract

Reinforcements are a well-established tool for alleviating small population pressures of inbreeding and genetic diversity loss. Some small populations also suffer from specific threats that pose a discrete selective pressure, like diseases. Uncertainty about reinforcing diseased populations exists, as doing so may increase disease prevalence and disrupt potential adaptive processes. However, without assisted gene flow, isolated populations are at high risk of extinction. Tasmanian devils (Sarcophilus harrisii) are a useful case study to test whether reinforcements can alleviate small-population pressures where there is an ongoing disease pressure. We investigated demographic, genome-wide and functional genetic diversity, and disease consequences of reinforcing a small population (<20 animals) that was severely impacted by devil facial tumour disease. Released animals from one source population successfully bred with incumbent individuals, tripling the population size, improving genome-wide and functional diversity and introducing 26 new putatively functional alleles, with no common alleles lost and no increase in disease prevalence. Results suggest, in the case of Tasmanian devils, reinforcements can alleviate small-population pressures without increasing disease prevalence. Because no common functional alleles were lost, it is likely that any adaptive processes in response to the disease may still occur in the reinforced population, perhaps even with greater efficiency due to reduced genetic drift (due to larger population size). Our study is presented as a comprehensive worked example of the IUCN’s guidelines for monitoring reinforcements, to showcase the value of genetic monitoring in a richly monitored system and provide realistic approaches to test similar questions in other taxa.

Tasmanian devil (Sarcophilus harrisii) gene flow and source-sink dynamics

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Type: Journal Article

Reference: Schraven, A. L., Hogg, C. J., & Grueber, C. E. (2024). Tasmanian devil (Sarcophilus harrisii) gene flow and source-sink dynamics. Global Ecology and Conservation, 52, e02960. https://doi.org/10.1016/j.gecco.2024.e02960

Abstract

Increased access to genetic data has substantially improved how we manage threatened species. The Tasmanian devil (Sarcophilus harrisii) is listed as endangered due to the ongoing threat of a highly contagious cancer, devil facial tumour disease (DFTD), causing more than 80% population reductions. To assist future management interventions (e.g. releases into wild sites) we expanded upon previous studies of gene flow for the devil by assessing more recent and broad-scale patterns. We use genome-wide single nucleotide polymorphisms generated via DArTSeq across 21 devil sites to delineate source-sink dynamics across the species’ range. Our findings revealed gene flow is stronger on the northeast and central regions of Tasmania, with high rates of bidirectional gene flow among central sites. The northwest exhibits weaker connectivity relative to other regions of Tasmania, while gene flow appears to be non-existent between the southwest and other areas. Northeast coastal sites tend to serve as ‘sources’ for inland central sites, whereas gene flow appears restricted to the coastline in the northwest. These results are consistent with genetic structure of devil sites and spatial spread of DFTD, which has yet to arrive in the southwest region of Tasmania. Southwest isolation is probably due to mountain ranges and lack of roadways. Interestingly, some waterbodies did not appear to restrict devil movement among sites. Conversely, areas of high elevation act as apparent barriers, as evidenced by limited gene flow observed between eastern and western sites. Integrating source-sink dynamics into conservation management planning will be crucial in developing effective strategies to safeguard the Tasmanian devil and other threatened species facing similar threats (i.e. disease, habitat loss).

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IT’S MOVING DAY: Threatened Species Edition

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by Andrea Achraven (PhD Student)

Moving house, city, or country always has its challenges, from adapting to a new environment to establishing connections with unfamiliar neighbours. For threatened species, the concept of moving from one area to another is no less daunting.

However, in the realm of conservation management, ‘moving day’ can be the difference between survival and extinction of endangered animals. Translocations are defined as the “intentional movement of living organisms from one are to another” by the International Union for Conservation of Nature (IUCN), and they represent a strategic effort to give struggling species a fighting chance.

Translocations come in many forms, each serving a unique purpose in species conservation management:

  • Re-introduction involves moving individuals back in areas where they use to exist but have disappeared, thereby giving them a second chance to thrive in their historical habitat.
  • Reinforcements help already existing populations of a species that are currently struggling by moving in additional individuals from another population to boost their chances of persisting.

Assisted Colonisations will introduce a species to a new and suitable habitat where they can establish themselves, often occurring when a species is unable to survive in its original habitat.

Releasing Tasmanian Devil on Maria Island, Australia. © Luke Silver

Deciding on where to move a species to is more than just merely picking the best house in the neighbourhood. Managers of a species must carefully consider numerous factors when choosing their new home. This includes evaluating the availability of resources, identifying potential threats that may jeopardize long term sustainability, and understanding behavioural dynamics such as competition among individuals.

Moreover, determining the effectiveness of translocations necessitates continued monitoring and assessment after the release. Population viability in the long term requires documenting a translocated individual’s ability to acclimate to their new environment and monitoring their survival. Additionally, managers need to monitor the reproductive output and analyse population growth trends to determine if the population is sustainable, or if continued interventions are required.

So next time you here about a species being relocated or released into the wild, remember – it’s not just a new home, but a translocation that could be a potential lifeline for the survival of an entire species.

Author

Andrea Schraven (PhD Student; co-supervised with Dr Catherine Grueber) is projecting the long-term impacts of supplementation to improve the status of wild Tasmanian devil populations with the ongoing threat of DFTD. By evaluating population genetic and fitness data before and after translocations, she is comparing how populations change over a few generations, and then feeding the data into computational models to simulate “evolutionary time”. The results will directly inform conservation management decisions for the species long-term recovery.

Andrea_Schraven

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How to catch a Tasmanian devil

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by Dr Elspeth McLennan (Post-doc)

Tasmanian devils are nocturnal. We set traps during the day and overnight curious devils will come to investigate. The traps we use are made of strong PVC plastic fashioned into a cylinder with a spring trap door (see cover picture). The traps are baited with a devil’s favourite treat, a piece of fresh lamb or wallaby. The meat is tied onto the end of a string, fed through the trap, and tied to a pin which holds the door open.

Tasmanian devil inside trap

When a devil comes investigating the smell of the meat, they walk to the end of the trap and take the bait. When the meat is pulled and eaten, the pin holding the door open is pulled free and the door swings shut. A second pin slides forward as the door closes and locks it. Devils spend the night in a cosy enclosed space with a full belly. The field biologists begin checking the traps as soon as the sun is up. As its daylight, we often find devils snoozing in their traps.

To perform a health check on the devil, we place a hessian sack over the opening of the trap, gently tilt the trap and the devil slides forward into the sack. The sack is used to keep the devil’s eyes covered to keep them calm making them easier to handle while we check them over. We take their weight, check their body condition, look for wounds and record pouch young in females. For populations suffering from devil facial tumour disease (DFTD), the disease status of each animal is also recorded. Once the devil has been processed, they are released. On a single trapping trip, we will often see the same devils a few times. The free food and somewhere to crash is clearly a good draw.

Author

Dr Elspeth McLennan

Dr Elspeth McLennan (Post-doc) is working the on the Koala Genome Survey, investigating both neutral and functional diversity across the koala’s range to better understand the impacts of a changing climate. Elspeth has expertise in conservation genetics and using translocation and assisted colonisations as a conservation management tool.

@ellemclennan

Tasmanian devil cathelicidins exhibit anticancer activity against Devil Facial Tumour Disease (DFTD) cells

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Type: Journal Article

Reference: Petrohilos, C., Patchett, A., Hogg, C.J. et al. Tasmanian devil cathelicidins exhibit anticancer activity against Devil Facial Tumour Disease (DFTD) cells. Science Report 13, 12698 (2023). doi: 10.1038/s41598-023-39901-0

Abstract

The Tasmanian devil (Sarcophilus harrisii) is endangered due to the spread of Devil Facial Tumour Disease (DFTD), a contagious cancer with no current treatment options. Here we test whether seven recently characterized Tasmanian devil cathelicidins are involved in cancer regulation. We measured DFTD cell viability in vitro following incubation with each of the seven peptides and describe the effect of each on gene expression in treated cells. Four cathelicidins (Saha-CATH3, 4, 5 and 6) were toxic to DFTD cells and caused general signs of cellular stress. The most toxic peptide (Saha-CATH5) also suppressed the ERBB and YAP1/TAZ signaling pathways, both of which have been identified as important drivers of cancer proliferation. Three cathelicidins induced inflammatory pathways in DFTD cells that may potentially recruit immune cells in vivo. This study suggests that devil cathelicidins have some anti-cancer and inflammatory functions and should be explored further to determine whether they have potential as treatment leads.

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My Favorite Culture Shock: Australia’s Wildlife

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by Meadhbh Molloy (PhD Student)

I remember when I learned about the Tasmanian devil and DFTD in my Conservation Medicine textbook as a new master’s student in Virginia, USA. Since I was a child, I loved learning about different animals from all over the world but admittedly, I did know little about the Tasmanian devil. I was inspired by the many amazing researchers that were working on their conservation. I kept thinking about the Tasmanian devil throughout my master’s program and thought that maybe…I can go to Australia…and research Tasmanian devils as well for my PhD (I remember my first Zoom meeting with Carolyn…I was so excited!). After many more Zoom meetings, proposal drafts, a scholarship offer (thank you American Australian Association!), and a pandemic, I finally arrived in Sydney in August 2022. While I was eagerly looking forward to the first time I would see a Tasmanian devil, I have some honorable mentions of the other wildlife I have seen.

The mammals. This is my favorite taxonomic group, so I was most excited to see the mammals of Australia. I’ve seen potoroos scampering about, fruit bats flying at dusk, koalas at a sanctuary in Brisbane, an echidna crossing the road near Royal National Park, and of course the iconic kangaroo grazing right by my camping site in Jervis Bay. The Virginia opossum is our only native marsupial in North America. I was delighted to see brushtail possums (the arguably cuter cousin) in trees and sidewalks in the city, and digging through our food while camping. We also have a mammal that likes to dig through our stuff at campsites- the American black bear. It’s ok! You can put all your food up in a “bear bag” and it (mostly) helps.

The spiders. When I was researching my move to Australia, I came across a blog post titled “Every American remembers their first huntsman spider”. I thought “oh, well I’ll be in a city, they probably don’t get that big, assuming they are even there!”. Wrong. Listen, I appreciate spiders and their ecological role. I know they are probably “more scared of me than I am of them”. That does not mean I was calm and collected when I saw my first huntsman on the bathroom floor. Back at home we have big spiders (mainly wolf) that roam around, but they are no match for a huntsman’s speed! While I’m still a little scared of spiders, my definition of what a large spider is has certainly changed.

All the birds! It’s hard to pick a favorite Australian bird, but I would have to go with the kookaburra (even though one stole the sausage right out of my hands at a barbecue). The first time I heard one, it was 5:30am and I thought a monkey was outside my apartment window. We also don’t have wild parrots where I am from, so my phone is now filled with photos of beautiful white cockatoos and rainbow lorikeets. I remember going on a walk around my new neighborhood within the first few days of arriving. I saw a magnificent bird and told my roommate, Kimberley, about it when I returned. The bird had long legs, a beautifully contrasting white and black body, and was strutting around a park. Upon showing her a photo she said “oh yeah, a bin chicken”.  A bin chicken? Not the nicest name. I now understand why they are called that.

I’ve seen many other amazing animals while traveling around Australia, including saltwater crocodiles near Port Douglas, stunning marine life while snorkeling at the Great Barrier Reef, and even a camel when I visited Uluru (it was well-timed that I read “Tracks” by Robyn Davidson before my trip). I happened to feel particularly homesick when I went to Taronga Zoo on a nice spring day, only a couple months after I landed in Sydney. I arrived at the enclosure that I was most excited to see. I have waited a long time to come to Australia, and The Tasmanian devil has morphed from being the topic of one of my research chapters, to being a symbol of resilience and patience for my entire PhD. Immediately, the Tasmanian devil got up from a shady spot and walked across the enclosure to lie down in front of me. Did this little devil know it would be the first devil I would see in person, and knew the weight of this moment? Obviously not, it just wanted to sunbathe. Of all the animals I have seen so far, the Tasmanian devil remains to be my favorite. I look forward to seeing more of Australia’s wildlife before I return to the United States.

Author

Meadhbh Molloy (PhD Student) is characterising the gut microbiome profile of Tasmanian devils at multiple locations across Tasmania

@MeadhbhMolloy

Assisted Colonisation as a Conservation Tool: Tasmanian Devils and Maria Island

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Type: Book Chapter

Reference: Hogg, C., & Wise, P. (2022). Assisted Colonisation as a Conservation Tool: Tasmanian Devils and Maria Island. In M. Gaywood, J. Ewen, P. Hollingsworth, & A. Moehrenschlager (Eds.), Conservation Translocations (Ecology, Biodiversity and Conservation, pp. 476-483). Cambridge: Cambridge University Press. doi:10.1017/9781108638142.029

Summary

Tasmanian devils are endangered due to an infectious clonal cancer that has reduced populations by up to 80 per cent since it first arose in 1996. As part of a management strategy for the species, an island population was established through an assisted colonisation event on Maria Island
National Park. The original scope of the Maria Island population was to establish and maintain a disease-free population of devils. The island is now used as a source site for these trial releases of devils to mainland Tasmania populations. The 2012 release cohort to the island had a high degree of relatedness. However, through dedicated management strategies, including contraception and selective harvesting, this situation has been rectified and the Maria Island population now represents a genetically diverse group. Monitoring, using traditional methods of trapping and camera traps, in addition to genetic monitoring, has been essential to the establishment and maintenance of the Maria
Island population.

See all our publications HERE!

Conversations That Matter: Can genomics save the ‘devil’

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For the past 12 years, Dr. Carolyn Hogg has been working with the Save the
Tasmanian devil Program utilizing genomics as a vital tool to save this
endangered marsupial. Carolyn joined a Conversation That Matters about the role genomics is playing in an all-out effort to save the Tasmanian devil.

Listen to the whole interview here: https://vancouversun.com/news/conversations-that-matter-can-genomics-save-the-devil