We are looking for a highly motivated student who loves field work and is interested in social behaviour and either eco-physiology or ultrasound communication to apply for any of these two PhD projects which are described in detail below:
1. Living in a heated home in a biodiversity hotspot: Lodge ecology of the bush Karoo rat
2. The secret social life of solitary mammals: Ultrasound communication in a mainly solitary rodent, the South African bush Karoo rat
Procedure:
1. The student has to send a motivation letter of 1 page (why you apply for that specific project) and her CV including all her marks and how she was ranked in her masters to carsten.schradin@iphc.cnrs.fr. I will then make interviews and select the best candidate depending on the (1) probability that the student will be invited by the ED for the concours and (2) suitability for the project. See here how to write a proper application: http://dx.doi.org/10.13140/RG.2.2.35829.29927
2. The selected student has to apply at the Ecole Doctorale (ED) des Sciences de la Vie ed de la Sante in Strasbourg for the PhD project submitted by Dr. Carsten Schradin (note: only the project on ultrasound has been submitted, but the topic can change to lodge ecology). http://ed.vie-sante.unistra.fr/sujets-de-these/
For every project offered by the ED (about 60 in total) only one student can apply. The ED will then invite the best 40 students (based on their marks and ranking) for an interview, the concours. The best 20 will then receive a fellowship from the ED to do a PhD for three years. Deadlines:
11th June: Deadline for students to subscribe at the ED
20th June: Deadline to submit marks from the master (24th June for students outside Strasbourg).
25th June: ED selects who to invite to the concours,
8-10 July: Concours
12. July: Results of concours
1. October: Start of PhD
Criteria 1: What is needed from the applicant to be invited to the concours: Ranked within the top 10% of your master (you must be able to show this) and a mark >14, better >15.
Criteria 2: What we expect: Good statistical skills. For project 2, good skills in bioacoustics analyses are essential. High motivation to do field work to understand how free-living mammals cope with their environment. The student is expected to spend 9 months in the field in year one and 6 months in year two. Field work will be done at the Succulent Karoo Research Station: https://www.stripedmouse.com/research-station.html.
For living conditions see:
https://www.stripedmouse.com/uploads/1/4/3/0/143013892/general_information_research_station_aug_2023.pdf
Both criteria must be met to be considered as an applicant.
Living in a heated home in a biodiversity hotspot: Lodge ecology of the bush Karoo rat
Animal architectures, from simple burrows in the ground to complex large nests (Laidre 2021), are often long-lasting and also can have long lasting effects on ecosystem functioning. Understanding the building of refuges that function as extended phenotypes in a social and ecological context is a hot topic in ecology (Laidre 2021; Page & Dechmann 2022; Woods et al. 2021). In particular, the ability to create shelters to test species resilience needs to be understood as it determines species resilience to climate change (Woods et al. 2021). Shelters represent critical resources for individual fitness, so it is important to understand how they are used over time. Interestingly, indirect evidence from dispersal patterns indicates that such shelters might be inherited within matrilines even in solitary species (Onley et al. 2022), but direct observations are needed to confirm this.
The 100g heavy bush Karoo rat (Otomys unisulcatus) is Africa smallest folivore, living in the semi-desert Succulent Karoo, one of the 20 most biodiverse regions globally due to a high number of endemic plant species (Cowling, Esler & Rundel 1999; Myers et al. 2000). It is well-known for collecting plant material and dung from their surroundings to build stick lodges that can be more than 1.5m high and 3m in diameter (Vermeulen & Nel 1988) from which the forage in the surrounding. A few lodges that are currently occupied on our field site were already present at the onset of our long-term field studies in 2001. Thus, we know the minimum age is 2 decades, but some lodges might be much older.
The Succulent Karoo biodiversity hotspot is a winter rainfall area (Allsopp 1999). Thus, winter is the moist season with night temperatures often below freezing, and day temperature ranging between 10 and 25°C. This represents good conditions for decomposition. Bush Karoo rats collect fresh plant material to their lodges in winter, for food and lodge building (Shangweni et al unpubl.). Therefore, winter might represent the period when plant material decomposes at lodges and then enriches the soil. At the same time, this might function as a kind of central heating for bush Karoo rats. As small mammals easily lose body heat (Canals, Rosenmann & Bozinovic 1989), winter temperatures impose high thermoregulatory costs for bush Karoo rats which have the thermoneutral zone at around 28°C (Du Plessis, Erasmus & Kerley 1989). We hypothesize that lodges function as a shelter providing inbuilt heating (from decomposition) during the moist cold winter. If this hypothesis is supported, this would add an important new aspect to our understanding of animal constructions that function as extended phenotypes (Laidre 2021; Page & Dechmann 2022; Woods et al. 2021).
Aim, hypotheses and objectives
We will answer the question in how far lodges allow bush Karoo rats to save energy, enabling their success in a harsh environment. Specifically, there will be three hypotheses and objectives:
1. We predict that lodges provide sufficient insulation to keep nesting chambers warm, like a tent. For this, using i-button temperature loggers, we will measure temperatures inside occupied lodges, unoccupied lodges, and in grass nests (resembling nesting chambers) put inside shrubs without a lodge.
2. We predict that lodges create heat in winter due to decomposition. For this, we will use infra-red imaging to determine the temperature of occupied lodges, unoccupied lodges, and shrubs without lodges, in the dry and in the moist season.
3. We will determine the age of lodges using 14C dating and investigate the effect of lodges on soil composition, expecting lodges to be many decades old and to enrich the soil with nutrients.
Wished skills :
• good knowledge of R and very good statistical skills
• Hard working
• Ability to work hard and independently in the field
• Good knowledge of English spoken and written
• Enthusiasm for studying social evolution.
Expertises which will be acquired during the training :
1. Time management skills
2. Project management skills
3. Scientific writing
4. Personnel competences: working in an international team
Collaborators
Prof. Neville Pillay, University of the Witwatersrand, Johannesburg, South Africa.
Dr. Christine Hatte, CEA CNRS UVSQ, Université Paris-Saclay, Laboratoire des Sciences du Climat et de l’Environnement (LSCE).
PROJECT: The secret social life of solitary mammals: Ultrasound communication in a mainly solitary rodent, the South African bush Karoo rat
Context:
As most mammals are solitary living, understanding how solitary mammals can cope with their environment is essential to conserve mammalian biodiversity in a changing world. While so far research focused on sociable species, more and more research finds that solitary mammals are not asocial but have important interactions with neighbours, which are not random. The mainly solitary living bush Karoo rat (Otomys unisulcatus) from South Africa offers a good model as it is a diurnal mammal that occupies an open habitat and has small home ranges. Most live solitarily, but sometimes small groups form. It lives in kin clusters (spatial structure) and differentiates between kin and non-kin. In neutral dyadic encounter tests we found little behavioural differences, though individuals behaved more often amicably towards kin neighbours than non-kin neighbours. However, ultrasound recordings from these encounters indicate that more happened on the level of ultrasound communication than on the behavioural level, and it seems like more ultrasound communication occurred between kin than non-kin.
Social structure describes how individuals interact with each other and has until recently been mainly study in social species. However, multiple studies on solitary mammals such as puma, mustelids, and several species of solitary rodents indicate that they also have complex non-random social interactions. Indeed, for a solitary mammal it might be very important to know its neighbours and to differentiate between same and opposite sex individuals, kin and non kin, competitors and non-competitors.
Like most aspects of animal behaviour, communication has so far been mainly studied in highly sociable species. However, as we find social structure to be also very important for solitary mammals, their communication might also be more important and more complex than so far realised. The project here will be the first study focussing on ultra-sound communication in a solitary mammal. We expect this project to change the field of animal communication in a similar way as studies on social interactions did the last 10 years: We expect to show that communication in solitary species is important, more complex than so far realised, and adapted to a species specific ecology.
Aim, hypotheses and objectives
We want to understand how solitary bush Karoo rats use ultrasound communication. We expect the project to be very novel and innovative, for the first time showing how important ultrasound communication can be also in a solitary species. This adds to emerging research showing that solitary mammals are not primitive but have a complex social life: https://zslpublications.onlinelibrary.wiley.com/doi/10.1111/jzo.13145
Specifically, there will be three hypotheses and objectives:
1. Determine the ultrasound repertoire of bush Karoo rats and the function of the different sounds.
2. We predict that more ultrasound-communication occurs between close kin than non-kin, both under natural field conditions and under standardized conditions in the lab.
3. We will test whether bush Karoo rats have a warning sound like the closely related wishtling rats (Parotomys spec.) with which they warn closely living kin in the case of danger.
Many additional questions can be addressed, such as ultra-sound communication within the few social pairs observed in this species (about 5% of individuals live in sibling pairs with a close kin at the start of the dry season), seasonal differences in ultra-sound communication (breeding vs non-breeding season), comparison with the sympatric more sociable striped mouse (during encounter tests done for both species the same way), ultrasound communication during competition with striped mice (bush Karoo rats often chase them away from their nests), and individual signatures of sounds.
Wished skills :
• good knowledge of R and very good statistical skills
• knowledge in bioacousttics
• Enthusiasm for field work
• Ability to work hard and independently in the field
• Good knowledge of English spoken and written
Expertises which will be acquired during the training :
5. Field work techniques
6. Acoustic analyses
7. Time management skills
8. Project management skills
9. Scientific writing
10. Personnel competences: working in an international team
Methods:
Trapping, marking and observation of rodents. The student is expected to contribute to the overall project with this.
Ultrasound recordings in the field and in the field laboratory. We will first develop a model in Deepsqueak to extract and characterize vocalizations. Then, we’ll use various software to analyse acoustic parameters and spectrogram shapes of vocalizations, and to see if we can bring some new information to the team in South Africa.
The PhD student would be based in Strasbourg supervised by Carsten Schradin https://www.stripedmouse.com/carsten-schradin.html and co-supervised by the ENEES lab in St Etienne https://www.eneslab.com/ where the student will spend significant amount of time to analyse the recorded sounds.
Allsopp, N. 1999. Effects of grazing and cultivation on soil patterns and processes in the Paulshoek area of Namaqualand. Plant Ecology, 142, 179-187.
Canals, M., Rosenmann, M. & Bozinovic, F. 1989. Energetics and geometry of huddling in small mammals. Journal of Theoretical Biology, 141, 181-189.
Cowling, R. M., Esler, J. J. & Rundel, P. W. 1999. Namaqualand, South Africa – an overview of a unique winter-rainfall desert ecosystem. Plant Ecology, 142, 3-21.
Du Plessis, A., Erasmus, T. & Kerley, G. I. H. 1989. Thermoregulatory patterns of two sympatric rodents: Otomys unisulcatus and Parotomys brantsii. Comp Biochem Physiol, 94, 215-220.
Laidre, M. E. 2021. Animal architecture. Current Biology, 31, R1458-R1464.
Myers, N., Mittermeier, R. A., Mittermeier, C. G., Fonseca, G. A. B. D. & Kent, J. 2000. Biodiversity hotspots for conservation priorities. Nature, 403, 853-858.
Onley, I. R., Austin, J. J., Mitchell, K. J. & Moseby, K. E. 2022. Understanding dispersal patterns can inform future translocation strategies: A case study of the threatened greater stick-nest rat (Leporillus conditor). Austral Ecology, 47, 203-215.
Page, R. A. & Dechmann, D. K. N. 2022. Roost making in bats. Current Biology, 32, R1252-R1259.
Vermeulen, H. C. & Nel, J. A. J. 1988. The bush Karoo rat Otomys unisulcatus on the Cape West coast. South African Journal of Zoology, 23, 103-111.
Woods, H. A., Pincebourde, S., Dillon, M. E. & Terblanche, J. S. 2021. Extended phenotypes: buffers or amplifiers of climate change? Trends in Ecology & Evolution, 36, 889-898.
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