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The reproductive biology of the solitary Cape mole-rat, Georychus capensis and the social Natal mole-rat, Cryptomys hottentotus natalensis (Rodentia : Bathyergidae)
Thesis (PhD)--University of Pretoria, 2008.
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University of Pretoria
2013
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| _version_ | 1867613502881923072 |
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| access_status_str | Open Access |
| author2 | Bennett, Nigel Charles |
| author_browse | Bennett, Nigel Charles |
| author_facet | Bennett, Nigel Charles |
| collection | Thesis |
| dc_rights_str_mv | © 2007, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Thesis (PhD)--University of Pretoria, 2008. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/26792 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:37:10.603Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/26792 The reproductive biology of the solitary Cape mole-rat, Georychus capensis and the social Natal mole-rat, Cryptomys hottentotus natalensis (Rodentia : Bathyergidae) Bennett, Nigel Charles moosthuizen@zoology.up.ac.za Coen, Clive W. Oosthuizen, Maria Kathleen Cape mole-rat (Georychus capensis) Western Cape Province, South Africa Winter rainfall period Reproduction Natal mole-rat Georychus capensis Cryptomys hottentotus natalensis UCTD Thesis (PhD)--University of Pretoria, 2008. The seasonality of wild caught Cape mole-rats was investigated, focusing on endocrine, neuroendocrine and neuroanatomical parameters. The Cape mole-rat reproduces only during the winter rainfall period of the western Cape Province. Interestingly, the gonadal steroid hormones do not show any significant seasonal patterns in either males or females. In addition, the pituitary does not exhibit a reduced sensitivity to GnRH stimulation during the non-breeding season in either sex. Moreover, in the brain the distribution, number and size of GnRH perikarya do not differ with respect to season. Therefore, although only producing young during a specific period of the year, the Cape mole-rat does not appear to be physiologically repressed from reproducing throughout the year. The results of this study imply that the Cape mole-rat is an opportunistic breeder that is reproductively quiescent during the dry season as a consequence of ecological factors such as lack of favourable burrowing conditions and that when opportunities avail themselves following aseasonal rainfall, reproduction may occur. The seasonality and socially induced infertility of the Natal mole-rat was examined via endocrine, neuroendocrine and neuroanatomical investigations. In contrast with the phylogenetically closely related common mole-rat and highveld mole-rat, the Natal mole-rat does not appear to breed seasonally. Post-mortem examination of animals collected revealed pregnant reproductive females throughout the year. A similar scenario is reflected in gonadal steroid concentrations, with no major seasonal differences observed in either males or females. Likewise, pituitary sensitivity to GnRH does not change over season in males or females, and all neuroanatomical parameters investigated remained stable over season in both males and females. Natal mole-rats captured for this study occur in an area with a high annual rainfall, (almost double that of the common mole-rat habitat and one and a half times that of the highveld mole-rat) and the relatively higher rainfall and hence soil moisture content may provide the Natal mole-rat with increased foraging time a result of increased periods over which the soil is optimal for burrowing. Socially induced infertility in the Natal mole-rat appears to be enforced behaviourally as a result of active incest avoidance. The circulating testosterone concentrations were not significantly different in reproductive and non-reproductive males, and likewise oestrogen concentrations did not differ between reproductive and non-reproductive females. Progesterone concentrations were very low in subordinate females, but markedly higher in reproductive females. This is not surprising since the Natal mole-rat is an induced ovulator, thus coitus is required to induce the LH surge that stimulates ovulation. The sensitivity of the pituitary to a GnRH challenge did not differ between reproductive and non-reproductive animals from either sex. No neuroanatomical differences were observed between reproductive and non-reproductive animals of either sex, however, non-reproductive males and females had significantly higher amounts of GnRH in the median eminence, implying that GnRH is synthesized and transported to the median eminence but not released in the portal system to the anterior pituitary. These findings suggest that non-reproductive animals of both sexes are not sterile, but merely sexually quiescent. Copyright Zoology and Entomology unrestricted 2013-09-07T07:59:16Z 2008-08-11 2013-09-07T07:59:16Z 2007-09-06 2008-08-11 2008-07-29 Thesis Oosthuizen, MK 2007, The reproductive biology of the solitary Cape mole-rat, Georychus capensis and the social Natal mole-rat, Cryptomys hottentotus natalensis (Rodentia : Bathyergidae), PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/26792 > D382/ag http://hdl.handle.net/2263/26792 http://upetd.up.ac.za/thesis/available/etd-07292008-100114/ © 2007, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf University of Pretoria |
| spellingShingle | Cape mole-rat (Georychus capensis) Western Cape Province, South Africa Winter rainfall period Reproduction Natal mole-rat Georychus capensis Cryptomys hottentotus natalensis UCTD The reproductive biology of the solitary Cape mole-rat, Georychus capensis and the social Natal mole-rat, Cryptomys hottentotus natalensis (Rodentia : Bathyergidae) |
| title | The reproductive biology of the solitary Cape mole-rat, Georychus capensis and the social Natal mole-rat, Cryptomys hottentotus natalensis (Rodentia : Bathyergidae) |
| title_full | The reproductive biology of the solitary Cape mole-rat, Georychus capensis and the social Natal mole-rat, Cryptomys hottentotus natalensis (Rodentia : Bathyergidae) |
| title_fullStr | The reproductive biology of the solitary Cape mole-rat, Georychus capensis and the social Natal mole-rat, Cryptomys hottentotus natalensis (Rodentia : Bathyergidae) |
| title_full_unstemmed | The reproductive biology of the solitary Cape mole-rat, Georychus capensis and the social Natal mole-rat, Cryptomys hottentotus natalensis (Rodentia : Bathyergidae) |
| title_short | The reproductive biology of the solitary Cape mole-rat, Georychus capensis and the social Natal mole-rat, Cryptomys hottentotus natalensis (Rodentia : Bathyergidae) |
| title_sort | reproductive biology of the solitary cape mole rat georychus capensis and the social natal mole rat cryptomys hottentotus natalensis rodentia bathyergidae |
| topic | Cape mole-rat (Georychus capensis) Western Cape Province, South Africa Winter rainfall period Reproduction Natal mole-rat Georychus capensis Cryptomys hottentotus natalensis UCTD |
| url | http://hdl.handle.net/2263/26792 http://upetd.up.ac.za/thesis/available/etd-07292008-100114/ |