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Reproductive physiology of the Tasmanian devil (Sarcophilus harisii) and spotted-tailed quail (Dasyurus maculatus)

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Hesterman, H (2008) Reproductive physiology of the Tasmanian devil (Sarcophilus harisii) and spotted-tailed quail (Dasyurus maculatus). PhD thesis, University of Tasmania.

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Abstract

The Tasmanian devil (Sarcophilis harrisii) and the spotted-tailed quoll (Dasyurus
maculatus) are the world's largest extant carnivorous marsupials. These two closely
related dasyurid species coexist only on the island of Tasmania, and both are listed as
Threatened.
The aim of this study was to develop a definitive understanding of the reproductive
processes of these large, sympatric dasyurids to gain insight into how aspects of the
physical and social environment shape evolutionary life history strategies. Although
both species are solitary, the devil is gregarious and relatively abundant in comparison
with the spott~d-tailed quoll. Furthermore, in Tasmania D. maculatus experiences a
high degree of interspecific competition for food - the ultimate factor influencing
breeding timing and synchrony. I hypothesised that these differences in population
density, the level of sociality, and access to nutritional resources would be reflected in
the species' reproductive biology, including the duration of breeding season, mechanism
of ovulation, synchrony of oestrus, fecundity and lifetime reproductive effort.
The ovarian and testicular cycles were characterised in captive and free-ranging devil
and spotted-tailed quoll populations, and breeding seasonality was compared with
patterns found in other dasyurids.
In female devil and spotted-tailed quoll, longitudinal endocrine profiles revealed a
biphasic pattern of plasma progesterone, with a characteristic pro-estrous pulse during
the follicular phase (FP), occurring up to several weeks prior to onset of the luteal phase
(LP). The patterns of faecal metabolites (20a-OH-pregnanes, 20-oxo-pregnanes) were
positively correlated with fluctuations in plasma progesterone. Mean duration of the
oestrous cycle (FP + LP) was ~32 days for devils and ~38 days for spotted-tailed quolls.
Significant differences between the pattern of progestagens and estrogens concentrations
during the pregnant and non-mated oestrous cycle, suggest maternal recognition of
pregnancy in the devil.
Changes in pouch appearance during oestrous have been documented as an indicator of
breeding condition in a number of dasyurids. Pouch condition of female devils and quolls was assessed based on size, colour and secretions, and found to accurately reflect
reproductive status. The stage of pouch development was also correlated with
underlying changes in development of the reproductive tract.
In male devils peak androgen concentrations occurred between December - March
(austral spring/summer). There was no seasonal change in scrotal dimension or
size/mass of the testes, epididymides or prostate. In devils, an extended period of
spermatogenesis was apparent: sperm were produced from November until August. In
spotted-tailed quolls, peak androgen concentrations were recorded between April - July
, (austral autumn/winter). Spermatogenesis in the spotted-tailed quoll began by January,
and sperm were produced from April until August. Differences in the annual timing of
breeding in these two species is likely caused by differing responses to photoperiod -
with the devil cued by increasing day length during spring, and the quoll stimulated by
decreasing photoperiod in autumn.
Although breeding was not tightly synchronised within either devil or spotted-tailed
quoll populations, late lactation and weaning usually occurred during the optimal period
of late spring/summer. Findings indicate that timing of reproductive events can be
relaxed in species where ecological and reproductive attributes permit a level of
flexibility. In devils and spotted-tailed quolls these are large body size, generalist flesheating
diet, facultative polyoestry and variation in the length of lactation. This study
confirms the devil is facultatively polyoestrous and can breed at 12 months of age,
therefore can now be classified alongside the spotted-tailed quoll as having a strategy III
life-history.
The fundamental information gained on the reproductive biology of the largest dasyurids
will be applied to improve and assist in situ and ex situ conservation and management of
these threatened marsupial species.

Item Type: Thesis (PhD)
Keywords: Tasmanian devil, Spotted-tailed quoll, Reproduction
Copyright Holders: The Author
Copyright Information:

Copyright 2008 the author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).

Additional Information:

Chapter 2 appears to be the equivalent of a post-print of an article published as: Hesterman, H., Jones, S.M., Schwarzenberger, F. (2008), Reproductive endocrinology of the largest dasyurids: characterization of ovarian cycles by plasma and fecal steroid monitoring. Part I. The Tasmanian devil (Sarcophilus harrisii), General and comparative endocrinology, 155(1), 234-244

Chapter 3 appears to be the equivalent of a post-print of an article published as: Hesterman, H., Jones, S.M., Schwarzenberger, F. (2008), Reproductive endocrinology of the largest Dasyurids: Characterization of ovarian cycles by plasma and fecal steroid monitoring.: Part II. The spotted-tailed quoll (Dasyurus maculatus), General and comparative endocrinology, 155(1), 245-254

Chapter 4 appears to be the equivalent of the peer reviewed version of the following article: Hesterman, H., Jones, S.M., Schwarzenberger, F., (2008), Pouch appearance is a reliable indicator of the reproductive status in the Tasmanian devil and the spotted-tailed quoll, Journal of zoology, London, 275(2), 130 -138,which has been published in final form at 101111/j.1469-7998.2008.00419.x This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.

Chapter 5 appears to be the equivalent of a post-print of an article published as: Hesterman, H., Jones, S.M., (2008), Longitudinal monitoring of plasma and faecal androgens in the Tasmanian devil (Sarcophilus harrisii) and the spotted-tailed quoll (Dasyurus maculatus), Animal reproduction science, 112(3-4), 334-346

Date Deposited: 19 Dec 2014 02:52
Last Modified: 09 Aug 2016 01:33
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