Research Articles (Mammal Research Institute)

Permanent URI for this collectionhttp://hdl.handle.net/2263/5233

A collection containing some of the full text peer-reviewed/ refereed articles published by researchers from the Mammal Research Institute

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Volatile odours reflect breeding status but not social group membership in captive Damaraland mole-rats
(Elsevier, 2025-04) Nichols, Hazel J.; Caspers, Barbara A.; Arbuckle, Kevin; Bennett, Nigel Charles; Hoffman, Joseph I.
In mammals, olfaction plays a key role in social behaviour, for example, in identifying mating opportunities and potential rivals. However, we still have a limited understanding of how social information is encoded in animal odours, including the social determinants of chemical similarity and diversity. Here, we used gas chromatography to analyse the chemical composition of swabs taken from the facial and anogenital regions of Damaraland mole-rats, Fukomys damarensis, a highly social subterranean mammal that relies almost exclusively on olfactory and tactile social cues. We found no sign of individual identity across the two body areas sampled; samples from the facial region and samples of the anogenital region from the same individual were not similar to each other, suggesting that these regions carry different information. However, chemical profiles varied significantly by sex and breeding status; female breeders differed from nonbreeders in their anogenital profiles and had higher chemical diversity in their facial profiles compared with both males and nonbreeders. Interestingly, we found no signals of social group identity. Instead, individual identity may be conveyed through signature mixes that are learned through frequent contact, rather than through specific odours associated with genetic kinship or social group membership. Our results highlight the complexity of chemical communication systems in social species and suggest that signals of group level identity are not necessary for behavioural responses based on group membership.
Local nutrient addition drives plant diversity losses but not biotic homogenization in global grasslands
(Nature Research, 2025-05) Chen, Qingqing; Blowes, Shane A.; Harpole, W. Stanley; Ladouceur, Emma; Borer, Elizabeth T.; Macdougall, Andrew S.; Martina, Jason P.; Bakker, Jonathan D.; Tognetti, Pedro M.; Seabloom, Eric W.; Daleo, Pedro; Power, Sally; Roscher, Christiane; Adler, Peter B.; Donohue, Ian; Wheeler, George; Stevens, Carly; Veen, G.F. Ciska; Risch, Anita C.; Wardle, Glenda M.; Hautier, Yann; Estrada, Catalina; Hersch-Green, Erika; Niu, Yujie; Peri, Pablo L.; Eskelinen, Anu; Gruner, Daniel S.; Venterink, Harry Olde; D’Antonio, Carla; Cadotte, Marc W.; Haider, Sylvia; Eisenhauer, Nico; Catford, Jane; Virtanen, Risto; Morgan, John W.; Tedder, Michelle; Bagchi, Sumanta; Caldeira, Maria C.; Bugalho, Miguel N.; Knops, Johannes M.H.; Dickman, Chris R.; Hagenah, Nicole; Jentsch, Anke; Macek, Petr; Osborne, Brooke B.; Laanisto, Lauri; Chase, Jonathan M.
Nutrient enrichment typically causes local plant diversity declines. A common but untested expectation is that nutrient enrichment also reduces variation in nutrient conditions among localities and selects for a smaller pool of species, causing greater diversity declines at larger than local scales and thus biotic homogenization. Here we apply a framework that links changes in species richness across scales to changes in the numbers of spatially restricted and widespread species for a standardized nutrient addition experiment across 72 grasslands on six continents. Overall, we find proportionally similar species loss at local and larger scales, suggesting similar declines of spatially restricted and widespread species, and no biotic homogenization after 4 years and up to 14 years of treatment. These patterns of diversity changes are generally consistent across species groups. Thus, nutrient enrichment poses threats to plant diversity, including for widespread species that are often critical for ecosystem functions.
Measuring urofecal glucocorticoid metabolites in broiler chicken : a noninvasive tool for assessing stress as a marker of welfare
(Elsevier, 2024-11) Wolf, Tanja Esther; Toppel, Kathrin; Jacobsen, Lea; Andersson, Robby; Touma, Chadi
The poultry industry is an important and still growing sector in many parts of the world. For ethical reasons and due to increased consumer awareness for animal welfare in production animals, it is of importance to establish a reliable and objective test system for monitoring and improving health and welfare. During the rearing process, broiler chickens are exposed to numerous potential stressors and management interventions (e.g. weighing of individual animals, preslaughter fasting and capture processes), but assessing the level of stress perceived by the animals entirely through behavioral observations can be challenging. Monitoring stress-related physiological markers, such as glucocorticoids, can be an accurate and presumably more objective addition. To avoid additional stressors induced by blood collection, a noninvasive approach using urofecal samples is advisable. However, a thorough validation is needed to establish a suitable test system for measuring stress hormone levels, including potential effects of the time of day of collection or the time that has elapsed since defecation. Therefore, the aim of this study was to test the stability of urofecal glucocorticoid metabolites (ufGCM) postdefecation, to determine time of day effects on ufGCM levels, and to investigate the effect of standard management procedures on ufGCM concentrations in broiler chickens. Our results revealed a time window of 4 h in which fecal samples from broilers can be collected without major alterations to the ufGCM concentrations. In this regard, a “fecal box” proved useful for collecting uncontaminated fresh samples. The time of day of sample collection did not influence ufGCM concentrations significantly. Moreover, the used assay proved to be sensitive enough to detect even small and short-lasting activations of the HPA axis induced by handling, confinement, and fasting. Thus, the system used can be a powerful and easy to apply tool in a chicken production setup for assessing stress as a marker of welfare in commercially housed broiler chickens, which in the long-term can also improve production, particularly with regard to process quality.
Garbage consumption by Arctic terrestrial predators in one of the most pristine land areas on Earth
(Norsk Polarinstitutt, 2024-01) Gort-Esteve, Araceli; Abrham, Muzit; Carøe, Christian; Masviken, Johannes; Freire, Susana; Lecomte, Nicolas; Pecnerova, Patricia; Angerbjorn, Anders; Filella, Jordi Bartolome; Noren, Karin; Dalerum, Fredrik
Garbage may cause substantial environmental perturbations, in part because of its consumption by wildlife. Such consumption may have direct health implications for animals and may also influence trophic relationships. Even in pristine Arctic ecosystems, wildlife feeding in marine environments consume garbage in the form of plastic debris transported by ocean currents. We show that Arctic wildlife in pristine terrestrial environments may also ingest garbage or food items derived from abandoned camp sites. We found the remains of a chocolate wrapper and a milk powder bag in two Arctic fox (Vulpes lagopus) scats and a piece of cloth in an Arctic wolf (Canis lupus arctos) scat collected near Nares Strait, northern Greenland, one of the most pristine terrestrial wilderness regions on Earth. Found on Washington Land and associated with long-abandoned camp sites, these three scats were among 657 Arctic fox scats and 92 wolf scats collected as part of a larger study. Our study demonstrates that these two highly opportunistic predators managed to consume garbage despite the almost complete lack of human activity in this High-Arctic region. Our results highlight that abandoned anthropogenic material in the High Arctic may function as a source of garbage for local terrestrial wildlife over extended time periods, and that garbage consumption may become a potential issue if human activity in remote Arctic regions increases.
Evaluating the use of marine subsidies by Arctic foxes without direct coastal access ; insights from stable isotopes
(Springer, 2024-09) Angerbjorn, Anders; Liden, Kerstin; Roth, James D.; Dalerum, Fredrik
The trophic structures of tundra ecosystems are often viewed as a result of local terrestrial primary productivity. However, other resources can be brought in through long-distant migrants or be directly accessible in coastal areas. Hence, trophic structures may deviate from predictions based on local terrestrial resources. The Arctic fox (Vulpes lagopus) is a small canid that may use marine resources when available. We used stable isotope values in Arctic fox fur and literature data on potential prey to evaluate Arctic fox summer resource use in a mountain tundra without coastal access. The dietary contribution of local prey, presumably mostly rodents, declined with declining rodent abundance, with a subsequent increased contribution of migratory prey relying on marine resources. Stable isotope values did not differ between this terrestrial area and an area with direct coastal access during years of high rodent abundance, but isotope values during low rodent abundances suggested less marine input than in a coastal population feeding primarily on marine prey. Our study shows that marine resources may be used by animals in areas without any coastal access, and we highlight that such partial coupling of ecosystems must be included in the modeling and assessments of tundra environments.
First record of ocular albinism in sub-Antarctic fur seal (Arctocephalus tropicalis) pups on Marion Island
(Springer, 2024-02) Shihlomule, Yinhla Desmond; Weideman, Eleanor A.; Van der Vyver, J.S. Fredrik; Conry, Danielle S.; Jordaan, Rowan Keith; De Bruyn, P.J. Nico
We report on an occurrence of ocular albinism in sub-Antarctic fur seal (Arctocephalus tropicalis) pups born on Marion Island, Prince Edward Archipelago. While previous observations have documented pups with atypical lanugo pelage colorations, this is the first case involving hypopigmentation of both fur and other tissues, including the eyes and nails. During the austral summer of 2021/22, we encountered four sub-Antarctic fur seal pups displaying this anomalous pigmentation. These anomalous individuals were found along two beaches on the island’s western side and one beach on the eastern side during an island-wide fur seal census. Although the characteristics observed strongly suggest ocular albinism, confirmation would be necessary through genetic analyses. The absence of melanin in mammalian eyes is known to compromise visual acuity, which may likely result in reduced survival beyond the weaning period, explaining the paucity of such adults in this well-observed population.
Forb diversity globally is harmed by nutrient enrichment but can be rescued by large mammalian herbivory
(Nature Research, 2025-03) Nelson, Rebecca A.; Sullivan, Lauren L.; Hersch-Green, Erika I.; Seabloom, Eric W.; Borer, Elizabeth T.; Tognetti, Pedro M.; Adler, Peter B.; Biederman, Lori; Bugalho, Miguel N.; Caldeira, Maria C.; Cancela, Juan P.; Carvalheiro, Luísa G.; Catford, Jane A.; Dickman, Chris R.; Dolezal, Aleksandra J.; Donohue, Ian; Ebeling, Anne; Eisenhauer, Nico; Elgersma, Kenneth J.; Eskelinen, Anu; Estrada, Catalina; Garbowski, Magda; Graff, Pamela; Gruner, Daniel S.; Hagenah, Nicole; Haider, Sylvia; Harpole, W. Stanley; Hautier, Yann; Jentsch, Anke; Johanson, Nicolina; Koerner, Sally E.; Lannes, Lucíola S.; Macdougall, Andrew S.; Martinson, Holly; Morgan, John W.; Olde Venterink, Harry; Orr, Devyn; Osborne, Brooke B.; Peri, Pablo L.; Power, Sally A.; Raynaud, Xavier; Risch, Anita C.; Shrestha, Mani; Smith, Nicholas G.; Stevens, Carly J.; Veen, G.F. Ciska; Virtanen, Risto; Wardle, Glenda M.; Wolf, Amelia A.; Young, Alyssa L.; Harrison, Susan P.
Forbs (“wildflowers”) are important contributors to grassland biodiversity but are vulnerable to environmental changes. In a factorial experiment at 94 sites on 6 continents, we test the global generality of several broad predictions: (1) Forb cover and richness decline under nutrient enrichment, particularly nitrogen enrichment. (2) Forb cover and richness increase under herbivory by large mammals. (3) Forb richness and cover are less affected by nutrient enrichment and herbivory in more arid climates, because water limitation reduces the impacts of competition with grasses. (4) Forb families will respond differently to nutrient enrichment and mammalian herbivory due to differences in nutrient requirements. We find strong evidence for the first, partial support for the second, no support for the third, and support for the fourth prediction. Our results underscore that anthropogenic nitrogen addition is a major threat to grassland forbs, but grazing under high herbivore intensity can offset these nutrient effects.
Interactive and unimodal relationships between plant biomass, abiotic factors, and plant diversity in global grasslands
(Nature Research, 2025-01) Spohn, Marie; Bagchi, Sumanta; Bakker, Jonathan D.; Borer, Elizabeth T.; Carbutt, Clinton; Catford, Jane A.; Dickman, Christopher R.; Eisenhauer, Nico; Eskelinen, Anu; Hagenah, Nicole; Hautier, Yann; Koerner, Sally E.; Komatsu, Kimberly J.; Laanisto, Lauri; Lekberg, Ylva; Martina, Jason P.; Martinson, Holly; Partel, Meelis; Peri, Pablo L.; Risch, Anita C.; Smith, Nicholas G.; Stevens, Carly; Veen, G.F. Ciska; Virtanen, Risto; Yahdjian, Laura; Young, Alyssa L.; Young, Hillary S.; Seabloom, Eric W.
Grasslands cover approximately a third of the Earth’s land surface and account for about a third of terrestrial carbon storage. Yet, we lack strong predictive models of grassland plant biomass, the primary source of carbon in grasslands. This lack of predictive ability may arise from the assumption of linear relationships between plant biomass and the environment and an underestimation of interactions of environmental variables. Using data from 116 grasslands on six continents, we show unimodal relationships between plant biomass and ecosystem characteristics, such as mean annual precipitation and soil nitrogen. Further, we found that soil nitrogen and plant diversity interacted in their relationships with plant biomass, such that plant diversity and biomass were positively related at low levels of nitrogen and negatively at elevated levels of nitrogen. Our results show that it is critical to account for the interactive and unimodal relationships between plant biomass and several environmental variables to accurately include plant biomass in global vegetation and carbon models.
Frequent failure of nutrients to increase plant biomass supports the need for precision fertilization in agriculture
(Nature Research, 2025-04) Carroll, Oliver H.; Seabloom, Eric W.; Borer, Elizabeth T.; Harpole, W. Stanley; Wilfahrt, Peter; Arnillas, Carlos A.; Bakker, Jonathan D.; Blumenthal, Dana M.; Boughton, Elizabeth; Bugalho, Miguel N.; Caldeira, Maria; Campbell, Malcolm M.; Catford, Jane; Chen, Qingqing; Dickman, Christopher R.; Donohue, Ian; DuPre, Mary Ellyn; Eskelinen, Anu; Estrada, Catalina; Fay, Philip A.; Fraser, Evan D.G.; Hagenah, Nicole; Hautier, Yann; Hersh-Green, Erika; Jonsdottir, Ingibjoerg S.; Kadoya, Taku; Komatsu, Kimberly; Lannes, Luciola; Liang, Maowei; Venterink, Harry Olde; Peri, Pablo; Power, Sally A.; Price, Jodi N.; Ren, Zhengwei; Risch, Anita C.; Sonnier, Gregory; Veen, G.F.; Virtanen, Risto; Wardle, Glenda M.; Waring, Elizabeth F.; Wheeler, George; Yahdjian, Laura; Macdougall, Andrew S.
Implementing precision fertilization to maximize crop yield while minimizing economic and environmental impacts has become critical for agriculture. Variability in biomass response to fertilization within fields, among regions, and over time creates simultaneous risks of under-yielding and overfertilization. We quantify factors determining fertilization responsiveness (i.e., biomass increases with fertilization) up to 15 years in 61 unfertilized rangelands on six continents. We demonstrate widespread multi-year variability in responsiveness, with fertilization increasing average yield by 43% but failing to improve biomass 26% of the time. All sites were responsive at least once, but only four of 61 responded in all plots and years. Modelled management scenarios highlighted that fertilizer cessation is likely to generate sizable economic savings but always reduces yield because of the difficulty in predicting when and where biomass will be unresponsive. This work reveals substantial scale-dependent variability in fertilization responsiveness globally, while clarifying the prospects and pitfalls of managing more spatially and temporally precise nutrient application.
Bacterial blood microbiome of Mastomys rodents : implications for disease spill-over at the animal-human interface within the Bushbuckridge-East community, South Africa
(Frontiers Media, 2025-02) Kolo, Agatha Onyemowo; Brayton, Kelly A.; Collins, Nicola E.; Bastos, Armanda D.S.; Matthee, Sonja; Gall, Cory A.; Wentzel, Jeanette Maria; Neves, L.C.B.G.D. (Luís); Oosthuizen, Marinda C.
The Bushbuckridge-East community in Mpumalanga Province, South Africa is bordered by nature reserves, including the Manyeleti Game Reserve. Murid rodents are prevalent in both Manyeleti and communal rangelands adjoining the community households. Although rodents are reservoir hosts for a broad range of viral, bacterial and parasitic pathogens, the rodent microbial diversity and transmission of zoonotic agents to humans in the community is understudied. In this study we investigated bacterial diversity in wild and commensal rodents sampled from different habitats. The 16S rRNA gene was amplified from DNA extracted from the blood of 24 wild Mastomys and one Steatomys sp. and subjected to PacBio circular consensus sequencing. As Bartonella species were dominant in the blood microbiome, gltA gene characterization was performed to delineate species. Rodents sampled from peri-urban and communal rangelands had higher proportions of Bartonella spp. [Hlalakahle (77.7%), Gottenburg (47.8%), Tlhavekisa (83.8%)] compared to those from the protected habitat (43.8%). Ehrlichia spp., Anaplasma spp., and Coxiella burnetii were detected at <1% of the sequence reads. Conventional PCR and sequencing validated the detection of Bartonella spp. with the first confirmation of Bartonella mastomydis infection in Mastomys in South Africa. Additionally, 317 mites, 90 fleas, 10 ticks and eight lice were collected from the rodents, providing evidence of possible vectors of the organisms detected. The detection of zoonotic agents in rodents in Bushbuckridge-East community, together with prior serological confirmation of Bartonella and Coxiella in non-malarial acute febrile patients from this community, highlights the possible risks that commensal rodents pose to human health.
Good moms : dependent young and their mothers cope better than others with longer dry season in plains zebras
(Springer, 2025-03) Thel, Lucie; Bonenfant, Christophe; Chamaillé-Jammes, Simon
In large herbivores, the timing of births often coincides with the seasonal peak of food resources availability, likely to improve juvenile survival and reduce reproduction costs. Some species, however, breed year-round, even in seasonal environments. Demographic processes, such as to what extent being born during the lean season reduces survival of juveniles and reproductive females, remain understudied in large mammals inhabiting tropical ecosystems. We investigated survival rates in plains zebras (Equus quagga) in Hwange National Park (Zimbabwe), a highly seasonal savanna ecosystem. We used capture–recapture models to analyse long-term demographic data (2008–2019). We investigated the effect of seasonality as a categorical (wet versus dry season) and continuous (duration of the dry season) variable on survival. We found little variability in early juvenile survival (φ = 0.458 ± 0.044 SE, < 6 m.o.), whereas late juvenile and yearling survivals were higher and decreased with increasing length of the dry season (from 0.850 ± 0.095 SE to 0.480 ± 0.120 SE). Female survival was high (> 0.703 ± 0.057 SE and up to 0.995 ± 0.006 SE) but decreased with exposure to the dry season in non-reproductive females. The probability of females becoming reproductive in the following year was not affected by the length of the dry season (0.423 and 0.420 for reproductive and non-reproductive females, respectively). Our results highlight the importance of individual quality in reproductive performance, as reproductive females seem to buffer the effect of environmental variability on their own survival and that of their foal.
Examining park users' support for emerald ash borer (Agrilus planipennis) control in urban parks
(Wiley, 2025-05) Green, Mitchell A.; Barnes, Brittany F.; Gandhi, Kamal J.K.; Pienaar, Elizabeth Frances
Emerald ash borer (Agrilus planipennis Fairmare; EAB) is a woodboring beetle that is considered one of the most damaging invasive forest insects in North America, causing near-complete mortality of native ash (Fraxinus spp.) trees across multiple states. Management options include both biological control using parasitoid wasps from EAB's native range, and chemical control with systemic insecticides. Although both strategies are being used to control EAB, the public's support for these methods is not well understood. In 2023, we surveyed 174 urban park users in northeastern Georgia, United States, to identify determinants of their support for EAB control. Most respondents were not previously aware of EAB and ash trees, although they valued the ecosystem services provided by park trees. Respondents were more supportive of biological control than chemical control, perceiving greater ecological and human well-being risks from chemical control. Respondents' risk perceptions pertaining to control methods and EAB, and their attitudes towards ash trees influenced their support for EAB control. Birdwatchers were less likely to support chemical control and individuals who like to sit and enjoy nature were more likely to support biological control. Our results suggest that park managers' outreach about EAB control should emphasize the aesthetic appeal and ecosystem services provided by urban ash trees and the invasion impacts of EAB. Outreach should also highlight that EAB control does not pose ecological or human well-being risks, that parasitoid wasps help to secure ecosystem function through pest control and do not pose a risk to people, and that EAB control will not adversely impact recreational activities within the park.
Falconer perceptions of, and support for, rabbit hemorrhagic disease biosecurity actions
(Utah State University, 2023) Shapiro, Hannah G.; Pienaar, Elizabeth Frances
Rabbit hemorrhagic disease virus 2 (RHDV2) is a highly contagious virus that primarily infects wild and domestic rabbits and hares (lagomorphs). In the United States, state wildlife agencies rely on stakeholders to report RHDV2-related mortalities and engage in voluntary biosecurity actions to prevent the spread of RHDV2. However, stakeholder perceptions of RHDV2 and relevant biosecurity actions have not been evaluated. We conducted the first study in the United States on how falconers’ risk perceptions, knowledge, trust in state wildlife agencies to manage RHDV2, hunting behaviors, and demographic characteristics influenced their willingness to engage in voluntary biosecurity actions and support potential government-mandated biosecurity measures. To complete our study, we surveyed 480 falconers in 45 states using an online questionnaire from April 2021 to March 2022. Most respondents were aware of RHDV2 but did not know about the multiple vectors for RHDV2 transmission or that infected lagomorphs are unlikely to show signs of disease. Most respondents were willing to engage in all voluntary biosecurity actions (52.9–89.8%) and supported 3 of the 4 RHDV2 management strategies (56.0–62.5%). Respondents’ willingness to engage in or support biosecurity measures depended on the importance they placed on biosecurity, their risk perceptions, and their trust in state wildlife agencies to manage RHDV2. Consistent, up-to-date outreach efforts should communicate the economic and hunting risks associated with RHDV2 and how falconer adoption of biosecurity behaviors may lower the risk of human-mediated RHDV2 spread. State wildlife agencies may build trust with falconry groups by actively engaging falconers in lagomorph and RHDV2 monitoring efforts and working with falconers to implement biosecurity measures that are safe for raptors while also lowering the risk of human-mediated RHDV2 spread.
Southern Ocean food-webs and climate change : a short review and future directions
(Public Library of Science, 2024-03-11) Queiros, Jose P.; Borras-Chavez, Renato; Friscourt, Noemie; Groß, Jasmin; Lewis, Candice B.; Mergard, Georgia; O’Brien, Katie
Food-webs are a critical feature of ecosystems and help us understand how communities will respond to climate change. The Southern Ocean is facing rapid and accelerating changes due to climate change. Though having evolved in an isolated and somewhat extreme environment, Southern Ocean biodiversity and food-webs are among the most vulnerable. Here, we review 1) current knowledge on Southern Ocean food-webs; 2) methods to study foodwebs; 3) assessment of current and future impacts of climate change on Southern Ocean food-webs; 4) knowledge gaps; and 5) the role of Early Career Researchers (ECRs) in future studies. Most knowledge on Southern Ocean food-webs come from the pelagic environment, both at macro- and microbial levels. Modelling and diet studies of individual species are major contributors to the food-web knowledge. These studies revealed a short food-web, predominantly sustained by Antarctic Krill (Euphausia superba). Additionally, alternative pathways exist, involving other krill species, fish, and squid, which play equally important roles in connecting primary producers with top predators. Advantages and disadvantages of several techniques used to study Southern Ocean food-webs were identified, from the classical analyses of stomach contents, scats, or boluses to the most recent approaches such as metabarcoding and trophic-biomarkers. Observations show that climate change can impact the foodweb in different ways. As an example, changes to smaller phytoplankton species can lengthen the food-web, increasing assimilation losses and/or changing nutrient cycles. Future studies need to focus on the benthic-dominated food-webs and the benthopelagic coupling. Furthermore, research during the winter season and below the ice-shelves is needed as these areas may play a crucial role in the functioning of this ecosystem. ECRs can play a significant role in advancing the study of Southern Ocean food-webs due to their willingness for interdisciplinary collaboration and proficiency in employing various methodologies, contributing to the construction of high-resolution food-webs.
Successful alien plant species exhibit functional dissimilarity from natives under varied climatic conditions but not under increased nutrient availability
(Wiley, 2025-03) Milanovic, Marija; Bakker, Jonathan D.; Biederman, Lori; Borer, Elizabeth; Catford, Jane A.; Cleland, Elsa; Hagenah, Nicole; Haider, Sylvia; Harpole, W. Stanley; Komatsu, Kimberly; MacDougall, Andrew S.; Roemermann, Christine; Seabloom, Eric W.; Knapp, Sonja; Kuehn, Ingolf
AIMS : The community composition of native and alien plant species is influenced by the environment (e.g., nutrient addition and changes in temperature or precipitation). A key objective of our study is to understand how differences in the traits of alien and native species vary across diverse environmental conditions. For example, the study examines how changes in nutrient availability affect community composition and functional traits, such as specific leaf area and plant height. Additionally, it seeks to assess the vulnerability of high-nutrient environments, such as grasslands, to alien species colonization and the potential for alien species to surpass natives in abundance. Finally, the study explores how climatic factors, including temperature and precipitation, modulate the relationship between traits and environmental conditions, shaping species success. LOCATION : In our study, we used data from a globally distributed experiment manipulating nutrient supplies in grasslands worldwide (NutNet). METHODS : We investigate how temporal shifts in the abundance of native and alien species are influenced by species-specific functional traits, including specific leaf area (SLA) and leaf nutrient concentrations, as well as by environmental conditions such as climate and nutrient treatments, across 17 study sites. Mixed-effects models were used to assess these relationships. RESULTS : Alien and native species increasing in their abundance did not differ in their leaf traits. We found significantly lower specific leaf area (SLA) with an increase in mean annual temperature and lower leaf Potassium with mean annual precipitation. For trait–environment relationships, when compared to native species, successful aliens exhibited an increase in leaf Phosphorus and a decrease in leaf Potassium with an increase in mean annual precipitation. Finally, aliens' SLA decreased in plots with higher mean annual temperatures. CONCLUSIONS: Therefore, studying the relationship between environment and functional traits may portray grasslands' dynamics better than focusing exclusively on traits of successful species, per se.
Effect of exogenous manipulation of glucocorticoid concentrations on meerkat heart rate, behaviour and vocal production
(Elsevier, 2025-02) Driscoll, Isabel; Briefer, Elodie F.; Ganswindt, Andre; Manser, Marta B.
Encoding of emotional arousal in vocalisations is commonly observed in the animal kingdom, and provides a rapid means of information transfer about an individual's affective responses to internal and external stimuli. As a result, assessing affective arousal-related variation in the acoustic structure of vocalisations can provide insight into how animals perceive both internal and external stimuli, and how this is, in turn, communicated to con- or heterospecifics. However, the underlying physiological mechanisms driving arousal-related acoustic variation remains unclear. One potential driver of such variation in behaviour and vocal production are glucocorticoids. Through exogenous glucocorticoid manipulation, we aimed to gain insight on the relationship between arousal and physiological parameters, behaviour and vocal production in wild meerkats (Suricata suricatta). To this aim, we administered glucocorticoids to wild meerkats, and recorded their heart rate, vigilance behaviour, call rate and acoustic structure during natural behavioural contexts. The results suggest that, although the glucocorticoid treatment did increase plasma glucocorticoid levels, this did not result in observable changes in heart rate, vigilance, or vocal production. This lack of treatment effect suggests that, while glucocorticoids may be a significant component and correlate of the arousal response, they are not the direct drivers of affective arousal related changes in heart rate, behaviour, or vocal production.
Feeding through the ages : revisiting the diet of meerkats
(Elsevier, 2025-03) Jubber, Walter R.; Manser, Marta B.; Fuller, Andrea
We investigated the diet and foraging behaviour of a social carnivore, the meerkat (Suricata suricatta), living in stochastic dryland, and examined seasonal, as well as age-related variation in diet. Insecta constituted the highest percentage of prey eaten (88.4%), followed by Arachnida (5.7%), Diplopoda (4.3%), and Reptilia (1.1%). Within Insecta, Coleoptera (70.4%) was the most dominant prey order in the diet, followed by Lepidoptera and Hymenoptera. There was seasonal variation in the diet of meerkats, with the three main Coleoptera families eaten year-round, but higher consumption of Coleoptera adults in the wet season than in the dry season. We found that old adult meerkats (>24 months) consumed the most large-sized prey, while sub-adults (6–10 months) had the highest prey count of small adult Carabidae beetles. Yearlings (15–24 months) ate the highest percentage of Hepialidae caterpillars. Whether the high representation of Coleoptera in the meerkat diet reflects dietary opportunism associated with the relatively high abundance of Coleoptera, or specialisation in the diet regardless of abundance, remains to be determined.
The challenges, opportunities and future of comparative physiology in the Global South : perspectives of early-career researchers
(Company of Biologists, 2024-10) Bars-Closel, Melissa; Capparelli, Mariana V.; Conradie, Shannon R.; Diele-Viegas, Luisa Maria; Donaldson, Ashleigh C.; Kosmala, Georgia K.; Madelaire, Carla B.; De Mello, Daniela M.D.; Majelantle, Tshepiso L.; Martins, Mariana F.; Moreira, Daniel C.; Ngcamphalala, Celiwe A.; Noakes, Matthew J.; Shankar, Anusha; Webster, Andrea B.
Researchers in the Global South (GS, developing countries) make valuable contributions to the field of comparative physiology, but face economic and scientific disparities and several unique challenges compared with colleagues in the Global North (developed countries). This Perspective highlights some of the challenges, knowledge gaps and disparities in opportunity faced by GS researchers, especially those at early-career stages. We propose collaborative solutions to help address these issues, and advocate for promoting investment and cultural and societal change for a more inclusive research community. Additionally, we highlight the role of GS researchers in contributing expert knowledge on local biodiversity and the environment; this knowledge can help to shape the future of comparative physiology, allowing us to achieve a better understanding of the evolution of physiological mechanisms and to develop innovative solutions to environmental and biomedical challenges. With this Perspective, we hope to highlight the need to foster a more diverse, equitable and inclusive research landscape in comparative physiology; one that empowers GS scientists to address the global challenges associated with biodiversity loss, climate change and environmental pollution.
Light sensitivity of the circadian system in the social highveld mole-rat Cryptomys hottentotus pretoriae
(Company of Biologists, 2024-09) Chanel, Pauline N.C.; Bennett, Nigel Charles; Oosthuizen, Maria Kathleen
Highveld mole-rats (Cryptomys hottentotus pretoriae) are social rodents that inhabit networks of subterranean tunnels. In their natural environment, they are rarely exposed to light, and consequently their visual systems have regressed over evolutionary time. However, in the laboratory they display nocturnal activity, suggesting that they are sensitive to changes in ambient illumination. We examined the robustness of the Highveld mole-rat circadian system by assessing its locomotor activity under decreasing light intensities. Mole-rats were subjected to seven consecutive light cycles commencing with a control cycle (overhead fluorescent lighting at 150 lx), followed by decreasing LED lighting (500, 300, 100, 10 and 1 lx) on a 12 h light:12 h dark (L:D) photoperiod and finally a constant darkness (DD) cycle. Mole-rats displayed nocturnal activity under the whole range of experimental lighting conditions, with a distinct spike in activity at the end of the dark phase in all cycles. The mole-rats were least active during the control cycle under fluorescent light, locomotor activity increased steadily with decreasing LED light intensities, and the highest activity was exhibited when the light was completely removed. In constant darkness, mole-rats displayed free-running rhythms with periods (τ) ranging from 23.77 to 24.38 h, but was overall very close to 24 h at 24.07 h. Our findings confirm that the Highveld mole-rat has a higher threshold for light compared with aboveground dwelling rodents, which is congruent with Previous neurological findings, and has implications for behavioural rhythms.
Evolutionary shifts in the thermal biology of a subterranean mammal : the effect of habitat aridity
(Company of Biologists, 2024-12) Merchant, Hana N.; Hart, Daniel William; Bennett, Nigel Charles; Janse van Vuuren, Andries Koch; Freeman, Marc Trevor; McKechnie, Andrew E.; Faulkes, Chris G.; Mordaunt, Nathan D.; Portugal, Steven J.
Subterranean mammals representing a single subspecies occurring along an aridity gradient provide an appropriate model for investigating adaptive variation in thermal physiology with varying levels of precipitation and air temperature. This study examined the thermal physiological adaptations of common mole-rats (Cryptomys hottentotus hottentotus) across five populations along an aridity gradient, challenging the expectation that increased aridity would lead to reduced metabolic rate, lower body temperatures and broader thermoneutral zones. No significant, consistent differences in metabolic rate, body temperature or thermal conductance were observed between populations, suggesting uniform thermoregulatory mechanisms across habitats. Instead, behavioural strategies such as huddling and torpor may play a more prominent role than physiological adaptations in managing temperature regulation and water balance. The study also observed osmoregulatory differences, with populations employing distinct behavioural cooling strategies in response to water availability. These results underscore the need for further research into the responses of subterranean species to climate change, particularly in understanding how increasing global temperatures and aridification might influence species distribution if they lack the physiological capacity to adapt to future climatic conditions.

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