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Seasonality of reproduction in ungulates : the effect of photoperiod on reproduction in a seasonal breeder, the sheep (Ovis aries) and a putative aseasonal breeder, the springbok (Antidorcas marsupialis)
Dissertation (MSc)--University of Pretoria, 1998.
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| Format: | Thesis |
| Language: | English |
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University of Pretoria
2022
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| _version_ | 1867613567031705600 |
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| access_status_str | Open Access |
| author2 | Skinner, J.D. (John Dawson), 1932- |
| author_browse | Skinner, J.D. (John Dawson), 1932- |
| author_facet | Skinner, J.D. (John Dawson), 1932- |
| collection | Thesis |
| dc_rights_str_mv | © 2021 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 | Dissertation (MSc)--University of Pretoria, 1998. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/83290 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:38:11.690Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| 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:2263/83290 Seasonality of reproduction in ungulates : the effect of photoperiod on reproduction in a seasonal breeder, the sheep (Ovis aries) and a putative aseasonal breeder, the springbok (Antidorcas marsupialis) Skinner, J.D. (John Dawson), 1932- Malpaux, Benoit Skinner, Donal C. Richter, Trevor Aubrey UCTD Seasonality reproduction in ungulates Dissertation (MSc)--University of Pretoria, 1998. I investigated reproduction in springbok (Antidorcas marsupialis) to determine whether the basic physiological system that underpins seasonal reproduction exists in this putatively aseasonal ungulate. In addition, I examined the transition from reproductive quiescence to activity in female mammals using the sheep (Ovis aries) as a model species. My analysis of reproduction in wild and captive springbok populations suggested that springbok, unlike seasonal breeders, do not use photoperiod or other climatic variables to cue reproduction. This was reinforced by the finding that the reproductive characteristics of a captive herd of springbok ewes are not the same as typical seasonal breeders. However, the pineal-melatonin system of springbok functions in the same way as in photoperiodic species. Thus, I suggest that springbok ignore photoperiodic information that could potentially be used to cue reproduction, which suggests that the physiological basis of aseasonality in springbok lies downstream from the pineal-melatonin system. The results of the investigation of the sheep suggested that the neurotransmitters that have been implicated in the regulation of reproduction might have differential roles that are determined by the reproductive state of an animal. The results supported the contention that there is a complex system of interneurons that link melatonin to the modulation of gonadotrophin secretion. In conclusion, the physiological system that regulates reproduction in ungulates is complex but nevertheless seems to be fundamentally similar in seasonal and aseasonal species. Thus, it seems that aseasonal breeders may not be physiologically bound to reproduce aseasonally, but reproduce in the manner that they do because it is an adaptive advantage. Zoology and Entomology MSc Unrestricted 2022-01-12T06:01:23Z 2022-01-12T06:01:23Z 19/8/2021 1998 Dissertation * http://hdl.handle.net/2263/83290 en © 2021 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 University of Pretoria |
| spellingShingle | UCTD Seasonality reproduction in ungulates Seasonality of reproduction in ungulates : the effect of photoperiod on reproduction in a seasonal breeder, the sheep (Ovis aries) and a putative aseasonal breeder, the springbok (Antidorcas marsupialis) |
| title | Seasonality of reproduction in ungulates : the effect of photoperiod on reproduction in a seasonal breeder, the sheep (Ovis aries) and a putative aseasonal breeder, the springbok (Antidorcas marsupialis) |
| title_full | Seasonality of reproduction in ungulates : the effect of photoperiod on reproduction in a seasonal breeder, the sheep (Ovis aries) and a putative aseasonal breeder, the springbok (Antidorcas marsupialis) |
| title_fullStr | Seasonality of reproduction in ungulates : the effect of photoperiod on reproduction in a seasonal breeder, the sheep (Ovis aries) and a putative aseasonal breeder, the springbok (Antidorcas marsupialis) |
| title_full_unstemmed | Seasonality of reproduction in ungulates : the effect of photoperiod on reproduction in a seasonal breeder, the sheep (Ovis aries) and a putative aseasonal breeder, the springbok (Antidorcas marsupialis) |
| title_short | Seasonality of reproduction in ungulates : the effect of photoperiod on reproduction in a seasonal breeder, the sheep (Ovis aries) and a putative aseasonal breeder, the springbok (Antidorcas marsupialis) |
| title_sort | seasonality of reproduction in ungulates the effect of photoperiod on reproduction in a seasonal breeder the sheep ovis aries and a putative aseasonal breeder the springbok antidorcas marsupialis |
| topic | UCTD Seasonality reproduction in ungulates |
| url | http://hdl.handle.net/2263/83290 |