https://search.dev.ndltd.org/etd/pretoria/oai:repository.up.ac.za:2263/31288
type: CreativeWork
name: The reproductive biology of two small southern African mammals, the spiny mouse, Acomys spinosissimus (Rodentia: Muridae) and the Eastern rock elephant-shrew, Elephantulus myurus (Macroscelidea: Macroscelididae)
description: Since the energy available to an animal for cell growth, thermoregulation, reproduction and other physiological functions is highly dependent on seasonal environmental changes many small mammals breed seasonally during times when environmental conditions are most favourable for growth and survival of the young. In the tropics and sub-tropics, seasonal rainfall appears to be the main reason for seasonal breeding. In order to maximize fitness, it is important for an animal to be able to anticipate these seasonal changes and to trigger reproductive events at the correct time. Photoperiod is used to time reproduction in many temperate mammalian species, but is also used by several seasonally breeding sub-tropical and tropical mammals. The neuroendocrine system is crucial in relaying these environmental signals to the reproductive system. A number of recent studies have suggested that kisspeptin may play a major part in the regulation of the hypothalamo-pituitary-gonadal axis and ultimately reproduction. The exact role of kisspeptin signalling in seasonal breeders is, however, unclear. The present study investigated the seasonality of reproduction and the reproductive photoresponsiveness of two southern hemisphere species, the spiny mouse (Acomys spinosissimus) and the Eastern rock elephant-shrew (Elephantulus myurus) from South Africa. Furthermore, it compared hypothalamic kisspeptin expression in males and females of both species between the breeding and non-breeding seasons to ascertain if kisspeptin had any potential role in seasonal breeders under natural conditions. Both A. spinosissimus and E. myurus breed seasonally in South Africa. The breeding season extended through the spring and summer months, whereas the gonads were regressed and steroid hormone levels of both sexes were low during the autumn and winter months of the southern hemisphere. Testes mass and volume of A. spinosissimus were smaller and plasma testosterone concentrations lower under short-day than…
abstract: Since the energy available to an animal for cell growth, thermoregulation, reproduction and other physiological functions is highly dependent on seasonal environmental changes many small mammals breed seasonally during times when environmental conditions are most favourable for growth and survival of the young. In the tropics and sub-tropics, seasonal rainfall appears to be the main reason for seasonal breeding. In order to maximize fitness, it is important for an animal to be able to anticipate these seasonal changes and to trigger reproductive events at the correct time. Photoperiod is used to time reproduction in many temperate mammalian species, but is also used by several seasonally breeding sub-tropical and tropical mammals. The neuroendocrine system is crucial in relaying these environmental signals to the reproductive system. A number of recent studies have suggested that kisspeptin may play a major part in the regulation of the hypothalamo-pituitary-gonadal axis and ultimately reproduction. The exact role of kisspeptin signalling in seasonal breeders is, however, unclear. The present study investigated the seasonality of reproduction and the reproductive photoresponsiveness of two southern hemisphere species, the spiny mouse (Acomys spinosissimus) and the Eastern rock elephant-shrew (Elephantulus myurus) from South Africa. Furthermore, it compared hypothalamic kisspeptin expression in males and females of both species between the breeding and non-breeding seasons to ascertain if kisspeptin had any potential role in seasonal breeders under natural conditions. Both A. spinosissimus and E. myurus breed seasonally in South Africa. The breeding season extended through the spring and summer months, whereas the gonads were regressed and steroid hormone levels of both sexes were low during the autumn and winter months of the southern hemisphere. Testes mass and volume of A. spinosissimus were smaller and plasma testosterone concentrations lower under short-day than…
keywords: UCTD
date published: 2011-09-23
date modified: 2026-07-24T03:52:23Z
provider: University of Pretoria
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Pretoria

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2263/31288