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Montoya-Sanhueza G, Šaffa G, Šumbera R, Chinsamy A, Jarvis JUM, Bennett NC. Fossorial adaptations in African mole-rats (Bathyergidae) and the unique appendicular phenotype of naked mole-rats. Commun Biol 2022; 5:526. [PMID: 35650336 PMCID: PMC9159980 DOI: 10.1038/s42003-022-03480-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 05/11/2022] [Indexed: 01/02/2023] Open
Abstract
Life underground has constrained the evolution of subterranean mammals to maximize digging performance. However, the mechanisms modulating morphological change and development of fossorial adaptations in such taxa are still poorly known. We assessed the morpho-functional diversity and early postnatal development of fossorial adaptations (bone superstructures) in the appendicular system of the African mole-rats (Bathyergidae), a highly specialized subterranean rodent family. Although bathyergids can use claws or incisors for digging, all genera presented highly specialized bone superstructures associated with scratch-digging behavior. Surprisingly, Heterocephalus glaber differed substantially from other bathyergids, and from fossorial mammals by possessing a less specialized humerus, tibia and fibula. Our data suggest strong functional and developmental constraints driving the selection of limb specializations in most bathyergids, but more relaxed pressures acting on the limbs of H. glaber. A combination of historical, developmental and ecological factors in Heterocephalus are hypothesized to have played important roles in shaping its appendicular phenotype. Morphological and developmental analyses demonstrated that the naked mole-rats are the least anatomically specialized bathyergid for scratch-digging. Developmental, ecological and historical factors may be involved in such peculiar phenotype
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Affiliation(s)
- Germán Montoya-Sanhueza
- Department of Zoology, Faculty of Science, University of South Bohemia, Branišovská 1760, České Budějovice, 37005, Czech Republic. .,Department of Biological Sciences, University of Cape Town, Private Bag X3, Rhodes Gift 7701, Cape Town, South Africa.
| | - Gabriel Šaffa
- Department of Zoology, Faculty of Science, University of South Bohemia, Branišovská 1760, České Budějovice, 37005, Czech Republic
| | - Radim Šumbera
- Department of Zoology, Faculty of Science, University of South Bohemia, Branišovská 1760, České Budějovice, 37005, Czech Republic
| | - Anusuya Chinsamy
- Department of Biological Sciences, University of Cape Town, Private Bag X3, Rhodes Gift 7701, Cape Town, South Africa
| | - Jennifer U M Jarvis
- Department of Biological Sciences, University of Cape Town, Private Bag X3, Rhodes Gift 7701, Cape Town, South Africa
| | - Nigel C Bennett
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Pretoria, South Africa
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Buffenstein R, Amoroso V, Andziak B, Avdieiev S, Azpurua J, Barker AJ, Bennett NC, Brieño‐Enríquez MA, Bronner GN, Coen C, Delaney MA, Dengler‐Crish CM, Edrey YH, Faulkes CG, Frankel D, Friedlander G, Gibney PA, Gorbunova V, Hine C, Holmes MM, Jarvis JUM, Kawamura Y, Kutsukake N, Kenyon C, Khaled WT, Kikusui T, Kissil J, Lagestee S, Larson J, Lauer A, Lavrenchenko LA, Lee A, Levitt JB, Lewin GR, Lewis Hardell KN, Lin TD, Mason MJ, McCloskey D, McMahon M, Miura K, Mogi K, Narayan V, O'Connor TP, Okanoya K, O'Riain MJ, Park TJ, Place NJ, Podshivalova K, Pamenter ME, Pyott SJ, Reznick J, Ruby JG, Salmon AB, Santos‐Sacchi J, Sarko DK, Seluanov A, Shepard A, Smith M, Storey KB, Tian X, Vice EN, Viltard M, Watarai A, Wywial E, Yamakawa M, Zemlemerova ED, Zions M, Smith ESJ. The naked truth: a comprehensive clarification and classification of current 'myths' in naked mole-rat biology. Biol Rev Camb Philos Soc 2022; 97:115-140. [PMID: 34476892 PMCID: PMC9277573 DOI: 10.1111/brv.12791] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 08/17/2021] [Accepted: 08/18/2021] [Indexed: 12/17/2022]
Abstract
The naked mole-rat (Heterocephalus glaber) has fascinated zoologists for at least half a century. It has also generated considerable biomedical interest not only because of its extraordinary longevity, but also because of unusual protective features (e.g. its tolerance of variable oxygen availability), which may be pertinent to several human disease states, including ischemia/reperfusion injury and neurodegeneration. A recent article entitled 'Surprisingly long survival of premature conclusions about naked mole-rat biology' described 28 'myths' which, those authors claimed, are a 'perpetuation of beautiful, but falsified, hypotheses' and impede our understanding of this enigmatic mammal. Here, we re-examine each of these 'myths' based on evidence published in the scientific literature. Following Braude et al., we argue that these 'myths' fall into four main categories: (i) 'myths' that would be better described as oversimplifications, some of which persist solely in the popular press; (ii) 'myths' that are based on incomplete understanding, where more evidence is clearly needed; (iii) 'myths' where the accumulation of evidence over the years has led to a revision in interpretation, but where there is no significant disagreement among scientists currently working in the field; (iv) 'myths' where there is a genuine difference in opinion among active researchers, based on alternative interpretations of the available evidence. The term 'myth' is particularly inappropriate when applied to competing, evidence-based hypotheses, which form part of the normal evolution of scientific knowledge. Here, we provide a comprehensive critical review of naked mole-rat biology and attempt to clarify some of these misconceptions.
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Affiliation(s)
| | - Vincent Amoroso
- Department of Biological SciencesUniversity of Illinois at ChicagoChicagoIL60607U.S.A.
| | - Blazej Andziak
- Graduate Center City University of New York365 Fifth AvenueNew YorkNY10016U.S.A.
| | | | - Jorge Azpurua
- Department of AnesthesiologyStony Brook University101 Nicolls RoadStony BrookNY11794U.S.A.
| | - Alison J. Barker
- Max Delbrück Center for Molecular MedicineRobert‐Rössle‐Str 10Berlin‐Buch13092Germany
| | - Nigel C. Bennett
- Mammal Research Institute, Department of Zoology and EntomologyUniversity of PretoriaPretoria0002South Africa
| | - Miguel A. Brieño‐Enríquez
- Department of Obstetrics, Gynecology & Reproductive MedicineMagee‐Womens Research Institute204 Craft AvenuePittsburghPA15213U.S.A.
| | - Gary N. Bronner
- Department Biological SciencesRondeboschCape Town7701South Africa
| | - Clive Coen
- Reproductive Neurobiology, Division of Women's HealthSchool of Medicine, King's College LondonWestminster Bridge RoadLondonSE1 7EHU.K.
| | - Martha A. Delaney
- Zoological Pathology ProgramUniversity of Illinois3505 Veterinary Medicine Basic Sciences Building, 2001 S Lincoln AvenueUrbanaIL6180U.S.A.
| | - Christine M. Dengler‐Crish
- Department of Pharmaceutical SciencesNortheast Ohio Medical University4209 State Route 44RootstownOH44272U.S.A.
| | - Yael H. Edrey
- Northwest Vista College3535 N. Ellison DriveSan AntonioTX78251U.S.A.
| | - Chris G. Faulkes
- School of Biological and Chemical SciencesQueen Mary University of LondonMile End RoadLondonE1 4NSU.K.
| | - Daniel Frankel
- School of EngineeringNewcastle UniversityMerz CourtNewcastle Upon TyneNE1 7RUU.K.
| | - Gerard Friedlander
- Université Paris DescartesFaculté de Médecine12 Rue de l'École de MédecineParis5006France
| | - Patrick A. Gibney
- Cornell University College of Veterinary MedicineIthacaNY14853U.S.A.
| | - Vera Gorbunova
- Departments of BiologyUniversity of Rochester402 Hutchison HallRochesterNY14627U.S.A.
| | - Christopher Hine
- Cleveland ClinicLerner Research Institute9500 Euclid AvenueClevelandOH44195U.S.A.
| | - Melissa M. Holmes
- Department of PsychologyUniversity of Toronto Mississauga3359 Mississauga Road NorthMississaugaONL5L 1C6Canada
| | | | - Yoshimi Kawamura
- Department of Aging and Longevity ResearchKumamoto University1‐1‐1 HonjoKumamoto860‐0811Japan
| | - Nobuyuki Kutsukake
- Department of Evolutionary Studies of BiosystemsThe Graduate University for Advanced StudiesHayama240‐0193Japan
| | - Cynthia Kenyon
- Calico Life Sciences LLC1170 Veterans BlvdSouth San FranciscoCA94080U.S.A.
| | - Walid T. Khaled
- The School of the Biological SciencesUniversity of CambridgeTennis Court RoadCambridgeCB2 1PDU.K.
| | - Takefumi Kikusui
- Companion Animal Research, School of Veterinary MedicineAzabu UniversitySagamihara252‐5201Japan
| | - Joseph Kissil
- Department of Cancer BiologyThe Scripps Research InstituteScripps FloridaJupiterFL33458U.S.A.
| | - Samantha Lagestee
- Department of Biological SciencesUniversity of Illinois at ChicagoChicagoIL60607U.S.A.
| | - John Larson
- Department of Biological SciencesUniversity of Illinois at ChicagoChicagoIL60607U.S.A.
| | - Amanda Lauer
- Department of OtolaryngologyJohns Hopkins School of MedicineBaltimoreMD21205U.S.A.
| | - Leonid A. Lavrenchenko
- A.N. Severtsov Institute of Ecology and EvolutionRussian Academy of SciencesLeninskii pr. 33Moscow119071Russia
| | - Angela Lee
- Graduate Center City University of New York365 Fifth AvenueNew YorkNY10016U.S.A.
| | - Jonathan B. Levitt
- Biology DepartmentThe City College of New York138th Street and Convent AvenueNew YorkNY10031U.S.A.
| | - Gary R. Lewin
- Max Delbrück Center for Molecular MedicineRobert‐Rössle‐Str 10Berlin‐Buch13092Germany
| | | | - TzuHua D. Lin
- Calico Life Sciences LLC1170 Veterans BlvdSouth San FranciscoCA94080U.S.A.
| | - Matthew J. Mason
- The School of the Biological SciencesUniversity of CambridgeTennis Court RoadCambridgeCB2 1PDU.K.
| | - Dan McCloskey
- College of Staten Island in the City University of New York2800 Victory BlvdStaten IslandNY10314U.S.A.
| | - Mary McMahon
- Calico Life Sciences LLC1170 Veterans BlvdSouth San FranciscoCA94080U.S.A.
| | - Kyoko Miura
- Department of Aging and Longevity ResearchKumamoto University1‐1‐1 HonjoKumamoto860‐0811Japan
| | - Kazutaka Mogi
- Companion Animal Research, School of Veterinary MedicineAzabu UniversitySagamihara252‐5201Japan
| | - Vikram Narayan
- Calico Life Sciences LLC1170 Veterans BlvdSouth San FranciscoCA94080U.S.A.
| | | | - Kazuo Okanoya
- Department of Life SciencesThe University of Tokyo7‐3‐1 HongoTokyo153‐8902Japan
| | | | - Thomas J. Park
- Department of Biological SciencesUniversity of Illinois at ChicagoChicagoIL60607U.S.A.
| | - Ned J. Place
- Cornell University College of Veterinary MedicineIthacaNY14853U.S.A.
| | - Katie Podshivalova
- Calico Life Sciences LLC1170 Veterans BlvdSouth San FranciscoCA94080U.S.A.
| | | | - Sonja J. Pyott
- Groningen Department of OtorhinolaryngologyUniversity Medical CenterPostbus 30.001GroningenRB9700The Netherlands
| | - Jane Reznick
- Cologne Excellence Cluster for Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University Hospital CologneJoseph‐Stelzmann‐Street 26Cologne50931Germany
| | - J. Graham Ruby
- Calico Life Sciences LLC1170 Veterans BlvdSouth San FranciscoCA94080U.S.A.
| | - Adam B. Salmon
- Barshop Institute for Longevity and Aging StudiesUniversity of Texas Health Science Center4939 Charles Katz Dr.San AntonioTX78229U.S.A.
| | - Joseph Santos‐Sacchi
- Department of NeuroscienceYale University School of Medicine200 South Frontage Road, SHM C‐303New HavenCT06510U.S.A.
| | - Diana K. Sarko
- Department of AnatomySchool of Medicine, Southern Illinois University975 S. NormalCarbondaleIL62901U.S.A.
| | - Andrei Seluanov
- Departments of BiologyUniversity of Rochester402 Hutchison HallRochesterNY14627U.S.A.
| | - Alyssa Shepard
- Department of Cancer BiologyThe Scripps Research InstituteScripps FloridaJupiterFL33458U.S.A.
| | - Megan Smith
- Calico Life Sciences LLC1170 Veterans BlvdSouth San FranciscoCA94080U.S.A.
| | - Kenneth B. Storey
- Department of BiologyCarleton University1125 Colonel By DriveOttawaONK1S 5B6Canada
| | - Xiao Tian
- Department of Genetics – Blavatnik InstituteHarvard Medical School77 Avenue Louis PasteurBostonMA02115U.S.A.
| | - Emily N. Vice
- Department of Biological SciencesUniversity of Illinois at ChicagoChicagoIL60607U.S.A.
| | - Mélanie Viltard
- Fondation pour la recherche en PhysiologieUniversité Catholique de LouvainClos Chapelle‐aux‐Champs 30Woluwe‐saint Lambert1200Belgium
| | - Akiyuki Watarai
- Companion Animal Research, School of Veterinary MedicineAzabu UniversitySagamihara252‐5201Japan
| | - Ewa Wywial
- Biology DepartmentThe City College of New York138th Street and Convent AvenueNew YorkNY10031U.S.A.
| | - Masanori Yamakawa
- Department of Evolutionary Studies of BiosystemsThe Graduate University for Advanced StudiesHayama240‐0193Japan
| | - Elena D. Zemlemerova
- A.N. Severtsov Institute of Ecology and EvolutionRussian Academy of SciencesLeninskii pr. 33Moscow119071Russia
| | - Michael Zions
- Graduate Center City University of New York365 Fifth AvenueNew YorkNY10016U.S.A.
| | - Ewan St. John Smith
- The School of the Biological SciencesUniversity of CambridgeTennis Court RoadCambridgeCB2 1PDU.K.
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Bennett NC, Ganswindt A, Ganswindt SB, Jarvis JUM, Zöttl M, Faulkes CG. Evidence for contrasting roles for prolactin in eusocial naked mole-rats, Heterocephalus glaber and Damaraland mole-rats, Fukomys damarensis. Biol Lett 2019; 14:rsbl.2018.0150. [PMID: 29794008 DOI: 10.1098/rsbl.2018.0150] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Accepted: 05/03/2018] [Indexed: 12/23/2022] Open
Abstract
Elevated prolactin (PRL) has been associated with the expression of social and cooperative behaviours in a number of vertebrate species, as well as suppression of reproduction. As social mole-rats exhibit both of these traits, PRL is a prime candidate in mediating their social phenotype. While naked and Damaraland mole-rats (NMRs and DMRs) have evolved eusociality independently within their family, both species exhibit an extreme skew in lifetime reproductive success, with breeding restricted to a single female and one or two males. Non-breeding NMRs of both sexes are physiologically inhibited from reproducing, while in DMRs only the non-breeding females are physiologically suppressed. Newly emerging work has implicated the dopamine system and PRL as a component in socially induced reproductive suppression and eusociality in NMR, but the DMR remains unstudied in this context. To investigate evolutionary convergence in the role of PRL in shaping African mole-rat eusociality, we determined plasma PRL concentrations in breeders and non-breeders of both sexes, comparing DMRs with NMRs. Among samples from non-breeding NMRs 80% had detectable plasma PRL concentrations. As a benchmark, these often (37%) exceeding those considered clinically hyperprolactinaemic (25 ng ml-1) in humans: mean ± s.e.m.: 34.81 ± 5.87 ngml-1; range 0.00-330.30 ng ml-1 Conversely, 85% of non-breeding DMR samples had undetectable values and none had concentrations above 25 ng ml-1: 0.71 ± 0.38 ng ml-1; 0.00-23.87 ngml-1 Breeders in both species had the expected variance in plasma PRL concentrations as part of normal reproductive function, with lactating queens having significantly higher values. These results suggest that while elevated PRL in non-breeders is implicated in NMR eusociality, this may not be the case in DMRs, and suggests a lack of evolutionary convergence in the proximate control of the social phenotype in these mole-rats.
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Affiliation(s)
- N C Bennett
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa
| | - A Ganswindt
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa.,Department of Anatomy and Physiology, University of Pretoria, Onderstepoort 0110, South Africa
| | - S B Ganswindt
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa.,Department of Anatomy and Physiology, University of Pretoria, Onderstepoort 0110, South Africa
| | - J U M Jarvis
- Department of Biological Sciences, University of Cape Town, Cape Town, South Africa
| | - M Zöttl
- Department of Zoology, University of Cambridge, Cambridge, UK.,EEMiS, Department of Biology and Environmental Science, Linnaeus University, 39182 Kalmar, Sweden
| | - C G Faulkes
- School of Biological and Chemical Sciences, Queen Mary University of London, UK
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Torrents-Ticó M, Bennett NC, Jarvis JUM, Zöttl M. Growth affects dispersal success in social mole-rats, but not the duration of philopatry. Biol Lett 2018; 14:rsbl.2018.0005. [PMID: 29467175 DOI: 10.1098/rsbl.2018.0005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 01/26/2018] [Indexed: 11/12/2022] Open
Abstract
In naked mole-rats (Heterocephalus glaber), some non-breeding males show faster growth and are more likely to disperse than others. These differences have been suggested to be the result of a specialized developmental strategy leading to shorter philopatry and independent breeding, as opposed to extended philopatry as non-reproductive helpers. However, it is unclear whether fast-growing males disperse sooner than slow-growing males. An alternative explanation is that variation in quality between individuals causes high-quality individuals to grow quickly and maximize dispersal success without reducing philopatry. Here we show that in Damaraland mole-rats (Fukomys damarensis), males that subsequently disperse successfully grow faster than other non-reproductive males. This pattern is predicted by both hypotheses and does not discriminate between them. However, contrary to the suggestion that faster growth represents a developmental specialization for early dispersal, fast-growing and slow-growing males remained equally long in their natal groups. Our study provides no evidence for adaptive divergence in male development leading either to early dispersal or extended philopatry. Instead of representing specialized dispersers, fast-growing males of this species may be high-quality individuals.
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Affiliation(s)
- Miquel Torrents-Ticó
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Nigel C Bennett
- Department of Zoology, University of Pretoria, Pretoria, Hatfield 0028, South Africa
| | | | - Markus Zöttl
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK .,Ecology and Evolution in Microbial Model Systems, EEMiS, Department of Biology and Environmental Science, Linnaeus University, SE-391 82 Kalmar, Sweden
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Retief L, Bennett NC, Jarvis JUM, Bastos ADS. Subterranean Mammals: Reservoirs of Infection or Overlooked Sentinels of Anthropogenic Environmental Soiling? Ecohealth 2017; 14:662-674. [PMID: 29094221 DOI: 10.1007/s10393-017-1281-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 07/16/2017] [Accepted: 09/18/2017] [Indexed: 06/07/2023]
Abstract
Global reports of emergent pathogens in humans have intensified efforts to identify wildlife reservoirs. Subterranean mammals, such as bathyergid mole rats, are largely overlooked, despite their high-level exposure to soil-dwelling microbes. Initial assessment of bathyergid reservoir potential was determined using a broad-range 16S rRNA PCR approach, which revealed an 83% PCR-positivity for the 234 bathyergid lung samples evaluated. The presence of the Bacillus cereus complex, a ubiquitous bacterial assemblage, containing pathogenic and zoonotic species, was confirmed through nucleotide sequencing, prior to group- and species-specific PCR sequencing. The latter allowed for enhanced placement and prevalence estimations of Bacillus in four bathyergid species sampled across a range of transformed landscapes in the Western Cape Province, South Africa. Two novel Bacillus strains (1 and 2) identified on the basis of the concatenated 16S rRNA-groEL-yeaC data set (2066 nucleotides in length), clustered with B. mycoides (ATCC 6462) and B. weihenstephanensis (WSBC 10204), within a well-supported monophyletic lineage. The levels of co-infection, evaluated with a groEL strain-specific assay, developed specifically for this purpose, were high (71%). The overall Bacillus presence of 17.95% (ranging from 0% for Georychus capensis to 45.35% for Bathyergus suillus) differed significantly between host species (χ2 = 69.643; df = 3; P < 0.05), being significantly higher in bathyergids sampled near an urban informal settlement (χ2 = 70.245; df = 3; P < 0.05). The results highlight the sentinel potential of soil-dwelling mammals for monitoring anthropogenically introduced, opportunistic pathogens and the threats they pose to vulnerable communities, particularly in the developing world.
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Affiliation(s)
- Liezl Retief
- Mammal Research Institute, Department of Zoology & Entomology, University of Pretoria, Private Bag 20, Hatfield, 0028, South Africa
| | - Nigel C Bennett
- South African Research Chair of Mammal Behavioural Ecology and Physiology, Department of Zoology and Entomology, University of Pretoria, Private Bag 20, Hatfield, 0028, South Africa
| | - Jennifer U M Jarvis
- Department of Zoology, University of Cape Town, Rondebosch, Cape Town, 7700, South Africa
| | - Armanda D S Bastos
- Mammal Research Institute, Department of Zoology & Entomology, University of Pretoria, Private Bag 20, Hatfield, 0028, South Africa.
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Weber RE, Jarvis JUM, Fago A, Bennett NC. O 2 binding and CO 2 sensitivity in haemoglobins of subterranean African mole rats. ACTA ACUST UNITED AC 2017; 220:3939-3948. [PMID: 28851819 DOI: 10.1242/jeb.160457] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 08/23/2017] [Indexed: 01/05/2023]
Abstract
Inhabiting deep and sealed subterranean burrows, mole rats exhibit a remarkable suite of specializations, including eusociality (living in colonies with single breeding queens), extraordinary longevity, cancer immunity and poikilothermy, and extreme tolerance of hypoxia and hypercapnia. With little information available on adjustments in haemoglobin (Hb) function that may mitigate the impact of exogenous and endogenous constraints on the uptake and internal transport of O2, we measured haematological characteristics, as well as Hb-O2 binding affinity and sensitivity to pH (Bohr effect), CO2, temperature and 2,3-diphosphoglycerate (DPG, the major allosteric modulator of Hb-O2 affinity in red blood cells) in four social and two solitary species of African mole rats (family Bathyergidae) originating from different biomes and soil types across Central and Southern Africa. We found no consistent patterns in haematocrit (Hct) and blood and red cell DPG and Hb concentrations or in intrinsic Hb-O2 affinity and its sensitivity to pH and DPG that correlate with burrowing, sociality and soil type. However, the results reveal low specific (pH independent) effects of CO2 on Hb-O2 affinity compared with humans that predictably safeguard pulmonary loading under hypoxic and hypercapnic burrow conditions. The O2 binding characteristics are discussed in relation to available information on the primary structure of Hbs from adult and developmental stages of mammals subjected to hypoxia and hypercapnia and the molecular mechanisms underlying functional variation in rodent Hbs.
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Affiliation(s)
- Roy E Weber
- Department of Bioscience, Aarhus University, C.F. Møllers Alle 3, Aarhus C 8000, Denmark
| | | | - Angela Fago
- Department of Bioscience, Aarhus University, C.F. Møllers Alle 3, Aarhus C 8000, Denmark
| | - Nigel C Bennett
- Zoology and Entomology Department, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa
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Puttick GM, Jarvis JUM. The Functional Anatomy of the Neck and Forelimbs of the Cape Golden Mole, Chrysochloris Asiatica (Lipotyphla: Chrysochloridae). ACTA ACUST UNITED AC 2015. [DOI: 10.1080/00445096.1977.11447589] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Young AJ, Jarvis JUM, Barnaville J, Bennett NC. Workforce Effects and the Evolution of Complex Sociality in Wild Damaraland Mole Rats. Am Nat 2015; 186:302-11. [PMID: 26655158 DOI: 10.1086/682048] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Explaining the evolution of eusocial and cooperatively breeding societies demands that we understand the effects of workforce size on the reproductive success of breeders. This challenge has yet to be addressed in the family that arguably exhibits the most extreme outcomes of vertebrate social evolution, the African mole rats (Bathyergidae), leaving the ultimate causes of their many unusual adaptations open to debate. Here we report-using a 14-year field study of wild Damaraland mole rats, Fukomys damarensis-that workers appear to have strong but unusual effects on offspring. Groups with larger workforces exhibited substantially higher rates of offspring recruitment while maintaining high juvenile survival rates, relationships that may have favored the evolution of the delayed dispersal, cooperation, morphological specialization, and unusual patterns of longevity that characterize such societies. Offspring reared by larger workforces also showed slower growth, however. That reduced offspring growth in larger groups has also been documented under ad lib. food conditions in the laboratory raises the possibility that this reflects socially induced growth restraint rather than simple constraints on resource availability. Our findings shed new light on the evolution of complex sociality in this enigmatic clade and highlight further departures from the norms reported for other cooperative vertebrates.
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Affiliation(s)
- Andrew J Young
- Centre for Ecology and Conservation, School of Biosciences, University of Exeter, Penryn, Cornwall TR10 9FE, United Kingdom
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Schmidt CM, Jarvis JUM, Bennett NC. The long-lived queen: reproduction and longevity in female eusocial Damaraland mole-rats (Fukomys damarensis). African Zoology 2015. [DOI: 10.1080/15627020.2013.11407583] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Davies KC, Jarvis JUM. The burrow systems and burrowing dynamics of the mole-rats Bathyergus suillus and Cryptomys hottentotus in the fynbos of the south-western Cape, South Africa. J Zool (1987) 2011. [DOI: 10.1111/j.1469-7998.1986.tb03570.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
Females in many species engage in matings with males that are not their social mates. These matings are predicted to increase offspring heterozygosity and fitness, and thereby prevent the deleterious effects of inbreeding. We tested this hypothesis in a cooperative breeding mammal, the common mole-rat Cryptomys hottentotus hottentotus. Laboratory-based studies suggested a system of strict social monogamy, while recent molecular studies indicate extensive extra-pair paternity despite colonies being founded by an outbred pair. Our data show that extra-pair and within-colony breeding males differed significantly in relatedness to breeding females, suggesting that females may gain genetic benefits from breeding with non-resident males. Extra-colony male mating success was not based on heterozygosity criteria at microsatellite loci; however, litters sired by extra-colony males exhibited increased heterozygosity. While we do not have the data that refute a relationship between individual levels of inbreeding (Hs) and fitness, we propose that a combination of both male and female factors most likely explain the adaptive significance of extra-pair mating whereby common mole-rats maximize offspring fitness by detecting genetic compatibility with extra-pair mates at other key loci, but it is not known which sex controls these matings.
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Affiliation(s)
- Jacqueline M Bishop
- Department of Zoology, University of Cape Town, Private Bag X3, Rondebosch 8001, South Africa.
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Hart L, Chimimba CT, Jarvis JUM, O'Riain J, Bennett NC. Craniometric Sexual Dimorphism and Age Variation in the South African Cape Dune Mole-rat (Bathyergus suillus). J Mammal 2007. [DOI: 10.1644/06-mamm-a-058r1.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Hart L, O'Riain MJ, Jarvis JUM, Bennett NC. The pituitary potential for opportunistic breeding in the Cape dune mole-rat, Bathyergus suillus. Physiol Behav 2006; 88:615-9. [PMID: 16814330 DOI: 10.1016/j.physbeh.2006.05.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2005] [Revised: 05/16/2006] [Accepted: 05/22/2006] [Indexed: 10/24/2022]
Abstract
In this paper we investigated the effect of sex and season on baseline and post-GnRH challenge luteinising hormone (LH) levels in a solitary, seasonally breeding mole-rat. Circulating basal concentrations of luteinising hormone (LH) were found to differ significantly with season in both sexes. However, no significant difference was found in circulating basal LH concentration between the sexes either within or out of the breeding season. The magnitude of the LH response to an exogenous pharmacological overdose of GnRH both in and out of the breeding season in males and females respectively was not significant. This finding suggests that there is no down regulation of GnRH receptors on the pituitary during the non-breeding season. Cape dune mole-rats thus have the potential for opportunistic breeding outside of the typical breeding period. We argue that this represents an adaptation to limited and brief opportunities for mating in this xenophobic and aggressive species.
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Affiliation(s)
- Leanne Hart
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa
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Lewis ER, Narins PM, Jarvis JUM, Bronner G, Mason MJ. Preliminary evidence for the use of microseismic cues for navigation by the Namib golden mole. J Acoust Soc Am 2006; 119:1260-8. [PMID: 16521787 DOI: 10.1121/1.2151790] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Insect prey of the Namib golden mole congregate beneath clumps of grass scattered among the sand dunes of the Namib Desert. In the presence of the light winds that typically blow over the Namib Desert, these grass clumps emit low-amplitude vibrations that are transmitted through the sand. While foraging in the sand-swimming mode (a few centimeters below the surface of the sand), some moles apparently were attracted toward manmade sources emitting vibrations matching those recorded from the grass clumps. This is the first direct evidence that these desert mammals use seismic cues for navigation.
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Affiliation(s)
- Edwin R Lewis
- Department of Electrical Engineering and Computer Science, University of California, Berkeley, California 94720-1771, USA.
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Burland TM, Bennett NC, Jarvis JUM, Faulkes CG. Colony structure and parentage in wild colonies of co-operatively breeding Damaraland mole-rats suggest incest avoidance alone may not maintain reproductive skew. Mol Ecol 2004; 13:2371-9. [PMID: 15245409 DOI: 10.1111/j.1365-294x.2004.02233.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Colonies of co-operatively breeding African mole-rats have traditionally been thought to be composed of a single breeding female, one or two breeding males, and their offspring. In the naked mole-rat (Heterocephalus glaber), the occurrence of facultative inbreeding means incest avoidance cannot prevent reproduction in subordinate group members, and physiological suppression of reproductive function by the breeding female occurs in both sexes. In contrast, previous studies of captive colonies of the Damaraland mole-rat (Cryptomys damarensis) suggest that breeding within a colony is restricted to a single breeding pair, simply because all other colony members are highly related (first- or second-order relatives) and this species is an obligate outbreeder. Using microsatellite markers, we investigated parentage and colony composition in 18 wild Damaraland mole-rat colonies to determine whether inbreeding avoidance alone can explain the high levels of reproductive skew in this species. Multiple and unidentified paternity was widespread within colonies and immigrants of both sexes were regularly identified. Unrelated, opposite-sex nonbreeders were found coexisting in two colonies. These results suggest that, in the wild, conditions exist where nonreproductive females can come into contact with unrelated males, even when they do not disperse from their natal colony. Inbreeding avoidance alone is therefore insufficient to maintain the high levels of reproductive skew identified in this species suggesting that the breeding female somehow suppresses the reproductive function in nonbreeding females.
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Affiliation(s)
- Tamsin M Burland
- School of Biological Sciences, Queen Mary, University of London, London, E1 4NS, UK
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Bishop JM, Jarvis JUM, Spinks AC, Bennett NC, O'Ryan C. Molecular insight into patterns of colony composition and paternity in the common mole-rat Cryptomys hottentotus hottentotus. Mol Ecol 2004; 13:1217-29. [PMID: 15078457 DOI: 10.1111/j.1365-294x.2004.02131.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the discovery of intraspecific variation in both colony composition and patterns of paternity in two populations of the social common mole-rat Cryptomys hottentotus hottentotus. These two populations represent the mesic and arid habitat extremes of the species' broad ecological range in South Africa. Until recently colonies of the common mole-rat were thought to consist of familial groups whereby all colony members were the offspring of a monogamous reproductive pair. The remaining colony members were thought to forego reproduction until both social and ecological conditions favoured dispersal and opportunities for independent outbreeding. Results from genetic assignment tests using microsatellite markers indicate that while colony composition is dominated by familial groups, colonies within both populations included both adult and subadult foreign conspecifics. Analysis of parentage reveals that the social organization of C. h. hottentotus is not that of strict monogamy; paternity of offspring was not assigned consistently to the largest, most dominant male within the colony. Moreover, a number of significantly smaller males were found to sire offspring, suggesting a sneak-mating strategy by subordinate within-colony males. Extra-colony extra-pair paternity (ECP) was also found to characterize C. h. hottentotus colonies, occurring with similar frequencies in both habitats. Both dominant established breeding males and subordinate males were identified as siring young in nonsource colonies. Furthermore, established breeding males were found to sire extra-colony young in the same season as siring young within their source colonies. We discuss the significance of these results within the context of the divergent ecological regimes characterizing the two sites and observe that our results revisit the accuracy of using behavioural and morphological characters, which have structured the basis of our understanding of the behavioural ecology of this species, as indicators of breeding status in mark-recapture studies.
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Affiliation(s)
- J M Bishop
- Department of Zoology, University of Cape Town, Private Bag, Rondebosch, 7701, Cape Town, South Africa.
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Faulkes CG, Verheyen E, Verheyen W, Jarvis JUM, Bennett NC. Phylogeographical patterns of genetic divergence and speciation in African mole-rats (Family: Bathyergidae). Mol Ecol 2004; 13:613-29. [PMID: 14871365 DOI: 10.1046/j.1365-294x.2004.02099.x] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
African mole-rats are subterranean Hystricomorph rodents, distributed widely throughout sub-Saharan Africa, and displaying a range of social and reproductive strategies from solitary dwelling to the 'insect-like' sociality of the naked mole-rat, Heterocephalus glaber. Both molecular systematic studies of Rodentia and the fossil record of bathyergids indicate an ancient origin for the family. This study uses an extensive molecular phylogeny and mitochondrial cytochrome b and 12s rRNA molecular clocks to examine in detail the divergence times, and patterns of speciation of the five extant genera in the context of rift valley formation in Africa. Based on a value of 40-48 million years ago (Myr) for the basal divergence of the family (Heterocephalus), we estimate divergence times of 32-40 Myr for Heliophobius, 20-26 Myr for Georychus/Bathyergus and 12-17 Myr for Cryptomys, the most speciose genus. While early divergences may have been independent of rifting, patterns of distribution of later lineages may have been influenced directly by physical barriers imposed by the formation of the Kenya and Western Rift, and indirectly by accompanying climatic and vegetative changes. Rates of chromosomal evolution and speciation appear to vary markedly within the family. In particular, the genus Cryptomys appears to have undergone an extensive radiation and shows the widest geographical distribution. Of the two distinct clades within this genus, one exhibits considerable karyotypic variation while the other does not, despite comparatively high levels of sequence divergence between some taxa. These different patterns of speciation observed both within the family and within the genus Cryptomys may have been a result of environmental changes associated with rifting.
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Affiliation(s)
- C G Faulkes
- School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK.
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O'Connor TP, Lee A, Jarvis JUM, Buffenstein R. Prolonged longevity in naked mole-rats: age-related changes in metabolism, body composition and gastrointestinal function. Comp Biochem Physiol A Mol Integr Physiol 2002; 133:835-42. [PMID: 12443939 DOI: 10.1016/s1095-6433(02)00198-8] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Aging is characterized by declines in all physiological processes and concomitant changes in body composition. Age-related changes in metabolism, body composition and gastrointestinal function were investigated in naked mole-rats (Heterocephalus glaber), rodents that exhibit extended longevity. Maximum lifespan of these 40 g rodents (>27 year) is approximately 9 times greater than predicted allometrically. We investigated changes in basal metabolic rate (BMR), body composition and intestinal glucose transport in 1, 5, 10 and 20-year-old male individuals. Body composition was measured using dual X-ray absorptiometry and activity of sodium glucose co-transporters (SGLT1) determined using everted gut sleeves. One-year-olds had lower body mass than other age cohorts, as they had not attained full adult form. Among the 5, 10, and 20-year-olds, no age-related changes in body mass, BMR, percentage body fat, fat-free mass or bone mineral density were found. SGLT1 activity declined moderately (<20%) from 5 to 20 years and was similar at 10-20 years, whereas age-related declines are 40-60% in mice. Although mole-rats have low metabolic rates, their prolonged longevity results in a lifetime energy expenditure more than 4 times that of mice. Since lifetime energy expenditure is an important index of potential exposure to oxidative damage, naked mole-rats may be valuable for studying mechanisms of aging.
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Affiliation(s)
- Timothy P O'Connor
- Department of Biology, City College of City University of New York, 138th Street and Convent Avenue, New York, NY 10031, USA
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Abstract
We report a new record for the world's longest-lived rodent, a male naked mole rat (Heterocephalus glaber). On the basis of his weight at capture, this animal was approximately 1 year old when collected near Mtito Andei, Kenya in July/August 1974. He died in April 2002, indicating that he lived for more than 28 years. As such, his life-span surpassed the previous longevity record for a rodent, which was held by a porcupine (Hystrix brachyura) that lived for 27 years and 4 months.
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Affiliation(s)
- Rochelle Buffenstein
- Department of Biology, City College of the City University of New York, New York, NY 10031, USA.
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Burland TM, Bennett NC, Jarvis JUM, Faulkes CG. Eusociality in African mole-rats: new insights from patterns of genetic relatedness in the Damaraland mole-rat (Cryptomys damarensis). Proc Biol Sci 2002; 269:1025-30. [PMID: 12028759 PMCID: PMC1690998 DOI: 10.1098/rspb.2002.1978] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
After the discovery of eusociality in the naked mole-rat, it was proposed that inbreeding and high colony relatedness in this species were the major underlying factors driving cooperative breeding in African molerats. By contrast, field and laboratory studies of the eusocial Damaraland mole-rat (Cryptomys damarensis) have raised the possibility that this species is an obligate outbreeder, although the build-up of inbreeding over several generations could still occur. Using microsatellite markers, we show that most breeding pairs in wild colonies of the Damaraland mole-rat are indeed unrelated (R = 0.02 +/- 0.04) and that mean colony relatedness (R = 0.46 +/- 0.01), determined across 15 colonies from three separate populations, is little more than half that previously identified in naked mole-rats. This finding demonstrates that normal familial levels of relatedness are sufficient for the occurrence of eusociality in mammals. Variation in the mean colony relatedness among populations provides support both for the central role played by ecological constraints in cooperative breeding and for the suggestion that inbreeding in naked mole-rats is a response to extreme constraints on dispersal. Approaches that determine the relative importance of an array of extrinsic factors in driving social evolution in African mole-rats are now required.
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Affiliation(s)
- Tamsin M Burland
- School of Biological Sciences, Queen Mary, University of London, London E1 4NS, UK.
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Spinks AC, Jarvis JUM, Bennett NC. Comparative patterns of philopatry and dispersal in two common mole-rat populations: implications for the evolution of mole-rat sociality. J Anim Ecol 2000. [DOI: 10.1046/j.1365-2656.2000.00388.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Spinks AC, Branch TA, Croeser S, Bennett NC, Jarvis JUM. Foraging in wild and captive colonies of the common mole-rat Cryptomys hottentotus hottentotus (Rodentia: Bathyergidae). J Zool (1987) 1999. [DOI: 10.1111/j.1469-7998.1999.tb00752.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
At 22°C the resting oxygen consumption of G. capensis is 1.13±0.05 cm3O2·g-1·h-1 (mean± S.E.). In loose sandy soil the burrowing metabolic rate was approximately three times that of resting (3.41±0.19 cm3O2·g-1· h-1). Rate of oxygen consumption while burrowing bears a linear relationship with rate of burrowing. The equation of the regression line describing this relationship was used to construct a model for calculating energy expenditure of burrowing in free-living mole-rats. The diet of G. capensis consists of some green plant material and geophyte corms. The latter has a mean gross energy content of 16.36 kJ·g-1 dry weight. The digestibility coefficient for captive G. capensis fed on sweet potato, was 97.42±0.41%. Data collected from an excavated burrow system revealed that the total energetic cost of constructing the burrow amounted to 79% of the estimated digestible energy available from geophyte corms in the area. A food store in the same burrow system was sufficient to meet the maintenance requirements of an adult G. capensis, resting at 22°C, for approximately 80-85 days. Soil samples taken at random adjacent to the burrow contained corms with a mean estimated digestible energy value of 2084 kJ per m3 of soil. A comparison of energetic cost of burrowing and randomly available digestible energy in the field suggests that foraging patterns are not random.
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Affiliation(s)
- J T Du Toit
- Zoology Department, University of Cape Town, 7700, Rondebosch, South Africa
| | - J U M Jarvis
- Zoology Department, University of Cape Town, 7700, Rondebosch, South Africa
| | - G N Louw
- Zoology Department, University of Cape Town, 7700, Rondebosch, South Africa
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