The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Hynek Burda - One of the best experts on this subject based on the ideXlab platform.

  • Light perception in ‘blind’ subterranean Zambian mole-rats
    Animal Behaviour, 2006
    Co-Authors: Regina E. Wegner, Sabine Begall, Hynek Burda
    Abstract:

    Because of their constantly dark habitat and microphthalmia, subterranean African mole-rats have hitherto been considered as blind. Recent morphological findings, however, revealed a qualitatively rather well-developed, although quantitatively reduced, visual system and questioned the prevailing idea of blindness. We investigated the reactions of Zambian mole-rats of the bathyergid genus Fukomys (formerly Cryptomys) to white light during nest building. Using a two-armed test chamber with a choice between strong halogen light and darkness, we found that mole-rat pairs avoided the illuminated chamber and nested significantly more often in the dark box. With the same protocol in an eight-armed maze, we confirmed this heliophobic (or scotophilic) behaviour under natural daylight conditions. Zambian mole-rats can thus perceive natural light intensities and use photic information, for example to decide where to nest.

  • Kairomone-guided food location in subterranean Zambian mole-rats (Cryptomys spp., Bathyergidae)
    Folia Zoologica, 2005
    Co-Authors: Birgit Neumann, Simone Lange, Petra Hagemeyer, Hynek Burda
    Abstract:

    A b s t r a c t . A recent study (H e t h et al. 2002) challenged the idea of “blind” foraging in herbivorous underground dwellers by showing that subterranean rodents of several species use olfaction to discriminate between soils in which plants had or had not been growing. Here we address additional questions about odour-based foraging underground. We tested responses of Zambian mole-rats (Cryptomys anselli and C. kafuensis) to putative carrot kairomones using tunnel T-mazes. Mole-rats distinguished peat moistened with hydroponic as well as filtered hydroponic “carrot water” from peat moistened with distilled water. Furthermore, mole-rats detected carrot kairomones that percolated over the course of a week through the soil to a distance of 30 cm. These results demonstrate that 1) Attractiveness of soil is given by contents of primary root kairomones not caused by microbial activity in planted soil. 2) Carrot-kairomones are water-soluble molecules of less than 0.6 µm diameter. 3) Carrot-kairomones diffuse around the plant, making plants detectable from a distance.

  • subcortical visual system of the african mole rat Cryptomys anselli to see or not to see
    European Journal of Neuroscience, 2004
    Co-Authors: Pavel Nemec, Hynek Burda, Leo Peichl
    Abstract:

    Abstract We studied the retinal projections, the distribution of cytochrome oxidase activity and the cyto- and myeloarchitecture of the subcortical visual system in the subterranean Ansell's mole-rat Cryptomys anselli. The optic nerve contained 1500 myelinated and a similar number of unmyelinated fibres. The retina projected to all the visual structures described in surface-dwelling sighted rodents. The suprachiasmatic nucleus was large and received bilateral retinal input. All other visual nuclei were reduced in size, were cytoarchitecturally poorly developed and received almost exclusively contralateral retinal projections. The dorsal and ventral lateral geniculate nuclei were moderately reduced and heavily innervated. The intergeniculate leaflet could be identified between these two nuclei. Pretectal nuclei were also relatively well-developed. The nucleus of the optic tract, the olivary pretectal nucleus, and the anterior and posterior pretectal nuclei were innervated by the retina. By contrast, the superficial, retinorecipient layers of the superior colliculus showed extreme reduction. The strata zonale, griseum superficiale and opticum were collapsed to a single layer 40 micro m thick. The accessory optic system was vestigial. These findings indicate that the functional subsystems involved in photoperiod perception, form and brightness discrimination, and movement analysis are anatomically rather well developed, whereas those involved in coordination of visuomotor reflexes are severely reduced. Thus, the visual system of C. anselli is much better developed than that of the blind mole-rat Spalax ehrenbergi. We suggest that Cryptomys anselli has retained basic visual capabilities.

  • molecular phylogenetics and taxonomy of the african mole rats genus Cryptomys and the new genus coetomys gray 1864
    Molecular Phylogenetics and Evolution, 2004
    Co-Authors: Colleen M Ingram, Hynek Burda, Rodney L. Honeycutt
    Abstract:

    Abstract Cryptomys represents the most speciose and widely distributed genus of the Bathyergidae (Mammalia; Rodentia), a family of mole-rats endemic to sub-Saharan Africa. Throughout its range in southern, central, and western Africa, Cryptomys displays diversity in terms of morphology, patterns of behavior, and chromosome number, thus complicating the systematics of the group. A molecular phylogeny was obtained by separate and combined analyses of the mitochondrial 12S rRNA and intron I of the nuclear transthyretin gene for chromosomally and geographically diverse populations of Cryptomys . Our results show that Cryptomys sensu lato is comprised of two distinct and divergent monophyletic clades: hottentotus and mechowi . Based on our analyses, we propose the elevation of the mechowi clade to the genus Coetomys , retaining Cryptomys as the generic epithet of the South African hottentotus clade. This is supported by: (1) reciprocal monophyly of the two lineages based on independent datasets, (2) the level of sequence divergence observed between these lineages relative to other genera (i.e., Bathyergus and Georychus ), and (3) different patterns of chromosomal evolution, with Cryptomys sensu stricto being karyotypically conserved (2N=54) and Coetomys exhibiting high karyotypic diversity (2N=40–78).

  • unusual cone and rod properties in subterranean african mole rats rodentia bathyergidae
    European Journal of Neuroscience, 2004
    Co-Authors: Leo Peichl, Pavel Nemec, Hynek Burda
    Abstract:

    : We have determined the presence of spectral cone types, and the population densities of cones and rods, in subterranean mole-rats of the rodent family Bathyergidae, for which light and vision seems of little importance. Most mammals have two spectral cone types, a majority of middle- to long-wave-sensitive (L-) cones, and a minority of short-wave-sensitive (S-)cones. We were interested to see whether the subterranean bathyergids show the same pattern. In three species, Ansell's mole-rat Cryptomys anselli, the giant mole-rat Cryptomys mechowi and the naked mole-rat Heterocephalus glaber, spectral cone types and rods were assessed immunocytochemically with opsin-specific antibodies. All three species had rod-dominated retinae but possessed significant cone populations. A quantitative assessment in C. anselli and C. mechowi revealed surprisingly low photoreceptor densities of 100 000-150 000/mm(2), and high cone proportions, approximately 10% (8000-15 000/mm(2)). In all three species, the vast majority of the cones were strongly S-opsin-immunoreactive; L-opsin immunoreactivity was much fainter. In C. anselli, approximately 20% of the cones showed exclusive S-opsin label, approximately 10% exclusive L-opsin label and approximately 70% strong S-opsin and faint L-opsin double label (potential dual-pigment cones). This is the first observation in any mammal of an S-opsin dominance and low levels of L-opsin across the entire retina. It contrasts starkly with the situation in the muroid blind mole-rat Spalax ehrenbergi, which has been reported to possess L-opsin but no S-opsin. Evidently, within rodents an adaptation to subterranean life is compatible with very different spectral cone properties.

Chris G Faulkes - One of the best experts on this subject based on the ideXlab platform.

  • the distribution of gastrointestinal parasites in two populations of common mole rats Cryptomys hottentotus hottentotus
    Journal of Parasitology, 2017
    Co-Authors: Chris G Faulkes, Elizabeth Archer, Kerstin Junker, Heike Lutermann
    Abstract:

    Abstract The spread of parasites through a host population is based on the variation in behavior and immune function between individuals and is rarely uniform. We studied the gastrointestinal parasites of common mole-rats (Cryptomys hottentotus hottentotus, Lesson 1826) from 2 sites and assessed the levels of infection based on host sex, breeding status, and season. Only nematode species were found: Neoheligmonella sp. and Mammalakis macrospiculum (Ortlepp, 1939) and a single specimen of Trichuris sp., all of which have direct life cycles. Parasite burden and species richness was greater in the mesic habitat. The abundance of Neoheligmonella sp. differed significantly between seasons, and the season of peak abundance differed between sites, perhaps due to differences in host densities between sites. In addition, parasite burden did not differ between the sexes, but breeding animals had higher infections of Neoheligmonella sp. and M. macrospiculum than non-breeding animals. This and previous studies thus s...

  • phylogeographical patterns of genetic divergence and speciation in african mole rats family bathyergidae
    Molecular Ecology, 2004
    Co-Authors: Chris G Faulkes, Erik Verheyen, W Verheyen
    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.

  • Microsatellite primers for the African mole-rat genus Cryptomys and cross-species amplification within the family Bathyergidae
    Molecular Ecology Notes, 2001
    Co-Authors: Tamsin M. Burland, Jacqueline M. Bishop, Colleen O'ryan, Chris G Faulkes
    Abstract:

    We report 11 microsatellite loci for the African mole-rat genus Cryptomys (Rodentia: Bathyergidae), isolated from the Damaraland mole-rat (Cryptomys damarensis) and the Common mole-rat (C. hottentotus hottentotus). All loci are highly polymorphic in the source species, with between six and 13 alleles and observed heterozygosity ranging from 0.54 to 0.86. Two C. damarensis loci (DMR1 and 6) may be located on the X-chromosome. Cross-species amplification was investigated in 10 Bathyergid species, representative of the five genera. The majority of loci amplified polymorphic product in all Cryptomys species tested. Amplification was also widespread in the other genera, except in Heterocephalus.

  • ecological constraints drive social evolution in the african mole rats
    Proceedings of The Royal Society B: Biological Sciences, 1997
    Co-Authors: Chris G Faulkes, Michael William Bruford, H P Obrien, G H Aguilar
    Abstract:

    The African mole-rats (family Bathyergidae) are subterranean hystricomorph rodents occurring in a variety of habitats and displaying levels of sociality which range from solitary to eusocial, making them a unique mammalian taxonomic group to test ecological influences on sociality. Here, we use an extensive DNA-based phylogeny and comparative analysis to investigate the relationship between ecology, sociality and evolution within the family. Mitochondrial cytochrome-b and 12s rRNA trees reveal that the solitary species are monophyletic when compared to the social species. The naked mole-rat (Heterocephalus glaber) is ancestral and divergent from the Damaraland mole-rat (Cryptomys damarensis), supporting previous findings that have suggested the multiple evolution of eusociality within the family. The Cryptomys genus is species-rich and contains taxa exhibiting different levels of sociality, which can be divided into two distinct clades. A total of seven independent comparisons were generated within the phylogeny, and three ecological variables were significantly correlated with social group size: geophyte density (p < 0.05), mean months per year of rainfall greater than 25 mm (p < 0.001), and the coefficient of rainfall variation (p = 0.001). These results support the food-aridity hypothesis for the evolution of highly social cooperative behaviour in the Bathyergidae, and are consistent with the current theoretical framework for skew theory.

  • thermoregulation in three species of afrotropical subterranean mole rats rodentia bathyergidae from zambia and angola and scaling within the genus Cryptomys
    Oecologia, 1994
    Co-Authors: G H Aguilar, Chris G Faulkes
    Abstract:

    The thermoregulatory characteristics of three species of Cryptomys from Zambia and Angola are examined and, together with published data on four other species of Cryptomys from southern Africa, used to determine whether scaling occurs in this genus of subterranean rodents. The thermoregulatory properties of acclimated giant Zambian mole-rats, Cryptomys mechowi ( $$\bar x$$ =267 g), Angolan mole-rats, Cryptomys bocagei ( $$\bar x$$ =94 g) and Zambian common mole-rats Cryptomys hottentotus amatus ( $$\bar x$$ =77 g) are as follows. Mean resting metabolic rates (RMRs) within the respective thermoneutral zones were 0.60±0.08 cm3 O2 g-1 h-1 (n=12) for C. mechowi; 0.74±0.06 cm3 O2 g-1 h-1 (n=8) for C. bocagei and 0.63±0.06 cm3O2 g-1 h-1 (n=21) for C. h. amatus. The thermoneutral zones (TNZs) of all three species are narrow: 29–30°C for C. mechowi; 31.5–32.5°C for C. bocagei and 28–32° C for C. h. amatus. The increase in mean RMR at the lowest temperatures tested (15° C for C. mechowi, 18° C for C. bocagei and C. h. amatus) was 2.35, 2.2 and 3.82 times their RMR in the TNZ respectively. Body temperatures are low, 34±0.53° C (n=24) for C. mechowi, 33.7±0.32° C (n=20) for C. bocagei and 33.8±0.43° C (n=40) for C. h amatus. At the lower limit of thermoneutrality, conductances are 0.09±0.01 cm3 O2 g-1 h-1 °C-1 (n=30) in C. mechowi; 0.12±0.01 cm3 O2 g-1 h-1 °C-1 (n=20) in C. bocagei and 0.12±0.03 cm3 O2 g-1 h-1 °C-1 (n=32) in C. h. amatus. The range in mean body mass among the seven species of Cryptomys examined for scaling was 60 g (C. darlingi) to 267 g (C. mechowi). There is no clear relationship between RMR within the TNZ and body mass. The resultant relationship is represented by the power curve RMR=2.45 mass-0.259.

A J Molteno - One of the best experts on this subject based on the ideXlab platform.

  • REPRODUCTIONRESEARCH
    2015
    Co-Authors: A J Molteno, N C Bennett, J A King, C W Coen
    Abstract:

    A neuroanatomical and neuroendocrinological study into the relationship between social status and the GnRH system in cooperatively breeding female Damaraland mole-rats, Cryptomys damarensi

  • rainfall dispersal and reproductive inhibition in eusocial damaraland mole rats Cryptomys damarensis
    Journal of Zoology, 2006
    Co-Authors: A J Molteno
    Abstract:

    Non-reproductive female Damaraland mole-rats Cryptomys damarensis that were caught before a period of good rainfall (during which 90% of the average annual fell) (Group 1), exhibited a significantly lower pituitary sensitivity to gonadotrophin-releasing hormone compared to non-reproductive females (Group 2) caught in the same area, close to the end of the wet period. Group 2 were also significantly heavier than Group 1. Pituitary sensitivity was not significantly correlated to body mass within either group of females, nor within groups of reproductive males and non-reproductive males from a laboratory held colony. This suggests that rainfall may have resulted in the simultaneous, but unrelated, increase in pituitary sensitivity and body mass. Larger size and reduced sexual inhibition assist dispersal and the probability of successful independent reproduction, during periods when environmental constraints on dispersal are relaxed. These findings support the hypothesis that low rainfall may be an important constraint on dispersal and an important factor promoting the evolution of reproductive inhibition, and consequently eusociality, in this species.

  • melatonin secretion in a strictly subterranean mammal the damaraland mole rat Cryptomys damarensis
    Journal of Zoology, 2003
    Co-Authors: T A Richter, Benoît Malpaux, A J Molteno, Patricia A Fleming
    Abstract:

    Subterranean mammals inhabit an environment that is normally devoid of light and are therefore deprived of photoperiodic information that can be used to time important life-history events. An assessment was made of whether melatonin secretion in a strictly subterranean rodent, the Damaraland mole-rat Cryptomys damarensis, can be modified by photoperiod. In experiment 1, a clear diurnal rhythm of melatonin secretion in animals housed under a neutral photoperiod (12L:12D) was observed, with significantly higher melatonin concentrations in the dark compared to the light phase. The same diurnal melatonin rhythm was found 1 day after animals were transferred to either continuous light or continuous dark, suggesting that a circadian rhythm was maintained under acute exposure to light and dark. In experiment 2, melatonin secretion was monitored in a long (14L:10D) and short day (10L:14D) photoperiod and was found to be modified by the photoperiodic change. We therefore suggest that the Damaraland mole-rat possesses a circadian melatonin rhythm that can be physiologically modulated in response to photoperiod.

  • Melatonin secretion in a strictly subterranean mammal, the Damaraland mole-rat (Cryptomys damarensis)
    2003
    Co-Authors: T A Richter, Benoît Malpaux, A J Molteno, Patricia A Fleming, N C Bennett
    Abstract:

    Subterranean mammals inhabit an environment that is normally devoid of light and are therefore deprived of photoperiodic information that can be used to time important life-history events. An assessment was made of whether melatonin secretion in a strictly subterranean rodent, the Damaraland mole-rat Cryptomys damarensis, can be modified by photoperiod. In experiment 1, a clear diurnal rhythm of melatonin secretion in animals housed under a neutral photoperiod (12L:12D) was observed, with significantly higher melatonin concentrations in the dark compared to the light phase. The same diurnal melatonin rhythm was found 1 day after animals were transferred to either continuous light or continuous dark, suggesting that a circadian rhythm was maintained under acute exposure to light and dark. In experiment 2, melatonin secretion was monitored in a long (14L:10D) and short day (10L:14D) photoperiod and was found to be modified by the photoperiodic change. We therefore suggest that the Damaraland mole-rat possesses a circadian melatonin rhythm that can be physiologically modulated in response to photoperiod. Key words: subterranean, mole-rat, melatonin, photoperiod, Cryptomys damarensi

  • social suppression in nonreproductive female damaraland mole rats Cryptomys damarensis no apparent role for endogenous opioid peptides
    Hormones and Behavior, 2002
    Co-Authors: A J Molteno
    Abstract:

    The role of endogenous opioid peptides (EOPs) on LH secretion was examined to investigate the neuronal mechanisms responsible for the inhibition of GnRH and the resultant infertility in nonreproductive female Damaraland mole-rats, Cryptomys damarensis. The endorphin antagonist naloxone was administered to five groups of females to determine its effect on plasma LH levels: Grouping was determined by social status, social environment, and whether the females were ovariectomized. A single injection of naloxone had no significant effect on LH secretion in either intact or hystero-ovariectomized females. Multiple injections with naloxone failed to affect basal LH concentrations but did result in a decrease in GnRH-stimulated LH secretion in ovariectomized nonreproductive and reproductive females. A significant response to a single naloxone injection following GnRH priming was obtained in both nonreproductive females and in nonreproductive females housed in the absence of the reproductive pair. These results suggest EOPs play a role in sexual function but that socially induced infertility is unlikely to be mediated through the EOP system.

N C Bennett - One of the best experts on this subject based on the ideXlab platform.

  • Masticatory musculature of the African mole-rats (Rodentia: Bathyergidae).
    'PeerJ', 2020
    Co-Authors: Pg Cox, Cg Faulkes, N C Bennett
    Abstract:

    The Bathyergidae, commonly known as blesmols or African mole-rats, is a family of rodents well-known for their subterranean lifestyle and tunnelling behaviour. Four of the five extant bathyergid genera (Cryptomys, Fukomys, Georychus and Heliophobius) are chisel-tooth diggers, that is they dig through soil with their enlarged incisors, whereas the remaining genus (Bathyergus) is a scratch-digger, only using its forelimbs for burrowing. Heterocephalus glaber, the naked mole-rat, is also a chisel-tooth digger and was until recently included within the Bathyergidae (as the most basally branching genus), but has now been placed by some researchers into its own family, the Heterocephalidae. Given the importance of the masticatory apparatus in habitat construction in this group, knowledge and understanding of the morphology and arrangement of the jaw-closing muscles in Bathyergidae is vital for future functional analyses. Here, we use diffusible iodine-based contrast-enhanced microCT to reveal and describe the muscles of mastication in representative specimens of each genus of bathyergid mole-rat and to compare them to the previously described musculature of the naked mole-rat. In all bathyergids, as in all rodents, the masseter muscle is the most dominant component of the masticatory musculature. However, the temporalis is also a relatively large muscle, a condition normally associated with sciuromorphous rodents. Unlike their hystricomorphous relatives, the bathyergids do not show an extension of the masseter through the infraorbital foramen on to the rostrum (other than a very slight protrusion in Cryptomys and Fukomys). Thus, morphologically, bathyergids are protrogomorphous, although this is thought to be secondarily derived rather than retained from ancestral rodents. Overall, the relative proportions of the jaw-closing muscles were found to be fairly consistent between genera except in Bathyergus, which was found to have an enlarged superficial masseter and relatively smaller pterygoid muscles. It is concluded that these differences may be a reflection of the behaviour of Bathyergus which, uniquely in the family, does not use its incisors for digging

  • Africa
    2016
    Co-Authors: T. C. Bray, N C Bennett
    Abstract:

    Eight microsatellite markers were developed for African mole-rats using the Fast Isolation by AFLP of Sequences Containing repeats (FIASCO) protocol and pyrosequencing. The markers were developed in Bathyergus suillus and applied to a selection of individuals from seven related taxa: Bathyergus janetta, Cryptomys hottentotus hottentotus, C. h. pretoriae, Fukomys damarensis, F. darlingi, F. mechowii and Georychus capensis. The markers displayed low to moderate variation with allele numbers ranging between one and six per species. We propose that larger repeat numbers at di-, tri- and tetranucleotide repeat loci generally yield higher levels of polymorphism. Manuscript Click here to download Manuscript: Brayetal_mrat_main_consgenres2010.doc The family Bathyergidae represents an endemic African radiation of subterranean rodents (Jarvis & Bennett, 1990). Mole-rat ecology is highly variable across species, varying with mode of social organisation and habitat preference (Bennett et al. 2000). There are still relatively few published species-specific molecular markers available for African mole-rats that may be used at a population level (Burland et al. 2001). As a consequence only a handfu

  • REPRODUCTIONRESEARCH
    2015
    Co-Authors: A J Molteno, N C Bennett, J A King, C W Coen
    Abstract:

    A neuroanatomical and neuroendocrinological study into the relationship between social status and the GnRH system in cooperatively breeding female Damaraland mole-rats, Cryptomys damarensi

  • Seasonal changes in burrow geometry of the common mole rat (Rodentia: Bathyergidae)
    Naturwissenschaften, 2013
    Co-Authors: H. G. Thomas, M. Scantlebury, D. Swanepoel, P. W. Bateman, N C Bennett
    Abstract:

    Sociality in mole rats has been suggested to have evolved as a response to the widely dispersed food resources and the limited burrowing opportunities that result from sporadic rainfall events. In the most arid regions, individual foraging efficiency is reduced, and energetic constraints increase. In this study, we investigate seasonal differences in burrow architecture of the social Cryptomys hottentotus hottentotus in a mesic region. We describe burrow geometry in response to seasonal weather conditions for two seasons (wet and dry). Interactions occurred between seasons and colony size for the size of the burrow systems, but not the shape of the burrow systems. The fractal dimension values of the burrow systems did not differ between seasons. Thus, the burrow complexity was dependent upon the number of mole rats present in the social group.

  • Dissection of a Y-autosome translocation in Cryptomys hottentotus (Rodentia, Bathyergidae) and implications for the evolution of a meiotic sex chromosome chain
    Chromosoma, 2008
    Co-Authors: N C Bennett, J. L. Deuve, A. Ruiz-herrera, P.d. Waters, Janice Britton-davidian, T.j. Robinson
    Abstract:

    We describe the outcome of a comprehensive cytogenetic survey of the common mole-rat, Cryptomys hottentotus, based on G and C banding, fluorescence in situ hybridisation and the analysis of meiotic chromosomes using immunostaining of proteins involved in the formation of synaptonemal complex (SCP1 and SCP3). We identified the presence of a Y-autosome translocation that is responsible for a fixed diploid number difference between males (2n=53) and females (2n=54), a character that likely defines the C. hottentotus lineage. Immunostaining, combined with C banding of spermatocytes, revealed a linearised sex trivalent with X-1 at one end and X-2 at the other, with evidence of reduced recombination between Y and X-2 that seems to be heterochromatin dependant in the C. hottentotus lineage. We suggest that this could depict the likely initial step in the differentiation of a true neo-X, and that this may mimic an early stage in the mammalian meiotic chain formation, an evolutionary process that has been taken to an extreme in a monotreme mammal, the platypus.

Mathias Kawalika - One of the best experts on this subject based on the ideXlab platform.

  • natural history of the giant mole rat Cryptomys mechowi rodentia bathyergidae from zambia
    Journal of Mammalogy, 2001
    Co-Authors: Andreas Scharff, Mathias Kawalika, Oliver Lockergrutjen, Hynek Burda
    Abstract:

    Abstract We present the 1st detailed field study on the giant mole-rat (Cryptomys mechowi), a eusocial subterranean bathyergid rodent from mesic areas of subequatorial central Africa. In Copperbelt Province, Zambia, we found giant mole-rats in a variety of habitats including agricultural fields, bushland, marshes, and forests. Soil types varied in hardness and air content, and varied vertically and horizontally. Burrow systems of single colonies were 0.2–2.5 ha. The diameter of burrows was about 8 cm, and the maximum depth was about 200 cm. Nests were found at an average depth of 91 cm (n = 8). Further characteristics of nests, food and defecation chambers, diet, helminth parasites, and commensals are described. Colony size ranged from 3 to >20 with a sex ratio of 1:1.2 (n = 65) in favor of females, with 8% juveniles, 39% subadults, and 53% adults. A significant sexual dimorphism was found in the body mass (345 g ± 95 SD in males versus 252 ± 34 g in females). A defined breeding season was not apparent. B...

  • Parasites in social subterranean Zambian mole-rats (Cryptomys spp., Bathyergidae, Rodentia)
    Journal of Zoology, 1997
    Co-Authors: Andreas Scharff, František Tenora, Hynek Burda, Mathias Kawalika
    Abstract:

    Three out of 18 examined common mole-rats (Cryptomys sp., Xkaryotype 2n = 58) from Zambia were infested with cestodes (Inermicapsifer nmdagascariensis and an undetermined species) and a nematode (Protospirura muricola). Four out of 14 examined Zambian giant mole-rats (Cryptomys mechowi) hosted cestodes (Raillietina (R) sp. and an undetermined species) and nematodes (Protospirura muricola, Capillaria sp.). Helminths and circumstances of findings are briefly described. No ectoparasites were found. The influences of subterranean and social way of life and feeding habits upon occurrence of parasites in mole-rats are discussed. Burrow conditions and social behaviour seem not to favour infestation by parasites.

  • allozyme differentiation and systematic relationship of zambian giant mole rats Cryptomys mechowi bathyergidae rodentia
    Zeitschrift f&#252;r S&#228;ugetierkunde : im Auftrage der Deutschen Gesellschaft f&#252;r S&#228;ugetierkunde e.V., 1997
    Co-Authors: M Macholan, Maria Grazia Filippucci, Hynek Burda, Mathias Kawalika
    Abstract:

    Allozymic Variation encoded by 31 gene loci was studied in giant mole-rats {Cryptomys mechowi) and two Speeles of common mole-rats from Zambia, and allozymic diversity encoded by 22 loci was re-analysed in Cryptomys damarensis, C h. hottentotus, and C. h. natalensis from South Africa. The Zambian common mole-rat of the karyotype 2 n = 68 is more closely related to the giant mole-rat than to the common mole-rat of the karyotype 2 n = 58. There is a clear dichotomy between the three Zambian taxa and C. damarensis, on the one hand, and C. h. hottentotus and C. h. natalensis, on the other hand. The relationship (based upon the allozymic Variation) does not correspond to the current geographical and ecological distribution or to morphological (particularly coloration and size) differentiation.

  • karyotype of the giant mole rat Cryptomys mechowi rodentia bathyergidae
    Cytogenetic and Genome Research, 1993
    Co-Authors: M Macholan, Hynek Burda, Jan Zima, I Misek, Mathias Kawalika
    Abstract:

    The karyotype of the giant mole-rat, Cryptomys mechowi (Rodentia, Bathyergidae), from Zambia was investigated in one male and one female by means of G-, C-, and AgNOR-banding techniques. The diploid chromosomal set consisted of 40 biarmed chromosomes (2n = 40, NF = 80). A pair of autosomes in the male and the X chromosomes in the female were heteromorphic. The sex chromosomes were unusually large.