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1
Rosario Carotenuto, Angelo, Federico Guarracino, Radim Šumbera, and Massimiliano Fraldi. "Burrowing below ground: interaction between soil mechanics and evolution of subterranean mammals." Journal of The Royal Society Interface 17, no. 162 (January 2020): 20190521. http://dx.doi.org/10.1098/rsif.2019.0521.
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The evolution of species is governed by complex phenomena in which biological and environmental features may interact dynamically. Subterranean mammals dig tunnels whose diameter minimizes energetic costs during excavations and display anatomical adaptations in order to burrow structurally stable tunnels according to specific features of the soil. These animals weight from less than 50 g up to 1–2 kg, and dig tunnels with diameters from 3 to 15 cm. The use of allometric laws has enabled these data to be correlated. However, since tunnels need to be stable with respect to the geomechanical characteristics of the resident soils, a mathematical treatment linking the admissible dimensions of tunnels to the environment here suggests a mechanically grounded correlation between the body mass of subterranean mammals and the maximum dimensions of tunnels. Remarkably, such theoretical findings reflect very well the empirical allometric relationship and contribute to explain the wide differences observed in body sizes of subterranean mammals. In this respect, a far from ancillary role of environmental mechanics on the morphological evolution of subterranean mammals can be hypothesized.
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Faulkes, Christopher G., Kalina T. J. Davies, Stephen J. Rossiter, and Nigel C. Bennett. "Molecular evolution of the hyaluronan synthase 2 gene in mammals: implications for adaptations to the subterranean niche and cancer resistance." Biology Letters 11, no. 5 (May 2015): 20150185. http://dx.doi.org/10.1098/rsbl.2015.0185.
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The naked mole-rat (NMR) Heterocephalus glaber is a unique and fascinating mammal exhibiting many unusual adaptations to a subterranean lifestyle. The recent discovery of their resistance to cancer and exceptional longevity has opened up new and important avenues of research. Part of this resistance to cancer has been attributed to the fact that NMRs produce a modified form of hyaluronan—a key constituent of the extracellular matrix—that is thought to confer increased elasticity of the skin as an adaptation for living in narrow tunnels. This so-called high molecular mass hyaluronan (HMM-HA) stems from two apparently unique substitutions in the hyaluronan synthase 2 enzyme (HAS2). To test whether other subterranean mammals with similar selection pressures also show molecular adaptation in their HAS2 gene, we sequenced the HAS2 gene for 11 subterranean mammals and closely related species, and combined these with data from 57 other mammals. Comparative screening revealed that one of the two putatively important HAS2 substitutions in the NMR predicted to have a significant effect on hyaluronan synthase function was uniquely shared by all African mole-rats. Interestingly, we also identified multiple other amino acid substitutions in key domains of the HAS2 molecule, although the biological consequences of these for hyaluronan synthesis remain to be determined. Despite these results, we found evidence of strong purifying selection acting on the HAS2 gene across all mammals, and the NMR remains unique in its particular HAS2 sequence. Our results indicate that more work is needed to determine whether the apparent cancer resistance seen in NMR is shared by other members of the African mole-rat clade.
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Koyabu, Daisuke, Misato Hosojima, and Hideki Endo. "Into the dark: patterns of middle ear adaptations in subterranean eulipotyphlan mammals." Royal Society Open Science 4, no. 9 (September 2017): 170608. http://dx.doi.org/10.1098/rsos.170608.
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Evolution of the middle ear ossicles was a key innovation for mammals, enhancing the transmission of airborne sound. Radiation into various habitats from a terrestrial environment resulted in diversification of the auditory mechanisms among mammals. However, due to the paucity of phylogenetically controlled investigations, how middle ear traits have diversified with functional specialization remains unclear. In order to identify the respective patterns for various lifestyles and to gain insights into fossil forms, we employed a high-resolution tomography technique and compared the middle ear morphology of eulipotyphlan species (moles, shrews and hedgehogs), a group that has radiated into various environments, such as terrestrial, aquatic and subterranean habitats. Three-dimensional geometric morphometric analysis was conducted within a phylogenetically controlled framework. Quantitative shapes were found to strongly reflect the degree of subterranean lifestyle and weakly involve phylogeny. Our analyses demonstrate that subterranean adaptation should include a relatively shorter anterior process of the malleus, an enlarged incus, an enlarged stapes footplate and a reduction of the orbicular apophysis. These traits arguably allow improving low-frequency sound transmission at low frequencies and inhibiting the low-frequency noise which disturbs the subterranean animals in hearing airborne sounds.
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Lacey, EA, JL Patton, and GN Cameron. "Life Underground: The Biology Of Subterranean Rodents." Australian Mammalogy 23, no. 1 (2001): 75. http://dx.doi.org/10.1071/am01075_br.
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SUBTERRANEAN rodents are intriguing subjects for research. On the one hand they display extreme variability in social organisation and life history, and exhibit a range of unique adaptations in morphology and physiology that allow exploitation of different habitats. On the other hand, field studies of subterranean rodents are exceptionally challenging as the animals are seldom observed. Subterranean rodents are also widely distributed, occurring on all continents except Australia and Antarctica. Life underground: The biology of subterranean rodents provides an excellent summary of what we know (and what we do not know) about this cryptic group of mammals, and also succeeds in conveying the joys and frustrations of studying them.
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Emerling, Christopher A., and Mark S. Springer. "Eyes underground: Regression of visual protein networks in subterranean mammals." Molecular Phylogenetics and Evolution 78 (September 2014): 260–70. http://dx.doi.org/10.1016/j.ympev.2014.05.016.
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de Villiers, M. S. "A COMPARISON OF SUBTERRANEAN HERBIVORY BY FOSSORIAL AND TERRESTRIAL MAMMALS." Transactions of the Royal Society of South Africa 48, no. 2 (January 1993): 257–64. http://dx.doi.org/10.1080/00359199309520274.
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Faulkes, Chris G. "Mosaic Evolution of Subterranean Mammals — Regression, Progression and Global Convergence." Heredity 84, no. 4 (April 2000): 493–94. http://dx.doi.org/10.1046/j.1365-2540.2000.0726b.x.
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Thorley, Jack. "The case for extended lifespan in cooperatively breeding mammals: a re-appraisal." PeerJ 8 (May 19, 2020): e9214. http://dx.doi.org/10.7717/peerj.9214.
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Recent comparative studies have suggested that cooperative breeding is associated with increases in maximum lifespan among mammals, replicating a pattern also seen in birds and insects. In this study, we re-examine the case for increased lifespan in mammalian cooperative breeders by analysing a large dataset of maximum longevity records. We did not find any consistent, strong evidence that cooperative breeders have longer lifespans than other mammals after having controlled for variation in body mass, mode of life and data quality. The only possible exception to this general trend is found in the African mole-rats (the Bathyergid family), where all members are relatively long-lived, but where the social, cooperatively breeding species appear to be much longer-lived than the solitary species. However, solitary mole-rat species have rarely been kept in captivity or followed longitudinally in the wild and so it seems likely that their maximum lifespan has been underestimated when compared to the highly researched social species. Although few subterranean mammals have received much attention in a captive or wild setting, current data instead supports a causal role of subterranean living on lifespan extension in mammals.
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Montoya-Sanhueza, Germán, and Anusuya Chinsamy. "Cortical bone adaptation and mineral mobilization in the subterranean mammalBathyergus suillus(Rodentia: Bathyergidae): effects of age and sex." PeerJ 6 (June 11, 2018): e4944. http://dx.doi.org/10.7717/peerj.4944.
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The patterns of bone modeling and mineral mobilization (skeletal homeostasis) among mammals other than humans and laboratory rodents are still poorly known. In this study we assessed the pattern of bone formation and bone resorption in the femur of a wild population of Cape dune molerats,Bathyergus suillus(n= 41) (Bathyergidae), a solitary subterranean mammal with a marked extended longevity among rodents, and which also lives in a naturally deficient state of vitamin D. In order to determine ontogenetic and sex effects on histomorphometric parameters of transversal undecalcified bone sections, two-way ANOVA, linear mixed-effects model and regression statistical analyses were performed. During ontogeny,B. suillusincreased their cross sectional area, cortical area and cortical thickness, and most importantly, they showed scarce endosteal bone resorption which resulted in a retained medullary cavity size during ontogeny. This resulted in a positively imbalanced bone modeling, where bone formation considerably surpasses bone loss by almost 100-fold in adulthood. This differs markedly from other terrestrial mammals with relatively thin cortical walls. Regarding bone loss and remodeling, three main processes involving intracortical resorption were observed: modeling-related bone loss in early postnatal growth; secondary osteon formation occurring in both sexes; and subendosteal secondary reconstruction observed only in females. The latter is accompanied by females having six-fold more relative bone loss than males, which is evidenced by the development of enlarged resorption cavities (RCs) distributed circumferentially around the medullary cavity. Males have smaller, more circular and randomly distributed RCs. In general, our data indicate no age-related decline in mineral content inB. suillus, and provides strong support for a pattern of sexual dimorphism in skeletal homeostasis, similar to that occurring in humans and other mammals, with females losing more bone throughout aging as compared to males due to reproductive factors. Interestingly as well, despite the high mechanical loads experienced during burrow construction, bone remodeling inB. suillusis kept at very low levels throughout their lifespan, and dense Haversian tissue never forms. This study represents the first comprehensive assessment of skeletal homeostasis in a subterranean mammal, and it enables a better understanding of the complex processes governing the acquisition and maintenance of bone properties in this species with extraordinary fossorial adaptations.
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Retief, Liezl, Nigel C. Bennett, Jennifer U. M. Jarvis, and Armanda D. S. Bastos. "Subterranean Mammals: Reservoirs of Infection or Overlooked Sentinels of Anthropogenic Environmental Soiling?" EcoHealth 14, no. 4 (November 1, 2017): 662–74. http://dx.doi.org/10.1007/s10393-017-1281-6.
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Malewski, Sandra, Sabine Begall, Cristian E. Schleich, C. Daniel Antenucci, and Hynek Burda. "Do subterranean mammals use the Earth’s magnetic field as a heading indicator to dig straight tunnels?" PeerJ 6 (October 31, 2018): e5819. http://dx.doi.org/10.7717/peerj.5819.
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Subterranean rodents are able to dig long straight tunnels. Keeping the course of such “runways” is important in the context of optimal foraging strategies and natal or mating dispersal. These tunnels are built in the course of a long time, and in social species, by several animals. Although the ability to keep the course of digging has already been described in the 1950s, its proximate mechanism could still not be satisfactorily explained. Here, we analyzed the directional orientation of 68 burrow systems in five subterranean rodent species (Fukomys anselli, F. mechowii, Heliophobius argenteocinereus, Spalax galili, and Ctenomys talarum) on the base of detailed maps of burrow systems charted within the framework of other studies and provided to us. The directional orientation of the vast majority of all evaluated burrow systems on the individual level (94%) showed a significant deviation from a random distribution. The second order statistics (averaging mean vectors of all the studied burrow systems of a respective species) revealed significant deviations from random distribution with a prevalence of north–south (H. argenteocinereus), NNW–SSE (C. talarum), and NE–SW (Fukomys mole-rats) oriented tunnels. Burrow systems of S. galili were randomly oriented. We suggest that the Earth’s magnetic field acts as a common heading indicator, facilitating to keep the course of digging. This study provides a field test and further evidence for magnetoreception and its biological meaning in subterranean mammals. Furthermore, it lays the foundation for future field experiments.
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Hart, Daniel W., Barry van Jaarsveld, Kiara G. Lasch, Kerryn L. Grenfell, Maria K. Oosthuizen, and Nigel C. Bennett. "Ambient Temperature as a Strong Zeitgeber of Circadian Rhythms in Response to Temperature Sensitivity and Poor Heat Dissipation Abilities in Subterranean African Mole-Rats." Journal of Biological Rhythms 36, no. 5 (August 3, 2021): 461–69. http://dx.doi.org/10.1177/07487304211034287.
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Mammals have evolved circadian rhythms in internal biological processes and behaviors, such as locomotor activity (LA), to synchronize to the environmental conditions they experience. Photic entrainment of LA has been well established; however, non-photic entrainment, such as ambient temperature ( Ta), has received much less attention. To address this dearth of knowledge, we exposed two subterranean endothermic-homeothermic African mole-rat species, the solitary Cape mole-rat ( Georychus capensis [GC]) and social Mahali mole-rat ( Cryptomys hottentotus mahali [CHM]), to varying Ta cycles in the absence of light. We showed that the LA rhythms of these two species entrain to Ta cycles and that the majority of LA occurred during the coolest 12-h period. LA confined to the coolest Ta periods may be the direct consequence of the poor heat dissipation abilities of African mole-rats brought about by physiological and ecological constraints. Recently, it has been hypothesized that Ta is only a strong zeitgeber for circadian rhythms in species whose thermoregulatory abilities are sensitive to changes in Ta (i.e., heterotherms and ectotherms), which previously has excluded endothermic-homeothermic mammals. However, this study demonstrates that Ta is a strong zeitgeber or entrainer for circadian rhythms of LA in subterranean endothermic-homeothermic mammals as a consequence of their sensitivity to changes in Ta brought about by their poor heat dissipation abilities. This study reinforces the intimate link between circadian rhythms and thermoregulation and conclusively, for the first time, provides evidence that Ta is a strong zeitgeber for endothermic-homeothermic mammals.
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Emerling, Christopher A. "Regressed but Not Gone: Patterns of Vision Gene Loss and Retention in Subterranean Mammals." Integrative and Comparative Biology 58, no. 3 (April 25, 2018): 441–51. http://dx.doi.org/10.1093/icb/icy004.
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Ben-Shlomo, R., H.-S. Shin, and E. Nevo. "Period-homologous sequence polymorphisms in subterranean mammals of the Spalax ehrenbergi superspecies in Israel." Heredity 70, no. 2 (February 1993): 111–21. http://dx.doi.org/10.1038/hdy.1993.19.
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Pleštilová, Lucie, Jan Okrouhlík, Hynek Burda, Hana Sehadová, Eva M. Valesky, and Radim Šumbera. "Functional histology of the skin in the subterranean African giant mole-rat: thermal windows are determined solely by pelage characteristics." PeerJ 8 (April 8, 2020): e8883. http://dx.doi.org/10.7717/peerj.8883.
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Excavation of burrows is an extremely physically demanding activity producing a large amount of metabolic heat. Dissipation of its surplus is crucial to avoid the risk of overheating, but in subterranean mammals it is complicated due to the absence of notable body extremities and high humidity in their burrows. IR-thermography in a previous study on two species of African mole-rats revealed that body heat was dissipated mainly through the ventral body part, which is notably less furred. Here, we analyzed the dorsal and ventral skin morphology, to test if dermal characteristics could contribute to higher heat dissipation through the ventral body part. The thickness of the epidermis and dermis and the presence, extent and connectivity of fat tissue in the dermis were examined using routine histological methods, while vascular density was evaluated using fluorescent dye and confocal microscopy in the giant mole-rat Fukomys mechowii. As in other hitherto studied subterranean mammals, no subcutaneous adipose tissue was found. All examined skin characteristics were very similar for both dorsal and ventral regions: relative content of adipose tissue in the dermis (14.4 ± 3.7% dorsally and 11.0 ± 4.0% ventrally), connectivity of dermal fat (98.5 ± 2.8% and 95.5 ± 6.8%), vascular density (26.5 ± 3.3% and 22.7 ± 2.3%). Absence of large differences in measured characteristics between particular body regions indicates that the thermal windows are determined mainly by the pelage characteristics.
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Lacey, Eileen A., Shannon L. O’Brien, Raúl Sobrero, and Luis A. Ebensperger. "Spatial relationships among free-living cururos (Spalacopus cyanus) demonstrate burrow sharing and communal nesting." Journal of Mammalogy 100, no. 6 (July 30, 2019): 1918–27. http://dx.doi.org/10.1093/jmammal/gyz117.
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Abstract Spatial relationships among conspecifics can provide insights into numerous aspects of social behavior. Spatial data may be particularly important for characterizing the behavior of difficult-to-study species such as subterranean rodents, direct observations of which are challenging. To characterize the social organization of the cururo (Spalacopus cyanus), a subterranean species in the rodent family Octodontidae, we used radiotelemetry to quantify spatial relationships within populations of this species located in Parque Nacional Bosque Fray Jorge and Santuario de la Naturaleza Yerba Loca, Chile. Specifically, we sought to determine if adults in this diurnal species share burrows and subterranean nests, the two criteria typically used to identify subterranean rodents as social. Analyses of radio fixes collected during February–March 2003 revealed that cururos at both Fray Jorge and Yerba Loca shared nighttime nest sites; cluster analyses of these data identified multiple spatially distinct subsets of adults in each population. Overlap of minimum convex polygons constructed from radio fixes collected during daylight hours suggested burrow sharing by animals in both populations. Cluster analyses of overlap values revealed the same spatially distinct groups of individuals identified from analyses of nest sharing; in addition, these analyses revealed one cluster of animals in each population that was not evident from analyses of nighttime data. Collectively, these results confirm that cururos are social, with adults in both study populations sharing burrow systems and communal nests. Our findings add to the growing understanding of social organization in octodontid rodents and reveal a new system for comparative studies of the ecology and evolution of behavioral variation in burrow-dwelling mammals.
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Begall, Sabine, and Milton H. Gallardo. "Spalacopus cyanus (Rodentia: Octodontidae): an extremist in tunnel constructing and food storing among subterranean mammals." Journal of Zoology 251, no. 1 (May 2000): 53–60. http://dx.doi.org/10.1111/j.1469-7998.2000.tb00592.x.
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Buffenstein, R., I. N. Sergeev, and J. M. Pettifor. "Vitamin D hydroxylases and their regulation in a naturally vitamin D-deficient subterranean mammal, the naked mole rat (Heterocephalus glaber)." Journal of Endocrinology 138, no. 1 (July 1993): 59–64. http://dx.doi.org/10.1677/joe.0.1380059.
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ABSTRACT The vitamin D hormone 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) is generated by a series of hydroxylation steps in the liver and kidneys. We investigated whether naturally vitamin D-deficient subterranean mammals (naked mole rats, Heterocephalus glaber) employ the same enzymatic pathways, and whether these are regulated in a similar manner to that established for other mammals. Vitamin D3-25-hydroxylase in the liver and both 25-hydroxyvitamin D3-l-hydroxylase and 25-hydroxyvitamin D3-24 hydroxylase (1-OHase and 24-OHase) in the kidney were detectable in mole rats. As expected for vitamin D-deficient mammals, the 1-OHase activity predominated over the 24-OHase. After mole rats received a supraphysiological supplement of vitamin D3, 1-OHase activity was suppressed and 24-OHase activity was enhanced. Irrespective of vitamin D status, forskolin (a protein kinase A activator) and dibutyryl cyclic AMP did not alter the activity of either 1-OHase or 24-OHase. These findings suggest that the response of renal hydroxylases to parathyroid hormone was blunted. Phorbol esters, 12-O-tetradecanoylphorbol 13-acetate (TPA) and 1-oleoyl-2-acetylglycerol (OAG) (protein kinase C activators), suppressed 1-OHase activity. 24-OHase activity was induced by TPA but not by OAG. These effects were similar to those illicited by vitamin D3 supplementation but were additive in that they increased the responses shown in vitamin D-replete mole rats. These data confirm that naturally vitamin D-deficient mole rats can convert vitamin D3 to the hormone, 1,25(OH)2D3. Furthermore, the enzymes 1-OHase and 24-OHase present in the kidneys of these mammals are regulated independently by 1,25(OH)2D3 and protein kinase C-mediated pathways of intracellular signalling, but are not regulated by the cyclic AMP–protein kinase A signal transduction pathway. Journal of Endocrinology (1993) 138, 59–64
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Nevo, Eviatar, M. Grazia Filippucci, and Avigdor Beiles. "Genetic polymorphisms in subterranean mammals (Spalax ehrenbergi superspecies) in the Near East revisited: patterns and theory." Heredity 72, no. 5 (May 1994): 465–87. http://dx.doi.org/10.1038/hdy.1994.65.
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Pfaff, Cathrin, Thomas Martin, and Irina Ruf. "Bony labyrinth morphometry indicates locomotor adaptations in the squirrel-related clade (Rodentia, Mammalia)." Proceedings of the Royal Society B: Biological Sciences 282, no. 1809 (June 22, 2015): 20150744. http://dx.doi.org/10.1098/rspb.2015.0744.
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The semicircular canals (SCs) of the inner ear detect angular acceleration and are located in the bony labyrinth of the petrosal bone. Based on high-resolution computed tomography, we created a size-independent database of the bony labyrinth of 50 mammalian species especially rodents of the squirrel-related clade comprising taxa with fossorial, arboreal and gliding adaptations. Our sampling also includes gliding marsupials, actively flying bats, the arboreal tree shrew and subterranean species. The morphometric anatomy of the SCs was correlated to the locomotion mode. Even if the phylogenetic signal cannot entirely be excluded, the main significance for functional morphological studies has been found in the diameter of the SCs, whereas the radius of curvature is of minor interest. Additionally, we found clear differences in the bias angle of the canals between subterranean and gliding taxa, but also between sciurids and glirids. The sensitivity of the inner ear correlates with the locomotion mode, with a higher sensitivity of the SCs in fossorial species than in flying taxa. We conclude that the inner ear of flying and gliding mammals is less sensitive due to the large information flow into this sense organ during locomotion.
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ROSSIN, M. A., A. I. MALIZIA, J. T. TIMI, and R. POULIN. "Parasitism underground: determinants of helminth infections in two species of subterranean rodents (Octodontidae)." Parasitology 137, no. 10 (May 26, 2010): 1569–75. http://dx.doi.org/10.1017/s0031182010000351.
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SUMMARYPatterns of infection among hosts in a population are often driven by intrinsic host features such as age or sex, as well as by positive or negative interactions between parasite species. We investigated helminth parasitism in 2 South American rodent species,Ctenomys australisandC. talarum(Octodontidae), to determine whether the unusual solitary and subterranean nature of these hosts would impact their patterns of infection. We applied generalized linear models to infection data on a total of 7 helminth species (1 inC. australisand 6 inC. talarum). Host age and season of capture influenced infection levels in some of the helminth species, but none were influenced by host body condition. InC. talarum, 4 pairs of helminth species showed significant associations, either asymmetrical or symmetrical, and with 3 of the 4 being positive; strong inter-specific facilitation appears likely in 1 case. Also, we found that female hosts, especially non-pregnant ones, harboured heavier infections of 2 nematode species than male hosts. This is in sharp contrast to the general male-bias reported for most studies of nematodes in wild mammals, and we develop explanations for these results based on the unusual ecology of these subterranean rodents.
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Avivi, Aaron, Alma Joel, and Eviatar Nevo. "The lens protein α-B-crystallin of the blind subterranean mole-rat: high homology with sighted mammals." Gene 264, no. 1 (February 2001): 45–49. http://dx.doi.org/10.1016/s0378-1119(00)00603-x.
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Jiang, Mengwan, Luye Shi, Xiujuan Li, Qianqian Dong, Hong Sun, Yimeng Du, Yifeng Zhang, et al. "Genome‐wide adaptive evolution to underground stresses in subterranean mammals: Hypoxia adaption, immunity promotion, and sensory specialization." Ecology and Evolution 10, no. 14 (June 3, 2020): 7377–88. http://dx.doi.org/10.1002/ece3.6462.
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Legendre, Lucas J., and Jennifer Botha-Brink. "Digging the compromise: investigating the link between limb bone histology and fossoriality in the aardvark (Orycteropus afer)." PeerJ 6 (July 11, 2018): e5216. http://dx.doi.org/10.7717/peerj.5216.
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Bone microstructure has long been known as a powerful tool to investigate lifestyle-related biomechanical constraints, and many studies have focused on identifying such constraints in the limb bones of aquatic or arboreal mammals in recent years. The limb bone microstructure of fossorial mammals, however, has not been extensively described. Furthermore, so far, studies on this subject have always focused on the bone histology of small burrowers, such as subterranean rodents or true moles. Physiological constraints associated with digging, however, are known to be strongly influenced by body size, and larger burrowers are likely to exhibit a histological profile more conspicuously influenced by fossorial activity. Here, we describe for the first time the limb bone histology of the aardvark (Orycteropus afer), the largest extant burrowing mammal. The general pattern is very similar for all six sampled limb bones (i.e., humerus, radius, ulna, femur, tibia, and fibula). Most of the cortex at midshaft is comprised of compacted coarse cancellous bone (CCCB), an endosteal tissue formed in the metaphyses through the compaction of bony trabeculae. Conversely, the periosteal bone is highly resorbed in all sections, and is reduced to a thin outer layer, suggesting a pattern of strong cortical drift. This pattern contrasts with that of most large mammals, in which cortical bone is of mostly periosteal origin, and CCCB, being a very compliant bone tissue type, is usually resorbed or remodeled during ontogeny. The link between histology and muscle attachment sites, as well as the influence of the semi-arid environment and ant-eating habits of the aardvark on its bone microstructure, are discussed. We hypothesize that the unusual histological profile of the aardvark is likely the outcome of physiological constraints due to both extensive digging behavior and strong metabolic restrictions. Adaptations to fossoriality are thus the result of a physiological compromise between limited food availability, an environment with high temperature variability, and the need for biomechanical resistance during digging. These results highlight the difficulties of deciphering all factors potentially involved in bone formation in fossorial mammals. Even though the formation and maintaining of CCCB through ontogeny in the aardvark cannot be unambiguously linked with its fossorial habits, a high amount of CCCB has been observed in the limb bones of other large burrowing mammals. The inclusion of such large burrowers in future histological studies is thus likely to improve our understanding of the functional link between bone growth and fossorial lifestyle in an evolutionary context.
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Gerlach, Frank, Aaron Avivi, Alma Joel, Thorsten Burmester, Eviatar Nevo, and Thomas Hankeln. "Genomic Organization and Molecular Evolution of the Genes for Neuroglobin and Cytoglobin in the Hypoxiatolerant Israeli Mole Rat, Spalax Carmeli." Israel Journal of Ecology and Evolution 52, no. 3-4 (April 12, 2006): 389–403. http://dx.doi.org/10.1560/ijee_52_3-4_389.
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The genes for the two respiratory proteins neuroglobin (Ngb) and cytoglobin (Cygb) in the subterranean Israeli mole rat Spalax carmeli have been sequenced and compared to other mammals including human. Coding regions of both Spalax genes are highly conserved on the nucleotide and amino acid level. The ratios of non-synonymous to synonymous nucleotide substitutions suggest strong purifying selection acting on Ngb and Cygb in all mammals. Thus, there appears to be no special sequence level adaptation in the two respiratory proteins within the hypoxia-tolerant mole rat. On the genomic level, Spalax Ngb and Cygb gene regions revealed the conserved 4-exon-3-intron structure and conserved CpG-rich islands in the 5' region. The Spalax Cygb gene promoter contains a conserved hypoxia-responsive transcription factor binding site, indicating a possible up-regulation of Cygb under oxygen deprivation. In Cygb intron 1, we observed a stretch of highly conserved putatively non-coding sequence of yet unknown (regulatory?) importance. In the Spalax Ngb gene, we note the presence of candidate hypoxia-responsive elements, which are not conserved in Ngb of hypoxia-sensitive mammals. Both globin gene regions harbor Spalax-specific simple sequence regions, which might be of adaptive value. We conclude that adaptations for hypoxia in mole rats are most likely to be found in regulatory functions rather than in protein structure.
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Holler, Jr, Cato, Jonathan Mays, and Matthew Niemiller. "The fauna of caves and other subter-ranean habitats of North Carolina, USA." Journal of Cave and Karst Studies 82, no. 4 (December 15, 2020): 221–60. http://dx.doi.org/10.4311/2019lsc0133.
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Over 1,500 caves have been documented in North Carolina, however, cave fauna in the Blue Ridge Mountains and Piedmont regions of North Carolina have been overlooked historically compared to the cave-rich karst terrains in the Appalachian Valley and Ridge and Interior Low Plateau to the west. Here, we provide the first comprehensive faunal list of caves and other subterranean habitats in the state based on over 40 years of periodic surveys and compilation of literature, biodiversity databases, and museum records. We report 475 occurrences from 127 caves, springs, and wells in 29 counties, representing 5 phyla, 17 classes, 43 orders, 90 families, 124 genera, and at least 164 species. Vertebrate fauna comprised 32 species, including 4 fishes, 9 salamanders, 1 lizard, 4 snakes, 2 birds, and 12 mammals (8 bats). Diverse invertebrate groups included spiders (11 families and 18 genera), springtails (7 families and 9 genera), segmented worms (3 families and 8 genera), and snails (6 families and 9 genera). At least 25 taxa are troglobites/stygobites (cave obligates), including 5 species of cave flatworms, 5 cave springtails, and 5 cave amphipods. Most troglobitic/stygobitic fauna documented in this study are endemic to North Carolina. Counties with the greatest cave biodiversity include Rutherford, McDowell, Swain, Henderson, Polk, and Avery counties. Over 20 species documented are of conservation concern, including 14 troglobites and 3 federally-listed bats. Although not as diverse as adjacent states, caves and other subterranean habitats in North Carolina support a diverse community of invertebrates and vertebrates. Our review serves as a base line for future cave biological surveys in the state and highlights the importance of subterranean habitats for North Carolina biodiversity.
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Srikosamatara, Sompoad. "Density and biomass of large herbivores and other mammals in a dry tropical forest, western Thailand." Journal of Tropical Ecology 9, no. 1 (February 1993): 33–43. http://dx.doi.org/10.1017/s026646740000691x.
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ABSTRACTDensity and biomass of four ungulate species, elephant (Elephas maximus) and seven other mammal species were estimated in an area of about 50 km2 in a dry tropical forest in Huai Kha Khaeng Wildlife Sanctuary, western Thailand. Density estimations employed line transects, using either direct sightings or indirect signs. Total biomass of these ungulates and elephant was 1450 kg km–2 which was lower than that found in a well protected and managed area of similar forest, Nagarahole National Park, in India. This is due to the intensive poaching activity and the lack of wildlife management in this study site. Three species of ungulate, banteng (Bos javanicus), gaur (Bos gaurus) and sambar deer (Cervus unicolor), contributed over 70% of the estimated herbivore biomass. This situation is similar to that found in other parts of Asia. The high biomass of a subterranean mammal, Cannomys badius, has not been documented elsewhere in Asia; this species probably influences the forest dynamics and ecology of small carnivores in this area.
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Antenucci, C. D., and F. Luna. "Macrophysiology of subterranean mammals. Ctenomys: A model to assess the effect of global warming on physiology and distribution." Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 157 (September 2010): S18. http://dx.doi.org/10.1016/j.cbpa.2010.06.049.
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Nevo, Eviatar, Rachel Ben-Shlomo, Avigdor Beiles, Charles P. Hart, and Frank H. Ruddle. "Homeobox DNA polymorphisms (RFLPs) in subterranean mammals of theSpalax ehrenbergi superspecies in Israel: Patterns, correlates, and evolutionary significance." Journal of Experimental Zoology 263, no. 4 (October 1, 1992): 430–41. http://dx.doi.org/10.1002/jez.1402630411.
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Marcovitz, Amir, Yatish Turakhia, Heidi I. Chen, Michael Gloudemans, Benjamin A. Braun, Haoqing Wang, and Gill Bejerano. "A functional enrichment test for molecular convergent evolution finds a clear protein-coding signal in echolocating bats and whales." Proceedings of the National Academy of Sciences 116, no. 42 (September 30, 2019): 21094–103. http://dx.doi.org/10.1073/pnas.1818532116.
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Distantly related species entering similar biological niches often adapt by evolving similar morphological and physiological characters. How much genomic molecular convergence (particularly of highly constrained coding sequence) contributes to convergent phenotypic evolution, such as echolocation in bats and whales, is a long-standing fundamental question. Like others, we find that convergent amino acid substitutions are not more abundant in echolocating mammals compared to their outgroups. However, we also ask a more informative question about the genomic distribution of convergent substitutions by devising a test to determine which, if any, of more than 4,000 tissue-affecting gene sets is most statistically enriched with convergent substitutions. We find that the gene set most overrepresented (q-value = 2.2e-3) with convergent substitutions in echolocators, affecting 18 genes, regulates development of the cochlear ganglion, a structure with empirically supported relevance to echolocation. Conversely, when comparing to nonecholocating outgroups, no significant gene set enrichment exists. For aquatic and high-altitude mammals, our analysis highlights 15 and 16 genes from the gene sets most affected by molecular convergence which regulate skin and lung physiology, respectively. Importantly, our test requires that the most convergence-enriched set cannot also be enriched for divergent substitutions, such as in the pattern produced by inactivated vision genes in subterranean mammals. Showing a clear role for adaptive protein-coding molecular convergence, we discover nearly 2,600 convergent positions, highlight 77 of them in 3 organs, and provide code to investigate other clades across the tree of life.
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Dudarev, Alexey, Valery Chupakhin, Sergey Vlasov, and Sveta Yamin-Pasternak. "Traditional Diet and Environmental Contaminants in Coastal Chukotka II: Legacy POPs." International Journal of Environmental Research and Public Health 16, no. 5 (February 27, 2019): 695. http://dx.doi.org/10.3390/ijerph16050695.
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The article is the second in the series of four that present the results of a study on environmental contaminants in coastal Chukotka, conducted in the context of a multi-disciplinary investigation of indigenous foodways in the region. The article presents the results of the analysis of legacy Persistent Organic Pollutants (POPs) found in the samples of locally harvested food and indoor matters, collected in 2016 in coastal Chukotka. Temporal trends and circumpolar comparisons of POPs in food have been carried out. Estimated daily intakes (EDIs) of POPs by local food consumption were calculated based on the food intake frequencies (questionnaire data). Concentrations of the studied legacy POPs in marine mammal blubber were relatively high (up to 100–200 µg/kg ww) but not exceeding the allowable limits. Gray whale blubber and whale mantak were the most contaminated foods, followed by the ringed, spotted and bearded seal blubber, then by walrus blubber and fermented walrus (deboned walrus parts aged in subterranean pits, typically over a period of 6 months). At the backdrop of general decrease or invariability (compared to the previous coastal Chukotka study 15 years ago) of the majority of POPs, an increasing tendency of HCB, mainly in marine mammals, were noted. Legacy POPs in marine mammals sampled in Chukotka were generally much lower than in those sampled in Alaska and northern Canada. We suggest that the Alaska Coastal Current from the Bering Sea plays a major role in this phenomenon. Analyses of the additional sources of in-home food contamination (home-brewed alcohol, domestic insecticides) have revealed relatively high levels of HCHs, DDTs and PCBs, which still represent a share of dietary exposure of local people to POPs.
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Davies, Kalina T. J., Nigel C. Bennett, Chris G. Faulkes, and Stephen J. Rossiter. "Limited Evidence for Parallel Molecular Adaptations Associated with the Subterranean Niche in Mammals: A Comparative Study of Three Superorders." Molecular Biology and Evolution 35, no. 10 (August 20, 2018): 2544–59. http://dx.doi.org/10.1093/molbev/msy161.
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Esperandio, Isadora Beraldi, Fernando Ascensão, Andreas Kindel, Ligia Tchaicka, and Thales Renato Ochotorena de Freitas. "Do roads act as a barrier to gene flow of subterranean small mammals? A case study with Ctenomys minutus." Conservation Genetics 20, no. 2 (January 4, 2019): 385–93. http://dx.doi.org/10.1007/s10592-018-01139-z.
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Caspar, Kai R., Katrin Moldenhauer, Regina E. Moritz, Pavel Němec, E. Pascal Malkemper, and Sabine Begall. "Eyes are essential for magnetoreception in a mammal." Journal of The Royal Society Interface 17, no. 170 (September 2020): 20200513. http://dx.doi.org/10.1098/rsif.2020.0513.
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Several groups of mammals use the Earth's magnetic field for orientation, but their magnetosensory organ remains unknown. The Ansell's mole-rat ( Fukomys anselli , Bathyergidae, Rodentia) is a microphthalmic subterranean rodent with innate magnetic orientation behaviour. Previous studies on this species proposed that its magnetoreceptors are located in the eye. To test this hypothesis, we assessed magnetic orientation in mole-rats after the surgical removal of their eyes compared to untreated controls. Initially, we demonstrate that this enucleation does not lead to changes in routine behaviours, including locomotion, feeding and socializing. We then studied magnetic compass orientation by employing a well-established nest-building assay under four magnetic field alignments. In line with previous studies, control animals exhibited a significant preference to build nests in magnetic southeast. By contrast, enucleated mole-rats built nests in random magnetic orientations, suggesting an impairment of their magnetic sense. The results provide robust support for the hypothesis that mole-rats perceive magnetic fields with their minute eyes, probably relying on magnetite-based receptors in the cornea.
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MILLS, STEPHEN L., and KENNETH C. CATANIA. "Identification of retinal neurons in a regressive rodent eye (the naked mole-rat)." Visual Neuroscience 21, no. 2 (March 2004): 107–17. http://dx.doi.org/10.1017/s0952523804043020.
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The retina consists of many parallel circuits designed to maximize the gathering of important information from the environment. Each of these circuits is comprised of a number of different cell types combined in modules that tile the retina. To a subterranean animal, vision is of relatively less importance. Knowledge of how circuits and their elements are altered in response to the subterranean environment is useful both in understanding processes of regressive evolution and in retinal processing itself. We examined common cell types in the retina of the naked mole-rat,Heterocephalus glaberwith immunocytochemical markers and retrograde staining of ganglion cells from optic nerve injections. The stains used show that the naked mole-rat eye has retained multiple ganglion cell types, 1–2 types of horizontal cell, rod bipolar and multiple types of cone bipolar cells, and several types of common amacrine cells. However, no labeling was found with antibodies to the dopamine-synthesizing enzyme, tyrosine hydroxylase. Although most of the well-characterized mammalian cell types are present in the regressive mole-rat eye, their structural organization is considerably less regular than in more sighted mammals. We found less precision of depth of stratification in the inner plexiform layer and also less precision in their lateral coverage of the retina. The results suggest that image formation is not very important in these animals, but that circuits beyond those required for circadian entrainment remain in place.
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Lungmus, Jacqueline K., and Kenneth D. Angielczyk. "Antiquity of forelimb ecomorphological diversity in the mammalian stem lineage (Synapsida)." Proceedings of the National Academy of Sciences 116, no. 14 (March 18, 2019): 6903–7. http://dx.doi.org/10.1073/pnas.1802543116.
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Mammals and their closest fossil relatives are unique among tetrapods in expressing a high degree of pectoral girdle and forelimb functional diversity associated with fully pelagic, cursorial, subterranean, volant, and other lifestyles. However, the earliest members of the mammalian stem lineage, the “pelycosaur”-grade synapsids, present a far more limited range of morphologies and inferred functions. The more crownward nonmammaliaform therapsids display novel forelimb morphologies that have been linked to expanded functional diversity, suggesting that the roots of this quintessentially mammalian phenotype can be traced to the pelycosaur–therapsid transition in the Permian period. We quantified morphological disparity of the humerus in pelycosaur-grade synapsids and therapsids using geometric morphometrics. We found that disparity begins to increase concurrently with the emergence of Therapsida, and that it continues to rise until the Permo-Triassic mass extinction. Further, therapsid exploration of new regions of morphospace is correlated with the evolution of novel ecomorphologies, some of which are characterized by changes to overall limb morphology. This evolutionary pattern confirms that nonmammaliaform therapsid forelimbs underwent ecomorphological diversification throughout the Permian, with functional elaboration initially being more strongly expressed in the proximal end of the humerus than the distal end. The role of the forelimbs in the functional diversification of therapsids foreshadows the deployment of forelimb morphofunctional diversity in the evolutionary radiation of mammals.
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Avivi, Aaron, Leonid Brodsky, Eviatar Nevo, and Mark R. Band. "Differential expression profiling of the blind subterranean mole rat Spalax ehrenbergi superspecies: bioprospecting for hypoxia tolerance." Physiological Genomics 27, no. 1 (September 2006): 54–64. http://dx.doi.org/10.1152/physiolgenomics.00001.2006.
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The blind subterranean mole rat of the Spalax ehrenbergi superspecies, living underground and exposed to fluctuating oxygen and carbon dioxide levels, is an excellent model of hypoxic tolerance. Unique structural and functional adaptations of the cardiovascular and respiratory systems allow these underground mammals to survive at severely reduced oxygen tension. Elucidation of the natural variation and evolutionary changes under hypoxia within this superspecies may have biomedical applications in ischemic syndromes and cancer. In this study, we have compared expression profiles of muscle tissue at normoxic (21%) and hypoxic (3%) levels of oxygen concentration between two allospecies of the S. ehrenbergi superspecies exhibiting differential hypoxia tolerance in accordance with their ecological regimes. Profiling was performed by cross-species hybridization using a mouse cDNA array containing 15,000 gene elements. Results uncover species-specific responses to hypoxic stress among numerous genes involved in angiogenesis, apoptosis, and oxidative stress management. Among the most striking results are differential expressions of cardiac ankyrin repeat protein ( Carp), activating transcription factor 3 ( Atf3), LIM and cysteine-rich domains 1 ( Lmcd1), cysteine and glycine-rich protein 2 ( Csrp2), and ras homolog gene family, member B ( RhoB). These findings support the hypothesis that allospecies of the S. ehrenbergi superspecies are variably adapted to fluctuating oxygen tension. Differences may involve specific metabolic pathways and functional adaptations at the structural and molecular levels.
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Emerling, Christopher A., Mark S. Springer, John Gatesy, Zachary Jones, Deana Hamilton, David Xia-Zhu, Matt Collin, and Frédéric Delsuc. "Genomic evidence for the parallel regression of melatonin synthesis and signaling pathways in placental mammals." Open Research Europe 1 (July 1, 2021): 75. http://dx.doi.org/10.12688/openreseurope.13795.1.
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Background: The study of regressive evolution has yielded a wealth of examples where the underlying genes bear molecular signatures of trait degradation, such as pseudogenization or deletion. Typically, it appears that such disrupted genes are limited to the function of the regressed trait, whereas pleiotropic genes tend to be maintained by natural selection to support their myriad purposes. One such set of genes is involved in the synthesis (AANAT, ASMT) and signaling (MTNR1A, MTNR1B) of melatonin, a hormone secreted by the vertebrate pineal gland. Melatonin provides a signal of environmental darkness, thereby influencing the circadian and circannual rhythmicity of numerous physiological traits. Therefore, the complete loss of a pineal gland and the underlying melatonin pathway genes seems likely to be maladaptive, unless compensated by extrapineal sources of melatonin. Methods: We examined AANAT, ASMT, MTNR1A and MTNR1B in 123 vertebrate species, including pineal-less placental mammals and crocodylians. We searched for inactivating mutations and modelled selective pressures (dN/dS) to test whether the genes remain functionally intact. Results: We report that crocodylians retain intact melatonin genes and express AANAT and ASMT in their eyes, whereas all four genes have been repeatedly inactivated in the pineal-less xenarthrans, pangolins, sirenians, and whales. Furthermore, colugos have lost these genes, and several lineages of subterranean mammals have partial melatonin pathway dysfunction. These results are supported by the presence of shared inactivating mutations across clades and analyses of selection pressure based on the ratio of non-synonymous to synonymous substitutions (dN/dS), suggesting extended periods of relaxed selection on these genes. Conclusions: The losses of melatonin synthesis and signaling dates to tens of millions of years ago in several lineages of placental mammals, raising questions about the evolutionary resilience of pleiotropic genes, and the causes and consequences of losing melatonin pathways in these species.
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Friesen, T. Max, and Lauren E. Y. Norman. "The Pembroke Site: Thule Inuit Migrants on Southern Victoria Island." ARCTIC 69, no. 1 (March 1, 2016): 1. http://dx.doi.org/10.14430/arctic4545.
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This paper presents description and interpretation of the Pembroke site, the earliest known Thule Inuit occupation in the southeastern Victoria Island region, Nunavut. The site has 11 extant dwellings, including five heavy tent rings, five light semi-subterranean dwellings, and a <em>qalgiq </em>(large communal structure). The site’s economy revolved mainly around the acquisition of caribou, Arctic char, and lake trout, with minimal consumption of sea mammals. Radiocarbon dates, reinforced by artifact analyses, indicate an occupation around AD 1400. Based on several lines of evidence, including the extremely small artifact samples, the site is interpreted as having been occupied relatively briefly. It represents the first colonization of the region by Thule people, approximately 200 years after the initial Thule migration from Alaska into the eastern Arctic. Thus, it documents a second migration wave: an expansion of Thule peoples from their initially occupied territories to other, in some ways less optimal, regions
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Stewart, R. A., C. Jarret, C. Scott, S. A. White, and D. J. McCafferty. "Water vole (Arvicola amphibius) abundance in grassland habitats of Glasgow." Glasgow Naturalist 27, no. 1 (2019): 10–19. http://dx.doi.org/10.37208/tgn27102.
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Water vole (Arvicola amphibius) populations have undergone a serious decline throughout the UK, and yet a stronghold of these small mammals is found in the greater Easterhouse area of Glasgow. The water voles in this location are mostly fossorial, living a largely subterranean existence in grasslands, rather than the more typical semi-aquatic lifestyle in riparian habitats. In this study, we carried out capture-mark-recapture surveys on water voles at two sites: Cranhill Park and Tillycairn Drive. We made a total of 62 captures including retraps, and the resulting population estimates were 78 individuals (95% confidence interval 41-197) for Cranhill Park and 42 individuals (20-141) for Tillycairn Drive. From these figures we estimated a population density of water voles, which appeared to be higher than other reports from the UK. Despite the difficulties of sampling in urban environments that resulted in relatively low capture rates, our data suggest that the greater Easterhouse area of Glasgow holds water voles at relatively high population densities. These results will inform future conservation in the City of Glasgow and surrounding areas, as well as raise awareness of important water vole populations in urban environments.
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Li, Kexin, Wei Hong, Hengwu Jiao, Guo-Dong Wang, Karl A. Rodriguez, Rochelle Buffenstein, Yang Zhao, Eviatar Nevo, and Huabin Zhao. "Sympatric speciation revealed by genome-wide divergence in the blind mole rat Spalax." Proceedings of the National Academy of Sciences 112, no. 38 (September 4, 2015): 11905–10. http://dx.doi.org/10.1073/pnas.1514896112.
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Sympatric speciation (SS), i.e., speciation within a freely breeding population or in contiguous populations, was first proposed by Darwin [Darwin C (1859) On the Origins of Species by Means of Natural Selection] and is still controversial despite theoretical support [Gavrilets S (2004) Fitness Landscapes and the Origin of Species (MPB-41)] and mounting empirical evidence. Speciation of subterranean mammals generally, including the genus Spalax, was considered hitherto allopatric, whereby new species arise primarily through geographic isolation. Here we show in Spalax a case of genome-wide divergence analysis in mammals, demonstrating that SS in continuous populations, with gene flow, encompasses multiple widespread genomic adaptive complexes, associated with the sharply divergent ecologies. The two abutting soil populations of S. galili in northern Israel habituate the ancestral Senonian chalk population and abutting derivative Plio-Pleistocene basalt population. Population divergence originated ∼0.2–0.4 Mya based on both nuclear and mitochondrial genome analyses. Population structure analysis displayed two distinctly divergent clusters of chalk and basalt populations. Natural selection has acted on 300+ genes across the genome, diverging Spalax chalk and basalt soil populations. Gene ontology enrichment analysis highlights strong but differential soil population adaptive complexes: in basalt, sensory perception, musculature, metabolism, and energetics, and in chalk, nutrition and neurogenetics are outstanding. Population differentiation of chemoreceptor genes suggests intersoil population's mate and habitat choice substantiating SS. Importantly, distinctions in protein degradation may also contribute to SS. Natural selection and natural genetic engineering [Shapiro JA (2011) Evolution: A View From the 21st Century] overrule gene flow, evolving divergent ecological adaptive complexes. Sharp ecological divergences abound in nature; therefore, SS appears to be an important mode of speciation as first envisaged by Darwin [Darwin C (1859) On the Origins of Species by Means of Natural Selection].
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Matveevsky, Sergey, Tsenka Chassovnikarova, Tatiana Grishaeva, Maret Atsaeva, Vasilii Malygin, Irina Bakloushinskaya, and Oxana Kolomiets. "Kinase CDK2 in Mammalian Meiotic Prophase I: Screening for Hetero- and Homomorphic Sex Chromosomes." International Journal of Molecular Sciences 22, no. 4 (February 17, 2021): 1969. http://dx.doi.org/10.3390/ijms22041969.
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Cyclin-dependent kinases (CDKs) are crucial regulators of the eukaryotic cell cycle. The critical role of CDK2 in the progression of meiosis was demonstrated in a single mammalian species, the mouse. We used immunocytochemistry to study the localization of CDK2 during meiosis in seven rodent species that possess hetero- and homomorphic male sex chromosomes. To compare the distribution of CDK2 in XY and XX male sex chromosomes, we performed multi-round immunostaining of a number of marker proteins in meiotic chromosomes of the rat and subterranean mole voles. Antibodies to the following proteins were used: RAD51, a member of the double-stranded DNA break repair machinery; MLH1, a component of the DNA mismatch repair system; and SUN1, which is involved in the connection between the meiotic telomeres and nuclear envelope, alongside the synaptic protein SYCP3 and kinetochore marker CREST. Using an enhanced protocol, we were able to assess the distribution of as many as four separate proteins in the same meiotic cell. We showed that during prophase I, CDK2 localizes to telomeric and interstitial regions of autosomes in all species investigated (rat, vole, hamster, subterranean mole voles, and mole rats). In sex bivalents following synaptic specificity, the CDK2 signals were distributed in three different modes. In the XY bivalent in the rat and mole rat, we detected numerous CDK2 signals in asynaptic regions and a single CDK2 focus on synaptic segments, similar to the mouse sex chromosomes. In the mole voles, which have unique XX sex chromosomes in males, CDK2 signals were nevertheless distributed similarly to the rat XY sex chromosomes. In the vole, sex chromosomes did not synapse, but demonstrated CDK2 signals of varying intensity, similar to the rat X and Y chromosomes. In female mole voles, the XX bivalent had CDK2 pattern similar to autosomes of all species. In the hamster, CDK2 signals were revealed in telomeric regions in the short synaptic segment of the sex bivalent. We found that CDK2 signals colocalize with SUN1 and MLH1 signals in meiotic chromosomes in rats and mole voles, similar to the mouse. The difference in CDK2 manifestation at the prophase I sex chromosomes can be considered an example of the rapid chromosome evolution in mammals.
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Smith, Andrew. "Environmental monitoring programs: recognising the importance of conservation values." APPEA Journal 53, no. 2 (2013): 480. http://dx.doi.org/10.1071/aj12091.
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The Gorgon Project will develop the Gorgon and Jansz-Io gas fields, located in the Greater Gorgon area, about 130 km off the northwest coast of WA. It includes the construction of a 15 million tonne per annum (mtpa) LNG plant on Barrow Island and a domestic gas plant with the capacity to provide 300 terajoules per day to supply gas to WA. Barrow Island—where Gorgon will be located—is an internationally significant nature reserve and the site of Australia’s largest onshore operating oil field for the past 45 years. As a world-class example of environmental management, it has shown that conservation and development can successfully co-exist. Recognising the importance of Barrow Island’s conservation values, the terrestrial and subterranean environmental monitoring program encompasses key ecological elements on Barrow Island including birds, mammals, subterranean fauna, vegetation, and surface water and land forms. These elements are monitored in relation to the potential impact from environmental stressors identified during pre-construction environmental impact assessments. Here, the author describes the monitoring surveys conducted during the year as appropriate according to the element being considered. All surveys are executed using the Gorgon Project field mobilisation and deployment process, a stringent and dedicated system that ensures all essential health and safety processes are in place and adhered to. Each element is monitored for signs of positive or negative impact across Barrow Island with comparisons made between the pre-determined Terrestrial Disturbance Footprint (TDF) and areas outside of the TDF in which the Gorgon Project is committed to causing zero environmental harm. Statistical control charts and tiered response triggers based on standard deviations are used to inform management decisions about potential environmental effects attributable to the Gorgon Project. A continuous review process is in place to ensure all monitoring programs are scientifically robust and use up-to-date methodologies. Monitoring reports are used to assess the validity of each program and supplementary programs aimed at addressing gaps in existing knowledge are started as and when needed. A reporting framework is in place to ensure regulatory authorities are informed and collaborations are sought to advance overall understanding of the ecology and biology of Barrow Island fauna and flora. The Gorgon Project is operated by an Australian subsidiary of Chevron and is a joint venture of the Australian subsidiaries of Chevron (about 47%), ExxonMobil (25%), Shell (25%), Osaka Gas (1.25%), Tokyo Gas (1%) and Chubu Electric Power (0.417%).
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Burger, Tomáš, Marcela Lucová, Regina E. Moritz, Helmut H. A. Oelschläger, Rastislav Druga, Hynek Burda, Wolfgang Wiltschko, Roswitha Wiltschko, and Pavel Němec. "Changing and shielded magnetic fields suppress c-Fos expression in the navigation circuit: input from the magnetosensory system contributes to the internal representation of space in a subterranean rodent." Journal of The Royal Society Interface 7, no. 50 (March 10, 2010): 1275–92. http://dx.doi.org/10.1098/rsif.2009.0551.
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The neural substrate subserving magnetoreception and magnetic orientation in mammals is largely unknown. Previous experiments have demonstrated that the processing of magnetic sensory information takes place in the superior colliculus. Here, the effects of magnetic field conditions on neuronal activity in the rodent navigation circuit were assessed by quantifying c-Fos expression. Ansell's mole-rats ( Fukomys anselli ), a mammalian model to study the mechanisms of magnetic compass orientation, were subjected to natural, periodically changing, and shielded magnetic fields while exploring an unfamiliar circular arena. In the undisturbed local geomagnetic field, the exploration of the novel environment and/or nesting behaviour induced c-Fos expression throughout the head direction system and the entorhinal–hippocampal spatial representation system. This induction was significantly suppressed by exposure to periodically changing and/or shielded magnetic fields; discrete decreases in c-Fos were seen in the dorsal tegmental nucleus, the anterodorsal and the laterodorsal thalamic nuclei, the postsubiculum, the retrosplenial and entorhinal cortices, and the hippocampus. Moreover, in inactive animals, magnetic field intensity manipulation suppressed c-Fos expression in the CA1 and CA3 fields of the hippocampus and the dorsal subiculum, but induced expression in the polymorph layer of the dentate gyrus. These findings suggest that key constituents of the rodent navigation circuit contain populations of neurons responsive to magnetic stimuli. Thus, magnetic information may be integrated with multimodal sensory and motor information into a common spatial representation of allocentric space within this circuit.
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Partha, Raghavendran, Amanda Kowalczyk, Nathan L. Clark, and Maria Chikina. "Robust Method for Detecting Convergent Shifts in Evolutionary Rates." Molecular Biology and Evolution 36, no. 8 (May 11, 2019): 1817–30. http://dx.doi.org/10.1093/molbev/msz107.
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AbstractIdentifying genomic elements underlying phenotypic adaptations is an important problem in evolutionary biology. Comparative analyses learning from convergent evolution of traits are gaining momentum in accurately detecting such elements. We previously developed a method for predicting phenotypic associations of genetic elements by contrasting patterns of sequence evolution in species showing a phenotype with those that do not. Using this method, we successfully demonstrated convergent evolutionary rate shifts in genetic elements associated with two phenotypic adaptations, namely the independent subterranean and marine transitions of terrestrial mammalian lineages. Our original method calculates gene-specific rates of evolution on branches of phylogenetic trees using linear regression. These rates represent the extent of sequence divergence on a branch after removing the expected divergence on the branch due to background factors. The rates calculated using this regression analysis exhibit an important statistical limitation, namely heteroscedasticity. We observe that the rates on branches that are longer on average show higher variance, and describe how this problem adversely affects the confidence with which we can make inferences about rate shifts. Using a combination of data transformation and weighted regression, we have developed an updated method that corrects this heteroscedasticity in the rates. We additionally illustrate the improved performance offered by the updated method at robust detection of convergent rate shifts in phylogenetic trees of protein-coding genes across mammals, as well as using simulated tree data sets. Overall, we present an important extension to our evolutionary-rates-based method that performs more robustly and consistently at detecting convergent shifts in evolutionary rates.
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Herbin, M., J. P. Rio, J. RepéRant, H. M. Cooper, E. Nevo, and M. Lemire. "Ultrastructural study of the optic nerve in blind mole-rats (Spalacidae, Spalax)." Visual Neuroscience 12, no. 2 (March 1995): 253–61. http://dx.doi.org/10.1017/s0952523800007938.
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AbstractThe optic nerve in two species of subterranean mole-rats (Spalacidae) has been examined at the ultrastructural level. The axial length of the eye and the diameter of the optic nerve are 1.9 mm and 52.5 μm in Spalax leucodon, and 0.7 mm and 80.8 μm in Spalax ehrenbergi, respectively. An anti-glial fibrillary acidic protein postembedding procedure was used to distinguish glial cell processes from axons. In both species, the optic nerve is composed exclusively of unmyelinated axons and a spatial distribution gradient according to the size or the density of fibers is lacking. The optic nerve of S. leucodon contains 1790 fibers ranging in diameter from 0.07–2.30 μm (mean = 0.57 μm), whereas in S. ehrenbergi, only 928 fibers, with diameters of 0.04–1.77 μm (mean = 0.53 μm) are observed. In S. ehrenbergi, a higher proportion of glial tissue is present and the fascicular organization of optic fibers is less obvious. Distribution gradients according to size frequency or density of fibers in the optic nerve are absent in both species. Comparison with other mammals suggests that although ocular regression in microphthalmic species is correlated with a significant decrease in the total number of optic fibers and the relative proportion of myelinated fibers, no difference in the absolute size range of unmyelinated axons is observed. The total absence of myelinated fibers in Spalax may be related to the subcutaneous location of the eyes. The unique presence of unmyelinated fibers in the optic nerve is discussed in relation to the possible conservation of a single class of W-like ganglion cells in the retina, in relation to photoperiodic perception.
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Bego, Ferdinand, Enerit Saçdanaku, Michela Pacifici, and Carlo Rondinini. "Small terrestrial mammals of Albania: distribution and diversity (Mammalia, Eulipotyphla, Rodentia)." ZooKeys 742 (March 12, 2018): 127–63. http://dx.doi.org/10.3897/zookeys.742.22364.
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In this paper new records are reported for 23 species of small terrestrial mammals (STM) of Albania collected during the field work campaigns organised in the framework of the project “Strengthening capacity in National Nature Protection – preparation for Natura 2000 network” (NaturAL) in Albania during the summer and autumn of 2016 and 2017 Data on small mammals were primarily collected through Sherman live-trapping campaigns in six high priority protected areas of Albania: Korab-Koritnik, Bredhi i Hotovës, Tomorri, Llogara-Karaburun, Divjakë-Karavasta, Liqeni i Shkodrës (Skadar lake), Lëpushë-Vermosh. Other data were obtained by analysis of owl pellets or by direct observation of individuals (dead or alive) in the field. For 21 species Erinaceus roumanicus, Neomys anomalus, Crocidura suaveolens, Crocidura leucodon, Suncus etruscus, Talpa stankovici/caeca, Myocastor coypus, Sciurus vulgaris, Glis glis, Dryomys nitedula, Muscardinus avellanarius, Microtus levis/arvalis, Microtus subterraneus, Microtus thomasi, Microtus felteni, Myodes glareolus, Apodemus sylvaticus, Apodemus flavicollis, Apodemus epimelas, Mus musculus, and Mus macedonicus additional records are provide and their distributions reviewed, while the presence of two new species of shrews (Sorex araneus and Sorex minutus) for Albania is reported for the first time. A comprehensive review of the published and unpublished distribution records of STM species of the country is made, together with an updated checklist and distribution maps of the species.
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Gryz, Jakub, Grzegorz Lesiński, Dagny Krauze-Gryz, and Przemysław Stolarz. "Woodland reserves within an urban agglomeration as important refuges for small mammals." Folia Forestalia Polonica 59, no. 1 (March 1, 2017): 3–13. http://dx.doi.org/10.1515/ffp-2017-0001.
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Abstract The aim of the study was to determine the species richness (S, Chao- 1 index) and diversity (Shannon-Wiener H’ index, diversity profiles) of small mammal assemblages in woodland reserves in an urban agglomeration and to compare the similarity of assemblages (with the use of Ward’s method) in terms of proportions of small mammals connected to the habitats of different level of naturalness. The work was conducted from 2004-2015 at 9 woodland reserves in Warsaw (Poland). On the basis of the analysis of pellets of tawny owls Strix aluco, 2792 individuals were identified (24 species). Reserves supported from 7 to 16 of the small mammal species, the highest overall number of species estimated (Chao-1) was 19. Species present in every reserve were Apodemus flavicollis, A. agrarius, Rattus norvegicus, Sorex araneus and Talpa europaea. Least frequent were Microtus agrestis and M. subterraneus. Seven species of bats were detected. Species diversity was lower in the biggest forest complexes, where forest rodents dominated small mammal assemblage. The heterogeneity of habitats within reserve and in the surroundings, in combination with limited human-interference, resulted in an increase in the species diversity. Overall, the reserves under study were an important refuge for small mammals within the Warsaw agglomeration. However, safeguarding of adjacent areas against excessive anthropogenic change is needed and ecological corridors that link different areas need to be retained.
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Purger, J. Jenő. "Kisemlősök faunisztikai felmérése Somogy megye északkeleti részén, gyöngybagoly Tyto alba (Scopoli, 1769) köpetek vizsgálata alapján." Kaposvári Rippl-Rónai Múzeum Közleményei, no. 1 (2013): 81–90. http://dx.doi.org/10.26080/krrmkozl.2013.1.81.
Full textAbstract:
Pellets were collected between 1999 and 2009, from 20 localities (investigated area: BT80, BS79, BS78, BS77, BS89 and BS88, according to 10×10 km UTM grids). In a total of 1570 Barn Owl pellets there were 4127 prey rem-nants. Small mammals were dominating (97.8%). 22 mammal species were evidented: Crocidura leucodon, C. suaveolens, Sorex araneus, S. minutus, Neomys anomalus, Talpa euro-paea, Eptesicus serotinus, Muscardinus avellanarius, Microtus agrestis, M. arvalis, M. oeconomus, M. subterraneus, Arvicola amphibius, Myodes glareolus, Apodemus agrarius, A. flavicol-lis, A. sylvaticus, A. uralensis, Micromys minutus, Mus mus-culus, M. spicilegus, Rattus norvegicus). Remnants of birds, amphibians and insects consisted 2.2 % of total prey.
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Pitcher, T., I. N. Sergeev, and R. Buffenstein. "Vitamin D metabolism in the Damara mole-rat is altered by exposure to sunlight yet mineral metabolism is unaffected." Journal of Endocrinology 143, no. 2 (November 1994): 367–74. http://dx.doi.org/10.1677/joe.0.1430367.
Full textAbstract:
Abstract Vitamin D may be endogenously synthezised in the skin in the presence of sunlight or, alternatively, acquired from dietary sources. Cryptomys damarensis appear to have a naturally impoverished vitamin D status with low plasma concentrations of both 25-hydroxyvitamin D (25(OH)D; <5 ng/ml) and 1,25-dihydroxyvitamin D (1,25(OH)2D; <20 pg/ml). We attribute this to their underground habitat and herbivorous habits. We questioned whether these subterranean mammals could utilize sunlight-mediated pathways and therefore compared vitamin D metabolism and function when animals were (a) housed naturally (control), (b) given an oral vitamin D3 (D3) supplement (1 IU/g dry matter food eaten per day) and (c) exposed to 10 h of sunlight. Control animals exhibited a highly efficient apparent fractional absorption of both calcium (Ca) and inorganic phosphorus (Pi) (>90%), passive mode of intestinal mineral uptake, yet tightly regulated serum ionized calcium (Ca2+). The ratio of 25(OH)D-1α-hydroxylase (1-OHase) to 25(OH)D-24R-hydroxylase (24-OHase) activity in the kidney, corresponded with a state of vitamin D deficiency. Cryptomys damarensis responded to both oral D3 supplementation and sun exposure by an increase in plasma concentration of 1,25(OH)2D with a commensurate decline (P<0·05) in 1-OHase activity, and a resulting decrease (P<0·05) in the ratio of 1-OHase:24-OHase activity. Despite these changes, the intestinal mode of Ca uptake and plasma total Ca, Ca2+ and Pi remained unchanged with either treatment. Responses to sunlight were less pronounced than that of oral D3 supplementation. These data confirm that naturally vitamin D-deficient mole-rats can convert vitamin D to the active hormone 1,25(OH)2D, and indicate that mole-rats function optimally at the low concentrations of vitamin D metabolites found naturally. Furthermore, these animals exhibit a highly efficient vitamin D-independent mode of intestinal Ca absorption. Journal of Endocrinology (1994) 143, 367–374